Risk Assessment of Short-Term Dietary Exposure to Chemical Residues

The dietary intake of residues of some pesticides and veterinary drugs can pose acute hazards. For this reason, a risk assessment of short-term dietary exposure to chemical residues, which involves scientists from the Department of Health and Ageing, the APVMA and Food Standards Australia and New Zealand (FSANZ), is undertaken.

The reference health standard for short-term dietary exposure is the Acute Reference Dose (ARfD), which is established by the toxicologists from the Department of Health and Ageing. The ARfD is an estimate of the amount of a substance in food or drinking water that can be ingested over a short period of time without appreciable health risk to the consumer, on the basis of all known facts at the time of the evaluation. It is usually expressed in milligrams of the chemical per kilogram of body weight.

The APVMA conducts a short-term dietary exposure according to a protocol that has been agreed by the APVMA and FSANZ, and that is in accordance with international standards. Under the agreement, APVMA provides FSANZ with dietary exposure assessments for all new and review chemicals, and for existing chemicals where the calculated exposure is >90% of the ARfD. The risk assessment conducted utilises point estimate (or deterministic) methodology to calculate the National Estimated Short-Term Dietary Intake (NESTI). The model uses single values of residue concentrations, consumption, and bodyweight to provide a point estimate of dietary exposure for individual commodities. In order to protect the population, values for the high-end consumption (for the 97.5th percentile consumer from the 1995 National Nutrition Survey) and the highest residue concentration found in the commodity residues trials are used. The model also takes into account the variability of residues across commodity units and unit weight of the commodity. It may be necessary to refine the estimated dietary exposure, which could require new studies or other risk management options, such as modifying use patterns.

The estimate of short-term dietary exposure is then compared with the reference health standard (ARfD), and dietary exposure is considered acceptable if the best estimate of dietary exposure indicates that the health standard is not exceeded. The APVMA will not register a chemical where the health standard has been exceeded.

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