Human health risk assessment of dioxins in Australia

Preface

Dioxins are a group of fat-soluble chemicals which are highly persistent in the environment and which can accumulate in the body fat of animals. If exposure to dioxins is sufficiently extensive, they can cause a range of toxic effects in animals and humans, including skin lesions, reproductive disorders and cancer.

In Australia, relevant Australian Government agencies have been undertaking monitoring programs to determine whether dioxins and related compounds are present in humans, the environment, food, and in certain agricultural commodities. As part of these monitoring programs and their reporting, the Department of Environment and Heritage (DEH) and the Department of Agriculture, Fisheries and Forestry (DAFF) sought advice from the Department of Health and Ageing (DoHA) on establishing a tolerable intake for dioxins and related compounds.

Largely based on the deliberations of (1) the consultation between technical experts representing the World Health Organization European Centre for Environmental Health (WHO-ECEH) and the International Programme on Chemical Safety (IPCS) in May 1998; (2) the meeting of the European Community Scientific Committee on Food (ECSCF) on the risk assessment of dioxins and dioxin-like polychlorinated biphenyls (PCBs) in food, in May 2001; and (3) the Joint Food and Agriculture Organization of the United Nations (FAO)/WHO Expert Committee on Food Additives (JECFA) evaluation of dioxins, at its 57th meeting in June 2001, Australia established a Tolerable Monthly Intake (TMI) for dioxins of 70 pg TEQ/kg bodyweight from all sources combined. This tolerable intake is equal to that set by JECFA, and includes polychlorinated dioxins, polychlorinated furans and dioxin-like PCBs, as specified under the WHO 1998 TEF scheme. This TMI was endorsed by the National Health and Medical Research Council (NHMRC) on 24th October 2002, as outlined in the booklet, Dioxins: Recommendation for a Tolerable Monthly Intake for Australians, published jointly by the NHMRC and the Therapeutic Goods Administration (TGA¹), organisations within DoHA.

The tolerable intake value is a human health standard based on the toxicological effects of dioxins and related compounds in animals and humans, following known exposures. The tolerable intake value is not a measure of human exposure to dioxins and it is not an action level for dioxins in food or the environment. Rather, it is an intake standard, against which estimated human exposure from all sources combined should be compared.

This risk assessment document has estimated exposure of the Australian population to dioxins, based on levels measured in monitoring programs conducted by the DEH (air, soil, water sediments etc.), by DAFF (agricultural commodities) and Food Standards Australia New Zealand (food). Intake estimates have been compared with the tolerable monthly intake value in order to make an assessment as to whether there are likely to be any health risks to different segments of the Australian population. Furthermore, intake estimates and body burdens of dioxin-like compounds have been compared with equivalent values estimated in other countries, to see whether the population is more or less exposed than populations in other parts of the world.

It should be noted that occupational exposures are not specifically considered in this public health risk assessment, other than the inclusion of some relatively general comments about intakes from some specific exposure sources.

Further information

• More about dioxins