The importance of respecting withdrawal periods

The importance of respecting withdrawal periods

We receive a lot of questions about the withdrawal periods of drugs. Therefore we will provide some more information about withdrawal periods and why it is important to respect them, how drug withdrawal periods can affect human health and about the costs of adhering to withdrawal periods.

When drugs are given to animals, part of the drug and its by-products will end up in the meat, milk and eggs. This level gradually declines after some days. The withdrawal period is the time that passes between the last administration of a drug and the moment when the level of drug residues in the meat, milk or eggs, falls below the maximum allowable limit (Maximum Residue Limit – MRL). The animal or its products are not fit for human consumption during the withdrawal period.

A large margin of safety is used while determining withdrawal periods, to ensure that the consumer will not be at risk. In many countries there are strict laws to make sure that farmers obey withdrawal periods. Samples of animal products are taken from farms, shops, slaughter houses and at the border. They are tested to make sure that residues are not above the maximum allowable limit. This test also shows if prohibited or illegal drugs are used. If there is violation, investigation is carried out and offenders are prosecuted if appropriate.

How drug withdrawal periods can affect human health

Drug residues can lead to allergy, cancer, antibiotic resistance and other negative health effects. Residual penicillin, tetracycline, sulphonamides and aminoglycosides in meat, milk and eggs can cause an allergic reaction to people. One of the most important concerns is antibiotic resistance in humans. The resistant bacteria in a human body can cause diseases which are difficult to treat. The bacteria may also transfer the resistance to other human pathogens (disease-causing organisms).

Figure 1 – How bacteria become resistant

It is important to always use the prescribed dose of antibiotics. Too small amounts of antibiotics can cause a small fraction of bacteria to become resistant. These are the bacteria that will survive and replicate, thereby passing on the resistance. This replication will result in larger...

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