tag:theconversation.com,2011:/ca-fr/topics/iarc-3987/articlesIARC – La Conversation2023-07-14T01:24:43Ztag:theconversation.com,2011:article/2088442023-07-14T01:24:43Z2023-07-14T01:24:43ZDoes artificial sweetener aspartame really cause cancer? What the WHO listing means for your diet soft drink habit<figure><img src="https://images.theconversation.com/files/536737/original/file-20230711-23-sl30n6.jpg?ixlib=rb-1.1.0&rect=4%2C0%2C3240%2C2155&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>The International Agency for Research on Cancer (IARC), which is the specialised cancer agency of the World Health Organization, has declared aspartame may be a <a href="https://www.who.int/news/item/14-07-2023-aspartame-hazard-and-risk-assessment-results-released">possible carcinogenic hazard to humans</a>. </p>
<p>Another branch of the WHO, the Joint WHO and Food and Agriculture Organization’s Expert Committee on Food Additives has assessed the risk and developed recommendations on how much aspartame is safe to consume. They have recommended the acceptable daily intake be 0 to 40mg per kilo of body weight, as we currently have <a href="https://www.foodstandards.gov.au/consumer/additives/aspartame/Pages/default.aspx">in Australia</a>.</p>
<p>A hazard is different to a risk. The hazard rating means it’s an agent that is capable of causing cancer; a risk measures the likelihood it could cause cancer.</p>
<p>So what does this hazard assessment mean for you?</p>
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<h2>Firstly, what is aspartame?</h2>
<p><a href="https://www.foodstandards.gov.au/consumer/additives/aspartame/Pages/default.aspx">Aspartame is an artificial sweetener</a> that is 200 times sweeter than sugar, but without any kilojoules. </p>
<p>It’s used in a <a href="https://www.foodstandards.gov.au/consumer/additives/aspartame/Pages/default.aspx">variety of products</a> including carbonated drinks such as Coke Zero, Diet Coke, Pepsi Max and some home brand offerings. You can identify aspartame in drinks and foods by looking for additive number 951. </p>
<p>Food products such as yogurt and confectionery may also contain aspartame, but it’s not stable at warm temperatures and thus not used in baked goods. </p>
<p>Commercial names of aspartame include Equal, Nutrasweet, Canderel and Sugar Twin. In Australia the acceptable daily intake is 40mg per kilo of body weight per day, which is about 60 sachets.</p>
<p><a href="https://www.fda.gov/food/food-additives-petitions/aspartame-and-other-sweeteners-food#:%7E:text=How%20many%20packets%20can%20a,based%20on%20its%20sweetness%20intensity%3F&text=Notes%20About%20the%20Chart%3A,50%20mg%2Fkg%20bw%2Fd">In America</a> the acceptable daily intake has been set at 75 sachets. </p>
<h2>What evidence have they used to come to this conclusion?</h2>
<p><a href="https://www.who.int/news/item/14-07-2023-aspartame-hazard-and-risk-assessment-results-released">IARC looked closely</a> at the <a href="https://cdn.who.int/media/docs/default-source/nutrition-and-food-safety/july-13-final-summary-of-findings-aspartame.pdf?sfvrsn=a531e2c1_5&download=true">evidence base</a> from around the world – using data from observational studies, experimental studies and animal studies. </p>
<p>They found there was some limited evidence in human studies linking aspartame and cancer (specifically liver cancer) and limited evidence from animal studies as well. </p>
<p>They also considered the biological mechanism studies which showed how cancer may develop from the consumption of aspartame. Usually these are lab-based studies which show exactly how exposure to the agent may lead to a cancer. In this case they found there was limited evidence for how aspartame might cause cancer.</p>
<p>There were only three human studies that looked at cancer and aspartame intake. These large observational studies used the intake of soft drinks as an indicator of aspartame intake. </p>
<p>All three found a positive association between artificially sweetened beverages and liver cancer in either all of the population they were studying or sub-groups within them. But these studies could not rule out other factors that may have been responsible for the findings. </p>
<p>A study <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6284800/">conducted in Europe</a> followed 475,000 people for 11 years and found that each additional serve of diet soft drink consumed per week was linked to a 6% increased risk of liver cancer. However the scientists did conclude that due to the rarity of liver cancer they still had small numbers of people in the study.</p>
<p><a href="https://pubmed.ncbi.nlm.nih.gov/35728406/">In a study from the US</a>, increased risk of liver cancer was seen in people with diabetes who drank more than two or more cans of a diet soda a week.</p>
<p>The <a href="https://aacrjournals.org/cebp/article/31/10/1907/709398/Sugar-and-Artificially-Sweetened-Beverages-and">third study</a>, also from the US, found an increase in liver cancer risk in men who never smoked and drank two or more artificially sweetened drinks a day. </p>
<p>From this they have decided to declare aspartame as a Group 2b “possible carcinogen”. But they have also said more and better research is needed to further understand the relationship between aspartame and cancer. </p>
<p>IARC has four categories (groupings) available for potential substances (or as they are referred to by IARC, “agents”) that may cause cancer.</p>
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<a href="https://images.theconversation.com/files/536738/original/file-20230711-26-ln4ks.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Cup of frothy soda" src="https://images.theconversation.com/files/536738/original/file-20230711-26-ln4ks.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/536738/original/file-20230711-26-ln4ks.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=401&fit=crop&dpr=1 600w, https://images.theconversation.com/files/536738/original/file-20230711-26-ln4ks.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=401&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/536738/original/file-20230711-26-ln4ks.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=401&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/536738/original/file-20230711-26-ln4ks.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/536738/original/file-20230711-26-ln4ks.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/536738/original/file-20230711-26-ln4ks.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">An Australian would have to consume unrealistic amounts of aspartame to reach the daily limit.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
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<h2>What does each grouping mean?</h2>
<p><strong>Group 1 Carcinogenic to humans:</strong> an agent in this group is carcinogenic, which means there is convincing evidence from human studies and we know precisely <em>how</em> it causes cancer. There are 126 agents in this group, including tobacco smoking, alcohol, processed meat, radiation and ionising radiation.</p>
<p><strong>Group 2a Probably carcinogenic to humans:</strong> there are positive associations between the agent and cancer in humans, but there may still be other explanations for the association which were not fully examined in the studies. There are 95 agents in this group, including red meat, DDT insecticide and night shift work.</p>
<p><strong>Group 2b Possibly carcinogenic in humans:</strong> this means limited evidence of causing cancer in humans, but sufficient evidence from animal studies, or the mechanism of how the agent may be carcinogenic is well understood. This basically means the current evidence indicates an agent may possibly be carcinogenic, but more scientific evidence from better conducted studies is needed. There are now <a href="https://monographs.iarc.who.int/agents-classified-by-the-iarc/">323</a> agents in this group, including aloe vera (whole leaf extract), ginkgo biloba and lead.</p>
<p><strong>Group 3 Not classifiable as a carcinogen:</strong> there’s not enough evidence from humans or animals, and there is limited mechanistic evidence of how it may be a carcinogen. There are 500 agents in this group.</p>
<h2>So do I have to give up my diet soft drink habit?</h2>
<p>For a 70kg person you would need to consume about 14 cans (over 5 litres) of soft drink sweetened with aspartame a day to reach the acceptable daily intake.</p>
<p>But we need to remember there may also be aspartame added in other foods consumed. So this is an unrealistic amount to consume, but not impossible. </p>
<p>We also need to consider all the evidence on aspartame together. The foods we typically see aspartame in are processed or ultra-processed, which have recently also been <a href="https://theconversation.com/ultra-processed-foods-are-trashing-our-health-and-the-planet-180115">shown to be detrimental to health</a>.</p>
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Read more:
<a href="https://theconversation.com/ultra-processed-foods-are-trashing-our-health-and-the-planet-180115">Ultra-processed foods are trashing our health – and the planet</a>
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<p>And artificial sweeteners (including aspartame) <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2892765/#!po=59.3750">can make people crave more sugar</a>, making them want to eat more food, potentially causing them to gain more weight.</p>
<p>All together, this indicates we should be more careful about the amount of artificial sweeteners we consume, since they <a href="https://theconversation.com/the-who-says-we-shouldnt-bother-with-artificial-sweeteners-for-weight-loss-or-health-is-sugar-better-205827">do not provide any health benefits</a>, and have possible adverse effects. </p>
<p>But overall, from this evidence, drinking the occasional or even daily can of a diet drink is safe and probably not a cancer risk.</p>
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<p><em>Correction: this article originally stated each serve of soft drink in a study was linked to a 6% increased risk of liver cancer, however it was each additional serve per week. This has been amended.</em></p><img src="https://counter.theconversation.com/content/208844/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Evangeline Mantzioris is affiliated with Alliance for Research in Nutrition, Exercise and Activity (ARENA) at the University of South Australia. Evangeline Mantzioris has received funding from the National Health and Medical Research Council, and has been appointed to the National Health and Medical Research Council Dietary Guideline Expert Committee.</span></em></p>IARC has listed the artificial sweetener aspartame as possibly cancer causing. Here’s how to digest the findings.Evangeline Mantzioris, Program Director of Nutrition and Food Sciences, Accredited Practising Dietitian, University of South AustraliaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1934312023-01-30T13:12:57Z2023-01-30T13:12:57ZDoes this cause cancer? How scientists determine whether a chemical is carcinogenic – sometimes with controversial results<figure><img src="https://images.theconversation.com/files/506177/original/file-20230124-18-m5hdd.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C3000%2C1500&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Carcinogenic chemicals are labeled with a health hazard warning symbol. </span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/illustration/serious-health-hazard-royalty-free-illustration/1353836395">Peter Etchells/iStock via Getty Images Plus</a></span></figcaption></figure><p>People are <a href="https://www.universityofcalifornia.edu/news/toxic-exposure-chemicals-are-our-water-food-air-and-furniture">exposed to numerous chemicals</a> throughout their lifetimes. These chemicals can be from the air, foods, personal care items, household products and medications. Unfortunately, exposure to certain chemicals can cause harmful health effects, including cancer. Substances that cause cancer are called <a href="https://www.genome.gov/genetics-glossary/Carcinogen">carcinogens</a>. Familiar examples include <a href="https://monographs.iarc.who.int/wp-content/uploads/2018/06/mono100E-6.pdf">tobacco smoke</a>, <a href="https://monographs.iarc.who.int/wp-content/uploads/2018/06/mono100D-9.pdf">radon</a>, <a href="https://monographs.iarc.who.int/wp-content/uploads/2018/06/mono100C-11.pdf">asbestos</a> and <a href="https://www.iarc.who.int/news-events/iarc-diesel-engine-exhaust-carcinogenic/">diesel engine exhaust</a>.</p>
<p>To protect the health of the public, national and international health agencies evaluate many new and existing chemicals to determine if they are likely to be carcinogens in a process called <a href="https://pubmed.ncbi.nlm.nih.gov/9715519/">cancer hazard identification</a>. If agencies judge the chemicals to be carcinogenic, they conduct further assessments to determine the level of risk, and legislators may put regulations in place to limit, or completely halt, the production and use of these chemicals.</p>
<p><a href="https://www.engr.colostate.edu/cbe/people/brad-reisfeld/">I am a scientist</a> who studies how the human body processes foreign chemicals, like environmental pollutants and drugs, and the effects of these chemicals on health. As part of my work, I have participated in chemical and cancer hazard identifications for several agencies, including the World Health Organization’s <a href="https://www.iarc.who.int">International Agency for Research on Cancer</a>. Here’s how chemicals can cause cancer, and how we classify chemicals based on on how carcinogenic they are – sometimes with controversial results.</p>
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<span class="caption">Glyphosate, an herbicide used in products like Roundup, was classified by the IARC as probably carcinogenic to humans in 2015.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/person-in-protective-suit-spraying-herbicide-on-royalty-free-image/1327771135">Adriana Duduleanu/EyeEm via Getty Images</a></span>
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<h2>How do chemicals cause cancer?</h2>
<p>The mechanisms behind how toxic chemicals can lead to cancer <a href="https://www.ncbi.nlm.nih.gov/books/NBK570326/">are complex</a>. </p>
<p>After a person is exposed to a carcinogen, the chemical is generally absorbed into the body and distributed into different tissues. Once the chemical has moved into the cells, it often undergoes chemical reactions that convert it into other forms. </p>
<p>The products of these reactions can directly or indirectly affect the cell’s genes. Altering genes, which contain the cell’s instructions on how to produce specific molecules, or the processes that regulate them can ultimately result in dysfunctional cells if the genetic damage isn’t repaired. These cells don’t respond normally to cellular signals and can grow and divide at abnormal rates, which are characteristic features of cancer cells.</p>
<h2>How are chemicals classified for carcinogenicity?</h2>
<p>To help safeguard the public and reduce the incidence of cancer, several agencies have developed procedures to classify and categorize chemicals based on their potential to be carcinogenic. </p>
<p><a href="https://www.atsdr.cdc.gov/pha-guidance/conducting_scientific_evaluations/indepth_toxicological_analysis/EvaluateEvidenceCancerEffects.html">Among them</a> are the International Agency for Research on Cancer, or IARC Monographs; the National Toxicology Program, or NTP; and the U.S. Environmental Protection Agency, or EPA. In general, these agencies examine a critical question: How strong is the evidence that a substance causes cancer or biological changes that could be related to cancer in people? Understanding the procedures used to answer this question can help with interpreting the decisions these agencies make.</p>
<p>The <a href="https://monographs.iarc.who.int/iarc-monographs-preamble-preamble-to-the-iarc-monographs/">procedures used by the IARC</a> – because of its long history, credibility and strong international reputation – provide a good example of how this process works. It’s designed to be transparent and minimize bias, spanning over a year from selecting a chemical for evaluation to its final classification. </p>
<p>In this process, the IARC selects and invites a panel of scientific experts on the chemical to be evaluated. The panel does not conduct new research on its own, but carefully reviews all available papers in the scientific literature on the chemical’s carcinogenicity in cell and bacterial cultures, animals and people. To assess the strength of the evidence, the panel carefully considers the number of studies that are available and the consistency of the results, as well as the scientific quality and relevance of each study to cancer in people.</p>
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<figcaption><span class="caption">Chemicals can be carcinogenic to varying degrees.</span></figcaption>
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<p>After discussing and deliberating on the results, the panel makes a final consensus classification. This classification places the chemical into one of four groups: Group 1 indicates that the chemical is carcinogenic to people, Group 2A that it is probably carcinogenic to people, Group 2B that it is possibly carcinogenic to people, and Group 3 that it is not classifiable. A Group 3 classification does not indicate that the compound is not carcinogenic, but rather that the panel could not draw a conclusion about whether there is a causal link between the chemical and cancer from available studies. For example, exposure to several chemicals can make it unclear which ones are responsible for a later cancer diagnosis.</p>
<p>During its 50-year history, the IARC has evaluated and classified <a href="https://monographs.iarc.who.int/wp-content/uploads/2018/07/cumulative-cross-index.pdf">over 1,000 chemicals and other hazards</a>. Many of these classifications have had broad societal implications, such as those for tobacco smoke, ambient air pollution, diesel engine exhaust and processed meat. All were classified as Group 1, or confirmed to be carcinogenic to humans. <a href="https://www.iarc.who.int/pressrelease/iarc-classifies-radiofrequency-electromagnetic-fields-as-possibly-carcinogenic-to-humans/">Electromagnetic radiation</a> emitted by mobile phones was classified as Group 2B, or possibly carcinogenic, and <a href="https://www.iarc.who.int/featured-news/media-centre-iarc-news-redmeat/">red meat</a> was classified as Group 2A, or probably carcinogenic. Though they haven’t directly led to any regulations, these classifications have motivated <a href="https://doi.org/10.3389/fpubh.2019.00223">additional</a> <a href="https://doi.org/10.1007/s13668-021-00377-x">scientific studies</a>. While the IARC can advise regulators, it’s up to countries to implement policies.</p>
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<p>It is important to note that classifications do not indicate the size of the risk but are important in supporting health agencies worldwide as they implement actions to limit exposures to known, probable and possible carcinogens. In 2020, when the IARC <a href="https://www.iarc.who.int/news-events/iarc-monographs-evaluation-of-the-carcinogenicity-of-opium-consumption/">classified opium consumption as Group 1</a>, or carcinogenic to humans, this led the government of Iran to <a href="https://www.youtube.com/watch?v=hJDlJhtPeiQ">implement policies</a> to reduce opium addiction in the country.</p>
<h2>Controversies in carcinogenicity classifications</h2>
<p>Though classifications from the IARC are based on robust scientific evidence, some have <a href="https://doi.org/10.1093/carcin/bgv062">proved to be controversial</a>. </p>
<p>For instance, in 2015, the IARC evaluated the carcinogenicity of <a href="https://publications.iarc.fr/Book-And-Report-Series/Iarc-Monographs-On-The-Identification-Of-Carcinogenic-Hazards-To-Humans/Some-Organophosphate-Insecticides-And-Herbicides-2017">glyphosate</a>, a widely used weedkiller found in products like Roundup, which is produced by Monsanto. A panel of 17 experts from 11 countries systematically reviewed results from over 1,000 scientific studies and classified glyphosate as “probably carcinogenic to humans,” or Group 2A.</p>
<p>Owing to its widespread usage and <a href="https://www.transparencymarketresearch.com/glyphosate-market.html">multibillion-dollar market value</a>, a cancer classification decision for glyphosate has significant potential financial and legal consequences. Following its evaluation, the IARC received support from many <a href="https://oehha.ca.gov/proposition-65/general-info/oehha-statement-regarding-us-epas-press-release-and-registrant-letter">regulatory</a> and <a href="https://www.env-health.org/campaigns/glyphosate-why-the-eu-needs-to-protect-health-ban-the-popular-weedkiller/">scientific bodies</a> but was <a href="https://www.science.org/content/article/who-rebuts-house-committee-criticisms-about-glyphosate-cancer-warning">criticized by others</a>. Other agencies, <a href="https://www.gao.gov/products/gao-19-280">including</a> <a href="https://www.epa.gov/office-inspector-general/report-epa-needs-improve-transparency-its-cancer-assessment-process">the EPA</a>, have seen similar controversies and politicization of their hazard identifications and regulatory decisions.</p>
<p>I believe that agencies like the IARC play a critical role in evaluating the health effects of certain chemicals and in reducing exposure to potential carcinogens. Helping people better understand how these agencies evaluate chemicals can go a long way to ensure transparency and help protect environmental and public health.</p><img src="https://counter.theconversation.com/content/193431/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Brad Reisfeld does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>The WHO’s International Agency for Research on Cancer convenes a panel of scientific experts to review available evidence on whether specific chemicals or occupational exposures may cause cancer.Brad Reisfeld, Professor of Chemical and Biological Engineering, Colorado State UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1045542018-10-08T07:08:28Z2018-10-08T07:08:28ZStop worrying and trust the evidence: it’s very unlikely Roundup causes cancer<figure><img src="https://images.theconversation.com/files/239671/original/file-20181008-72103-8as2pz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Roundup is the most common weed killer used worldwide.</span> <span class="attribution"><span class="source">from shutterstock.com</span></span></figcaption></figure><p>The common weed killer <a href="http://npic.orst.edu/factsheets/glyphogen.html">Roundup</a> (glyphosate) is back in the news after a <a href="https://www.smh.com.au/world/north-america/dying-cancer-patient-awarded-a395m-in-monsanto-roundup-case-20180811-p4zwww.html">US court ruled</a> it contributed to a man’s terminal cancer (non-Hodgkin lymphoma). Following the court’s order for manufacturer Monsanto to compensate the former school ground’s keeper US$289 million, more than 9,000 people are reportedly also suing the company.</p>
<p>In light of this, Cancer Council Australia is calling for <a href="http://www.abc.net.au/news/2018-08-11/cancer-council-monsanto-should-come-clean/10109760">Australia to review glyphosate’s safety</a>. And tonight’s <a href="http://www.abc.net.au/4corners/">Four Corner’s</a> report centres around Monsanto’s possible cover-up of the evidence for a link between glyphosate and cancer.</p>
<p>Juries don’t decide science, and this latest court case produced no new scientific data. Those who believe glyphosate causes cancer often refer to the 2015 report by the <a href="http://publications.iarc.fr/Book-And-Report-Series/Iarc-Monographs-On-The-Evaluation-Of-Carcinogenic-Risks-To-Humans/Some-Organophosphate-Insecticides-And-Herbicides-2017">International Agency for Research on Cancer</a> (IARC) that classified the herbicide as “probably carcinogenic to humans”.</p>
<p>IARC’s conclusion was arrived at using a narrower base of evidence than other recent peer-reviewed papers and governmental reviews. Australia’s regulator, the Australian Pesticides and Veterinary Medicines Authority (<a href="https://apvma.gov.au/">APVMA</a>), reviewed the safety of glyphosate after IARC’s determination. It’s <a href="https://apvma.gov.au/node/13891">2016 report</a> concluded that</p>
<blockquote>
<p>based on current risk assessment the label instructions on all glyphosate products – when followed – provides adequate protection for users.</p>
</blockquote>
<p>The <a href="https://www.ncbi.nlm.nih.gov/pubmed/29136183">Agricultural Health Study</a>, which followed more than 50,000 people in the US for over ten years, was published in 2018. This real world study in the populations with the highest exposure to glyphosate showed that if there is any risk of cancer from glyphosate preparations, it is exceedingly small. </p>
<p>It also showed that the risk of non-Hodgkin lymphoma is negligible. It is unclear to what extent this study was used in the recent court case.</p>
<h2>What did the IARC and others find?</h2>
<p>Glyphosate is one of the most used herbicides worldwide. It kills weeds by targeting a specific pathway (the <a href="https://en.wikipedia.org/wiki/Shikimate_pathway">shikimic acid pathway</a>) that exists in plants and a type of bacteria (eubacteria), but not animals (or humans). </p>
<p>In terms of short-term exposure, glyphosate is less toxic than table salt. However, it’s chronic, or long-term, exposure to glyphosate that’s causing the controversy. </p>
<p>Pesticides and herbicides are periodically re-evaluated for their safety and several studies have done so for glyphosate. For instance, in 2015, Germany’s <a href="https://www.bfr.bund.de/en/the_bfr_has_finalised_its_draft_report_for_the_re_evaluation_of_glyphosate-188632.html">Federal Institute for Risk Assessment</a> suggested glyphosate was neither mutagenic nor carcinogenic.</p>
<p>But then came the IARC’s surprising classification. And the subsequent 2015 review by the <a href="https://www.efsa.europa.eu/en/efsajournal/pub/4302">European Food Safety Authority</a>, that concluded glyphosate was unlikely to pose a carcinogenic hazard, didn’t alleviate sceptics. </p>
<p>The key differences between the IARC’s and other reports revolve around the breadth of evidence considered, the weight of human studies, consideration of physiological plausibility and, most importantly, risk assessment. The IARC did not take into account the extent of exposure to glyphosate to establish its association with cancer, while the others did.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/council-workers-spraying-the-weed-killer-glyphosate-in-playgrounds-wont-hurt-your-children-54831">Council workers spraying the weed-killer glyphosate in playgrounds won't hurt your children</a>
</strong>
</em>
</p>
<hr>
<h2>Demonstrating the mechanism</h2>
<p>Establishing whether a chemical can cause cancer in humans involves demonstrating a mechanism in which it can do so. Typical investigations examine if the chemical causes mutations in bacteria or damage to the DNA of mammalian cells.</p>
<p>The studies reviewed by IARC, and the other bodies mentioned, that looked at glyphosate’s ability to produce mutations in bacteria and to mammalian cells were negative. The weight of evidence also indicated glyphosate was unlikely to cause significant DNA damage.</p>
<h2>Animal studies</h2>
<p>Animal studies are typically conducted in rats or mice. The rodents are given oral doses of glyphosate for up to 89% of their life spans, at concentrations much higher than humans would be exposed to. </p>
<p>Studies examined by the <a href="https://www.efsa.europa.eu/en/efsajournal/pub/4302">European Food Safety Authority</a> included nine rat studies where no cancers were seen. Out of five mouse studies, three showed no cancers even at the highest doses. One study showed tumours, but these were not dose dependent (suggesting random variation, not causation) and in one study tumours were seen at highest doses in males only. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/239674/original/file-20181008-72130-z8h3sq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/239674/original/file-20181008-72130-z8h3sq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/239674/original/file-20181008-72130-z8h3sq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/239674/original/file-20181008-72130-z8h3sq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/239674/original/file-20181008-72130-z8h3sq.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/239674/original/file-20181008-72130-z8h3sq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/239674/original/file-20181008-72130-z8h3sq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/239674/original/file-20181008-72130-z8h3sq.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Glyphosate works by disrupting a pathway that exists in plants but not animals or humans.</span>
<span class="attribution"><span class="source">from shutterstock.com</span></span>
</figcaption>
</figure>
<p>This led to the European Food Safety Authority’s overall conclusion that glyphosate was unlikely to be a carcinogenic hazard to humans.</p>
<p>The <a href="https://monographs.iarc.fr/iarc-monographs-on-the-evaluation-of-carcinogenic-risks-to-humans-4/">IARC</a> evaluation included only six rat studies. In one study, cancer was seen but this wasn’t dose dependent (again suggesting random variation). They evaluated only two mouse studies, one of which was negative for cancer and that showed a statistically significant “trend” in males. </p>
<p>The IARC thus concluded there was sufficient evidence of carcinogenicity in animals but there was no consistency in tumour type (mouse vs rat) or location.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/are-common-garden-chemicals-a-health-risk-65643">Are common garden chemicals a health risk?</a>
</strong>
</em>
</p>
<hr>
<h2>Human studies</h2>
<p>This is an enormous field so I can only briefly summarise the research. The <a href="https://www.efsa.europa.eu/en/efsajournal/pub/4302">European Food Safety Authority </a> looked at 21 human studies and found no evidence for an association between cancer and glyphosate use. The <a href="https://monographs.iarc.fr/iarc-monographs-on-the-evaluation-of-carcinogenic-risks-to-humans-4/">IARC</a> looked at 19 human trials and found no statistically significant evidence for an association with cancer. It did find three small studies that suggested an association with non-Hodgkin lymphoma (not statistically significant).</p>
<p>As already mentioned, the large Agricultural Health Study found no association between cancer and glyphosate in humans. And the 2016 review by Australia’s regulator concluded glyphosate was safe if used as directed.</p>
<p>It’s possible the animus towards Monsanto and genetically modified organisms may have influenced the recent juries’ decision far more than any science. However, these materials <a href="http://www.efsa.europa.eu/sites/default/files/topic/20170608_glyphosate_statement.pdf">had no impact on the scientific findings</a>.</p><img src="https://counter.theconversation.com/content/104554/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Ian Musgrave has previously received funding from the National Health and Medical Research Council to study adverse reaction to herbal medicines and has previously been funded by the Australian Research Council to study potential natural product treatments for Alzheimer's disease. He has collaborated with SA water on studies of cyanobacterial toxins and their implication for drinking water quality. He does not consult or work for any Agricultural crop company. He did give an invited talk at the 5th South Australia Weeds Conference, for which he received a rather nice muffin and a free cup of coffee.</span></em></p>A US court recently ruled the weed killer Roundup contributed to a former gardener’s cancer. Juries don’t decide science. The weight of evidence shows Roundup has little association with cancer.Ian Musgrave, Senior lecturer in Pharmacology, University of AdelaideLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/646222016-10-12T08:51:22Z2016-10-12T08:51:22ZNot all processed meats carry the same cancer risk<figure><img src="https://images.theconversation.com/files/139918/original/image-20160930-9928-ttye65.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="http://www.shutterstock.com/pic-264832343/stock-photo-crispy-organic-heritage-smoked-bacon-from-a-local-organic-farm.html?src=cxLLOQVdE7raMPP0ml8xrQ-1-1">farbled/Shutterstock.com</a></span></figcaption></figure><p>Eating processed meat can increase your risk of getting colorectal cancer. The World Health Organisation’s International Agency for Research on Cancer (IARC) says that each 50g portion of processed meat eaten daily (about two bacon rashers) <a href="https://www.ncbi.nlm.nih.gov/pubmed/26514947">increases bowel cancer risk by 18%</a>. But before you give up processed meats forever, read on.</p>
<p>There are three main cancer-causing agents in processed meat: iron, which occurs naturally in meat; N-nitroso, which forms when meat is processed; and MeIQx and PhIP, which are chemicals formed during cooking.</p>
<p>Iron is found in all meats. It is easily absorbed by the body and is an important part of our diets. Excess amounts, however, can increase the risk of cancer by acting as a catalyst for the formation of free radicals. As with many things – sunshine, salt, fats – the poison is the dose.</p>
<p>N-nitroso compounds only occur if the meat contains added nitrite or nitrate salts. The richest food sources of <a href="https://www.ncbi.nlm.nih.gov/pubmed/20161416">N-nitroso compounds in the US</a> are bacon, luncheon meats, sausage and hot dogs. However, the second highest food source is from fresh and smoked seafoods. Low to moderate sources include grains, dairy, oils, liquor and wine which means we are exposed to these chemicals through many non-meat food sources as well. </p>
<p>Although MeIQx and PhIP form during cooking, the concentration of these chemicals depends on the cooking method and how well the meat is cooked. </p>
<h2>From bresaola to nitrate-filled bangers</h2>
<p>But not all processed meats are the same, so the cancer risk can vary considerably depending on which product you’re talking about. For example, dried meat products such as bresaola or biltong are simply the result of drying lean meat in natural conditions or in an artificially created environment. Many of the nutritional properties, in particular the protein content, remain unchanged through drying. </p>
<p>Compare this with precooked-cooked meat products which contain mixes of lower-grade muscle trimmings, fatty tissues, head meat, animal skin, blood, liver and other edible slaughter byproducts. The first heat treatment precooks the raw meat and the second heat treatment cooks the finished product at the end of the processing stage. As you can see, these are two very different products. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/140864/original/image-20161007-8959-1i3fl8y.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/140864/original/image-20161007-8959-1i3fl8y.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/140864/original/image-20161007-8959-1i3fl8y.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/140864/original/image-20161007-8959-1i3fl8y.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/140864/original/image-20161007-8959-1i3fl8y.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/140864/original/image-20161007-8959-1i3fl8y.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/140864/original/image-20161007-8959-1i3fl8y.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">In a different class.</span>
<span class="attribution"><a class="source" href="http://www.shutterstock.com/pic-235972018/stock-photo-jamon-jamon-serrano-traditional-spanish-ham-on-black-close-up-slicing-hamon-iberico.html?src=b4LFVeY37vwXPb0qu_KtPg-1-16">Subbotina Anna/Shutterstock.com</a></span>
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<p>Unfortunately, the IARC report did not provide details of the risk of cancer associated with the different types of processed meat, as this data is not available. This important fact was either missed or deliberately under-reported by many in the media. Eating processed meat should not be considered an unhealthy pastime, but choosing the type you eat and how it is cooked is very important. </p>
<p>Some sausage manufacturers, do not include any of the nitrites or nitrates which should be avoided. Selecting products with the highest content of meat with only seasonings or plant food ingredients added (some now contain half meat, half vegetable protein) is prudent and not overcooking your meat is really important. The cancer causing chemicals formed during cooking vary dramatically depending on how well you cook your meat and the cooking method. For example, a very well done steak will contain between five and 10 times more MeIQx and PhIP than a medium cooked steak. </p>
<p>Eating processed meats which do not contain nitrates or nitrites and cooking it correctly is not the unhealthy option that some portray it to be and is fine as long as it is done in moderation (no more than <a href="https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/347871/A_quick_guide_to_govt_healthy_eating.pdf">70 grams per day</a> of red meat and processed meat), and as part of a well-balanced diet.</p><img src="https://counter.theconversation.com/content/64622/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>The authors do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>A bit of prosciutto as part of a well-balanced diet is not going to do you much harm.Chris Elliott, Professor of Molecular Biosciences, Queen's University BelfastMarie Cantwell, Senior lecturer, Queen's University BelfastLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/635532016-08-08T13:57:43Z2016-08-08T13:57:43ZDo mobile phones give you brain cancer?<figure><img src="https://images.theconversation.com/files/133365/original/image-20160808-18046-1dhuvwi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Time to hang up?</span> <span class="attribution"><a class="source" href="http://www.shutterstock.com/dl2_lim.mhtml?src=GxsxhjPHS6pDeLrM-xIreQ-1-19&id=395977894&size=medium_jpg">Shutterstock</a></span></figcaption></figure><p>It is a question any mobile phone user would be keen to have answered – and science does offer some clues. In 2011, for example, the International Agency for Research on Cancer (IARC) classified mobile phone radiation as a <a href="https://monographs.iarc.fr/ENG/Publications/Review2014-Radiation-Fatiha.pdf">possible human carcinogen, group 2B</a>. </p>
<p>The classification was based predominantly on evidence from population studies. A <a href="http://www.ncbi.nlm.nih.gov/pubmed/20483835">study</a> by the European Union-funded INTERPHONE group and <a href="http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3834325/">another</a> led by L. Hardell, a Swedish epidemiologist, showed an increased risk (40-170%) of developing glioma, a malignant brain cancer, in people who used a mobile phone for 30 minutes a day over ten years. </p>
<p>The idea of mobile phone radiation increasing the risk of cancer was strengthened by two other studies. The <a href="https://www.emf-portal.org/en/article/24860">Cerenat</a> study, published in 2013, confirmed observations of the INTERPHONE and Hardell studies. And an <a href="http://www.ncbi.nlm.nih.gov/pubmed/25749340">animal study</a> in 2015 showed cell phone radiation enhanced the carcinogenic effects of chemicals.</p>
<p>This evidence indicates that mobile phone radiation might indeed be “possibly carcinogenic” (IARC’s group 2B) or even “probably carcinogenic” (IARC’s group 2A) to humans. </p>
<p>IARC classifies agents as carcinogenic (group 1), probably carcinogenic (group 2A), possibly carcinogenic (group 2B), not classifiable as carcinogen (group 3), probably not carcinogenic (group 4).</p>
<p>However, <a href="http://www.ncbi.nlm.nih.gov/pubmed/22249239">other</a> <a href="https://www.emf-portal.org/en/article/29441">studies</a> show the number of people getting brain cancer has remained unchanged or only slightly increased. This is in spite of the dramatic increase in the number of users of mobile phones over the last ten to twenty years. </p>
<p>And so there is a contradiction between the evidence that shows an increased risk of brain cancer and the studies that show that the rate of brain cancer in populations “saturated” by mobile phones is fairly constant. </p>
<h2>Which view is right?</h2>
<p>Those who believe the case-control studies that indicate a causal link between brain cancer and mobile phone radiation to be correct suggest it is still too early to see the clear increase in brain cancer in the general population. There is, after all, a long latency for this cancer (tens of years) and it’s only during the last ten to 15 years that people have begun to use mobile phones intensively. Before that, they were too expensive. </p>
<p>Those who favour the studies that show no particular increase in brain cancer in populations with dramatically increased phone usage, meanwhile, consider the evidence from the case-control studies to be a statistical “glitch”.</p>
<p>But what if both views are correct? What if mobile phone radiation does not itself cause cancer but long-term exposure increases the risk of developing cancer from other causes?</p>
<p>This hypothesis may explain the apparent discrepancy.</p>
<p>Animal studies, evaluated by IARC experts in 2011, suggest that mobile phone radiation alone does not cause cancer. However, it may still have “co-carcinogen” properties. <a href="http://monographs.iarc.fr/ENG/Monographs/vol102/mono102-003.pdf">In five studies</a>, mobile phone radiation increased development of cancer in animals simultaneously exposed to low doses of known chemical carcinogens. One of the five was recently <a href="http://www.ncbi.nlm.nih.gov/pubmed/25749340">replicated</a> and confirmed the co-carcinogenic effect of mobile phone radiation.</p>
<p>To date there has only been a handful of co-carcinogenicity studies where animals or living cells were simultaneously exposed to chemicals and to mobile phone radiation. This poses a serious problem for proper risk estimation.</p>
<p>Based on the very limited, currently available knowledge, mobile phone radiation might not cause cancer itself. Instead, it might activate regulatory processes and accelerate development of the disease.</p>
<p>Using this hypothesis, it is possible to explain several of the “inexplicable” contradictory scientific results.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/133366/original/image-20160808-18030-1he13xg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/133366/original/image-20160808-18030-1he13xg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=402&fit=crop&dpr=1 600w, https://images.theconversation.com/files/133366/original/image-20160808-18030-1he13xg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=402&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/133366/original/image-20160808-18030-1he13xg.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=402&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/133366/original/image-20160808-18030-1he13xg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=505&fit=crop&dpr=1 754w, https://images.theconversation.com/files/133366/original/image-20160808-18030-1he13xg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=505&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/133366/original/image-20160808-18030-1he13xg.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=505&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Examining the brain.</span>
<span class="attribution"><a class="source" href="http://www.shutterstock.com/dl2_lim.mhtml?src=lbRD1O_Fg7csa5RQ0_wrKg-1-2&id=118491940&size=medium_jpg">Shutterstock</a></span>
</figcaption>
</figure>
<p>First, it could be that case-control studies show increased risk of brain cancer not because mobile phone radiation causes it, but because it accelerates the development of brain cancers caused by other carcinogens or which occur due to spontaneous gene mutations.</p>
<p>Second, the incidence of brain cancer is low compared with the high rate of mobile phone use because the increases are solely due to co-carcinogenic effects of mobile phone radiation. Not all users are in danger of developing brain cancer, only those who are developing it as a result of other carcinogenic or genetic factors. </p>
<p>Finally, published in May 2016 <a href="http://biorxiv.org/content/early/2016/06/23/055699">first results</a> from the animal study conducted at the US National Toxicology Program showed a lack of brain cancer in the control group and a very small number of brain cancer cases among the exposed rats. </p>
<p>Animals were exposed solely to mobile phone radiation and because of the small number of brain cancers caused by mobile phone radiation, some questioned the significance of this observation. But the above proposed hypothesis explains this result. Exposed animals developed a small number of brain cancers not because of the mobile phone radiation alone but because it accelerated the development of cancers caused by spontaneous mutations. In the control group, the same brain cancers, caused by spontaneous mutations, had no time to develop because there was no extra stimulus to accelerate them.</p>
<h2>Risk of brain cancer remains low</h2>
<p>Assuming the hypothesis is correct, mobile phone radiation would have less severe implications for public health than suggested by some epidemiological studies. Not all mobile phone users would be in danger of developing brain cancer. Only those exposed to carcinogenic factors or who develop spontaneous gene mutation would be at risk of the development and manifestation of the cancer.</p>
<p>The proposed hypothesis does not invalidate the IARC classification of mobile phone radiation as a possible carcinogen. IARC classification informs only that avid users have an increased risk of developing cancer. It does not say whether radiation is a “carcinogen” or a “co-carcinogen”.</p>
<p>So this hypothesis does not give mobile phone radiation a clean bill of health. It suggests, however, that it might be unlikely that there will be an epidemic of brain cancer but only a modest increase in prevalence.</p><img src="https://counter.theconversation.com/content/63553/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Dariusz Leszczynski is a Chief Editor of ‘Radiation and Health’, specialty of Frontiers in Public Health, Lausanne, Switzerland.
Former member of the Working Group of the International Agency for Research on Cancer that in 2011 classified cell phone radiation as a possible carcinogen.
He receives occasionally conference travel funding from Pandora Foundation and Competence Initiative, Germany, Cellraid, Finland, Telstra, Australia, Swinburne University of Technology, Australia or from conference organizers.</span></em></p>The evidence appears contradictory – but there may be a good reason for this.Dariusz Leszczynski, Adjunct Professor of Biochemistry, University of HelsinkiLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/611432016-06-17T04:11:18Z2016-06-17T04:11:18ZCoffee won’t give you cancer, unless it’s very very hot, then it might<figure><img src="https://images.theconversation.com/files/127015/original/image-20160616-15075-1jwbgip.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Whether or not coffee causes cancer has been under question since 1991.</span> <span class="attribution"><a class="source" href="https://unsplash.com/photos/ISFopTz7sBo">Merlene Goulet/unsplash</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><p>The World Health Organisation’s cancer arm <a href="http://www.iarc.fr/en/media-centre/pr/2016/pdfs/pr244_E.pdf">made two announcements this week</a>: one welcome and one not so welcome.</p>
<p>First, it announced there was no conclusive evidence to show coffee increases cancer risk. This is a reversal of the <a href="http://www.ncbi.nlm.nih.gov/pubmed/1674554?dopt=Abstract">1991 conclusion</a>, when the carcinogenicity of coffee was first tested, that classified the drink as being “possibly carcinogenic to humans”.</p>
<p>But the International Agency for Research on Cancer’s (IARC) <a href="http://www.thelancet.com/journals/lanonc/article/PIIS1470-2045(16)30239-X/fulltext">committee that exonerated coffee</a> also found drinking beverages at very high temperatures – as is the cultural norm in some parts of South America, the Middle East and China – probably accounts for oesophageal cancer in those communities. </p>
<h2>Not enough evidence</h2>
<p>IARC <a href="https://theconversation.com/not-everything-gives-you-cancer-but-eating-too-much-processed-meat-certainly-can-49812">evaluates the weight of evidence</a> that an agent can increase the risk of cancer by getting together working groups of expert scientists to review published studies.</p>
<p>The data used to conclude in 1991 that drinking coffee may increase the risk of bladder cancer was based on case-control studies. These studies were commonly used to test the verdict of almost all the studies of environmental agents suspected to cause cancer in humans back then.</p>
<p>Case-control studies involve asking a group of, for instance, bladder cancer patients and an equal number of healthy people how often they drank coffee ten, 20 or more years ago. The patients and healthy people would be matched for age, sex and socioeconomic status.</p>
<p>The data from these questionnaires then implicated, but certainly didn’t prove, coffee drinking as a cause of bladder cancer. Such studies are now recognised as relatively unreliable by comparison with prospective studies.</p>
<p>Prospective studies involve obtaining data about, for instance, smoking, drinking and dietary practices of typically half to one million people. When monitored over a decade or more, a few hundred may be diagnosed with bladder cancer. Their coffee drinking and other data may be compared with that data for others in the larger group not diagnosed with bladder cancer. </p>
<p>In general, prospective studies sometimes confirm case-control studies about agents considered carcinogenic. But in the case of coffee drinking, recently conducted prospective studies failed to indicate increased risk of bladder cancer or cancer at any other site correlated with coffee intake. </p>
<p>Some findings even suggest coffee reduced risk of some cancers, such as liver cancer. To use the formal IARC language, coffee drinking is unclassifiable as a human carcinogen.</p>
<h2>Very hot drinks</h2>
<p>Also dating back to 1991 was a determination that drinking hot <em>mate</em> – a tea-like infusion common in South America – was probably carcinogenic to humans. It was linked to oesophageal cancer.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/127018/original/image-20160617-15104-2pm12h.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/127018/original/image-20160617-15104-2pm12h.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/127018/original/image-20160617-15104-2pm12h.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/127018/original/image-20160617-15104-2pm12h.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/127018/original/image-20160617-15104-2pm12h.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/127018/original/image-20160617-15104-2pm12h.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/127018/original/image-20160617-15104-2pm12h.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"><em>Mate</em> is a a tea-like infusion common in South America.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/lazzarello/5513259601/in/photolist-9pbU12-3jx6w-aAUtc1-a3rZKb-5bN2ot-6APyFP-5RdDyT-qbSU-4pu8yd-7jyqSf-w37gP-qbT3-qbT8-qbUj-w2Yve-fXW32-6hP6Tw-5yXjwB-5yXjyH-5yXjCB-5z2BK5-pV7vi2-brXyci-meeX3-7vYaJe-vVLxB-7Y3UYh-q8nNt6-qbTX-qbTh-qbTt-qbSQ-qbTF-4hQdi4-6nou3m-5man5D-bWrJoF-Go9iVd-4mjk1C-3KDPuK-q65gzj-9HAxFm-9MMYCp-5yXjzv-5yXjxF-fsA8zq-3UN759-5yXjjx-xBoMG-brQeSr">Lee/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>Interestingly, in the early 1970s, incidence of oesophageal cancer was found to vary by as much as a hundred-fold between different communities living south of the Caspian Sea (in modern-day Iran). The consumption of very hot drinks was implicated in this difference.</p>
<p>So risk is not a consequence of the beverage type (<em>mate</em>, coffee or otherwise), but of the temperature at which beverages of varying types are consumed. How does temperature lead to cancer? </p>
<p>Hot drinks damage tissue, particularly the lining of the oesophagus, the tube running from the throat to the stomach. Scalding injury to body tissue is not known to cause cancer. </p>
<p>But experimental data suggest cancer may arise when tissue injury comes into contact with a carcinogen, such as <a href="http://www.sciencedirect.com/science/article/pii/030438359503786V">N-nitroso compounds</a>. The most infamous N-nitroso compounds are their derivatives in nicotine that occur in tobacco and specifically account for certain tobacco-attributable tumours. </p>
<p>Other studies have suggested these compounds can be found in <a href="http://www.bezpecnostpotravin.cz/userfiles/file/kvasnickova2/n-nitroso_database.pdf">cured meats</a>, bacon, smoked fish and beer.</p>
<figure class="align-left ">
<img alt="" src="https://images.theconversation.com/files/127032/original/image-20160617-30170-pddcqm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/127032/original/image-20160617-30170-pddcqm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=1117&fit=crop&dpr=1 600w, https://images.theconversation.com/files/127032/original/image-20160617-30170-pddcqm.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=1117&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/127032/original/image-20160617-30170-pddcqm.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=1117&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/127032/original/image-20160617-30170-pddcqm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1403&fit=crop&dpr=1 754w, https://images.theconversation.com/files/127032/original/image-20160617-30170-pddcqm.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1403&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/127032/original/image-20160617-30170-pddcqm.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1403&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The oesophagus is the tube that runs from the throat to your stomach.</span>
<span class="attribution"><span class="source">from shutterstock.com</span></span>
</figcaption>
</figure>
<p>There are a number of examples where exposure to a carcinogen combined with chronic injury or inflammation have been determined to have caused cancer. For instance, cases of stomach cancer have been attributed to the combination of N-nitroso compounds and a gastric infection.</p>
<p>The latest classification was based on data taken together with a range of experimental studies. It evaluated drinking very hot beverages (including water) at above 65 degrees Celsius as “probably carcinogenic to humans”. </p>
<p>Probably carcinogenic means that once all available evidence is considered together, there is a clear indication of cancer causation following the exposure.
At the same time, inconsistencies or less-than-comprehensive data preclude adoption of the more definitive finding that the agent is “carcinogenic to humans”. </p>
<p>This categorisation, which is applicable to agents such as tobacco, effectively means it has been proven to cause cancer in humans.</p>
<p>It’s important to note the latest outcome does not appear to have much relevance to Australia since drinking beverages at this temperature doesn’t account for a distinct fraction of oesophageal cancer cases here.</p>
<p>Not everything causes cancer, but a considerable amount of data needs to be set aside to clearly implicate cancer risk. More often than not, this clear implication becomes clear evidence when cancer incidence in people exposed to particular chemicals, such as in the workplace and to a far lesser extent by consuming certain foods or beverages, becomes known over time.</p><img src="https://counter.theconversation.com/content/61143/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Bernard Stewart does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Scalding injury to body tissue is not known to cause cancer. But experimental data suggest cancer may arise when injured tissue then comes into contact with carcinogens.Bernard Stewart, Professor, Paediatrics, Cancer and related disorders, Epidemiology, Biochemistry and Cell Biology, UNSW SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/548312016-02-17T10:43:44Z2016-02-17T10:43:44ZCouncil workers spraying the weed-killer glyphosate in playgrounds won’t hurt your children<figure><img src="https://images.theconversation.com/files/111757/original/image-20160217-19275-14g9ag8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Roundup, or the chemical glyphosate, is a very common herbicide used to kill weeds.</span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/jeepersmedia/14874003257">Mike Mozart/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><p>A group of rural Victorians has <a href="http://www.abc.net.au/news/2016-02-16/councils-still-using-herbicide-that-probably-causes-cancer/7168464">petitioned their local council</a> to stop using the household weed-killer Roundup (glyphosate). </p>
<p>Their concerns centre around an <a href="http://www.theguardian.com/cities/2015/apr/21/glyphosate-probably-carcinogenic-pesticide-why-cities-use-it">assessment made last year by the International Agency for Research on Cancer (IARC)</a> – an arm of the World Health Organisation – that the common herbicide was “probably carcinogenic to humans”.</p>
<p>The IARC had found <a href="http://www.thelancet.com/journals/lanonc/article/PIIS1470-2045(15)70134-8/fulltext">limited evidence of carcinogenicity</a> in humans for non-Hodgkin’s lymphoma, mostly in agricultural workers.</p>
<p>Victoria’s Mount Alexander Shire Council has <a href="http://www.theage.com.au/victoria/weedkilling-herbicide-remains-councils-number-one-weapon-despite-community-cancer-concerns-20160216-gmvjzg.html">resolved to continue</a> using the herbicide. Councillors have, however, adopted a resolution to “seek alternative methods” to reduce “the use of glyphosate and other weed control chemicals”. </p>
<p>In Queensland, <a href="http://www.abc.net.au/news/2016-02-17/qld-council-peak-body-seeks-legal-advice-on-weedkiller/7176460">councils are also investigating</a> whether they should continue using glyphosate for the same reason.</p>
<p>But the concern of the councils and residents isn’t warranted. Glyphosate isn’t actually dangerous at the levels at which children, or the incidental park passerby, are exposed.</p>
<h2>‘Probably’ carcinogenic</h2>
<p><a href="http://www.glyphosate.eu/glyphosate-basics/how-glyphosate-works">Glyphosate is an organic compound</a> that kills weeds by interfering with the plants’ metabolism. In Australia, <a href="http://apvma.gov.au/node/13891">it’s been registered for use</a> for more than 40 years.</p>
<p>But it’s also classified as “probably carcinogenic to humans”, which means children should stay away from it. Right? Well, no.</p>
<p>The <a href="http://monographs.iarc.fr/ENG/Classification/">IARC classifies agents that “probably” cause human cancers</a> into Group 2A. This is below Group 1 that hosts agents definitely proven to be carcinogenic to humans. They include tobacco smoke and asbestos. </p>
<p>For Group 1 substances, relevant studies are consistent and indicate cancer causation definitively. But then there’s Group 2A with the term “probably”. Here some scientific data fall short of proof. For glyphosate and many other chemicals, the relevant studies are not consistent.</p>
<p>The people most heavily exposed to glyphosate are those employed to spray or apply it. These were the people subject to investigations on which IARC based its determination.</p>
<p><a href="http://www.thelancet.com/journals/lanonc/article/PIIS1470-2045(15)70134-8/fulltext">Some studies have shown workers using glyphosate</a> have more of a certain type of lymphoma (a cancer of blood-forming cells) than the average population. Other studies, including the biggest such investigation, have not. </p>
<p>Discrepancies are common in epidemiology, which is a study of diseases in populations. Epidemiologists use qualifiers such as “probably” or “possibly” rather than indicating that one or more studies are wrong. </p>
<p>But people often misunderstand what action must be taken when something has been determined as “probably carcinogenic”.</p>
<h2>Risk assessment</h2>
<p>The IARC evaluations identify hazards – that is, whether a certain substance has the biological capability to cause cancer. A hazard identification is only one part of the process to determine whether a chemical is dangerous for use.</p>
<p>If it is capable of causing cancer, or probably is, then a separate level of investigation is needed to determine under what circumstances people are exposed to the chemical, and then, what the likelihood is of it causing the cancer. </p>
<p>This exercise is called a “risk assessment” and is not addressed by IARC. </p>
<p>Risk assessment is the business of statutory authorities. For pesticide use in Australia, the relevant authority is the Australian Pesticides and Veterinary Medicines Authority (APVMA). </p>
<p>The APVMA regulates how glyphosate is to be used safely. Authorities like this take into account factors such as the circumstances of a chemical’s use, the level of exposure and availability of alternatives and protective measures – such as warning labels and protective equipment and clothing.</p>
<p>As already mentioned, glyphosate has only been found to be “probably” carcinogenic, and the studies on which this determination was based were confined to those most exposed to the chemical (those who use it occupationally). </p>
<p>But what about the rest of us, as in, the vast majority of Australians whose job doesn’t involve using glyphosate? </p>
<h2>Glyphosate and the average child</h2>
<p>Negative health effects of chemicals are mainly determined by the level of exposure to them. The good news is that <a href="https://en.wikipedia.org/wiki/Glyphosate">soil microbes degrade glyphosate</a> in a matter of days. It doesn’t accumulate the way some pesticides do. </p>
<p>The carcinogenicity evidence for glyphosate doesn’t involve incidental exposure for children. Such level of exposure, if measurable at all, would be hundreds of times below that of occupational exposure. </p>
<p>And when it comes to children, it’s not only the level of exposure that must be considered. It’s also the frequency of exposure when compared to those using it occupationally (possibly most days over a period of years, if not decades). So clearly, much less.</p>
<p>Children get to parks by crossing roads. That’s a risk and there are warning signs for it. When they get to a park, they also risk attack by dogs or humans, being struck by lightning or bitten by snakes. Although those risks are real, they don’t (in most cases) merit warning signs. </p>
<p>And then there’s the even lesser risk of cancer from residual glyphosate, which has never been documented. Just forget it.</p><img src="https://counter.theconversation.com/content/54831/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Bernard Stewart does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>The World Health Organization classifies the common herbicide glyphosate as “probably carcinogenic to humans”. But this doesn’t mean using it to kill weeds in playgrounds will hurt children.Bernard Stewart, Professor, Paediatrics, Cancer and related disorders, Epidemiology, Biochemistry and Cell Biology, UNSW SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/499242015-11-01T11:07:42Z2015-11-01T11:07:42ZCancer and meat – too much hype?<figure><img src="https://images.theconversation.com/files/100138/original/image-20151029-15358-4dy0mf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A report released by the World Health Organisation has ranked red meat as probably carcinogenic to humans, possibly causing bowel cancer. </span> <span class="attribution"><span class="source">Supplied</span></span></figcaption></figure><p>The World Health Organisation’s <a href="http://www.iarc.fr/en/media-centre/pr/2015/pdfs/pr240_E.pdf">report</a> warning of the link between processed meat and an increased cancer risk has taken the globe by storm and resulted in a flurry of overwhelmingly negative publicity around meat and meat <a href="https://www.meatinstitute.org/index.php?ht=display/ReleaseDetails/i/116609">products</a>. </p>
<p>According to the <a href="https://www.iarc.fr/en/media-centre/pr/2015/pdfs/pr240_E.pdf">International Agency for Research on Cancer</a>, every 50 gram portion of processed meat eaten daily increases the risk of bowel cancer by 18%. The panel ranked red meat lower, evaluating it as probably carcinogenic to humans, possibly causing bowel cancer. </p>
<p>The International Agency for Research on Cancer is part of the World Health Organisation. Its mission is to co-ordinate and conduct research on the causes of human cancer, the mechanisms of carcinogenesis, and to develop scientific strategies for cancer control. Although the report published a review of scientific findings, it has nevertheless led to misleading reports. </p>
<h2>A problematic study</h2>
<p>The agency represents the opinion of a selected group of 22 scientists from ten developed countries including Australia, the US, Sweden, Belgium, France and the Netherlands. Its evaluation did not introduce any new evidence. It was based on existing scientific literature, and the opinion it offered is not based on consensus in the <a href="http://www.beefusa.org/newsreleases1.aspx?newsid=5418">global scientific community</a>.</p>
<p>There are two key issues around process that we believe weaken the agency’s findings. The two are: majority agreement on the findings, and that a hazard – and not a risk – assessment was done. </p>
<p>The final classifications were based on a majority agreement and not on unanimous consensus of all members of the working group. These types of evaluations are historically based on unanimous <a href="http://www.beefusa.org/newsreleases1.aspx?newsid=5418">consensus</a>. </p>
<p>Also, the agency conducts hazard analyses, not <a href="https://en.wikipedia.org/wiki/Hazard_analysis">risk assessments</a>. This distinction is important. It means that for this case study, it considered whether meat at some level, under some circumstance, could be a hazard. Each substance is classified according to its potential hazard. Processed meat has been placed in Group 1: carcinogenic to <a href="http://www.iarc.fr/en/media-centre/pr/2015/pdfs/pr240_E.pdf">humans</a> along with tobacco. Red meat has been placed in Group 2A: probably <a href="http://www.iarc.fr/en/media-centre/pr/2015/pdfs/pr240_E.pdf">carcinogenic</a>. </p>
<p>Since the 1970s, the agency has reviewed more than 900 products, substances and exposures. More than 400 have been identified as carcinogenic, probably carcinogenic, or possibly carcinogenic to <a href="http://monographs.iarc.fr/">humans</a>.</p>
<p>However, frequency, intensity and potency of exposure to any hazard plays a large role in determining the potential risk. The IARC’s report has published a risk for processed meat. It warned against the risk of eating 50 grams of processed meat each day – the equivalent of two slices of ham – saying it could increase the risk of colorectal cancer by 18%. </p>
<p>Cancers are among the leading causes of morbidity and mortality <a href="http://www.who.int/mediacentre/factsheets/fs297/en/">worldwide</a>, with about 14 million new cases and 8.2 million cancer related deaths in 2012. Nearly one million cancer deaths per year are attributed to tobacco smoking while 600,000 cancer deaths each year are as a result of alcohol consumption. Another 200,000 cancer deaths a year are as a result of air pollution.</p>
<p>The most recent estimates by the <a href="http://www.who.int/mediacentre/factsheets/fs297/en/">Global Burden of Disease Project</a> show that across the globe, 34,000 cancer deaths per year are attributed to diets containing high intakes of processed meat. </p>
<p>In this context, the amount of cancer-related deaths attributed to excessive consumption of processed meats compared to other hazards are relatively small. </p>
<p>Quantifying the estimates further mean that increasing your risk by 18% when consuming more than 350 grams of processed meat per week, you increase your chance to develop colorectal cancer from <a href="http://www.theglobeandmail.com/globe-debate/go-ahead-have-that-blt-for-lunch/article26979606/">56 in 1000 to 66 in 1000</a>. </p>
<p>The agency is not saying that processed meat is as dangerous as <a href="http://scienceblog.cancerresearchuk.org/2015/10/26/processed-meat-and-cancer-what-you-need-to-know/">smoking</a>. The risk from processed meat and red meat remains smaller than tobacco smoke, alcohol consumption and air pollution. </p>
<h2>Down this road before</h2>
<p>It is not the first time a misleading message has put into the public domain. </p>
<p>In 1995, the <a href="http://www.bmj.com/content/311/7020/1589">UK Committee on Safety of Medicines</a> issued a warning that oral contraceptive pills increased the risk of potentially life-threatening thrombosis twofold. </p>
<p>The news provoked great anxiety and many women stopped taking the pill. This led to unwanted pregnancies and nearly 13,000 additional <a href="http://www.who.int/bulletin/volumes/87/8/09-069872/en/">abortions</a> in the next year in England and Wales. </p>
<p>Yet, when this daunting “twofold risk” was <a href="http://www.bmj.com/content/341/bmj.c4830">investigated</a> it was revealed that the incidence of thrombosis had increased from one in 7000 women who did not take the pill to two in 7000 women who do.</p>
<h2>A balanced diet</h2>
<p>After the International Agency for Research on Cancer released the report, the assistant director-general of the World Health Organisation, <a href="http://www.gazzettadelsud.it/news/english/164255/People-should-limit--not-eliminate--some-foods--WHO-official.html">Oleg Chestnov</a>, announced that some foods needed to be limited as part of a healthy diet but did not need to be eliminated:</p>
<p>He said the document linking red meats to cancer was aimed mainly at politicians, so that they can regulate the sector appropriately within their borders.</p>
<p>Most governments throughout the world promote balanced approaches to <a href="http://www.fao.org/nutrition/nutrition-education/food-dietary-guidelines/en/">diets</a> based on scientific evidence. They encourage moderate consumption of foods from all the food groups. </p>
<p>This is the sensible approach. Scaring people is not.</p><img src="https://counter.theconversation.com/content/49924/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Nicolette Hall consults to the Red Meat Industry of South Africa. She receives funding from Red Meat Research and Development South Africa for research not related to this topic. </span></em></p><p class="fine-print"><em><span>Hester Carina Schönfeldt consults to the South African Red Meat Industry. She is affiliated with Red Meat Research and Development South Africa. </span></em></p>The World Health Organisation’s report on the increased cancer risk with eating processed and red meat has been met with mixed reactions.Nicolette Hall, Researcher in Human Nutrition, University of PretoriaHettie Carina Schönfeldt, Associate Professor of Human Nutrition at the Institute of Food, Nutrition and Wellbeing, University of PretoriaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/193802013-10-25T01:22:17Z2013-10-25T01:22:17ZAir pollution causes cancer, so let’s do something about it<figure><img src="https://images.theconversation.com/files/33740/original/j2w2zs29-1382663927.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The International Agency for Research on Cancer has classified outdoor air pollution as carcinogenic to humans.</span> <span class="attribution"><span class="source">Andrew Tseng</span></span></figcaption></figure><p>Late last week, the world’s leading experts on cancer, the International Agency for Research on Cancer (IARC) classified outdoor air pollution as carcinogenic to humans. The agency’s report, <a href="http://www.west-info.eu/files/tmpwAzflG.pdf">Air Pollution and Cancer</a>, said there’s now sufficient evidence that components of outdoor air pollution can cause cancer. </p>
<p>The announcement caused quite a stir in the scientific community and rightly so. But we’re yet to see expressions of outrage from the community and the media. </p>
<p>The print media, for instance, has not been inundated with letters to editors expressing concern and demanding governments do something about air quality. </p>
<p>In fact, the reaction to the report has been muted and it’s all business as usual. In Australia, perhaps the impact of the media releases was understandably overtaken by the devastating bushfires in New South Wales.</p>
<p>Air pollution is one of the very few, perhaps the only, environmental hazard everyone is exposed to; we all have to breathe the air around us. </p>
<p>Even unborn children are exposed to the potential harm of air pollution, a complex mixture of particles that can be solids or aerosols, and gases. Particles are comprised of a myriad of individual chemical constituents and sizes.</p>
<p>Fine particles, about a 20th the diameter of a human hair and invisible to the naked eye, can be inhaled deep into the lungs. They are thought to be responsible for many of the negative health effects of air pollution. </p>
<p>Combustion sources such as motor vehicles, power plants and industry are major contributors to outdoor air pollution. And motor vehicle exhaust emissions are particularly significant in the large cities of the world.</p>
<p>Although much of the early research into the effects of air pollution was focussed on diseases of the lungs, such as asthma and bronchitis, it’s now becoming more apparent that air pollution also affects other body systems, <a href="http://webarchive.nationalarchives.gov.uk/+/www.dh.gov.uk/ab/COMEAP/DH_108448">especially the heart</a> and the circulation.</p>
<p>In 2012, the <a href="http://www.eea.europa.eu/publications/air-quality-in-europe-2012">European Environment Agency concluded</a> fine particles may cause heart attacks and abnormal heart rhythms, affect children’s neurodevelopment, lead to prematurity and smaller babies, cause lung cancer and decrease life expectancy. </p>
<p>The United States Environmental Protection Agency is <a href="http://cfpub.epa.gov/ncea/cfm/recordisplay.cfm?deid=216546">also in no doubt</a> that there’s now sufficient evidence to declare that fine particles are a cause of cardiovascular diseases and premature deaths.</p>
<p>The IARC estimates outdoor air pollution is responsible for 3% to 5% of all lung cancers. The <a href="http://www.thelancet.com/journals/lancet/article/PIIS0140-6736(12)61766-8/abstract">report also highlights</a> that exposure to outdoor fine particles contributes to 3.2 million premature deaths worldwide in 2010, mainly through cardiovascular disease, and 223,000 deaths from lung cancer. </p>
<p>Clearly, we can no longer ignore the health effects of air pollution. </p>
<p>The well-known London smog episode during the winter of 1952 resulted in an estimated additional 4,000 deaths over four days. </p>
<p>The scale of its effects was an important factor in the promulgation of the Clean Air Act 1956, the first legislation of its kind in the world to reduce emissions and improve air quality. </p>
<p>This IARC report is particularly timely as Australian air quality standards are currently under review. Only time will tell whether the IARC report will become an equally important catalyst for improving the country’s air quality.</p><img src="https://counter.theconversation.com/content/19380/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Bin Jalaludin currently has research funding from the National Health and Medical Research Council, Australian Research council, HCF Health and Medical Research Foundation, NSW Ministry of Health, Motor Accidents Authority of NSW and the Bushfire Cooperative Research Centre. He is affiliated with the University of New South Wales, the Woolcock Institute of Medical Research and the Ingham Institute of Applied Medical Research. </span></em></p>Late last week, the world’s leading experts on cancer, the International Agency for Research on Cancer (IARC) classified outdoor air pollution as carcinogenic to humans. The agency’s report, Air Pollution…Bin Jalaludin, Director, Centre for Research, Evidence Management and Surveillance & Conjoint Professor, School of Public Health and Community Medicine, UNSW SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/94872012-10-09T19:39:45Z2012-10-09T19:39:45ZAsbestos still haunts those exposed as kids in mining towns<figure><img src="https://images.theconversation.com/files/16324/original/hf3ftfjp-1349757112.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Growing evidence suggests asbestos exposure may cause many more diseases than we thought.</span> <span class="attribution"><span class="source">Natalie Blackburn</span></span></figcaption></figure><p>The relationship between asbestos exposure and diseases such as malignant mesothelioma and lung cancer is well established. But now other diseases not typically associated with asbestos may possibly be linked to occupational and non-occupational forms of exposure.</p>
<p>Asbestos refers to a number of naturally occurring minerals that have crystallised to form long thin fibres and fibre bundles. There are three main types that have been used commercially – crocidolite (blue asbestos), amosite (brown asbestos) and chrysotile (white asbestos).</p>
<p>The difference between these types has to do with the shape and size of their fibres. Crocidolite and amosite have long, straight fibres, while chrysotile fibres are short and curly. The shape of these fibres is thought to be central to the damage they do to human health. The long straight fibres, in particular, are thought to easily penetrate into the lungs. </p>
<p>So although all types of asbestos have been found to cause asbestos-related diseases, some types lead to more of these diseases than others. Blue asbestos (the type that was mined at Wittenoom, Western Australia) is the worst for human health, followed by amosite, and then chrysotile. </p>
<figure class="align-right ">
<img alt="" src="https://images.theconversation.com/files/16321/original/vwgvm697-1349755680.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/16321/original/vwgvm697-1349755680.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/16321/original/vwgvm697-1349755680.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/16321/original/vwgvm697-1349755680.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/16321/original/vwgvm697-1349755680.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/16321/original/vwgvm697-1349755680.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/16321/original/vwgvm697-1349755680.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">White chrysotile asbestos fibres are thought to cause certain diseases.</span>
<span class="attribution"><span class="source">Asbestorama/Flickr</span></span>
</figcaption>
</figure>
<h2>Asbestos and health</h2>
<p>Diseases most commonly attributed to asbestos exposure are malignant mesothelioma, asbestosis and lung cancer. There’s a clear relationship between the amount of asbestos exposure and the risk of developing mesothelioma and asbestosis, with the risk increasing as the level of exposure increases. </p>
<p><a href="http://www.iom-world.org/pubs/malignant_mesothelioma.PDF">Malignant mesothelioma</a> is a diffuse cancer that spreads over the lining of the lung or stomach. It has a long latency period, rarely developing within 15 years of first exposure. And it is universally fatal – the average survival rate, after diagnosis, is nine months.</p>
<p>Malignant mesothelioma is very rare in people who haven’t been exposed to asbestos. In England, cases were established from autopsy reports between 1910 and 1940, and the disease became more frequently diagnosed in the 1950s. The link between asbestos (crocidolite) exposure and mesothelioma was formally <a href="http://oem.bmj.com/content/17/4/260.full.pdf+html">established in 1960</a>.</p>
<p><a href="http://www.hse.gov.uk/ASBESTOS/exposure.pdf">Asbestosis</a> is defined as “fibrosis of the lungs caused by asbestos dust”. Patients with well-established asbestosis usually <a href="http://ajrccm.atsjournals.org/content/157/5/1666.full.pdf+html">present with symptoms</a> of shortness of breath and a dry cough. It’s a progressive disease but it’s not necessarily fatal. The <a href="http://books.google.com.au/books?hl=en&lr=&id=47qAj5oTFOcC&oi=fnd&pg=PA201&dq=Epidemiology+of+Asbestos-%20Related+Diseases+and+the+Knowledge+that+Led+to+What+is+Known+Today&ots=JW_vMAHq76&sig=CTFCXI7MM9-7kuyBMBDwHcQtpJY#v=onepage&q=Epidemiology%20of%20Asbestos-Related%20Diseases%20and%20the%20Knowledge%20that%20Led%20to%20What%20is%20Known%20Today&f=true">first case of asbestosis</a> was described in medical literature in 1906, in a 33-year-old man who had worked in an asbestos textile factory for 14 years.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/16322/original/t5pgz8fj-1349755863.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/16322/original/t5pgz8fj-1349755863.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/16322/original/t5pgz8fj-1349755863.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/16322/original/t5pgz8fj-1349755863.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/16322/original/t5pgz8fj-1349755863.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/16322/original/t5pgz8fj-1349755863.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/16322/original/t5pgz8fj-1349755863.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Children who grew up in Wittenoom, Western Australia between 1943-66 are dying of asbestos-related diseases in adulthood.</span>
<span class="attribution"><span class="source">Five Years/Wikipedia Commons</span></span>
</figcaption>
</figure>
<p>Other kinds of cancers are also more prevalent among workers exposed to occupational levels of asbestos than the general population. These include brain cancers, blood-related disorders (such as leukaemia), kidney cancer, cancer of the larynx, stomach and colorectal cancer. But the evidence that asbestos causes these other diseases is limited, mainly due to a lack of proof for an exposure-response relationship. </p>
<p>The <a href="http://www.iarc.fr/">International Agency for Research in Cancer</a> has recently <a href="http://monographs.iarc.fr/ENG/Monographs/suppl7/Suppl7-20.pdf">stated</a> that asbestos exposure causes <a href="http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3230399/pdf/ehp.1003283.pdf">ovarian cancer</a>. But there’s still some <a href="http://cebp.aacrjournals.org/content/20/7/1287.full.pdf+html.">debate</a> about this link in the scientific literature.</p>
<p>Few studies have found an excessive risk of these other cancers developing in people exposed to asbestos. Fewer still have found or reported a causal link.</p>
<h2>Will we ever know for sure?</h2>
<p>Former workers and residents of the blue asbestos mining and milling town of Wittenoom, Western Australia have been followed up through cancer and death registries and by regular questionnaires for over 30 years. Our <a href="http://onlinelibrary.wiley.com/doi/10.1002/ajim.22103/abstract">latest study</a> has revealed a relationship between cancers other than mesothelioma among people who, as children, lived in Wittenoom.</p>
<p>Now adults, this group were exposed to blue asbestos before the age of 15. We have found an increased risk of brain cancer among both the males and females of this group. </p>
<p>We also found higher rates of leukaemia, prostate and colorectal cancer among males, and ovarian cancer among females, compared with the general Western Australian population. These are very rare cancers, so it’s very difficult to state with absolute certainty that they’re caused by exposure to asbestos. Despite the significantly increased rates of cancer within this group, we may never know for sure whether asbestos is implicated.</p>
<figure class="align-right ">
<img alt="" src="https://images.theconversation.com/files/16323/original/bdhshgrp-1349756614.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/16323/original/bdhshgrp-1349756614.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=897&fit=crop&dpr=1 600w, https://images.theconversation.com/files/16323/original/bdhshgrp-1349756614.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=897&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/16323/original/bdhshgrp-1349756614.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=897&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/16323/original/bdhshgrp-1349756614.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1127&fit=crop&dpr=1 754w, https://images.theconversation.com/files/16323/original/bdhshgrp-1349756614.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1127&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/16323/original/bdhshgrp-1349756614.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1127&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Blue asbestos in Wittenoon, Western Australia still circulates in the air well after the town’s closure.</span>
<span class="attribution"><span class="source">oemebame/Flickr</span></span>
</figcaption>
</figure>
<p>The Wittenoom group also have a high rate of heart disease compared with the Western Australian population. Again, the evidence proving that exposure to asbestos causes heart disease is limited. Although we found an increased risk of heart disease in this group, we didn’t find that the risk increased as the level of asbestos exposure increased. </p>
<p>The Wittenoom children are still young and heart disease is not a major cause of death among them. Perhaps a link between heart disease and asbestos exposure will become apparent as they age. Recent work from the United Kingdom has shown that ischaemic heart disease and cerebrovascular disease were more prevalent among a large group of British workers exposed to occupational levels of asbestos. <a href="http://oem.bmj.com/content/69/6/417.full.pdf+html">In that study</a>, longer exposure was associated with a greater risk of ischaemic heart disease.</p>
<p>One of the ways we can prove that a disease is caused by asbestos is to find that the risk of disease increases with the amount of asbestos exposure. Where we do not find that relationship, we have to concede that the disease may be caused by other factors the group have in common. We may not have looked for such factors or perhaps were unable to look for them in our studies. </p>
<p>Following up the former Wittenoom children may reveal links between asbestos exposure and these other diseases. The longer they are followed up, the more information we will learn about the diseases they develop, and whether asbestos exposure is the cause. </p>
<p>This knowledge may help those still being exposed to asbestos, because we would be able to correctly identify diseases they may present with. But the best way of preventing asbestos-related diseases is to avoid exposure altogether. </p><img src="https://counter.theconversation.com/content/9487/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Alison Reid receives funding from the National Health and Medical Research Council and the Australian Research Council.</span></em></p>The relationship between asbestos exposure and diseases such as malignant mesothelioma and lung cancer is well established. But now other diseases not typically associated with asbestos may possibly be…Alison Reid, Research Associate Professor , The University of Western AustraliaLicensed as Creative Commons – attribution, no derivatives.