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High Concentration of Dioxins Found in Sydney Harbor

(Beyond Pesticides, November 1, 2010) The majestic Sydney Harbor, world famous for sights such as the Sydney Opera House and Harbor Bridge, has a more dubious distinction –dioxin contamination as a result of pesticide manufacturing. According to data collected by the New South Wales Department of Environment Climate Change and Water, pesticide manufacturing has caused large tracts of sediments in the harbor, which has some of the world’s highest rates of dioxin contamination. The high level of contamination spread over such a large area mean that despite cleanup efforts in Homebush Bay, the original site of the contamination, fishing bans in Sydney Harbor will stay in place for decades to come. While the source of the contamination is decades old, this issue highlights the long-term and unforeseen impacts of pesticide use and underscores the need to adopt organic products, practices and other green technologies.

Tests confirm the source of the contamination is a former Union Carbide site where the now-banned pesticide 2,4,5-T, a component of Agent Orange, was produced. For more than two decades, waste from the chemical plant thar was used for landfill leached into Homebush Bay. Union Carbide, the infamous pesticide manufacturer responsible for the world’s largest industrial disaster in Bhopal India, was purchased by Dow Chemical. When Union Carbide left Australia, it was not required to perform a comprehensive cleanup of its site. In the 1980s, tests showed waste from the site was the main source of contamination of fish in the bay.

Dioxin exposure has been linked to a myriad of health issues, including cancer, birth defects, and skin conditions.

In the 1990s, the New South Wales government bought the site with the intent of remediating it, but the efforts did not begin until 2004. The cleanup is scheduled to finish next year; however data obtained by the Sydney Morning Herald show dioxin contaminating an area ranging 10 kilometers (6.2 miles) up and downstream from the cleanup site. The area is too large to remediate so officials intend to wait until sediments cover the contaminated layer, and dioxin can no longer be absorbed by the fish and other aquatic life. When asked how long the ban on fishing may be in place NSW Department of Environment Climate Change and Water director of specialized regulation, Craig Lamberton, said, “We think it will be decades.”

Although water quality has improved a lot over the past few years, dioxin levels near the remediation area were as high as 610 picograms per gram of sediment. In a relatively clean estuary, levels would be 2.3 picograms per gram. Even ten kilometers from the remediation site reading are as high as 350 picograms per gram of sediment.

Since 2005, authorities have been warning people not to eat fish caught west of the Sydney Harbor Bridge, and to eat no more than 150 grams (5.3 oz) of fish per month if it was caught east of the bridge. Unfortunately, many recreational fishers are not heeding the government’s warnings. A Department of Industry survey found fishers caught and kept 25.3 metric tons (28 tons) of fish between 2007 and 2008.

Learn more about alternatives to pesticides used on food, lawns and landscapes, in schools and in the home.


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