Livestock, pesticide residues

Finally, even if most of the pesticides worldwide are used in fruit and vegetable crops, data on pesticide residues in animal products are also essential, taking into account that livestock can be easily exposed to pesticides directly or through residues in their feed. For instance, the 2009 European Union Report revealed the presence of 34 different pesticides in animal products [115]. Garcfa de Llasera et al. [128] revealed the presence of chlofenvinphos and chlorpyrifos in liver samples, whereas a-endosnlfan, endosulfan sulfate, and dichloran have been reported in pork and lamb samples (<10 pg/kg) [129]. Bolafios et al. [130] studied the occurrence of organochlorine pesticides and polychlorinated biphenyls in chicken eggs. Benzene hexachloride and 28 polychlorinated biphenyl were detected in only one of the 30 samples at concentrations of 15 and 10 ng/g, respectively. However, five samples also contained traces of OC and PCB residues, even if at concentration levels below the limit of quantification. Einally, a-endosulfan and P-endosulfan were found in commercial milk-based infant formulas at concentration levels from 1.18 to 5.03 pg/kg [35]. The same study also showed the presence of fenitrothion, chlorpyrifos ethyl, and bifenthrin at maximum concentrations of 0.23,1.30, and 0.68 pg/kg, respectively. 

If a pesticide is to be applied to livestock, or will result in residues in the feed of livestock, the possibility of residues in meat, milk, poultry, and eggs arises. Data on metabolism, analytical methods, and level of residue in animal food products are needed in those cases. The same considerations of identification of the terminal residue and developing analytical methods suitable for enforcement mentioned previously also apply to residues in animal products. The tolerances for animal products are based on the tolerances on the animal feed items, the significance of those feed items in the diet of livestock, and the potential... 

Tolerances for animal food commodities are required only if the pesticide is registered for use on crops that can be constituents of livestock or poultry diets. Allowable feed items are published in the USEPA s Residue Chemistry Test Guidelines (USEPA, 1996). Examples of crops not used for animal feed are strawberries, lettuce, grapes, and pecans. Examples of crops that can be included in livestock and poultry diets are wheat, com, citrus, apples, and almonds. 

With US 51 million applied to cotton each year, methamidophos - a neurotoxin that impairs the activity of key enzymes essential for the normal transmission of nerve impulses - is the fourth most significant pesticide applied to cotton worldwide . Cotton accounts for over 40% of global use . Methamidophos residues have been detected in cottonseed and derivatives and may pose a particular hazard to those who consume cottonseed oil, or who feed derivatives to livestock . In laboratory experiments, hens and goats reared with food containing methamidophos showed traces of the pesticide in their eggs and milk . 

Created in 1982, FARAD is a computer-based decision support system designed to provide livestock producers, extension specialists, and veterinarians with practical advice on how to avoid drug, pesticide, and environmental contaminant residue problems when products are used in an extralabel manner. It serves as the largest repository of animal pharmacokinetic data in the world, maintaining an up-to-date computerized compilation of current label information (including withdrawal times) on all drugs approved... 

Animal metabolism provides both a scientific and a regulatory contribution to the data base needed to register or re-register an agrochemical. Absorption, distribution, metabolism, and excretion (ADME) studies in the rat are required in the overall toxicological assessment of a chemical s safety. Metabolism studies in livestock are needed when pesticide use, either by direct treatment of animal feed items or by premises application, can result in residues in milk, meat, or eggs. 

As with nitrates, the increased demands on crop and livestock yields by an ever increasing population has required the intensive use of pesticides. Widespread application in agriculture has resulted in a significant diffuse source to aquatic systems. Many pesticides feature in the lists of priority pollutants (Table 9.3). The nature of environmental residues, behaviour and fate are still uncertain for many compounds . ... 

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