tag:theconversation.com,2011:/fr/topics/chlorine-2570/articlesChlorine – The Conversation2023-11-27T13:40:53Ztag:theconversation.com,2011:article/2139982023-11-27T13:40:53Z2023-11-27T13:40:53ZChlorine is a highly useful chemical that’s also extremely dangerous − here’s what to know about staying safe around it<figure><img src="https://images.theconversation.com/files/560460/original/file-20231120-27-fge83s.jpg?ixlib=rb-1.1.0&rect=10%2C0%2C3484%2C2326&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Jordanian forensics experts inspect the site of a chlorine gas explosion in the Port of Aqaba in June 2022. </span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/jordanian-forensics-experts-inspect-the-site-of-a-toxic-gas-news-photo/1241583752">Khalil Mazraawi/AFP via Getty Images</a></span></figcaption></figure><p>Many people encounter chlorine in their daily lives, whether it’s as an ingredient in household bleach or an additive that sanitizes water in swimming pools. Chlorine is also used as an antiseptic, a bleaching agent in the production of paper and cloth, and to kill microorganisms in drinking water.</p>
<p>But this familiar chemical is also extremely toxic. And because it’s ubiquitous in many industries across the U.S., it often is released in chemical accidents and spills. </p>
<p>As a <a href="https://scholar.google.com/citations?user=yI9ON-UAAAAJ&hl=en">pharmaceutical scientist</a>, I study ways in which chemicals and other materials affect the human body. Currently, I am working to develop <a href="https://ehsrc.public-health.uiowa.edu/ehsrc-investigators-receive-niehs-award-to-develop-cationic-camkiin-nanoparticles-that-reduce-chlorine-induced-airway-oxidative-stress/">therapies to counteract chlorine gas exposure</a> and to understand the mechanism by which chlorine harms people. One promising therapy that we are developing is inhalable nanoparticles that counteract lung damage following chlorine gas exposure. </p>
<h2>A common and dangerous chemical</h2>
<p><a href="https://www.rsc.org/periodic-table/element/17/chlorine">Chlorine</a> is an extremely toxic and widely used chemical. In the U.S., it is one of the top five chemicals by production volume, with an output of about 12 million tons (11 million metric tons) <a href="https://www.statista.com/statistics/299725/total-us-plastics-and-chemicals-shipments-by-type/">per year</a>. </p>
<p>A yellow-green gas at room temperature, chlorine is highly reactive, which means that it <a href="https://chemistrytalk.org/chlorine-element/">readily forms compounds with many other chemicals</a>. These reactions often are very intense. Chlorine <a href="https://www.cdc.gov/niosh/ershdb/emergencyresponsecard_29750024.html">reacts explosively or forms explosive compounds</a> with many common substances, including hydrogen, turpentine and ammonia.</p>
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<a href="https://images.theconversation.com/files/560471/original/file-20231120-26-48hv06.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Poster explaining how to use chlorine and other pool chemicals safely." src="https://images.theconversation.com/files/560471/original/file-20231120-26-48hv06.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/560471/original/file-20231120-26-48hv06.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=785&fit=crop&dpr=1 600w, https://images.theconversation.com/files/560471/original/file-20231120-26-48hv06.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=785&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/560471/original/file-20231120-26-48hv06.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=785&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/560471/original/file-20231120-26-48hv06.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=986&fit=crop&dpr=1 754w, https://images.theconversation.com/files/560471/original/file-20231120-26-48hv06.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=986&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/560471/original/file-20231120-26-48hv06.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=986&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">Even in everyday uses, chlorine requires special handling and precautions.</span>
<span class="attribution"><a class="source" href="https://www.cdc.gov/healthywater/swimming/pdf/Pool-Chemical-Safety-USE-poster-p.pdf">CDC</a></span>
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<p>Chlorine gas exposure, even for short periods of time and <a href="http://dx.doi.org/10.1513/pats.201001-008SM">at low levels</a>, leads to eye, throat and nose irritation and causes coughing and breathing problems and burning in the eyes. <a href="http://dx.doi.org/10.1513/pats.201001-008SM">Higher exposure levels</a> can cause chest pain, severe breathing difficulties, pneumonia, vomiting and fluid in the lungs. Very high levels can cause death. Chlorine also can be absorbed through the skin, resulting in pain, swelling, inflammation and blistering. </p>
<p>Our research has shown that exposure to chlorine gas leads to airway inflammation and <a href="http://dx.doi.org/10.1378/chest.123.3_suppl.411s">airway hyperreactivity</a> – swelling and narrowing of the bronchial tubes that carry air to and from your lungs, which makes it harder to breathe. This condition is a characteristic feature of asthma. </p>
<p>Chlorine’s toxicity made it one of the first chemical weapons used on a large scale in warfare. German troops <a href="https://www.denix.osd.mil/rcwmprogram/history/">released it against French and Canadian forces</a> in World War I. More recently, international observers report that <a href="https://apnews.com/article/syria-government-bashar-assad-3b283b4dd01f1765027aa567e53c24be">Syria has used chlorine weapons repeatedly</a> in that country’s civil war. In Iraq, insurgents <a href="https://www.reuters.com/article/us-iraq1/chlorine-bombs-mark-new-guerrilla-tactics-u-s-idUSKRA14854020070222/">used chlorine bombs against U.S. forces</a> in 2007 in and around Baghdad, and the Islamic State reportedly later <a href="https://www.bbc.com/news/world-middle-east-31847427">used chlorine in crude roadside bombs</a> in Iraq.</p>
<h2>Large-scale releases worldwide</h2>
<p>Some recent accidents show how commonly the release or mishandling of chlorine can create life-threatening situations. For example, on April 27, 2023, five workers at a spa in Brooklyn were hospitalized after employees <a href="https://abc7ny.com/midwood-brooklyn-world-spa-hazmat/13190043/">mixed two cleaning chemicals</a>, releasing chlorine gas – a reaction that is <a href="https://doh.wa.gov/community-and-environment/contaminants/bleach-mixing-dangers">surprisingly easy to generate</a>. </p>
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<a href="https://images.theconversation.com/files/560483/original/file-20231120-27-e5h8a7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A huge grey plume billows from an industrial facility." src="https://images.theconversation.com/files/560483/original/file-20231120-27-e5h8a7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/560483/original/file-20231120-27-e5h8a7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/560483/original/file-20231120-27-e5h8a7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/560483/original/file-20231120-27-e5h8a7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/560483/original/file-20231120-27-e5h8a7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/560483/original/file-20231120-27-e5h8a7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/560483/original/file-20231120-27-e5h8a7.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">A fire burns at the BioLab Inc. chemical plant in Westlake, La., on Aug. 27, 2020. Winds from Hurricane Laura damaged several buildings, and rainwater reached the chemicals stored there, triggering a fire that released a chlorine plume. The U.S. Chemical Safety and Hazard Investigation Board later concluded that the facility was not adequately prepared for extreme weather.</span>
<span class="attribution"><a class="source" href="https://newsroom.ap.org/detail/TropicalWeatherLouisiana/d351c48226b3451d91311a08a5f5ff31/photo">AP Photo/Gerald Herbert</a></span>
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<p>In a larger event, on April 18, 2022, a compressor fire caused a chlorine gas spill inside a <a href="https://www.theadvocate.com/baton_rouge/news/environment/at-least-23-hospitalized-after-chlorine-leak-at-chemical-plant-near-plaquemine-officials-say/article_bef9acf0-c1b8-11ec-98d7-5b060fdac504.html">Dow Chemicals facility</a> close to Plaquemine, Louisiana. Liquid chlorine quickly vaporized into the air and spread into adjoining neighborhoods. At least 23 people were hospitalized. </p>
<p>Large-scale shipments of chlorine can cause widespread injuries and even deaths in the event of accidents. For example, when a freight train derailed in Graniteville, South Carolina, in 2005, a tanker car ruptured and <a href="https://doi.org/10.1177/003335490712200610">released 60 tons of chlorine</a>. Nine people died, 72 were hospitalized and 525 received outpatient medical treatment.</p>
<p>The most dramatic recent case occurred at the <a href="https://www.reuters.com/world/middle-east/four-dead-70-injured-toxic-gas-leak-jordans-aqaba-port-state-tv-2022-06-27/">Port of Aqaba in Jordan</a> on June 27, 2022. A crane dropped a container loaded with 25 tons of chlorine onto a docked ship, where it broke and produced a massive release of toxic gas. The spill killed 13 people and injured more than 260.</p>
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<iframe width="440" height="260" src="https://www.youtube.com/embed/Gbng95zULgE?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">A deadly cloud of chlorine fumes was released after a tank fell onto the deck of a ship while being moved in the Jordanian Port of Aqaba on June 27, 2022.</span></figcaption>
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<h2>Protecting people from chlorine gas exposure</h2>
<p>Although the risks from chlorine gas exposure have been well understood for over a century, there are no current antidotes. This is because chlorine is a strong oxidizing agent that can <a href="https://wwwn.cdc.gov/TSP/MMG/MMGDetails.aspx">cause major tissue damage</a> in the body.</p>
<p>People who handle chlorine in the workplace should use respiratory equipment that meets <a href="https://www.cdc.gov/niosh/npg/npgd0115.html">federal regulatory standards</a>. They also should have rubber gloves, a protective apron or other protective clothing, goggles or a face mask, and access to a shower and eye-washing station.</p>
<p>Signs that <a href="https://chemtech-us.com/articles/what-does-chlorine-gas-smell-like-7-telling-signs-of-a-chlorine-gas-leak/">chlorine may be present</a> include a pungent, irritating odor, like very strong cleaning products; a yellowish-green gas; and irritation to the eyes and throat. If you suspect that you may have been exposed to chlorine gas, the <a href="https://www.cdc.gov/chemicalemergencies/factsheets/chlorine.html#anchor_63694">Centers for Disease Control and Prevention recommend</a> moving away from the area and removing all clothing and showering if possible. </p>
<p>Symptoms of chlorine exposure can be treated in a hospital. Therapies include providing patients with humidified oxygen, which is less irritating to the nose and throat than conventional oxygen, and inhaled <a href="https://www.ncbi.nlm.nih.gov/books/NBK548685/">beta-adrenergic agents</a> – medications that are widely used to manage bronchial asthma by relieving lung spasms and reducing airway resistance.</p>
<p>Researchers are studying <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2908650/">other medications</a> that may help reduce the severity of lung injury and help patients recover lung function. These include inhalable therapies that reduce lung damage following chlorine gas exposure and oral tablets or injectable therapies that reduce lung inflammation.</p>
<p>Chlorine is a safe and effective disinfectant <a href="https://www.ready.gov/household-chemical-emergencies">when handled appropriately</a>. But as with other household chemicals, it is very important to understand its risks, read labels before using it, store it in its original container in a secure place and dispose of it safely.</p><img src="https://counter.theconversation.com/content/213998/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Aliasger K. Salem receives funding from the National Institutes of Health. He serves on the Executive Board of the American Association for Pharmaceutical Scientists.</span></em></p>Chlorine is a widely used industrial chemical that’s frequently a factor in toxic accidents and workplace injuries. A pharmaceutical expert explains why it’s so hazardous.Aliasger K. Salem, Associate Vice President for Research and Bighley Chair and Professor of Pharmaceutical Sciences, University of IowaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2117362023-09-20T01:09:04Z2023-09-20T01:09:04ZWhy does my hair turn green from the swimming pool?<figure><img src="https://images.theconversation.com/files/548480/original/file-20230915-17-6zhh04.jpg?ixlib=rb-1.1.0&rect=0%2C342%2C5619%2C3665&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/portrait-blonde-woman-swimming-pool-happy-2060368673">Shutterstock</a></span></figcaption></figure><p>If you are a blonde like me and enjoy laps in a swimming pool, you may have noticed your hair acquires a green tint after frequent swims in chlorinated water.</p>
<p>This happens to both bleached and natural blondes. In fact, the green tinge happens to everyone, but it’s less visible on dark hair and those whose hair isn’t damaged by chemical treatments such as bleaching. </p>
<p>But what exactly causes this green discoloration, and what can we do about it? Most of us blame the chlorine in the pool water. However, although chlorine does play a part, it is not the main culprit. </p>
<h2>Which chemicals in the pool turn the hair green?</h2>
<p>The element to blame for the green staining of hair is copper. </p>
<p>The main source of copper is copper sulfate (CuSO₄), a compound added to swimming pools to prevent the growth of algae. <a href="https://www.sciencedirect.com/science/article/pii/S1568988320301803?via%3Dihub">Contact with algae</a> can cause skin irritation and respiratory issues, and ingesting water with algae can lead to serious gastrointestinal problems. Only a small amount (around 0.5mg per litre or 0.5 parts per million) of copper sulfate is needed to prevent algal growth.</p>
<p>However, copper can also enter swimming pools through the corrosion of water pipes, so concentrations may be higher in some pools. </p>
<p>Copper sulfate crystals are greenish-blue in colour. So, when hair comes into contact with copper ions – a positively charged variant of a copper atom with a deficiency of electrons – those ions get absorbed by the hair and cause the greenish hue.</p>
<p>Scientists were fascinated by the green “pool hair” phenomenon as far back as the 1970s, so we actually have research data on copper being the cause.</p>
<p>One very <a href="https://jamanetwork.com/journals/jamadermatology/article-abstract/538197">interesting study in 1978</a> performed experiments by immersing hair samples into water containing different concentrations of copper ions, chlorine and various pH values (neutral and basic). Their results showed hair exposed to free copper ions does turn green.</p>
<p>Furthermore, when hair is oxidised (meaning electrons are removed from the hair proteins) by chlorine, it actually damages the hair, enhancing the absorption of copper ions. Hair submerged in water with chlorine but without copper ions did not turn green. Meanwhile, hair exposed to water with only copper ions and no chlorine still formed a green colour.</p>
<p>Hence, chlorine by itself does not play a role in causing the green hue we see in “pool hair”, but it does exacerbate it.</p>
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<a href="https://images.theconversation.com/files/548491/original/file-20230915-19-ytaeeh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A hand in a blue glove tossing several white tablets into a reservoir next to a swimming pool" src="https://images.theconversation.com/files/548491/original/file-20230915-19-ytaeeh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/548491/original/file-20230915-19-ytaeeh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=407&fit=crop&dpr=1 600w, https://images.theconversation.com/files/548491/original/file-20230915-19-ytaeeh.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=407&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/548491/original/file-20230915-19-ytaeeh.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=407&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/548491/original/file-20230915-19-ytaeeh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=511&fit=crop&dpr=1 754w, https://images.theconversation.com/files/548491/original/file-20230915-19-ytaeeh.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=511&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/548491/original/file-20230915-19-ytaeeh.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=511&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">‘Pool chemicals’ do contribute to the green tinge in your hair – but chlorine is not the main culprit.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/female-hand-puts-white-tablets-into-1464180314">Shutterstock</a></span>
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<h2>So, how does copper get into the hair?</h2>
<p><a href="https://doi.org/10.1007/978-1-4684-0943-7_24">Other research teams</a> have conducted <a href="https://doi.org/10.1071/ch9682437">more extensive studies</a>, using sophisticated instruments, such as scanning electron microscopy, to examine how exactly copper ions attach to the hair. </p>
<p>Our hair is predominantly composed of protein called keratin. Keratin is classified as a “structural fibrous protein”, meaning it has an elongated, sheet-like structure.</p>
<p>The keratin structure is composed of various <a href="https://chem.libretexts.org/Courses/University_of_Kentucky/UK%3A_CHE_103_-_Chemistry_for_Allied_Health_(Soult)/Chapters/Chapter_4%3A_Structure_and_Function/4.4%3A_Functional_Groups">chemical groups</a> (types of atom groupings with similar properties), such as carboxyl groups, amino groups and disulfide groups. Copper ions have the ability to form bonds with these groups, forming a copper-keratin complex. This complex remains in the hair, causing it to appear green.</p>
<p>Interestingly, the most recent study <a href="https://doi.org/10.32657/10356/142466">conducted in 2020</a>, showed copper ions mainly bind to the disulfide groups. This study also found other metal ions such as zinc, lead, chromium and mercury also bind to hair in the same way. This is very useful in <a href="https://theconversation.com/forensic-breakthrough-study-suggests-humans-can-be-identified-by-the-proteins-in-their-hair-65051">forensic analysis</a>, for example, because forensic scientists can analyse hair samples to determine if a person has been exposed to a particular metal. </p>
<p>Light-coloured hair already has the most visible green discoloration, but research has shown that damaged hair, caused by bleaching, straightening, or exposure to sun, is the <a href="https://pubmed.ncbi.nlm.nih.gov/19586601/">most susceptible</a> to the binding of copper ions. This is because in damaged hair the disulfide groups have “broken bonds” (the link that holds the elements within these groups together is broken), making it easier for the copper ions to bind to the hair. </p>
<h2>Can I prevent the green colour or get rid of it?</h2>
<p>To prevent your hair from turning green in a swimming pool, you have two basic options. The first is a physical barrier – just wear a swim cap.</p>
<p>The second option is chemical – you can pre-treat your hair with an alkaline shampoo. <a href="https://www.sciencedirect.com/science/article/abs/pii/S0891584918310050">Studies have shown</a> under alkaline pH conditions, the copper ions won’t attach to the hair. To treat your hair before going to the pool, you can either use a shampoo with a pH higher than 7, or you can even try mixing some baking soda into your regular shampoo.</p>
<p>But what can you do if your hair has already turned greenish? Well, you can try washing your hair with a shampoo designed to achieve this, typically marketed as a “chlorine removal” shampoo. These products contain a chemical called EDTA – it can bind to metal ions (such as copper) and thus will remove copper from the hair.</p>
<p>You may have heard tomato sauce or ketchup is a good way to get the green out of your pool hair – potentially because the red pigments are supposed to “cancel out” the green ones. However, I’m not aware of any scientific evidence this would work.</p>
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Read more:
<a href="https://theconversation.com/why-do-fingers-get-wrinkly-after-a-long-bath-or-swim-a-biomedical-engineer-explains-204726">Why do fingers get wrinkly after a long bath or swim? A biomedical engineer explains</a>
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<p><em>Correction: This article has been amended to clarify that alkaline shampoos have a pH higher than 7, not lower. Additionally, a positively charged copper ion has a deficiency of electrons.</em></p><img src="https://counter.theconversation.com/content/211736/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Magdalena Wajrak 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>While chlorine plays a role in making your hair appear green, there’s actually another main culprit – copper.Magdalena Wajrak, Senior lecturer, Chemistry, Edith Cowan UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1470882020-09-29T23:34:57Z2020-09-29T23:34:57ZHow to reduce COVID-19 risk at the beach or the pool<p>Australians are emerging from winter and, where possible, enjoying trips to beaches and public pools. Beach-side picnics, barbecues and get-togethers are <a href="https://www.theage.com.au/national/victoria/swimmers-lap-up-reopening-of-outdoor-pools-20200928-p5602o.html">back on the cards</a> for many of us. </p>
<p>While daily COVID-19 case numbers have been looking promising in most places lately, we are still very much in a pandemic; your spring and summertime social activities might look a little different this year.</p>
<p>Here’s how to stay safe if you’re planning a trip to the beach or public pool.</p>
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Read more:
<a href="https://theconversation.com/heading-back-to-the-gym-heres-how-you-can-protect-yourself-and-others-from-coronavirus-infection-139681">Heading back to the gym? Here's how you can protect yourself and others from coronavirus infection</a>
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<a href="https://images.theconversation.com/files/360450/original/file-20200929-24-djvsqp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A person swims laps in a pool." src="https://images.theconversation.com/files/360450/original/file-20200929-24-djvsqp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/360450/original/file-20200929-24-djvsqp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/360450/original/file-20200929-24-djvsqp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/360450/original/file-20200929-24-djvsqp.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/360450/original/file-20200929-24-djvsqp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/360450/original/file-20200929-24-djvsqp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/360450/original/file-20200929-24-djvsqp.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">Your spring and summertime social activities might look a little different his year.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<h2>The three golden rules</h2>
<p>Outdoor activities are associated with reduced COVID-19 transmission risk compared to indoor activities. That said, whatever your plans, the three golden rules still apply: stay home if you are sick, keep up the hand hygiene and maintain physical distancing from others.</p>
<p>If you’re sick, you shouldn’t be socialising at all. You should be getting a COVID-19 test and self-isolating while you wait for results. Even outdoors, one sick person can spread COVID-19 to a large number of people.</p>
<h2>Going to the beach</h2>
<p>Firstly, pick a quieter beach. The extra time it takes to research and travel to a more secluded beach may be a hassle, but it’s less risky than going to a crowded beach (and often nicer, too).</p>
<p>Consider driving or cycling to the beach (if possible) rather than taking public transport. If you do use public transport, pick an off-peak time of day and wear a mask — avoid rush hour.</p>
<p>When you arrive, put your towels down in a spot on the sand at least 1.5m away from others — more is better, if you can. You should still swim between the flags, but you don’t need to be sitting close to other people.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/360440/original/file-20200929-22-xp8n6b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="An aerial shot of an ocean pool." src="https://images.theconversation.com/files/360440/original/file-20200929-22-xp8n6b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/360440/original/file-20200929-22-xp8n6b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/360440/original/file-20200929-22-xp8n6b.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/360440/original/file-20200929-22-xp8n6b.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/360440/original/file-20200929-22-xp8n6b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=565&fit=crop&dpr=1 754w, https://images.theconversation.com/files/360440/original/file-20200929-22-xp8n6b.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=565&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/360440/original/file-20200929-22-xp8n6b.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=565&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Pick a quieter swim spot or go at a less busy time.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<p>When swimming between the flags, it might feel crowded in the water during busy times or at busy beaches. If you are in that situation, think about reducing the time spent in the water — go in for five minutes, then come out for a bit, then go back in for another five, so you are not having prolonged contact next to another person.</p>
<p>If you see someone expelling mucus into a wave, try to avoid that wave and person if you can.</p>
<p>Remember to stay COVID-safe if you’re at a cafe for a post-swim snack or ice-block. Don’t bunch up in lines close to other people and maintain physical distance from others if you are sitting down for a meal. </p>
<p>In the past, it might have felt normal to share a plate of hot chips with mates or even offer a friend a sip of your drink — but we don’t do that anymore. If you’re having a beach-side picnic, make sure you’re not sharing utensils, double-dipping in the hummus or sticking your fingers into a shared bowl of olives.</p>
<p>Of course, all these general principles also apply to other outdoor swimming locations, such as rivers and dams.</p>
<h2>Going to the pool</h2>
<p>The ocean is probably less risky than going to the pool, because there’s more movement of water and a high level of dilution.</p>
<p>So you need to approach public pools with a degree of caution.</p>
<p>But if you have no choice, are living away from the coast and want a swim, it’s probably fine to go to an outdoor pool — especially if you are living in an area with a low level of community transmission. You can find out community transmission rates in your area from your state health department website. </p>
<p>Outdoor pools are less risky than indoor pools because of increased air flow. Confined spaces are associated with increased risk of COVID-19 transmission. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/360444/original/file-20200929-20-1ihs71n.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="An outdoor pool in Sydney." src="https://images.theconversation.com/files/360444/original/file-20200929-20-1ihs71n.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/360444/original/file-20200929-20-1ihs71n.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/360444/original/file-20200929-20-1ihs71n.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/360444/original/file-20200929-20-1ihs71n.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/360444/original/file-20200929-20-1ihs71n.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/360444/original/file-20200929-20-1ihs71n.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/360444/original/file-20200929-20-1ihs71n.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Outdoor pools are less risky than indoor pools,</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<p>Choose the right time to go a pool. Transmission risk decreases with fewer people, so try to go at less busy times. In the morning, the pool water has likely had time to be well-filtered and well-chlorinated overnight and not many people have swum in it yet that day.</p>
<p>Chlorine <a href="https://www.health.gov.au/resources/publications/coronavirus-covid-19-environmental-cleaning-and-disinfection-principles-for-health-and-residential-care-facilities">kills coronavirus</a>. The <a href="https://www.cdc.gov/coronavirus/2019-ncov/faq.html?CDC_AA_refVal=https%3A%2F%2Fwww.cdc.gov%2Fcoronavirus%2F2019-ncov%2Fphp%2Fwater.html#COVID-19-and-Water">CDC says</a> it is </p>
<blockquote>
<p>not aware of any scientific reports of the virus that causes COVID-19 spreading to people through the water in pools, hot tubs, or water playgrounds […] including saltwater pools.</p>
</blockquote>
<p>The risk of transmission, albeit potentially low, would also depend on how chlorinated the pool is and how long any coronavirus that may be in the water is exposed to chlorine before coming into contact with another person. </p>
<p>Theoretically, if someone is carrying the virus and some mucus goes out of their mouth and into the pool, there might be a certain period of time before any virus in that mucus is inactivated by the chlorine. If it gets to you before that inactivation happens, then it is possibly a bit more risky.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/360459/original/file-20200929-24-66bfjc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="People swim at a pool in Sydney." src="https://images.theconversation.com/files/360459/original/file-20200929-24-66bfjc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/360459/original/file-20200929-24-66bfjc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/360459/original/file-20200929-24-66bfjc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/360459/original/file-20200929-24-66bfjc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/360459/original/file-20200929-24-66bfjc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/360459/original/file-20200929-24-66bfjc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/360459/original/file-20200929-24-66bfjc.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">Whatever you have planned this summer, think about the local risks and what you can do to reduce them.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<p>Avoiding the change-rooms is another way to reduce risk, as these rooms are often in a confined space. Being careful to maintain physical distancing in the pool, poolside and at the cafe are also important measures.</p>
<p>In general, it should be fine to take the kids to the pool but, if there was a degree of community transmission in your area, perhaps reconsider. There is <a href="https://jamanetwork.com/journals/jamapediatrics/fullarticle/2771181">growing evidence</a> kids are less susceptible to COVID-19 compared to adults but it doesn’t necessarily mean they are not transmitting it.</p>
<p>Whatever you have planned this summer, think about the local risks and what you can do to reduce them.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/as-coronavirus-restrictions-ease-heres-how-you-can-navigate-public-transport-as-safely-as-possible-138845">As coronavirus restrictions ease, here's how you can navigate public transport as safely as possible</a>
</strong>
</em>
</p>
<hr>
<img src="https://counter.theconversation.com/content/147088/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Brett Mitchell is affiliated with the University of Newcastle, Editor-in-Chief (Infection, Disease and Health), member of the Infection Control Expert Advisory Group (Advising AHHPC), member of the COVID Evidence Taskforce Leadership Group, Fellow of the Australian College of Nursing and Australasian College for Infection Prevention and Control. Brett Mitchell has received funding from the NHMRC, HCF Foundation, Australian College of Nursing, Rosemary Norman Foundation, Australasian College for Infection Prevention and Control, Cardinal Health, MSD, and the Commonwealth (Innovations Connections).</span></em></p><p class="fine-print"><em><span>Philip Russo is the President of the Australasian College for Infection Prevention and Control. He is Deputy Chair of the Infection Control Expert Group to the Department of Health, a member of the COVID Evidence Taskforce Steering Committee, the Australian Strategic and Technical Advisory Group on AMR, the Healthcare Associated Infection Advisory Committee to the Australian Commission on Safety and Quality in Health Care, and a member of the Australian College of Nursing. He is also the recipient of a NHMRC Early Career Fellowship, and has received research funding from the Rosemary Norman Foundation, Cardinal Health, Australian College of Nursing and the Cabrini Institute</span></em></p>Australians are emerging from winter and, where possible, enjoying trips to beaches and public pools, beach-side picnics, barbecues and get-togethers. Here’s how to reduce your COVID-risk.Brett Mitchell, Professor of Nursing, University of NewcastlePhilip Russo, Associate Professor, Director Cabrini Monash University Department of Nursing Research, Monash UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/819212017-08-02T11:03:45Z2017-08-02T11:03:45ZChlorine-washed chicken Q&A: food safety expert explains why US poultry is banned in the EU<figure><img src="https://images.theconversation.com/files/180699/original/file-20170802-22374-1opsxvv.jpg?ixlib=rb-1.1.0&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><strong>Why are people talking about chickens that have been washed with chlorine?</strong></p>
<p>With Brexit on the horizon, the UK is now looking for ways to open up trade with countries outside the EU. A trade deal with the US is one of the most significant options politicians are exploring and an agreement that would increase imports and exports of food and drink could be an important component of this. This has raised the possibility of the UK accepting US food standards, and <a href="http://www.bbc.co.uk/news/uk-politics-40703368">a prominent example</a> of this is the use of chlorine to wash chicken carcasses, which is currently banned in the EU.</p>
<p><strong>Why are chickens washed with chlorine in the US?</strong></p>
<p>It all comes down to money and efficiency of space. The majority of farmers do care about rearing their birds, but as profit margins can be very tight, animal welfare is sidelined to keep costs down. In the EU, cost is also important, but the law means it can’t come at the expense of the birds’ basic welfare. There is a <a href="http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=OJ:L:2007:182:0019:0028:EN:PDF">legal minimum</a> amount of space, lighting and ventilation for EU poultry rearing houses. </p>
<p>The more space the birds have to move around in, the fewer can be housed in a single area, which in turn has an effect on production costs. As there are no laws governing this in the US, the birds can be crammed in tightly so they have limited movement, with little light or ventilation. This reduces production costs but increases the <a href="http://www.tandfonline.com/doi/full/10.1080/03079457.2013.874006">risks of disease and contamination</a> in a flock.</p>
<p>Washing the chickens in a strong chlorine solution (20-50 parts per million of chlorine) provides a brash, cost-effective method of killing any microorganisms on the surface of the bird, particularly bacteria such as species of <em>Salmonella</em> and <em>Campylobacter</em>. This helps prevent the meat being <a href="https://www.fsis.usda.gov/wps/wcm/connect/1d562776-ebfb-4ea5-a19b-e994776a02c6/Compliance_Guideline_Controlling_Salmonella_Poultry.pdf?MOD=AJPERES">contaminated with microbes</a> during slaughter and evisceration.</p>
<p><strong>Why is the process banned in the EU?</strong></p>
<p>US chicken has been <a href="https://fas.org/sgp/crs/row/R40199.pdf">banned in the EU since 1997</a> because of this chlorine washing process. But this isn’t because the treatment itself has been deemed dangerous. A report by the <a href="https://ec.europa.eu/food/sites/food/files/safety/docs/sci-com_scv_out14_en.pdf#page=16">EU Scientific Committee on Veterinary Measures</a>, for example, highlighted that the chemical cleaning treatment can be effective at removing foodborne pathogens depending on how it is used. The real fear is that heavily soiled birds may not be sufficiently disinfected, and that relying on chlorine washing could lead to poorer hygiene standards overall.</p>
<p>EU officials believe the food industry should be continually improving hygiene standards in all steps of processing – the “<a href="http://ec.europa.eu/dgs/health_food-safety/information_sources/docs/from_farm_to_fork_2004_en.pdf">farm to fork</a>” principle, and so have banned chickens washed in chlorine as a deterrent to poor practices. But in the US, there are no poultry welfare standards so the process is common. There have also been reports, including undercover <a href="https://www.youtube.com/watch?v=oNAo2cvvefQ">video evidence</a> by the <a href="http://blog.humanesociety.org/wp-content/uploads/2017/06/HSUS-undercover-report-pilgrims-pride.pdf">Humane Society of the United States</a>, of both inhumane and unsanitary practices being carried out within poultry houses due to a lack of animal welfare regulation.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/180704/original/file-20170802-20033-51yx6o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/180704/original/file-20170802-20033-51yx6o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/180704/original/file-20170802-20033-51yx6o.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/180704/original/file-20170802-20033-51yx6o.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/180704/original/file-20170802-20033-51yx6o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/180704/original/file-20170802-20033-51yx6o.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/180704/original/file-20170802-20033-51yx6o.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">Aiming for higher standards.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<p><strong>What are the potential health risks of chlorine washing?</strong></p>
<p>Although there are some benefits to this chlorine washing, there are concerns about it. Some US abattoirs and processing plants rely heavily on chlorination because their other <a href="https://www.wired.com/2014/12/cwif-craigwatts-perdue/">hygiene standards are so poor</a> that they would be illegal in Europe. The process is also very good at <a href="http://en.cnki.com.cn/Article_en/CJFDTOTAL-XDYI200605021.htm">removing odours</a> and surface slime, meaning the meat can be passed off as fresh for much longer than it should be.</p>
<p>Chlorine isn’t toxic at the levels used in the washing process and doesn’t itself cause cancer. But studies have shown that the treatment can cause carcinogens such as <a href="https://www.ncbi.nlm.nih.gov/pubmed/15204530">semicarbazide</a> and <a href="http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2621.1977.tb08411.x/abstract">trihalomethanes</a> to form in the poultry meat if the concentration of chlorine is high enough. The US <a href="https://www.fsis.usda.gov/wps/wcm/connect/bab10e09-aefa-483b-8be8-809a1f051d4c/7120.1.pdf?MOD=AJPERES">Food Safety and Inspection Service</a> does set limits to prevent this but there is always a risk they could be violated.</p>
<p><strong>Is there much evidence to support the EU ban?</strong></p>
<p>The EU ban is more precautionary than evidence based. When the ban was introduced, officials were keen that food manufacturers should focus on overall hygiene rather than relying on a single chemical decontamination step to eliminate microorganisms. It was also believed that the chemical decontamination step <a href="https://fas.org/sgp/crs/misc/R40199.pdf">could encourage antibiotic resistance</a>.</p>
<p>As a result, the EU <a href="http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=OJ:L:2004:139:0055:0205:EN:PDF">introduced regulations</a> laying down specific hygiene rules on the hygiene of foodstuffs. This prohibits the use of anything other than water to decontaminate meat and effectively bans US imports of poultry treated with antimicrobial rinses. However, the European Food Safety Authority has <a href="http://onlinelibrary.wiley.com/doi/10.2903/j.efsa.2010.1544/epdf">found no conclusive evidence</a> that antimicrobial chemicals used in food processing contribute to antibiotic resistance.</p>
<p><strong>If the UK started importing chlorinated chickens, wouldn’t consumers simply be able to choose whether or not to buy them?</strong></p>
<p>Under <a href="http://eur-lex.europa.eu/legal-content/EN/TXT/PDF/?uri=CELEX:32011R1169&from=EN">current EU rules</a>, the chlorine wash is classed as a processing aid rather than an ingredient and so wouldn’t have to be declared on the packaging. This means UK consumers would be unlikely to know whether imported US chicken had been through the chlorination process unless it was voluntarily declared. Of course, once the UK leaves the EU, it would be free to change the rules. But that doesn’t mean it necessarily would.</p><img src="https://counter.theconversation.com/content/81921/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Simon Dawson 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>Washing chickens in chlorine isn’t actually deemed dangerous – it’s what comes with it that’s the problem.Simon Dawson, Lecturer in Food Safety, Food Quality and Environmental Management, Cardiff Metropolitan UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/739362017-03-03T10:14:15Z2017-03-03T10:14:15ZWhy that ‘clean swimming pool’ smell is actually bad for your health<figure><img src="https://images.theconversation.com/files/159265/original/image-20170303-16352-lve2r2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The busier the pool, the worse it is.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/some-students-swim-racing-indoor-pool-96243236?src=rL0vSDm5a41Y094aKPZfvA-1-18">Shutterstock</a></span></figcaption></figure><p>It’s recently been reported that scientists have managed to create a <a href="https://www.theguardian.com/science/2017/mar/01/how-much-pee-is-in-our-swimming-pools-new-urine-test-reveals-the-truth">test to measure how much urine</a> is in a swimming pool. It seems that peeing in the pool has become commonplace, and even <a href="http://www.dailymail.co.uk/news/article-2254037/Michael-Phelps-Ryan-Lochte-right-say-theres-wrong-peeing-pool-say-scientists.html">high-profile swimmers have admitted</a> to doing it during rigorous training sessions, arguing that the chlorine “kills it”. Not only is this untrue, but the chemical reaction that occurs between your pee and the chlorine creates a chemical that has <a href="http://erj.ersjournals.com/content/19/5/827">been linked to asthma</a> and other respiratory issues.</p>
<p>Nitrogen trichloride, also known as <a href="https://www.acs.org/content/acs/en/molecule-of-the-week/archive/t/trichloramine.html?cid=home_motw">trichloramine</a>, is made when the urea in your pee reacts with chlorine – the disinfectant widely used in swimming pool water. Nitrogen trichloride is largely made by accident in pools these days, but this compound was originally made for interest in <a href="https://h2oblogged.wordpress.com/charts-calculators-indexes/swimming-pool-water-tests/nitrogen-trichloride-ncl3-airborne-test/nitrogen-trichloride/">1812 by Pierre Louis DuLong</a>.</p>
<p>DuLong made the chemical by bubbling chlorine gas through a solution of ammonium chloride. But, despite his success, DuLong’s joy at having made it was probably short-lived – he hadn’t counted on the fact that it would be explosive – the chemical exploded without warning and <a href="http://www.sciencedirect.com/science/article/pii/S0950423000000115">cost him an eye and a finger</a>. It’s extremely sensitive and will explode even under gentle shock or when exposed to sunlight.</p>
<p>Scientists Sir Humphry Davy and Michael Faraday also fell victim to the substance when they repeated DuLong’s work shortly after. An explosion also caused Davy to lose the use of an eye temporarily and Faraday did permanent damage to his fingers.</p>
<p>Luckily for professional swimmers, only pure nitrogen trichloride is explosive, and so the fact that it is mixed with water and other substances in a swimming pool should be reassuring. However, research suggests that nitrogen trichloride, among other products formed when you pee in chlorinated water, such as chloramine and dichloramine, is linked to eye and upper airway irritation. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/159263/original/image-20170303-16372-h7929s.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/159263/original/image-20170303-16372-h7929s.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/159263/original/image-20170303-16372-h7929s.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/159263/original/image-20170303-16372-h7929s.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/159263/original/image-20170303-16372-h7929s.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/159263/original/image-20170303-16372-h7929s.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/159263/original/image-20170303-16372-h7929s.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">Michael Phelps pees in the pool.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/rio-de-janeiro-brazil-august-8-469770791?src=HlZsTJarb4hxq4F0O0SzRA-1-2">Shutterstock</a></span>
</figcaption>
</figure>
<p>It’s rather ironic that the chlorine that is used to kill bacteria and protect the health of swimmers, is linked to the creation of toxic chemicals. But also that the <a href="http://www.waterandhealth.org/swimming-shower/">aroma that people associate with a clean pool</a>, is actually the stench of nitrogen trichloride and an indicator of plenty of pee.</p>
<h2>Occupational health hazard</h2>
<p>It is a volatile chemical, meaning it easily turns into a gas and hangs around in the air around the pool. One study has shown that people who work in swimming pools or spend a lot of time around them, such as lifeguards, have a <a href="https://www.ncbi.nlm.nih.gov/pubmed/17107995">higher level of airway issue symptoms</a> in comparison with the general population – poolside workers showed more frequent work-related upper respiratory issues than administrative staff.</p>
<p>It’s reported that one study found that a public swimming pool of <a href="https://www.theguardian.com/science/2017/mar/01/how-much-pee-is-in-our-swimming-pools-new-urine-test-reveals-the-truth">830,000 litres, can contain as much as 75 litres of urine</a> in the water at one time, which could react to form nitrogen trichloride. This may not sound like a lot, but the toxicity of chemicals is often in the dose and repeated exposure, so even low levels of nitrogen trichloride, will have damaging health effects. </p>
<p>But it <a href="https://www.acs.org/content/acs/en/pressroom/presspacs/2016/acs-presspac-august-3-2016/whats-really-in-your-swimming-pool.html">isn’t just pee that we should worry about</a> – the dirt on people’s bodies can consume up to 30% of the chlorine in the water on its own and in athletic swimmers, sweat – which also contains urea – can also contribute to the production of nitrogen trichloride. </p>
<p>So what can we do to combat it? Research which models the <a href="http://www.psep.ichemejournals.com/article/S0957-5820(14)00155-4/fulltext">amounts of nitrogen trichloride in a swimming pool</a> over time has led some researchers to suggest that lowering the levels of chlorine in a pool, while remaining above the legal lower limit, would reduce the amount of chlorine available to react to form the toxic chemical. However, this study was limited to a single pool, so more research is required to establish whether this could be a feasible solution.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/159264/original/image-20170303-16378-19nlb27.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/159264/original/image-20170303-16378-19nlb27.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=401&fit=crop&dpr=1 600w, https://images.theconversation.com/files/159264/original/image-20170303-16378-19nlb27.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=401&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/159264/original/image-20170303-16378-19nlb27.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=401&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/159264/original/image-20170303-16378-19nlb27.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=504&fit=crop&dpr=1 754w, https://images.theconversation.com/files/159264/original/image-20170303-16378-19nlb27.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=504&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/159264/original/image-20170303-16378-19nlb27.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=504&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Poolside workers are at risk.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/instructor-group-children-doing-exercises-near-405188230?src=h08PudiITt6GRQFMqUslkg-1-29">Shutterstock</a></span>
</figcaption>
</figure>
<h2>Don’t pee like a pro</h2>
<p>Swimming pools have long encouraged swimmers to take a <a href="http://www.waterandhealth.org/swimming-shower/">shower before they swim</a>, but the health implications of not showering are not emphasised enough. It’s not enough to recommend a shower to “reduce irritants” – swimmers need to know that these irritants can cause respiratory issues, and not just for them but also the pool staff. </p>
<p>Swimmers should also be encouraged to pee before they get into the pool, something that should extend to elite athletes too – <a href="http://uk.businessinsider.com/michael-phelps-everybody-pees-pool-2016-8?r=US&IR=T">Michael Phelps</a> might think it’s an accepted part of the sport, but it only gives licence to others if the professionals are doing it – they need to lead the way in pool hygiene. </p>
<p>Unfortunately, the “<a href="http://chemistry.about.com/od/waterchemistry/f/pool-urine-indicator.htm">swimming pool dye</a>” which changes colour on pee contact seems to be a mere myth in most countries and there do not appear to be any <a href="http://www.lims.hu/media/furdokonf/English/presentationsp/geradin_p.pdf">feasible alternatives to chlorine</a> which can disinfect a pool and not expose the staff to some harmful chemicals. So maybe it’s best to keep up the pretence if the prospect of embarrassment means people will actually go to the toilet.</p><img src="https://counter.theconversation.com/content/73936/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Laura Finney is affiliated with The Conversation as an intern. </span></em></p><p class="fine-print"><em><span>Simon Cotton 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>Nitrogen trichloride makes swimming pools smell and is a good indicator of plenty of pee.Simon Cotton, Senior Lecturer in Chemistry, University of BirminghamLaura Finney, PhD Candidate, University of NottinghamLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/650682016-09-07T16:47:47Z2016-09-07T16:47:47ZSyria chlorine attack claims: what this chemical is and how it became a weapon<p>New claims that the Syrian government have dropped barrel bombs full of chlorine <a href="http://www.bbc.co.uk/news/world-middle-east-37291182">on a suburb of Aleppo</a> are the latest in a <a href="https://theconversation.com/chlorine-attacks-continue-in-syria-with-no-prospect-of-assad-being-brought-to-account-39209">series of allegations</a> of chemical weapon use. Although the Syrian government denies using chemical weapons, a recent UN-led enquiry found it had used chlorine on <a href="http://www.bbc.co.uk/news/world-middle-east-37184856">at least two occasions</a>.</p>
<p>Here’s what you need to know about chlorine and its use as a chemical weapon.</p>
<h2>Greenish-yellow gas</h2>
<figure class="align-right ">
<img alt="" src="https://images.theconversation.com/files/136937/original/image-20160907-25272-pd45d2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/136937/original/image-20160907-25272-pd45d2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=800&fit=crop&dpr=1 600w, https://images.theconversation.com/files/136937/original/image-20160907-25272-pd45d2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=800&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/136937/original/image-20160907-25272-pd45d2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=800&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/136937/original/image-20160907-25272-pd45d2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1006&fit=crop&dpr=1 754w, https://images.theconversation.com/files/136937/original/image-20160907-25272-pd45d2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1006&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/136937/original/image-20160907-25272-pd45d2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1006&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Chlorine gas.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Chlorine_in_bottle.jpg">W Oelen/Wikimedia</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>The chemical element chlorine is too reactive to exist on its own in nature, but some of the compounds that contain it are essential to life. We use hydrochloric acid (HCl) in our stomachs to break down food and destroy bacteria, while sodium chloride (NaCl) – the common salt we add to food – is so important that it was once used as a currency.</p>
<p>Pure chlorine was first isolated from hydrochloric acid by Carl Wilhelm Scheele in 1774. Within a few years, its bleaching properties were discovered and in 1810 Humphry Davy announced that it was a chemical element. At room temperature, it is a greenish-yellow gas with a choking smell, which is denser than air.</p>
<p>Dry chlorine gas won’t bleach, but in water it forms hypochlorite, responsible for the bleaching action, and also responsible for its disinfectant action. It was first used to <a href="http://www.scientificamerican.com/article/how-does-chlorine-added-t/">disinfect tap water</a> at the time of a typhoid outbreak in Maidstone in 1897. Since then the process has been generally adopted.</p>
<p>Forty million tons of chlorine is manufactured a year, among other things for use in making many pharmaceuticals. Thousands of organic chlorine compounds occur naturally including vancomycin, which for many years was the antibiotic of last resort and is <a href="https://www.iupac.org/publications/pac/1996/pdf/6809x1699.pdf">made in nature</a> by a bacterium in the soil.</p>
<h2>Health dangers</h2>
<p>But chlorine itself is <a href="http://www.lenntech.com/periodic/elements/cl.htm">very reactive with the human body and very toxic</a>. It irritates the eyes and skin and, even at quite low levels, can causes permanent lung damage even if it does not kill you. Breathing high levels of chlorine causes pulmonary oedema – fluid buildup in the lungs.</p>
<p><a href="http://www.scientificamerican.com/article/chlorine-accidents-take-big-human-toll/">Accidents with chlorine</a> do happen. In Graniteville, South Carolina, on January 6 2005, a railroad tanker full of liquefied chlorine gas was punctured <a href="http://www.southcarolinaradionetwork.com/2015/01/06/we-couldnt-breathe-the-graniteville-train-derailment-a-decade-later/">killing eight people</a> that day, with another fatality three months later attributed to inhaling the gas. More than 5,000 people were evacuated from its immediate vicinity and some have health problems more than ten years later.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/136927/original/image-20160907-25249-kmyl5n.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/136927/original/image-20160907-25249-kmyl5n.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=424&fit=crop&dpr=1 600w, https://images.theconversation.com/files/136927/original/image-20160907-25249-kmyl5n.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=424&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/136927/original/image-20160907-25249-kmyl5n.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=424&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/136927/original/image-20160907-25249-kmyl5n.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=533&fit=crop&dpr=1 754w, https://images.theconversation.com/files/136927/original/image-20160907-25249-kmyl5n.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=533&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/136927/original/image-20160907-25249-kmyl5n.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=533&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"></span>
<span class="attribution"><a class="source" href="http://www.compoundchem.com/wp-content/uploads/2014/05/Chemical-Warfare-World-War-1-Poison-Gases1.png">Compound interest.</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<h2>Use as a weapon</h2>
<p><a href="http://chemicalweapons.cenmag.org/who-was-the-father-of-chemical-weapons/">Fritz Haber</a> (1868-1934) knew about the toxicity of chlorine when he chose it as his agent of warfare in 1915. He had already come up with the <a href="http://chemgeneration.com/milestones/the-haber-bosch-process.html">Haber-Bosch process</a>, patented in 1910, for the fixation of nitrogen as ammonia, which won him the 1918 Nobel Prize in chemistry. This made the manufacture of artificial fertilisers possible and the survival of millions of people today depends on it.</p>
<p>But it also enabled the mass production of nitric acid, source of the explosives that Germany used in World War I. Haber was an intensely patriotic German Jew. He was head of the chemistry section in the Ministry of War, coordinating the production of ammonia needed to fight the war. He was also in charge of chemical warfare, choosing chlorine gas as the agent. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/136933/original/image-20160907-25231-iisusu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/136933/original/image-20160907-25231-iisusu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=372&fit=crop&dpr=1 600w, https://images.theconversation.com/files/136933/original/image-20160907-25231-iisusu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=372&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/136933/original/image-20160907-25231-iisusu.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=372&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/136933/original/image-20160907-25231-iisusu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=467&fit=crop&dpr=1 754w, https://images.theconversation.com/files/136933/original/image-20160907-25231-iisusu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=467&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/136933/original/image-20160907-25231-iisusu.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=467&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">British chlorine gas casualties April 1915.</span>
<span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/Chemical_weapons_in_World_War_I#/media/File:British_55th_Division_gas_casualties_10_April_1918.jpg">Thomas Keith Aitken/Imperial War Museum</a></span>
</figcaption>
</figure>
<p>Haber supervised the installation of the <a href="http://chemicalweapons.cenmag.org/when-chemicals-became-weapons-of-war/">first chlorine gas cylinders</a> in the trenches on the Western front, near Ypres. He and the specialist troops waited for the wind to blow from the east towards the Allied trenches and launched the first gas attack on April 22 1915. As clouds of chlorine drifted towards the Allies, <a href="http://chemicalweapons.cenmag.org/first-hand-accounts-of-the-first-chlorine-gas-attack/">panic set in</a>. It was no good diving into a trench, as the dense chlorine was heavier than air and poured in. Of the 15,000 or more casualties, <a href="http://www.independent.co.uk/news/world/100-years-on-the-day-the-first-poison-gas-attack-changed-the-face-of-warfare-forever-10193976.html">5,000 soldiers were killed</a>.</p>
<p>Haber’s story ended tragically in several ways. He returned home to a celebration of the success of the attack on May 1 but that night his wife Clara committed suicide after an argument – possibly over the morality of what he was doing. A few years later he developed a system for getting rid of insect pests, using hydrogen cyanide. It became known as the Zyklon system. A derivative pesticide, Zyklon B, was used to exterminate millions in Nazi concentration camps, where many of Haber’s close relatives died.</p>
<p>Gas masks were developed to protect against chlorine attacks and other chemical warfare agents were developed. But chlorine remains the simplest chemical weapon and reappeared on the battlefield <a href="http://www.nytimes.com/2007/02/21/world/middleeast/21cnd-baghdad.html?_r=0">during the Iraq War</a> and allegedly now in Syria. In World War II, both sides of the conflict knew that the other side had weaponised chlorine and refrained from using it. Today in Syria, it sadly appears this may not have been the case.</p><img src="https://counter.theconversation.com/content/65068/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Simon Cotton 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 Assad government is accused of using chlorine gas as a weapon against its own people.Simon Cotton, Senior Lecturer in Chemistry, University of BirminghamLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/554762016-03-07T11:03:44Z2016-03-07T11:03:44ZCan drinking water be delivered without disinfectants like chlorine and still be safe?<figure><img src="https://images.theconversation.com/files/113776/original/image-20160303-10640-1jhlfwm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Chlorine needed? </span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/widnr/6589936511/in/photolist-b3k9x2-4rEQx7-4bkXk4-6CBiyf-8NSr6d-8iDosf-nSgb38-a9PRkt-hYYDMc-i5UAmL-rNwevY-xAn2g-fB48Wy-4VTdSZ-dmFFk5-HZYWy-tF6ru-5uwvB-x6nHWa-2s2P-4UqaCh-4MinEK-7vrHe8-7UDonh-nr3BY-9i5E4U-e2xk3-f7SJEQ-nvduJo-b3k8tX-oABSZ-qDS7E-7vUE4b-545GBd-bpKHvH-pQRMk-7vUEbW-fqBfCR-98ATRP-5LsPqT-6H64nT-4MinHn-9boK6e-319UEu-AjAaCa-CU64p-aqBWbC-adYWWF-99X47b-519pJo">Wisconsin Department of Natural Resources</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>When we open the tap, we expect the water to be safe. That is, the water should be free of pathogens that could make us sick and any chemicals that could cause problems later in life. </p>
<p>For the most part, potable water systems in the developed world have done a great job providing safe water. However, there are still unfortunate situations that develop, resulting in issues with the safety of drinking water. </p>
<p>Most notably, in the past several months, the city of Flint, Michigan, has been dealing with a <a href="http://www.nytimes.com/2016/01/18/us/obama-flint-michigan-water-fema-emergency-disaster.html">crisis</a> regarding their delivery of potable water. A significant number of the citizens of Flint were exposed to dangerously high concentrations of <a href="http://www.nytimes.com/2016/01/18/us/obama-flint-michigan-water-fema-emergency-disaster.html">lead</a> in their drinking water. The episode was triggered by a switch in drinking water source undertaken by the city, without the proper evaluation of the consequences regarding the <a href="https://theconversation.com/the-science-behind-the-flint-water-crisis-corrosion-of-pipes-erosion-of-trust-53776">change in the chemistry of the water</a>. </p>
<p>The episode has brought much attention to water treatment methods to ensure public safety. In many countries the use of a disinfectant, such as chlorine or chloramine, in the distribution system is required. These countries include the United States and the United Kingdom. A disinfectant is used as a final barrier to protect human health against potential contamination events during distribution. </p>
<p>However, there are a number of countries that do not carry a disinfectant that remains in the water once it’s distributed. How can these countries deliver safe water without this disinfectant included? </p>
<p>In a <a href="http://science.sciencemag.org/content/351/6276/912">recently published paper</a>, we, together with other colleagues, set out to evaluate this question. Our main motivation was to take a close look at whether municipalities could avoid some of the potential negative effects of a disinfectant while still ensuring public health. </p>
<h2>The pros and cons of disinfection</h2>
<p>One of the great public health successes of the 20th century was the eradication of most waterborne epidemics in the developed world. In the year 1902, chlorine was first added to water as a disinfectant in Belgium. Additional sites in the United States and the United Kingdom following suit by 1908. This resulted in a decrease in the incidence of waterborne diseases.</p>
<p>Fast forward to 1974, when Dutch researchers discovered the <a href="http://www.cdc.gov/safewater/publications_pages/thm.pdf">presence of chloroform</a>, a <a href="https://ntp.niehs.nih.gov/ntp/roc/content/profiles/chloroform.pdf">probable human carcinogen</a>, in potable water. </p>
<p>Ever since, scientists have identified hundreds of disinfection byproducts (DBPs), compounds that are formed by the reaction between chlorine and naturally present organic matter in the water. The concentrations of these compounds are regulated in the United States and Europe based on measurements of indicator groups of compounds, such as <a href="https://cfpub.epa.gov/ncer_abstracts/index.cfm/fuseaction/display.highlight/abstract/22">trihalomethanes</a>, which are known to be carcinogenic.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/113779/original/image-20160303-13754-spjwr9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/113779/original/image-20160303-13754-spjwr9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/113779/original/image-20160303-13754-spjwr9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=401&fit=crop&dpr=1 600w, https://images.theconversation.com/files/113779/original/image-20160303-13754-spjwr9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=401&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/113779/original/image-20160303-13754-spjwr9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=401&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/113779/original/image-20160303-13754-spjwr9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=504&fit=crop&dpr=1 754w, https://images.theconversation.com/files/113779/original/image-20160303-13754-spjwr9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=504&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/113779/original/image-20160303-13754-spjwr9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=504&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">American water treatment plants started using chlorine as a disinfectant about 100 years ago, but after the 1970s, some European countries found effective ways to treat water without chlorine.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/roome/4573367298/in/photolist-7Y8GLj-9V1tk2-hMRPo5-eeCr7s-eeCr6A-5w3UQL-nQr3zp-4kUko3-zwWxmB-o7nqJv-aDRJyb-9V1saP-6PQzfo-9wErFq-8Ub4SL-a4Dfi-dmiXzZ-55cNXB-77kSf3-qs7wyE-7gBJ6g-AkNFNL-p4s9Yg-oSTgUd-byRnQR-66QYkZ-7Qk7AJ-4zAtjX-49564G-7svcNK-pUewn7-3ZVu59-oNgsHq-dmDin2-qZoLNi-ps6hss-anYxtr-77h2oD-4Rgw1x-4RgwMX-4RkHh7-JKPB-73ikcU-9LebBp-aQoKnH-4kUmab-aub8tt-gVrHcM-n1zcd-hdLPon/">roome/flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc/4.0/">CC BY-NC</a></span>
</figcaption>
</figure>
<p>The discovery of DBP, coupled with negative public perceptions regarding the taste of chlorine, has motivated several countries, including the Netherlands, Switzerland and Germany, to move toward potable water delivery systems without disinfectants that remain with the water – known as residual disinfectants – and thus, reach people’s taps. This change started in the late 20th century. </p>
<p>All water treatment facilities include a disinfection step designed to inactivate pathogens. This process can include different disinfecting agents such as chlorine, ozone, chloramine and UV light. </p>
<p>After disinfection, the water is considered safe. In countries that do not carry a disinfectant that remains in the water beyond the treatment plant, engineers focus on producing water that does not contain high concentrations of biodegradable material that might encourage microbial growth in the pipes. Microbial growth in pipes in the form of biofilm can be undesirable because it contributes to corrosion and water quality degradation and could potentially harbor pathogens. Generally speaking, these countries also conduct a higher level of treatment of the water. </p>
<p>In the United States and United Kingdom, a residual disinfectant is required within the water distribution system as part of the final barrier. But the use of this disinfectant also means that concentrations of DBPs must be managed. The current best practice for managing DBPs includes reducing water age in the system through pumping and storage optimization, aeration for stripping of volatile compounds at storage facilities and dosing disinfectant at remote sites across the system.</p>
<p>In the Netherlands, Switzerland and Germany, by contrast, a residual disinfectant is not used as a barrier. In these countries water utilities rely instead on advanced treatment, improved physical integrity of the distribution system and careful management of distribution system operations. </p>
<p>Distribution system management in the Netherlands, for example, begins with network design. This includes trials of so-called self-cleaning networks using significantly smaller sized pipes than in North America to reduce water age. There are also proactive operational programs such as monitoring, flushing, break repair and precautionary boil water notices for customers.</p>
<p>It’s worth noting that water is distributed without a disinfectant only as long as sufficient barriers against contamination are in place. The concept of multiple barriers ensures safety in the event of a failure of one of these barriers, which include protecting the source water, multiple treatment steps and proactive management of the distribution system. </p>
<p>This prompts the question: which approach is right? </p>
<p>To answer this question, we need to define the parameters under which the approaches will be evaluated. Said simply, we need to address whether the presence of a disinfectant results in lower incidences of waterborne outbreaks. Regarding DBPs, we can agree that limiting exposure to them is a good thing.</p>
<h2>Is chlorine needed to protect human health?</h2>
<p>As it turns out, there is very little data showing that a disinfectant residual in the distribution system has prevented waterborne outbreaks. </p>
<p>A <a href="http://science.sciencemag.org/content/351/6276/912">comparison</a> of waterborne outbreak data from different countries shows that the Netherlands, the one country we evaluated that does not use disinfectant residual, has very little risk of waterborne disease. So in terms of microbial indicators of risks, systems with a residual disinfectant are not necessarily safer than those without.</p>
<p>One key difference between these countries could be the condition and operation of the pipes that distribute the water. In general, countries that do not carry a residual have invested in upgrading their distribution systems to limit contamination events from leaks and breaks.</p>
<p>For example, in the Netherlands, at least half of pipes have been replaced from cast iron to plastic since the 1970s, resulting in fairly young distribution systems. In the United States, there is a serious need to upgrade <a href="http://www.awwa.org/Portals/0/files/legreg/documents/BuriedNoLonger.pdf">infrastructure</a> and this will require a significant investment over the next decades. However, the investment is worth it to avoid another public health crisis like in Flint, Michigan.</p>
<p>One of the conclusions from our research is that potable water systems should consider moving beyond carrying a disinfectant and focus instead on maintaining and replacing their aging delivery systems and upgrading their water treatment steps. This will have the benefit of limiting exposure to DBP while also continuing to deliver safe water to consumers.</p><img src="https://counter.theconversation.com/content/55476/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Fernando Rosario-Ortiz receives funding from the Water Research Foundation, the US National Science Foundation and the US Environmental Protection Agency.</span></em></p><p class="fine-print"><em><span>Vanessa Speight receives funding from EPSRC and various water utilities in the US and UK. </span></em></p>Unlike the U.S., some European countries have stopped using chlorine to disinfect drinking water to avoid changing the taste and potential health problems. Which approach is better?Fernando Rosario-Ortiz, Associate Professor of Environmental Engineering, University of Colorado BoulderVanessa Speight, Senior research fellow, University of SheffieldLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/405212015-04-22T14:48:11Z2015-04-22T14:48:11ZA century after WWI gas attacks, scientists must unite against chemical weapons<figure><img src="https://images.theconversation.com/files/78918/original/image-20150422-1833-1htkjeo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Never again? A poison gas attack in World War I.</span> <span class="attribution"><a class="source" href="http://commons.wikimedia.org/wiki/File:Poison_gas_attack.jpg#/media/File:Poison_gas_attack.jpg">Wikimedia Commons</a></span></figcaption></figure><p>The first large-scale use of chemical weapons occurred 100 years ago at Ypres in Belgium. Its passing gives us all cause for reflection on the dreadful horrors of war – but more specifically on those that arise form chemical weapons.</p>
<p>At a commemoration of the April 1915 incident, the Secretary General of the Organisation for the Protection of Chemical Weapons emphasised that “chemical scientists must use chemistry only for the benefit of mankind and chemicals must never again be used to do harm.”</p>
<p>The event also saw a new <a href="http://www.diis.dk/en/node/4841">Ypres Declaration</a>, which commits the organisation to removing all chemical weapons, as well as calling for all countries that have not done so to sign and ratify the Convention on Chemical Weapons. It also emphasises the huge importance of ethically used chemicals and chemistry to the lives of all of us.</p>
<p>I am president of the European Association for Chemical and Molecular Sciences, which represents some 160,000 chemists in Europe and beyond. We recognise that as chemists, we have the ability to make, control and deactivate chemical weapons – and that it is incumbent on us to use these skills only for ethical purposes. </p>
<p>We have a particular responsibility to stand up and call for an end to the use of chemical weapons and for the destruction of all stockpiles. </p>
<h2>Holdouts</h2>
<p>The task is enormous. These weapons have remained in circulation even though the world has long acknowledged that they have no place in modern civilisation. </p>
<p>They were first banned by the Geneva Protocol of 1925, but the current regime is framed by the <a href="https://www.opcw.org/chemical-weapons-convention/">Convention on the Development, Production, Stockpiling and Use of Chemical Weapons</a>, adopted in Geneva in 1992.</p>
<p>Signatories to this treaty have to reveal what, if any, stocks of chemical weapons they hold. They are then given help to destroy any stockpiles, delivery systems or manufacturing facilities. For early signatories, a deadline of April 29 2012 was set for the destruction of stockpiles.</p>
<p>Of the 196 nations in the world, only <a href="http://www.opcw.org/about-opcw/non-member-states/">four</a> have not acceded to the convention: Angola, Egypt, North Korea and South Sudan. Israel has signed but not ratified the treaty, meaning that it has not declared its position; Myanmar (Burma) <a href="http://www.armscontrol.org/blog/ArmsControlNow/2015-01-28/Myanmar-Ratifies-Chemical-Weapons-Convention">recently ratified it</a>. (Taiwan, not being a recognised nation, is not included in the convention.) </p>
<p>It is known that some of these countries, notably <a href="http://www.nti.org/country-profiles/egypt/">Egypt</a>, <a href="http://www.telegraph.co.uk/news/worldnews/asia/northkorea/11394447/North-Korea-stages-chemical-warfare-drills.html">North Korea</a>, <a href="http://www.nti.org/country-profiles/israel/chemical/">Israel</a> and <a href="http://www.armscontrol.org/blog/ArmsControlNow/2015-01-28/Myanmar-Ratifies-Chemical-Weapons-Convention">Burma</a> have or have had the ability to make and supply chemical weapons. And although Russia and the US have worked to destroy their very large stockpiles or make them unavailable, they have not finished doing so.</p>
<p>The most recent signatory to the convention is Syria, which <a href="http://www.bbc.co.uk/news/world-middle-east-22557347">used chemical weapons against its own people in 2013</a>. An agreement was reached with the OPCW that other countries, mainly Russia and the US would remove and destroy chemical weapons by mid-2014. </p>
<p>By now, almost all are believed to have been destroyed – yet despite this, it is clear that barrel bombs containing chlorine, one of the agents used in Ypres in 1915, are <a href="https://theconversation.com/chlorine-attacks-continue-in-syria-with-no-prospect-of-assad-being-brought-to-account-39209">still being dropped on inhabited areas</a>.</p>
<h2>Everyday substances</h2>
<p>Chlorine is used in almost all countries as a water additive. It allows us to drink tap water without contracting typhoid or other diseases that were rampant before its use. Barrels of chlorine will be held by every water purification plant for perfectly benign purposes, but in the wrong hands, they can become weapons of mass destruction.</p>
<p>Phosgene, the other agent used in the April 1915 attack, is a key intermediate in the production of the tough, transparent polycarbonates and in the production of methyl isocyanate for making polyurethanes. But the devastating risks of its ineffective containment were made plain in the 1984 tragedy at Bhopal in India, where the failure of a methyl isocyanate plant is believed to have led to the release of hydrogen cyanide and phosgene. The Indian government estimates that <a href="http://www.theatlantic.com/photo/2014/12/bhopal-the-worlds-worst-industrial-disaster-30-years-later/100864/">around 15,000 people</a> were killed.</p>
<p>Meanwhile, some potential chemical agents are effective weapons because they attack fast-growing cells like those in mucous membranes. But many of these agents have found use as anti-cancer drugs, since cancer cells are also faster-growing than normal cells – again meaning that they are on the market as substances with legitimate uses.</p>
<h2>Stand up</h2>
<p>Ultimately, it is chemists and their knowledge who stand between these chemicals and states and forces that want to use them for lethal ends. </p>
<p>As president of the European Association for Chemical and Molecular Sciences (<a href="http://www.euchems.eu/">EuCheMS</a>), I call on all chemists worldwide to denounce chemical weapons and refuse to do any work on them other than on their control and deactivation. EuCheMS supports the efforts of the OPCW and urges it to redouble its efforts to remove the scourge of chemical weapons permanently from our planet.</p>
<p>I also urge all chemists involved in the peaceful and legitimate use of chemicals that can be chemical weapons themselves or can be precursors to them, to ensure that all supplies are stored in terrorist-proof ways.</p>
<p>Only if chemists use their skills and knowledge this way will we have any hope of stopping the repeat of what’s happening in Syria – and what happened at Ypres 100 years ago.</p><img src="https://counter.theconversation.com/content/40521/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>David Cole-Hamilton is a member of the Liberal Democrats and President of a Division of the Royal Society of Chemistry.</span></em></p>A century since chlorine gas was used at Ypres, beginning the era of chemical weapons, controlling lethal agents is harder than ever.David Cole-Hamilton, Emeritus Professor of Chemistry, University of St AndrewsLicensed as Creative Commons – attribution, no derivatives.