Chapter 17 Persistent Organic Pollutants: Occurrence and Health Risks in Australia

Abstract

Abstract The major persistent organic pollutants (POPs) in Australia are the persistent organochlorine pesticides (OCPs). The adverse effects of DDT were first recognised in Australia in the late 1960s. Subsequently, the Australian Government introduced a policy of phasing out the registered uses of this major pesticide and related substances so that their use in agriculture ceased by 1987. Australian foods are monitored on the basis of the National Residue Surveys and Australian Market Basket Surveys (now Total Dietary Survey). Only a low percentage of OCP residues have been detected in animal fats since 1996 and none in grains since 1992. Elevated intakes of residues (e.g. dieldrin and HCB) occurred in the early 1970s, which have since declined at approximately first-order kinetics to much lower and generally acceptable levels of intake in the 1990s. Total intakes of OCPs from the Australian diet and environment have been estimated from the 1970s to the 1990s and used to evaluate human health risks for the Australian population. The Hazard Index (HI) was estimated for the general Australian population for the OCPs for 1996 at 1×10−6 to 4×10−5. The level of health risk for the general Australian population was considered to be acceptable in 1996. Some scenarios for high-risk groups in the Australian population were examined. These indicated that dieldrin intake from contaminated fish, contaminated soils, or in indoor air following termiticide treatment was a potential risk for exposed persons. Also the exposure of breast-fed infants to DDT during 1996 with a HI of 0.9 was questionable. However, extrapolation to 2005 using first-order kinetics indicated that the HI for all OCPs was below 0.1 and thus not a hazard to health of the Australian population. The National Dioxin Program has extensively surveyed the levels of dioxins in Australian foods, human milk and the natural environment as well as identifying sources. As a result of this the risks to human health and the natural environment are considered to be minimal. Human health risks from exposure to POPs may continue to be an issue, because of increasing concerns about endocrine disruption and also the possible relationship between residues and specific cancers such as breast cancer.