62 JUNE 2013 • WORLD AQUACULTURE • WWW.WAS.ORG quantifying risk. What has emerged recently from EFSA (2012) is a positive opinion on the Threshold of Toxicological Concern (TTC) method. The TTC concept was first debated in academic circles in the mid-1990s and now has wide support within the chemicals industry. Thresholds of Toxicological Concern are already used by JECFA and the US Food and Drug Administration for deciding if a food additive needs to be evaluated for toxicity. The TTC 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. As with traditional interpretations of toxicity data, safety factors are built into the model to account for uncertainties in the estimates. Proponents of the TTC approach argue that for most chemicals there are only marginal benefits to be gained by carrying out low dose toxicity testing compared with adopting the TTC. However, EFSA’s particular interpretation of the TTC has yet to be implemented and it is not yet clear if it is capable of overturning the zero tolerance approach or if its adoption would provide any safety benefits to the consumer. By producing this opinion, EFSA appears to acknowledge that toxicity data cannot be collected for every chemical that might find its way into the food supply, whether maliciously, inadvertently or via a natural route. It also appears to indicate that EFSA is not entirely satisfied with current thinking that the presence of certain substances at abovezero levels is unacceptable, as enshrined in European legislation. We have yet to see how this can be translated into legislation and what effect this will have in practice. Conclusion As aquaculture expands, chemical residues will continue to be found in farmed products. Their cause may be the responsible use of permitted substances or the malicious or irresponsible use of chemical agents; or, they may enter the product from the environment, where the source of contamination may be anthropogenic or otherwise. Efforts are needed to continue to develop better methods for assessing the risk of chemical residues to human health and to develop strategies for dealing with contaminated product that are based on risk. Notes Ivan Bartolo, Seafood Importers and Processors Alliance (SIPA), Heiveldekens 4, 2550 Kontich, Belgium; i.bartolo@ seafoodalliance.org 1 Presentation made by G. Fedorova et al. at the World Aquaculture Society AQUA 2012 Conference, Prague, Czech Republic. She reported findings of residues of 34 antibiotics in 15 out of 97 samples; of these 15 positive samples, 8 were wild caught. References EFSA Scientific Committee. 2012. Scientific Opinion on exploring options for providing preliminary advice about the possible human health risks based on the concept of the Threshold of Toxicological Concern (TTC). EFSA Journal 10(7):2750 [103pp.] FAO (Food and Agriculture Organization of the United Nations) Fisheries and Agriculture Department. 2012. The State of the World Fisheries and Aquaculture. FAO, Rome, Italy. Heberer, T., M. Lahrssen-Wiederholt, H. Shafft, K. Abraham, H. Pzyrembel, K. J. Henning et al. 2007. Zero tolerances in food and animal feed – Are there any scientific alternatives? a European point of view in an international controversy. Toxicology Letters 175:118-135. Foresight. 2011. The future of food and farming: challenges and choices for future sustainability. Final project report. The Government Office for Science, London, England. Rico A., K., M. M. Satapornvanit, J. Haque, P. T. Min, T. C. Nguyen, P. J. Telfer and Van den Brink. 2012. Use of chemicals and biological products in Asian aquaculture and their potential environmental risks: a critical review. Reviews in Aquaculture 4:75-93. Tran N., N. L. W. Wilson and S. Anders. 2012. Standard harmonization as chasing zero (tolerance limits): the impact of veterinary drug residue standards on crustacean imports in the EU, Japan, and North America. American Journal of Agricultural Economics 94(2):496-502. Van Poucke C., C. Detavernier, M. Wille, J. Kwakman, P. Sorgeloos and C. Van Peteghem. Investigation into the possible natural occurrence of semicarbazide in Macrobrachium rosenbergii prawns. Journal of Agricultural and Food Chemistry 59:2107-2112.
RkJQdWJsaXNoZXIy MjExNDY=