WA farmers produce safe food by keeping their livestock free of residues. If WA livestock were found to contain residues above the agreed maximum residue limit, we could lose access to important markets and jeopardise the health of people, animals and the environment.
Farmers can manage residue risks by following label or veterinary directions, adopting responsible farming practices, keeping accurate records, identifying stock and recording all stock movements.
A residue is what remains of a chemical or metal (e.g. lead, arsenic, cadmium) in the animal after the animal has been exposed to the chemical or metal. The residue may be the original substance or a derivative (metabolite) of the original substance. All chemicals and metals can produce residues and the time taken for a residue to break down or be excreted varies depending on the substance and the animal.
Maximum Residue Limits or MRLs are the highest amount of agricultural, veterinary or environmental contaminant chemical residue that is legally allowed in a food product sold in Australia. MRLs for agricultural and veterinary chemicals are established by the Australian Pesticides and Veterinary Medicines Authority (APVMA).
MRLs are published under the MRL Standard in the Commonwealth Agricultural and Veterinary Chemical Gazette and also in Schedule 20 of the Food Standards Code.
Food Standards Australia and New Zealand (FSANZ) also set maximum levels (MLs) for contaminants in food and are published in Schedule 19 of the Food Standards Code.
The Australia New Zealand Food Standards Code and the Food Act (WA) 2008 define unsuitable food as containing an agricultural or veterinary chemical or a metal or non-metal contaminant that contravene the permitted level specified in the Food Standards Code.
Residues become unsuitable when the amount of residue in the animal exceeds the maximum residue limit (MRL) for the agricultural or veterinary chemical or metal or non-metal contaminant. A product which is found to have a residue more than the MRL is a residue exposed product and is not permitted to be supplied under the WA Biosecurity and Agriculture Management (Agriculture Standards) Regulations 2013.
Unsuitable residues may occur when:
- veterinary chemical label instructions or veterinary directions are not correctly followed.
- the withholding period (WHP) or export slaughter interval (ESI) of a veterinary chemical is not correctly observed.
- livestock are exposed to plant chemicals used to control weeds or insects.
- unregistered chemicals are used on livestock – these chemicals don’t have WHPs and are of an unknown residue risk.
- livestock have access to hazardous materials, such as lead batteries often found in places like farm dumps, sheds, old yards, old house sites or painted materials.
- livestock are grazed on land contaminated with persistent chemicals such as organochlorines(e.g. old potato paddocks, orchards, stock feed treated with a pesticide given to livestock, like pickled grain).
The presence of unsuitable residues is determined by analytical testing. In most cases this is done after the animal has been slaughtered, though for some chemicals appropriate samples can be taken from live animals.
In general, residues in livestock more than the MRL can occur when a product is not used according to label directions or if livestock are exposed to environmental contaminants. If the residues are high enough, livestock may be affected and show signs of poisoning.
If you suspect your livestock may contain harmful residues, contact your local Department of Primary Industries and Regional Development (DPIRD) Field Veterinary Officer for initial advice. Department staff can assist in the appropriate management of livestock before they enter the food chain.
A Residue Quarantine Notice (RQN) under the Biosecurity and Agriculture Management (Agriculture Standards) Regulations 2013 may be issued to restrict the animal food product from entering the food chain.
It is an offence to supply a contaminated animal or animal product in WA and the department undertakes appropriate investigation and follow up actions if a contaminated animal product is suspected or detected.
All producers in WA are responsible for ensuring that any food-producing animals or animal products they supply do not contain chemical residues or contaminants above the MRL. Producers should always assess the risk of residues whenever they intend to feed novel or byproduct feed materials to their animals.
It is also important to avoid exposing livestock to plant chemicals used to treat weeds or pests and always follow any grazing or label WHPs.
Producers can ensure livestock are free of residues by:
- following all veterinary chemical label directions or veterinary directions.
- observing any outlined WHPs or ESIs.
- avoiding exposure to plant chemicals used to treat weeds or pests.
- conducting a farm risk assessment to identify contaminated sites like old dips, spray races, farm dumps and areas sprayed with organochlorine chemicals (e.g. orchards, telegraph poles).
- undertaking testing of soil in areas where organochlorines or other persistent chemicals are known to have been used.
- restricting stock access to contaminated sites like farm dumps.
- permanently fencing, removing or burying potentially hazardous material in consultation with your local government authority or the Department of Water and Environmental Regulation (DWER).
- avoiding lead exposure by preventing access to lead batteries, lead-painted machinery or buildings, sump oil treated fence posts, old house sites etc.
- identifying and separating livestock exposed to residues to ensure they do not end up in the food chain.
- checking chemical records before selling animals, and correctly declare if sale animals are inside or outside of the WHP on National Vendor Declaration/Waybills.
Legislation governing residues in livestock
WA has laws to manage harmful residues in livestock. These laws safeguard the public and market access by helping to ensure animals are not supplied if they contain residues more than the MRL.
Requirements for animal feed and preventing unsuitable chemical residues in food-producing animals are contained in WA’s Biosecurity and Agriculture Management Act 2007 and Biosecurity and Agriculture Management (Agriculture Standards) Regulations 2013.
Under the WA legislation, a contaminant is not allowed to be present in supplied animal products unless Food Standards Australia and New Zealand (FSANZ) has set a safe allowed level (also known as a ML) for the contaminant and the contaminant does not exceed that level.