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Sydney Harbour’s toxic legacy shows value of green safety net

The NSW Government recommends not eating fish caught west of Sydney Harbour Bridge. Gord McKenna/Flickr

The story of dioxin contamination of Sydney Harbour shows us the great value of the green safety net of environmental law.

The laws that form this green safety net, particularly federal laws, have recently been under attack as “green tape”.

This term has become a negative political slogan that represents a sustained attempt to whittle away the protections that have been established, particularly over the past 20 years.

The federal government’s decision to shelve plans to devolve approval powers under its main environmental laws to state governments is sure to re-ignite this attack.

The irony of this sustained political attack on environmental law is that it is the very success of these laws in maintaining or restoring a healthy environment in Australia that has bred the complacency underpinning the attacks.

Many people have forgotten the problems that these laws were created to solve. The danger is that when such laws succeed in maintaining and restoring a healthy environment, they are taken for granted and, over time, holes in the safety net are allowed to grow.

The story of Sydney Harbour’s toxic legacy is timely to remember in this context.

Dioxin contamination of Sydney Harbour

Dioxins are a group of persistent environmental pollutants that accumulate in the food chain, mainly in the fatty tissue of animals. They are highly toxic and can cause reproductive and developmental problems; damage the immune system; interfere with hormones and also cause cancer.

The dioxin contamination of Sydney Harbour comes largely from a former industrial site at Rhodes adjacent to Homebush Bay.

Source of dioxin contamination in Sydney Harbour. Adapted from GoogleEarth

A long history of bad site management

The history of bad management of the site is explained in detail in the technical reports for the remediation of Homebush Bay.

From 1928 until its closure in 1986, the site was used for the manufacture of a wide range of highly toxic chemicals, including timber preservatives, herbicides, pesticides and plastics.

For the latter half of its operating life, the site was owned by Union Carbide Australia Ltd, although the company changed its name following the Bhopal gas disaster at the Union Carbide India Ltd pesticide plant in 1984.

From 1949 until 1976, the site was used to manufacture the herbicides 2,4,5-T and 2,4-D, the ingredients for Agent Orange that was used as a defoliant in the Vietnam War.

As a result of both chemical manufacturing and the use of contaminated fill for reclamation, soil and groundwater on the site were highly contaminated by various chemicals, including dioxins.

Overflow during reclamation and uncontrolled release of stormwater and wastewater into Homebush Bay, as well as possible spills while loading and unloading ships, also contributed to heavy contamination of the bay by dioxins and other chemicals.

This occurred until about 1970, when site management was improved to comply with new environmental laws. Extensive remediation of the site has since been carried out.

Union Carbide factory at Rhodes adjacent to Homebush Bay in the 1960s. Rhodes Remediation Projects

The toxic legacy

While the heavily contaminated former Union Carbide site has been extensively remediated, dioxins from the site have spread throughout the sediments at the bottom of Sydney Harbour.

Dioxins formed as a by-product of the manufacture of timber preservatives and 2,4,5-T at the site have been linked by a characteristic chemical profile to the dioxin contamination in other parts of Sydney Harbour. The site appears to be the major source of these contaminants in the harbour.

It is impracticable to remediate the extensive area of the harbour that is contaminated.

Dioxins from the contaminated sediments enter the marine food chain and are accumulated in fish, prawns and other organisms. The only practicable means to ‘remove’ the contaminants from the marine food chain is to allow other, clean sediments to cover the contaminants. For much of the harbour, this process will take decades.

Fishing banned for decades to come

Fishing bans have been in place around Homebush Bay since 1989, and were extended to parts of the Parramatta River in 1990.

The extent of contamination from the site was not recognised until 2006, when all commercial fishing was banned in Sydney Harbour after tests revealed elevated levels of dioxin in fish and crustaceans in the harbour.

Recreational fishing in the Harbour has not been banned but, based on advice from an expert panel, the NSW government recommends that:

  • No fish or crustaceans caught west of the Sydney Harbour Bridge should be eaten.

  • For fish caught east of the Sydney Harbour Bridge, generally no more than 150 grams per month should be consumed, except for species for which specific higher consumption limits have been established (for example, 1,200 grams of sand whiting).

A NSW government study suggested that much of Sydney Harbour remains contaminated by dioxins at levels that will make eating fish from much of the harbour unsafe for decades.

Environmental regulation is difficult

Regulating a site such as the former Union Carbide factory is difficult. It requires government agencies with the technical and administrative capability as well as the legal powers to do the job.

It is easy to look back and think, “how could the government have missed this happening?” but it is important to recognise in this context that the Union Carbide factory was one of thousands of industrial sites spread across an enormous geographic area.

It is easy to forget that lax laws in the past led to serious environmental problems.

Certainly all environmental laws should be subject to regular review to make them as efficient, effective and equitable as is practicable. That approach is simply what standard texts on policy design recommend.

But attacking the green safety net of environmental laws as “green tape” fails to recognise the history of environmental problems.

It also fails to recognise that our current laws need to be strengthened in many areas, not weakened. A glaring example of this is the profound inadequacy of our response to the unrivalled threat of climate change.

So, next time you walk barefoot on a clean beach and go for a swim in the ocean, spare a thought for the value of the green safety net of environmental law that is working to maintain the health of these places.

Editorial note: This is an abridged version of an article published in the November/December 2012 issue of Precedent.

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