Maximum residue levels/limits pesticides

Maximum residue level (MRL) Comparable to a U.S. tolerance level, the maximum residue level is the enforceable limit on food pesticide levels in some countries. Levels are set by the Codex Alimentarius Commission, a United Nations agency managed and funded jointly by the World Health Organization and the Food and Agriculture Organization. 

A maximum residue level was proposed at the limit of determination for pesticides in which all residues were non-detectable, even if the minimum sample requirements (59) were not met for satisfying the specified probability (> 95th percentile) and confidence (95%) limits for any of the sub-groups. 

Today, when a pesticide with no detectable residues is registered for use, a Tolerance or maximum residue limit (MRL) is established at the lowest concentration level at which the method was validated. However, for risk assessment purposes it would be wrong to use this number in calculating the risk posed to humans by exposure to the pesticide from the consumption of the food product. This would be assuming that the amount of the pesticide present in all food products treated with the pesticide and for which no detectable residues were found is just less than the lowest level of method validation (LLMV). The assumption is wrong, but there is no better way of performing a risk assessment calculation unless the limit of detection (LOD) and limit of quantification (LOQ) of the method were clearly defined in a uniformly acceptable manner. 

For example, in order to meet the demanding requirements of legislation such as the European Union (EU) Baby Food Directive (Directive 95/5/EC and subsequent revisions), analysts must improve on the scope and sensitivity of multiresidue methods of analysis. This Baby Food Directive, which became effective on 1 July 2002, limits residues of all pesticides to a maximum level of 0.01 mgkg There will also be a banned list of pesticides, annexed to the Directive, which will not permit the use of certain pesticides on crops intended for use in baby food production. As a consequence, food manufacturers often require residue results for raw or primary ingredients within 24 8 h of sample receipt at the laboratory. 

While all nations of the world possess the sovereign right to establish their own acceptable levels for pesticide residues in foods, many lack the resources to develop their own regulatory programs and instead rely upon a set of international standards developed by the Codex Alimentarius Commission, frequently referred to as Codex. The Codex international standards are termed maximum residue limits (MRLs) and, like U.S. tolerances, are established primarily as enforcement tools for determining whether pesticide applications are made according to established directions. While many countries have adopted Codex MRLs, others, such as the U.S. and several Asian countries, rely on their own standards. Thus, there is no uniformity among the world with respect to allowable levels of pesticides on foods. A pesticide-commodity... 

Examples of standard settings developed by the WHO include air quality guidelines (Section 9.2.1.1) and drinking water guidelines (Section 9.2.1.2), and (in collaboration with the FAO) maximum residue limits (MRLs) for pesticides and veterinary drugs and maximum levels for food additives (Section 9.2.1.3). 

A statistical survey study ( 5) conducted for the EPA by Cornell University researchers reported that 63% of rural homes have contaminated drinking water nearly 30% have excessive bacterial counts but few have detectable pesticide residues. Samples from wells at 267 sites were selected for analysis. The analyses were limited to only those six pesticides for which maximum contaminant levels (MCLs) are nationally established. Results of the study showed ... 

In Japan, the Positive List system was implemented on May 29, 2006. The Japanese Ministry of Health, Labour, and Welfare had established many provisional maximum residue limits (MRLs) in addition to present MRLs, and 586 pesticides were regulated under the Food Sanitation Law [1]. A uniform level of 0.01 ppm is established as the level having no potential to cause damage to human health [2], A rapid and sensitive multiresidue analytical method was required to conduct efficient and effective monitoring surveys of pesticide residues to ensure food safety. 

Amounts of pesticides and their metabolites above their maximum residue limits (MRLs) in drinking waters and foods have pathogenic effects on humans and animals. This has raised the need for fast, sensitive methods for the routine analysis of various classes of pesticides in environmental and physiological matrices. It is especially important to control the contaminant levels in foodstuffs and also of envirorunental (surface, groimd)... 

The TMRC is based upon tolerances established for raw agricultural commodities. It assumes all crops are treated and that all residues occur at the maximum level seen in use situations. Tolerances are usually set at the limit of analytical detection when residues are not expected to occur. For instance, fruit trees sprayed during dormancy with a product that degrades before fruit are formed hence such tolerances in the fruit are meaningless. Therefore, TMRC greatly exaggerates pesticide intake. 

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. 

Purity control limits contamination with pathogenic bacteria Staphylococcus aureus, Escherichia coli. Salmonella-species, Pseudomonas aeruginosa, Clostridium-species and others), yeasts, moulds, microbial toxins (aflatoxins, endotoxins), toxic heavy metals (lead, cadmium, mercury, arsenic e.g. from industrial emission), pesticide and herbicide residues, fumigants (ethylene oxide, methyl bromide, phosphine) and radionuclides. Furthermore, impurities with other plants parts ( foreign organic matter ) are limited. Moist levels must be below a certain maximum to avoid deterioration by microorganisms. Excreta of animals and dead insects must be absent. The ash value and acid-insoluble ash limits the amount of inorganic impurities (soil, sand). 

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