This report presents the conclusions of a Joint FAO/WHO expert committee convened to evaluate the safety of residues of selected veterinary drugs ihn food, to establish acceptable daily intakes for humans, and to recommend maximum residue limits that will fully protect the health of consumers.
The report marks the fourth time that this committee has considered the safety of veterinary drug residues in food.
The report opens with an explanation of several principles and proceudres followed when calculating acceptable daily intakes and establishing maximum residue limits. Because some of the drugs considered are tranquillizers used immediately prior to slaughter, the report draws attention to the risks to consumers posed by drugs still present in the animal at the time of slaughter and at a concentration compatible with a pharmacological effect.
The report notes the need to regard any major pharmacological effects in consumers as adverse effects and to assess these together with conventional toxicological effects.
Also discussed is the special problem of high concentration of residues at the injection site, particularly when such sites may be in non-discarded edible tissues. Other topics include the relationship of withdrawal time to recommended maximum residue limits and the need, when expressing these limits, to identify the animal species, the target tissue, and the marker residue.
Designation of an appropriate target tissue is intended to facilitate regulation of the maximum residue limit in international trade in meat as well as in national control programmes.
The main part of the report summarizes toxicological and residue data used to evaluate the safety of residues of ten veterinary drugs: one b-adrenoceptor-blocking agent (carazolol), three anthelminthics (febantel, fenbendazole, and oxfendazole), three antimicrobial agents (spira-mycin, sulfadimidine, and tylosin), and three tranquillizers (azaperone, chlorpromazine and propionylpromazine).
For carazolol, which is primarily used in pigs to prevent sudden death due to stress during transport, the evaluation gave particular attention to possible pharmacological risks in groups of humans, such as people suffering from cardiac disease or asthma. For the three tranquillizers, the report noted that all have been inadequately studied in certain respects, all are often used in pigs shortly before slaughter and all leave residues in edible tissues.
On the basis of available data, the report advises against the use of these drugs for any purpose in the immediate pre-slaughter period, especially when given by injection into the tissues.
The report further cautioned against the continued use of chlorpromazine and propionylpromazine in food-producing animals.
The report concludes with a tabular summary of end-points recommended for each of these compounds, lists of further studies required or desired, by a specified date, for the re-evaluation of eight of the drugs, a description of procedures for assessing the microbiological safety of anti-microbial drugs in food and a discussion of matters arising from the Fifth Session of the Codex Committee on the Residues of Veterinary Drugs in Foods.
