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What’s all the fuss about WHPs? And what does ‘off-label’ really mean??


Whenever you treat livestock, you need to know the withholding period (WHP).

This is the time period set to ensure that human safety isn’t affected by the treatment. WHPs also help protect Australia’s agricultural trade by making sure there are no risks of residues being found in products shipped overseas.

Figure shows goat being treated ‘off-label’ with a drench under veterinary prescription.
Figure shows goat being treated ‘off-label’ with a drench under veterinary prescription.

International regulatory background

Because of the importance of plant and animal products to human nutrition, there is an international body, Codex Alimentarius, set up by the World Health Organization (WHO) and the Food and Agricultural Organization (FAO) of the United Nations to oversee rules about residues in food products.  

One of the main outputs of Codex Alimentarius is a list of food products and their Maximum Residue Limits (MRLs). All common chemicals used for treatment of animals (or crops, fruit etc.) are listed and a risk assessment made based on toxicology studies to estimate what limits are allowed.

As a trading nation, Australia must adhere to these regulations to assure the World Trade Organization that our products satisfy the terms of importing countries. On top of this, some countries set even stricter limits than Codex, which usually means that they will only accept products that have no detectable residues at all. This is why Australian authorities also set Export Slaughter Intervals (ESIs).

All livestock, including pet goats, are classed as ‘food-producing animals’ due to the likelihood that they will at some stage end up in the food chain. Because of this, strict rules apply.

On top of this, wool has its own set of residues requirements to offset the risks to human or environmental safety (see below). 

 

National regulatory environment

Meat and milk withholding periods (WHPs) are set to satisfy the domestic market requirements, which usually mirror those of Codex. The relevant authority is the Australian Pesticides and Veterinary Medicines Authority (APVMA).

When companies register new products, they must submit trial reports showing results of studies that are conducted according to strict international guidelines. The APVMA then works out the WHP, ESI and other requirements which are written on the product label. It is a legal obligation on the user of the product to follow these directions. Compliance occurs through the supply chain and consignments of cattle, sheep and goats are sometimes turned away from feedlots or processors due to them being within the WHP or ESI after treatment.

To monitor potential residues in food products, the National Residues Survey (NRS) in the federal Department of Agriculture, Fisheries and Forestry conducts regular testing. The results are published annually to allow trading partners to gain confidence in the safety of Australian products.

Figure shows beef cattle after treatment with a product for external parasites. These cattle must not be processed for human consumption until after the Export Slaughter Interval has expired.
Figure shows beef cattle after treatment with a product for external parasites. These cattle must not be processed for human consumption until after the Export Slaughter Interval has expired.

What does it say on the product label?

The product label is a legal document that not only states the claims of the product, it defines the dose rate, storage conditions, application method and other vital information relating to its use. Before you purchase a product, you can look at the label information by searching the APVMA database known as PUBCRIS.

Note that label claims will vary over time, especially for products aimed at internal and external parasites, due to the parasites developing resistance. The older the product, the more likely it will be that the label claims are not up-to-date.

 

Key terms

Meat withholding period (WHP)- the length of time from when the animal is treated and when it can be processed for human consumption (for Australia’s domestic market)

Export Slaughter Interval (ESI)- the length of time from when the animal is treated and when it can be processed for human consumption (for all export markets)

Milk withholding period (Milk WHP)- the length of time from when the animal is treated and when the harvested milk can be processed for human consumption (for all markets)

Re-treatment interval – the time period between treatment of the animal and when it can be treated again with the same product.

Off-label use- all withholding periods are made based on the assumption that animals are being treated strictly according to the dose rate and use pattern approved by the APVMA and written on the label. All uses outside of these directions are known as ‘off-label use’ and include changes to dose rate, animal species treated or application method. Legally, ‘off-label use’ by a producer places them at risk of being held liable for residues violations in the treated animal products. As an example, there are recent cases where dairy producers have paid for the cost of thousands of litres of discarded milk.

Off-label use is sometimes done because not all animal species have products suitable or registered for them e.g. goats.

When this happens, a veterinarian who is registered with a Veterinary Surgeon’s Board, may legally allow an off-label use with appropriate dose rates and withholding periods. However, regulations vary according to state and due to the severe consequences including loss of trade access, legal action, fines and loss of veterinary licence, caution must be used.

Wool regulations – as well as meat residues, these are aimed at protecting worker safety and the environment due to potential discharge of chemical residues when the wool is processed. The relevant WHPs are the wool withholding period, known more accurately as the wool harvesting interval (WHI) and the sheep rehandling interval (SRI).

Restraints- these are specific instructions on the product label stating what must not be done, usually to prevent the risk of residues in food. e.g. “DO NOT USE in animals which are producing milk or milk products for human consumption”.

Contraindications- this term is similar to ‘restraints’ and also means ‘DO NOT USE’. It is focused on animal safety due to the pharmacological properties of the product. e.g. “This product is contraindicated for use in lambs under 6 weeks of age or less than 10kg body weight”.

For more information on withholding periods for sheep, cattle and goats see the product label or refer to the ParaBoss, TickBoss, LiceBoss, FlyBoss or WormBoss websites.