Approaches for grouping of pesticides into cumulative assessment groups for risk assessment of pesticide residues in food.

The European Food Safety Authority (EFSA) is developing approaches to cumulative risk assessment of pesticides by assigning individual pesticides to cumulative assessment groups (CAGs). For assignment to CAGs, EFSA recommended to rely on adverse effects on the specific target system. Contractors to EFSA have proposed to allocate individual pesticides into CAGs relying on NOAELs for effects on target organs. This manuscript evaluates the assignments by applying EFSAs criteria to the CAGs "Toxicity to the nervous system" and "Toxicity to the thyroid hormone system (gland or hormones)". Assignment to the CAG "Toxicity to the nervous system" based, for example, on neurochemical effects like choline esterase inhibition is well supported, whereas assignment to the CAG "Toxicity to the thyroid hormone system (gland or hormones)" has been based in the examined case studies on non-reproducible effects seen in single studies or on observations that are not adverse. Therefore, a more detailed effects evaluation is required to assign a pesticide to a CAG for a target organ where many confounders regarding effects are present. Relative potency factors in cumulative risk assessment should be based on benchmark doses from studies in one species with identical study design and human relevance of effects on specific target organs should be analyzed to define minimal margins of exposure.

Poly(methyltetradecylsiloxane) immobilized onto silica for extraction of multiclass pesticides from surface waters.

A new material based on poly(methyltetradecylsiloxane) (PMTDS) thermally immobilized onto a silica support has been tested as a sorbent for the solid-phase extraction (SPE) from water of several pesticides used in soybean cultivation. The SPE methodology was developed and validated for six of these pesticides (imazethapyr, imazaquin, metsulfuron-methyl, bentazone, chlorimuron-ethyl and tebuconazole) according to the International Conference on Harmonization directives and the results were compared with those obtained with a commercial C18 SPE cartridge. The PMTDS-based sorbent gives results similar to the commercial sorbent with recoveries and precisions in agreement with directives for residue analysis. The quantification limits, after concentration, of all the pesticides evaluated were 1.0 microg L(-1), below the levels imposed by the principal regulatory agencies. The PMTDS-based sorbent preparation is fast, easy and reproducible and the cartridges are less expensive than similar commercial SPE materials.