Pesticide use patterns

Regulating Pesticides in Food The De/anej Paradox, Report of Board on Agriculture, Committee on Scientific and Regulatory Issues Underlying Pesticide Use Patterns and Agricultural Innovation, U.S. National Research Council, National Academy Press, Washington, D.C., 1987, 272 pp. 

To date, JMPR has evaluated 240 pesticides, many of them repeatedly. JMPR establishes ADIs (based on chronic toxicity) and acute reference doses (based on acute toxicity) on the basis of the toxicological data and related information available on the substances that are being evaluated. In addition, JMPR reviews pesticide use patterns, data on the chemistry and composition of pesticides, and methods of analysis of pesticide residues. It recommends MRLs for pesticides that occur in food commodities following their use according to Good Agricultural Practice. The potential intake of pesticide residues is compared with the ADI and acute reference dose to estimate the potential dietary risks associated with the adoption of the MRLs. 

Residues monographs, which contain information on pesticide use patterns, data on the chemistry and composition of pesticides, methods of analysis for pesticide residues, and information on MRLs, are published in the FAO Plant Production and Protection Paper series. 

Historically, attempts to demonstrate cumulative affects among harvesters or other field workers have been frought with difficulty. For Instance an analysis of data generated by a 1970 EPA survey of 822 individuals in one California county found that farm workers had lower blood cholinesterase than similar non-field Individuals, that low blood enzyme levels were associated with symptoms of headache and enteric disturbances, and that at least some individuals exhibited seasonal inhibition but no clear seasonal trend was found for the group (24). In retrospect, this latter finding is not unexpected given not only the variability in pesticide use patterns both between and within crops, but even the variability within residues of a single pesticide-crop combination (, ). 

The record for monitoring priority chemicals, and of produce destined for processing was equally as good. When there have been alarms, e.g. in a recent National Academy of Sciences report (2P), residue chemistry stepped in to help define the parameters of the issue, and established baselines from which the impact of changes in pesticide use patterns could be determined. 

The application of pesticides to paddy fields represents a unique set of issues compared with many other use patterns. Agrochemicals used in rice production are introduced directly or indirectly into paddy water, and there are more opportunities for... 

Performance trials are conducted to determine the use pattern required for effective pesticide performance. Much effort goes into determining the minimum effective rate. Usually, about 30 trials are required per major pest. Initial performance testing is usually conducted on company research farms. For crops and pests that cannot be handled internally, contractors are used. The differences between residue and performance trials create difficulties in designing an electronic system that can handle both smdy types well. 

In Tables 14.9 and 14.10, the last column reports the environmental impact points (EIPs) for typical applications of organic and conventional pesticides derived from the Pesticide Environmental Assessment System, or PEAS. This model produces relative rankings of risks based on defined use rates and use patterns (the formulation used to apply a pesticide, timing, target of the application, spray equipment used, etc). PEAS scores reflect an equal balancing of acute pesticide risks to farm workers, chronic risks via dietary exposure and exposures to birds, Daphnia and bees. 

In several AT studies, pesticide levels in the Ebro were found to be high. Hildebrandt et al. [50] found a homogeneous contamination pattern from atrazine (and also from simazine from May 2000) in intensive Rioja cultivation areas throughout the Ebro. Nearer to the delta, Barata et al. [72] found high levels of bentazone, methyl-4-chlorophenoxyacetic acid, propanil, molinate and fenitrothion in water, while Kuster et al. [71] found low concentration levels of atrazine and simazine at the delta, but high levels of other pesticides used in rice cultivation. Importantly, Hildebrandt et al. [50] found that levels of pesticides in groundwater... 

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