60 JUNE 2013 • WORLD AQUACULTURE • WWW.WAS.ORG The global food security challenge facing us is how to produce safe and wholesome food to feed a growing population. Capture and farmed fish have been neglected in the context of food security policy until quite recently. They are now recognized as important components in the provision of high quality animal protein. For example, the UK think tank Foresight predicts that “Fish demand is expected to increase substantially... particularly in parts of east and south Asia. The majority of this extra demand will need to be met by further expansion of aquaculture” (Foresight 2011). The Food and Agriculture Organization (FAO) expects farmed seafood production to increase from 60 million t in 2010 to 80 million t by 2021 (FAO 2012). History has shown that increasing aquaculture production brings with it infectious diseases and, therefore, the requirement for increased disease control. Proactive disease prevention and, where practicable, reactive disease treatments are already integral to aquaculture. Indeed the development of disease prevention strategies has been critical to the development and intensification of production of all current aquaculture species. In common with land-based agriculture, disease prevention and treatment in aquaculture involves the use of chemical agents to some degree (Table 1). Chemical safety aside, this is an unfortunate situation on several levels: the farmer ideally does not want to spend money on chemicals; the food producer wants to provide a product that is as pure and untainted as possible; and, the consumer is wary of any substance in food that he or she feels should not be there. Good aquaculture practice can be used to minimize the use of these agents. Current practices, in the main, result in a product that is free from illegal levels of residues Maintaining a High Level of Health Protection from Chemical Residues and Contaminants: a Regulatory Perspective Ivan Bartolo and indeed the level of residues is usually so low that they are undetectable even by modern analytical instruments. The Health Risk A level close to zero or even ‘undetectable’ is no guarantee of safety, of course. Regulators and the aquaculture industry have a collective responsibility to evaluate the safety of their product and this includes evaluating the risk to human health of contaminants and residues in the product when they are present, whatever the level. With contaminants such as heavy metals and many organic pollutants, the toxicology tends to be well known. Risk assessments have been carried out and are reviewed regularly by bodies such as the Joint FAO/WHO Expert Committee on Additives (JECFA), the European Food Safety Authority (EFSA) and the US Food and Drug Administration (FDA). With most approved veterinary medicines, the developer of the drug is required to gather toxicity data and provide risk assessments, including safe levels of use and withdrawal periods, as a condition for approval. Safety factors are applied to take into account uncertainties so, when a maximum permitted limit is established for a residue, we can be sure there is no significant risk to human health. However, for some chemicals there is insufficient toxicity data to carry out a proper risk assessment. These chemicals include some less well-studied environmental contaminants and many of the chemicals not authorized for use as veterinary medicines. The latter are of importance to cultured products and include malachite green and crystal violet. It can be argued that, while data exists on their toxicity of chloramphenicol and some other drugs at therapeutic levels, toxicity data is unavailable for the substantially lower, nonThe Threshold of Toxicological Concern approach is to identify the chemical structure of a substance and then compare the structure with that of other chemicals of known toxicity. This allows the substance to be classified with other similar substances and an estimate made on the toxicity of the substance by comparison with the group. TABLE 1. Substances used in Asian aquaculture (from Rico et al. 2012). Use Number of substances Water and sediment treatment 13 Fertilizers including manures 14 Pesticides 29 Disinfectants 21 Antibiotics 36 Immunostimulants, growth promoters, hormones, vaccines, anaesthetics and probiotics 10 groupsa aThe authors identified 10 groups of substances used but did not enumerate the substances.
RkJQdWJsaXNoZXIy MjExNDY=