Questions and Answers about chemical residues

Q: Why are chemicals used in food production?

A: Whether growing crops or producing animals, there are inevitably pests and diseases that interfere with the production. Chemicals can be used to control these pests and diseases to allow for efficient food production. If the pests and diseases are not dealt with they can destroy or reduce production, and the quantity and quality of the food we have available today would be greatly reduced.

Q: What is a chemical residue?

A: When chemicals are applied to a crop or animal, they break down over time to other products. A chemical residue is what remains of the chemical at a particular time and can occur as the chemical itself or as breakdown products. All chemicals, when applied to crops, animals, water or soil, will leave residues. The size and nature of the residue, and the time it takes to break down, varies from chemical to chemical.

Q: How are chemical residues in food regulated?

A: The safety and performance of all chemicals that are used in food producing crops and animals must be assessed by the APVMA prior to registration to ensure that the health and safety of people is protected. As part of that assessment process using data submitted with the registration application, the APVMA also determines the likely level of chemical residues remaining at the time of harvesting or slaughter. Drawing on this information the APVMA recommends Maximum Residue Limits (MRLs). No product is registered unless these levels are safe for people, while also enabling the chemical to work effectively.
The MRLs are then advised to Food Standards Australia New Zealand (FSANZ) which proceeds to consider them in accordance with its legislation. Final MRLs are posted on the FSANZ web site (http://www.foodstandards.gov.au/foodstandardscode/ ).

Q: Are there any chemical residues in my food?

A: Chemicals are used in Australia in food production to control pests and diseases in crops and animals. The rate of breakdown of a chemical and therefore the level of chemical residue in the food varies with the type of chemical and the type of food. Therefore, residues of the chemicals could be present in your food when you purchase it. However if the chemical has been used as recommended on the label of the product, any residues that do occur should not exceed the maximum residue limit (MRL), which is set at the time of registration of the chemical product.

Q: What is a Maximum Residue Limit (MRL)?

A: The MRL is the highest concentration of a residue of a particular chemical that should occur in a food following use of a product on a crop or animal. The value of the MRL is based on trial data submitted to the APVMA and is set at a level that is known to be safe for people while still allowing the chemical to work effectively. The concentration of a residue is expressed in milligrams per kilogram (mg/kg) of the food. For example, the MRL for fenvalerate in celery is 2 mg/kg.

Q: Why do we need MRLs?

A: If a chemical is used to control pests or diseases in a crop or animal, the application or dose rate at which it can be used is listed on the label, along with other directions such as any withholding period. The rate was established through trial work at a level that will give effective control of the pest or disease. When a product is used according to label directions, it should not cause residues in food over the MRL. The MRL is the maximum residue that should occur when good agricultural practice is followed.

Q: Are MRLs health standards?

A: MRLs are set to reflect the legal use of a chemical and are not health standards as such. However, in setting an MRL, an estimation of daily intake of the chemical over a lifetime is made to ensure that consumers are not exposed to chemical residues in their diet that could be harmful.

Q: Then what is the health standard?

A: The health standard is called the Acceptable Daily Intake (ADI), which is derived from studies with animals to determine the most sensitive species and the level at which the chemical does not affect the animal. Once this is determined, a safety factor is applied to allow for any differences between animals and people.

Q: How do MRLs compare to the health standard?

A: In setting an MRL, a conservative estimation of daily intake of the chemical residue in all foods over a lifetime is made, which assumes that all foods will contain residues at the MRL. If the acceptable daily intake (ADI) were exceeded in the estimation of daily intake, the product would not be registered.

Q: How do I know it is safe for me to eat foods that contain residues?

A: The safety of eating foods containing residues is determined at registration, where dietary intake estimations are carried out. The estimate assumes the worst case, that all crops/animals that could be treated with the chemical are treated and contain residues at the MRL. A chemical product would not be registered by the APVMA if the estimated intake were likely to exceed the health standard, the Acceptable Daily Intake (ADI).

Q: How can I be confident that I will not be exposed to excessive residues in the food I eat?

A: Surveys of fresh foods by State Departments of Agriculture/Primary Industries and by major supermarket chains indicate that the vast majority of foods do not contain residues. The National Residues Survey also monitors residues in meat, grains and some fruit and vegetables. Reports of results are available from the respective web sites. (See the links section of the APVMA web site.) Food Standards Australia New Zealand also undertakes periodic surveys of the food we eat and results are available on its web site at http://www.foodstandards.gov.au/mediareleasespublications/publications/.

Q: What happens to the treated crop or animal food if residues exceed the MRL?

A: Responsibility for this rests with State Authorities. The situation would be investigated by them and could have serious implications for the producer. Any breach of MRLs could also result in an export market closing to Australia, either temporarily or long-term. A breach of an MRL is usually an indication that label directions have not been followed.

Q: What are the risks to me if I eat food with residues higher than the MRL?

A: Dietary intake estimates assume a worst-case, all-of-life consumption of foods with residues occurring at the MRL level. Consuming a food with residues above the MRL should not be a health hazard, because it is not an all-of-life exposure but a single event. It should also be remembered that most of our food does not contain any detectable residues.

Q: What is a withholding period?

A: A withholding period (WHP) is the time period that is set at registration for a chemical, to guide users of the chemical as to when residues will be below the MRL. It is based on the rate at which the chemical breaks down on the crop/animal. It is the minimum length of time between treatment of a crop or animal, and the suitability of the harvested crop or the animal product for human consumption.

Q: Are there withholding periods for all chemical products?

A: Only for those used in the production of food, whether crop or animal. They are printed on the label of a product and take into account normal production practices, and are determined from residues data. If users of a chemical adhere to the withholding period, as well as other label directions, residues should not exceed the MRL.