Residues limits legislation

Legislation related to residues limits for soil, water, and air... 

Some critical differences in risk assessment procedure lead to confusing situations on a worldwide basis. These differences are due to some very controversial areas of safety issues including the calculation of the acceptable daily intake (ADI), the assignment of the ADI to maximum residue limit (MRL)/tolerance, the validation of the analytical methods needed to regulate drug residues, and the fitness of legislation to toxicology. 

For some solvents, recent legislation in the USA, and proposed legislation in Europe, sets a maximum residual limit for processing chemicals in finished pharmaceutical products. The criteria are based on toxicity concerns ten solvents are present in the European Pharmacopoeia issued in July 1995, including methylene chloride, acetonitrile and secondary butanol. While their use is not precluded, greater care is now required to ensure compliance with the rules. This may involve more intensive and expensive recrystallisation procedures to remove trace amounts of solvent when they are used in the latter stages of the manufacturing process. 

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. 

In considering pesticide residues, it was clearly shown that crops from organic production systems contain no or significantly lower levels of pesticide residues than crops from conventional systems (Baker et al., 2002). However, while some scientists are concerned about the potential health impacts from such residues (Porter et al., 1999 Benbrook, 2002), pesticide legislators maintain that current pesticide risk assessments and pesticide registration procedures are adequate and that residues below the current legal limits can not have a negative health impact in humans (e.g. PSD, 2006). 

As a consequence of EU Directive 78/142/EEC, which introduced a limitation of vinyl chloride monomer both as residual amount in final articles (QM lmg/kg) intended to come into contact with foodstuffs and in migration to food (SML not detectable LOD 0.01 mg/kg), the corresponding necessary analytical methods were developed between several European expert laboratories and laid down as agreed methods in EU Directives 80/766/EEC and 81/432/EEC, respectively. This piece of the EU harmonization process was too time- and work-consuming to continue in this way. The vinyl chloride Directives therefore remain a unique feature in EU food packaging legislation since this was found to be impractical for generalization. 

Besides compliance of a product s composition with legislation, one needs to demonstrate that the product complies with the limits set for overall migration, specific migration, residual content and requirements. This is described in section 5.3 in more detail. 

Restrictions for the residual amount of a component instead of a specific migration limit are set by the legislator in cases where specific migration of a component is difficult to obtain (for example, because the component is very volatile) or impossible to determine directly (for example, if the component is very reactive and would react with the food simulant). There are two ways to determine the residual content, by worst-case calculation or by analytical determination. The generic approach is shown in Eig. 5.3. 

The enforcement of this legislation has led to an increasing need from analysts to develop reliable, effective methods for qualitative and quantitative pesticide residue analysis in environmental and food matrices. EEC Directive 80/778, which is concerned with the quality of water designated for human consumption, has established the maximum admissible concentration of each individual pesticide at 0.1 /rg/l and the total amount of pesticides at 0.5 /rg/1. Other countries (e.g., U.S.A. and Australia) have established concentration limits based on the values recommended by WHO. Such values are based on the acceptable daily intake (ADI), which is calculated as the 20% ADI for a person of 70 kg drinking 2 1 of water per day. "... 

The selection of an appropriate method (marker residues, analytical range) therefore depends in part on the regulatory application, given the different regulatory limits applied in different jurisdictions. Since the epimerization of CTC, OTC, and TC is an equilibrium reaction, the epimers are often present to a greater or lesser extent in analytical standards and can occur throughout the extraction and clean-up procedure. Analytical method development is further complicated by the need to separate and quantify parent and epimer, even when the local legislation does not demand it. 

As a result of these observations, recommendations have been made to include an incubation step in methods of analysis for lincosamides in liver. " If the aim is to detect lincosamide use, then inclusion of an incubation step is necessary to maximize the possibility of detection. However, as indicated earlier, MRLs, where set, are based on the parent compound only with no reference to the metabolites, either by summation of separate measurements or by conversion to a suitable marker. Thus, inclusion of an incubation step could lead to falsely high residue concentrations and the possibility of samples that fall within the legal limits being reported as non-compliant. As a result, analytically, steps should be taken to minimize enzymatic activity to prevent this reverse metabolism. A long-term solution to this issue might be to include the sulfoxides in the legislation as additional markers in some form. 

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