Maximum residues levels

Subdivision O guidelines for residue chemistry data were originally pubHshed by the EPA in 1982. These have been supplemented to improve the rate of acceptance by EPA reviewers of the many reports submitted by registrants in support of tolerances for pesticides in foods. The residue chemistry studies most frequently rejected include metaboHsm in plants, food processing (qv) studies, and studies on storage stabHity of residues in field samples (57). AH tolerances (maximum residue levels) estabHshed under FIFRA are Hsted in 40 CFR under Sections 180 for individual pesticides in/on raw agricultural commodities, 180 for exemptions from tolerances, 185 for processed foods, and 186 for animal feeds. 

When illegal residues have been found in monitoring studies conducted by the FDA or USD A, the reason has often been that no U.S. tolerance had been requested for that particular pesticide in that specific crop. For example, an imported crop would be deemed to be adulterated and would be seized at the port of entry into the United States if found to contain a pesticide residue in the absence of a tolerance in that crop. This is so even if tolerances have been set for the same pesticide in several crops grown in the United States and the pesticide had been used to control a pest that does not exist in the United States. Furthermore, an international maximum residue level (MRL) might already have been estabUshed for that pesticide—crop combination under the Codex system of standards for food of importance in international trade. The U.S. GAO issued two reports on food safety and pesticides in 1991 (89,90). 

A subsequent comparison of these ionization techniques for the study of another eight pesticides, this time including three of the five of interest [28], i.e. carbendazim, thiabendazole and thiophanate methyl, showed that ESI gave enough sensitivity to allow reliable determination of the pesticides at concentrations below their respective maximum residue levels. 

S. C. Fitzpatrick, S. D. Brynes, and G. B. Guest, Dietary intake estimates as a menas to the harmonization of maximum residue levels for veterinary drugs, J. Vet. Pharmacol. Ther, 18, 325 (1995). 

Very often a high degree of accuracy, i.e. a small number after the in the example above, is not important. This might be the case for trace analysis where the concentration of the contaminant is well below the permitted level. For example, the permitted maximum residue level of fluorine in complete animal... 

Maximum pinning force, 23 826 Maximum reflux ratio, <5 806 Maximum residue levels (MRLs), 14 337 18 541... 

Maximum residue levels in certain foods are set for the following contaminants nitrate, my cotoxins (aflatoxins, ochratoxin A, pamlin, deoxynivalenol, zearalenone, fumonisins, T -2 and HT-2-toxin), metals (lead, cadmium, mercury, inorganic tin), 3-MCPD (3-monochloro-propane-l,2-diol), dioxins and PCBs, and polycyclic aromatic hydrocarbons (benzo(a)pyrene) (EC 2007c). 

European Community Commission Regulation No. 2701/94 (21) states that the maximum residue level (MRL) for all substances belonging to the tetracycline group is the sum of the residues of all substances within the group. This legislative requirement necessitates the development and use of analytical methods capable of simultaneously detecting residues of more than one tetracycline. The MRLs for combined tetracycline residues are 600 yug/kg, 100 /U,g/kg, and 100 /u,g/kg in kidney, muscle, and milk, respectively (22). 

Chloramphenicol (CAP), florfenicol (FLO), and thiamphenicol (TAP) are broad-spectrum antibiotics suitable for the treatment of a variety of infectious organisms (5). Chloramphenicol, which could produce aplastic anemia in a small percentage of humans, is not approved for use in food-producing animals in the United States (129). Florfenicol is allowed for the treatment of bovine respiratory diseases in the United States. The FDA has set a level of 10 /Ug/L in milk (130). The maximum residue level of CAP is set by the EU at 10 yug/kg (15). In Table 6, the different HPLC methods can be found. 

Ivermectin (IVER) is a drug with a broad spectrum of activity against gastrointestinal nematodes and lung parasites in food-producing animals. In the EU, the maximum residue levels set for IVER in the liver of sheep, pigs, and cattle are 15,15, and 100 tg/kg, respectively (217). The use of automated SPE equipment was described for IVER HPLC analysis in animal liver samples. This automated system, ASPEC, was used for the SPE purification step in order to provide more efficient and faster sample preparation. Some tests were performed to obtain recovery and repeatability data. The mean recovery for spiked samples was more than 90% in the concentration range of 7.5-30 tg/kg. 

The use of pesticides in agriculture has obvious advantages, such as an increase in the quantity and quality of food crops. Nevertheless, pesticides are toxic substances, and their residues can pose a risk to man and environment. Therefore, pesticide residues in food are regulated at the international and national levels according to the toxicity of the compound and the human intake of a particular crop. The acute oral toxicity for rats and the maximum residue levels (MRLs) of carbamate and urea pesticides are listed in Tables 1 and 2. 

To protect consumers health, many countries have restricted the use of pesticides by establishing legal directives on maximum residue levels (MRLs) to control their levels in food (28). These MRLs sometimes cause conflicts, because residue levels acceptable in one country may be unacceptable in others. This problem has revealed the need to harmonize the different MRLs, which have been dealt with mainly by two international organizations, the European Union (EU) at the European Level, and the Codex Alimentarius Commision of the Food and Agriculture Organization (FAO) and the World Health Organization (WHO) (28,29). 

The U.S. Food and Drug Administration policy is based on the conclusions of the Joint FAO/ WHO Expert Committee on Food Additives (JECFA). In its Thirty-Second Report (1988), it concluded, on the basis of its safety assessment of residues of estradiol-17/3, progesterone, and testosterone, and in view of the difficulty of determining the levels of residues attributable to the use of these hormones as growth promoters in cattle, that it was unnecessary to establish an acceptable residue level. As to trenbolone acetate (TBA), a synthetic steroid with anabolic properties, JECFA concluded that its safety assessment could be based on establishing the no-hormonal-effect level. It therefore recommended a maximum residue level of 2 /zg/kg for /3-tren-bolone in meat and of 10 /xg/kg for a-trenbolone in liver on the basis of a daily intake by a 70-kg person of 500 g of meat. /3-Trenbolone is the major metabolite in muscle. For zeranol, an acceptable residue level of 10 /xg/kg for bovine liver and 2 /zg/kg for bovine muscle was established. 

FAO, Submission and Evaluation of Pesticide Residues Data for the Estimation of Maximum Residue Levels in Food and Feed, 1st ed., FAO, Rome, 2002. 

The acute toxicity of phenoxy-acid herbicides to humans and aquatic organisms is relatively low [87]. The USEPA maximum residue level for 2,4-D in drinking water is 70 000 ng/L, and the National Academy of Sciences has recommended a maximum concentration in water for protection of aquatic life of 3000 ng/L [78]. No Canadian guidelines for the protection of aquatic life and drinking water were exceeded (Table 8). 

Toxic chemical intake must be quantified in order that comparisons between different chemicals (e.g. pesticides), diets and countries can be made. Most countries in the developed world conduct surveys which involve analysing food for pesticide residues. These values are then put in context by comparing them to benchmarks of toxicity (Acceptable Daily Intake - ADI) or with trading standards (Maximum Residue Level -MRL) which are set to ensure that countries exporting food do not export excessive pesticide residues with that food. 

The procedures used to set permanent maximum residue levels (MRLs) for pesticide residues is described briefly below. In parallel with this, proposals for provisional MRLs are prepared in connection with the work on regulating the placing of plant protection products on the market according to Council Directive 91/414. 

Tolerances are primarily established to represent the maximum residues anticipated from the legal use of the pesticide on the commodity. The maximum residue levels are determined from the results of controlled field studies performed by the pesticide manufacturer in a variety of geographical regions. The manufacturer performs the studies under conditions that would likely yield the maximum residue levels such as applying the pesticide at the maximum recommended rate for the maximum number of applications anticipated and harvesting the commodity at the minimum expected preharvest interval. The highest residue levels detected under these worst-case application scenarios are identified and the manufacturer petitions the EPA to establish the tolerance levels at or slightly above the maximum residues encountered. 

EPA will establish the tolerance at or slightly above the maximum residue level detected from the manufacturer s controlled field trials. 

The procedures used by the US to establish tolerances are similar to those used by the Codex Alimentarius Commission to determine their analogous Maximum Residue Levels (MRLs). One comparison of US tolerances and Codex MRLs demonstrated that the two sets of standards were equivalent 47 percent of the time while US tolerances were lower 19 percent of the time and Codex MRLs were lower (and therefore more stringent) 34 percent of the time. Some of these differences were explained to result from different agricultural production and pest control practices, the use of different data sets, and differences in how the breakdown products of some pesticides are regulated (General Accounting Office, 1991). 

---