What are dioxins?
Dioxins are a group of chemically-related environmental pollutants. They can be found in small amounts world-wide, in the air we breathe, the food we eat, the water we drink and the land where we live.
Dioxins are produced during combustion and are a by-product of many industrial processes but can also result from natural sources such as bushfires.
Dioxins do not break down easily in the environment and nearly all people in developed countries have trace amounts of dioxins in their body. This is mainly from the food that we eat, in particular from meat and dairy products, and seafood. The level of dioxin in our bodies increases with age. However, around the world overall human levels of dioxin have been declining due to international efforts to reduce the production of dioxins. From 2001 to 2004 the Australian Governments National Dioxins Project completed a range of studies that demonstrated that Australia’s dioxin levels are generally low, as are the risks to human health and the environment.
What health effects can dioxins have?
All people have background exposure to dioxins and a certain level of dioxins in the body. Current background exposure is not expected to affect human health. However, at elevated levels, dioxins have the potential to be toxic and for this reason exposure should be minimised and reduced where possible.
Animal and human studies have found that long term exposure (over many years) to elevated levels of dioxins can increase the risk of cancer. Effects on hormones, reproduction and development have also been reported in animal studies however studies in humans are inconclusive.
These effects however have occurred at dioxin levels 100 to1000 times higher than the dioxin levels that people are generally exposed to in developed countries. The World Health Organisation states that there is a level of exposure below which cancer risk would be negligible.
Can I continue to eat seafood from Sydney Harbour and Parramatta River?
The NSW Food Authority has issued dietary advice for people wanting to eat their catch from Sydney Harbour and the Parramatta River. The affected area includes all of Port Jackson and its tributaries.
NSW Food Authority advises that:
- no seafood caught west of Sydney Harbour Bridge should be eaten. You should release your catch
- for seafood caughtor seafood caught east of the Sydney Harbour Bridge generally no more than 150 grams per month should be consumed
- testing of popular species has allowed for more specific dietary advice relating to individual seafood species caught in the region. For further information on recommended serving sizes for individual species please refer to NSW Food Authority.
What are the health effects of eating seafood containing dioxins?
Health effects from dioxins occur following long term exposure (over many years) to elevated levels of these compounds. To manage any potential health risks from exposure to dioxins Australian health authorities have established a 'Tolerable Monthly Intake' of dioxins. This is a health based guideline value that indicates the amount of dioxins people can consume on a regular basis over a lifetime without any significant health risk.
The current recommendations to restrict consumption of seafood from Sydney Harbour and the Parramatta River are based on this guideline and are considered to be protective of human health. It is unlikely that people who have been eating their catch from Sydney Harbor and the Parramatta River would have noticeable health effects from consumption of the seafood. However, the levels of dioxins in seafood are higher than normal, and people are advised to follow the dietary advice provided to reduce their exposure to dioxins to protect their health.
What if I am pregnant?
The same 'Tolerable Monthly Intake' applies for pregnant women as for the rest of the population. Pregnant women should restrict their intake of seafood from Sydney Harbour and Parramatta River as recommended above.
What about my young children?
It is recommended that children 6 years and younger should limit their intake of seafood caught east Sydney Harbour Bridge. No seafood caught west of Sydney Harbour Bridge should be eaten.
If you are serving your children recreationally caught seafood from Sydney Harbour east of the Harbour Bridge, consider halving their serving size to that of yourself and the rest of the house hold. For example, rather than serving your children 150 gram of seafood per month, children should be served no more than 75 grams per month.
This is due to their smaller body size. The ‘Tolerable Monthly Intake’ for children is the same as that of the rest of the population, however because their bodies are smaller, so is the amount of seafood they can consume before they reach their tolerable intake for dioxins.
I am concerned about my health. What should I do?
If you have been regularly eating seafood from Sydney Harbour or the Parramatta River and you are concerned about your health speak with your local doctor.
Should I have a health check if I have eaten seafood?
There is no test for dioxin levels that predicts health effects. There is also no test that can distinguish where an individual’s dioxin intake has come from. Undergoing routine health check-ups and limiting your exposure to dioxins is all that is recommended.
NSW Department of Primary Industries for further information on fishing in Sydney Harbour
NSW Food Authority for further information on eating seafood from Sydney Harbour
Food Standards Australia New Zealand for information on research underpinning dietary advice provided here and for further information on ongoing research into levels of dioxins in Sydney Harbour
Department of the Environment and Energy for information on the National Dioxins Project