Chemicals are broadly used in agriculture for controlling weeds, insects and other pests, treating or preventing animal diseases and infestations and providing soil nutrients. While the use of agricultural and veterinary chemicals provides many benefits, there is also some risk that residues of these chemicals may be found in agricultural produce.

The Agricultural and Veterinary Chemicals (Control of Use) Act 1995 imposes controls on the use of chemical products in Tasmania that aim to ensure that neither animal, human or environmental health, nor trade in agricultural produce are compromised by the use of these chemicals. This includes limiting the levels of chemical residues that may be present in produce presented for animal or human consumption.

In registering agricultural and veterinary chemical products for use in Australia, the Australian Pesticides and Veterinary Medicines Authority establishes Maximum Residue Limits for each product. Once ratified by Food Standards Australia New Zealand, these MRLs are legally enforceable limits on the levels of agricultural or veterinary chemical residues that may be present in food and fibre products.

Some chemicals eg. metals may enter the food chain from natural sources or as a consequence of fertiliser or other chemical applications or occurrences. Maximum Permitted Concentrations of metals and other contaminants apply to limit the extent of their occurrence in food.

Export Slaughter Interval

The Export Slaughter Interval (ESI) is the minimum suggested time interval that should elapse between the last treatment of an animal and its slaughter for export. ESIs are an industry standard to ensure export requirements are met.

Sheep and Cattle Withholding Periods and Export Slaughter Intervals are available from the Australian Pesticides and Veterinary Medicines Authority (APVMA). Visit their website at: http://apvma.gov.au/node/10806.

Some countries may have a lower MRL than Australia, or even no MRL for a particular chemical if it is not used in that country. To ensure that meat satisfies the requirements of these importing countries, a zero MRL, and extension of the withholding period is required. The extended withholding is the ESI, adopted by the Australian meat industry for animals treated with certain chemicals and prepared for the export market. The ESI is an adopted industry standard, not a regulatory requirement.

Maximum Permitted Concentration

The maximum permitted concentration is similar to a Maximum Residue Limit, but applies to naturally occurring elements such as metals.

The MPC is set for elements such as mercury, lead and cadmium with safety margins so that a provisional tolerable weekly intake is never exceeded.

Maximum Residue Limit

When the Australian Pesticides and Veterinary Medicines Authority (APVMA) registers an agricultural or veterinary chemical product, it evaluates the likelihood and extent of any residues of the product occurring in agricultural produce or commodities derived from treated plants or animals.

From this evaluation the APVMA determines Maximum Residue Limits (MRLs) for each product. That is, the maximum concentration of a residue in or on a food, commodity, or animal feed resulting from the registered use of an agricultural or veterinary chemical. The concentration is expressed in milligrams per kilogram of the commodity (or milligrams per litre in the case of a liquid commodity).

For human foods, the MRLs set by the APVMA are referred to Food Standards Australia New Zealand for incorporation into Standard 1.4.2 of the Food Standards Code. See Food Standards Australia New Zealand for more information.

MRLs often vary from one country to another, depending on each country's acceptance and use of specific chemicals. It is common for other countries to have lower or even zero tolerance for certain agricultural or veterinary chemicals where those chemicals are not used locally due to different pest and disease profiles. An understanding of these International MRLs is vital for Tasmanian exporters of agricultural commodities. Visit www.globalmrl.com for more information on International MRLs.

Withholding Period

WHP - The time taken after treatment for the amount of the chemical in meat or other produce to decrease to an acceptable and safe level, the MRL. The WHP is legally enforceable. It is an offence to submit an animal for slaughter for human consumption or to submit any agricultural produce for processing, before the expiry of the WHP.

A withholding period is the minimum period which must elapse between the last administration or application of an agricultural or veterinary chemical product and the slaughter, collection or harvesting of any produce for human consumption or use. It is a legal requirement that the WHP is applied.

Withholding periods are a necessary management tool in some situations to ensure that chemical residues do not exceed the Maximum Residue Limit.

Withholding period statements will usually appear on a chemical product label below the Directions for Use table. If a particular chemical use requires both harvest (H) and grazing (G) withholding periods, the label will identify these by including in the table either (H) or (G) after the appropriate figures.

Following are some examples of common withholding period statements:

DO NOT HARVEST FOR [...] DAYS AFTER APPLICATION
DO NOT GRAZE OR CUT FOR STOCK FOOD FOR [...] DAYS AFTER APPLICATION
REMOVE STOCK FROM TREATED AREA [...] DAYS BEFORE SLAUGHTER
DO NOT USE TREATED PRODUCE FOR HUMAN CONSUMPTION OR FOR STOCK FOOD WITHIN [...] DAYS OF TREATMENT
NOT REQUIRED WHEN USED AS DIRECTED

Where a product has no grazing withholding period, crops treated with the product should not be grazed prior to harvest. In these circumstances it is uncertain whether stock that graze the stubble or are fed by-products of the treated crop will develop detectable residues of the chemical. Where appropriate, advisers and users should contact the chemical manufacturer for advice on managing chemical residues in the crop or in stock.

You should not advise, or apply, withholding periods other than those that appear on the label of a registered product unless the use is allowed under Agricultural and Veterinary Chemicals (Control of Use) Act 1995 (see further information) or the use is approved by a permit issued by the Australian Pesticides and Veterinary Medicines. Visit their web site at: www.apvma.gov.au.

Withholding periods are often formulation specific as well product / active specific. It cannot be assumed for instance, that an emulsifiable concentrate (EC) formulation of a chemical will have the same withholding periods as the ultra low volume (ULV) formulation.

Residue Monitoring Programs

See the National Residue Survey at: http://www.agriculture.gov.au/ag-farm-food/food/nrs

The National Organochlorine Residue Management (NORM) Program aims to minimise the risk of cattle with residues of organochlorines such as DDT, dieldrin and heptachlor above the Australian Maximum Residue Limit being slaughtered for human consumption. While the use of most organochlorines has been prohibited for many years, their persistence in the environment requires that certain properties where they have been used in the past must be actively managed to contain this risk.

The National Antibacterial Residue Minimisation (NARM) Program is a joint Industry/State/Commonwealth initiative aimed at increasing the awareness of producers, processors and other industry groups of the risk to trade associated with the detection of antibacterial residues above the Maximum Residue Limit in meat. This increased awareness is designed to assist the beef industry minimise antibacterial residue contamination levels in bobby calves.

Quality Assurance

Meat and Livestock Australia
 
TQA Australia
www.tqaaustralia.com.au

Further Information

Australian Pesticides and Veterinary Medicines Authority
www.apvma.gov.au

National Residue Authority
http://www.agriculture.gov.au/ag-farm-food/food/nrs

Legislation
Agricultural and Veterinary Chemicals (Control of Use Act) 1995