Dioxins in Food: Questions and Answers
What are dioxins?
The term ‘dioxins’ refers to a group of chlorinated chemicals that are chemically stable and can remain in the environment for a long time. Dioxins include the polychlorinated dibenzodioxins (PCDDs or dioxins), the closely related polychlorinated dibenzofurans (PCDFs or furans) and certain polychlorinated biphenyls (dioxin-like PCBs, or PCBs).
These chemicals can accumulate in the body fat of animals and humans and can remain unchanged for prolonged intervals, resulting in concerns about their potential to cause possible adverse effects in humans.
Where do they come from?
PCDDs and PCDFs are unintentionally produced as by-products during combustion processes, such as the burning of household, hospital and industrial waste, and sewerage sludge. They are also produced during some industrial chemical processes. PCBs were intentionally synthesised for certain industrial uses but have not been allowed since the mid-1970s. In Australia, the major sources of dioxin emissions to the air are bushfires, prescribed fires and the burning of agricultural stubble.
How much dioxin is in Australian food?
Australian food generally has very low levels of dioxins. Levels of dioxins in Australian foods are similar to those found in New Zealand foods and lower than levels found in foods from other industrialised parts of the world.
Is Australian food safe?
Yes. The assessments carried out by FSANZ and the Department of Health and Ageing have shown that the risk to Australians from eating foods containing dioxins is very low. It is not considered to be of public health concern.
What foods are the most likely source of dioxins?
Levels of dioxins found in Australian foods were very low and the food was safe to eat. As dioxins are absorbed into animal fat, foods likely to contain dioxins are those that contain animal fat.
Examples of foods that are most likely to contain dioxins are: dairy products, meat and meat products, fish and eggs. Foods such as cheese, butter, some types of fish, pates, bacon and sausages that are generally high in animal fat would be likely to have higher dioxin contamination levels than products low in animal fats.
How do dioxins get into the food supply?
It is estimated that over 96 per cent of dioxins present in the environment have originated from air emissions. Dioxins are then deposited onto and occur in trace amounts on soil, plant and water surfaces.
Plants do not generally absorb dioxins. However dioxins can enter the food chain when animals eat plants on which dioxins have been deposited. In aquatic environments, filter-feeding animals can absorb dioxins when they filter sediments or particulate matter floating in the water.
Australian and international studies have concluded that more than 95 per cent of human exposure occurs through consumption of food, as shown in the chart below.
Do dioxins concentrate through the food chain?
Yes. Dioxins are generally present at very low concentrations in most foods. They are absorbed into the animal fat and increase in concentration (bioaccumulate) as they migrate up the food chain.
Humans are at the top of the food chain. When people eat food contaminated with dioxins these chemicals can remain in the body's fat stores for quite long periods of time.
Should I change my diet to avoid dioxins?
No. The levels of dioxins found in food in Australia are very low and are not a public health concern. However, if you wish to reduce your intake of dioxins, a healthy, balanced diet that is low in animal fats will reduce your risk of exposure. Eliminating fats completely however, is not recommended. It is likely that we all have some dioxins in our bodies. Dioxins are eventually metabolised, or broken down and excreted from our bodies over many years.
What is being done to reduce the amount of dioxins in Australian food?
Although levels of dioxins in Australian food are low, it is important that we continue to reduce the amount of dioxins released into the environment, therefore further reducing accumulation of dioxins in the food chain. In order to do this, the Australian Government funded the National Dioxin Program (NDP), implemented by the Department of the Environment and Heritage. The aims of the NDP are to:
- gather information about the current concentrations of dioxins in Australia;
- determine the level of risk to human health and the environment posed by the current level of dioxins in Australia; and
- develop measures to reduce, and where feasible, to eliminate the release of dioxins in Australia.
Dioxins in Australia: A Summary of the Findings of Studies Conducted from 2001 to 2004
Department of the Environment and Heritage, May 2004
The study, Dioxins in Food: Dietary Exposure Assessment and Risk Characterisation can be found on the Food Standards Australia New Zealand website: www.foodstandards.gov.au.
More information on the NDP and what stage it is up to, levels of dioxin emissions, levels of dioxins in the environment and humans, and the Ecological Risk Assessment is available from the Department of Environment and Heritage at: www.deh.gov.au/industry/chemicals/dioxins
The Human Health Risk Assessment for Australians, also including information on breast milk , is available from the Department of Health and Ageing at www.health.gov.au .
Information on levels of dioxins in agricultural products is available from the National Residue Survey, within the Department of Agriculture, Fisheries and Forestry, at www.affa.gov.au .
May 2004