Analytical approaches for determining human exposure to pesticides.

The presence of pesticides, both persistent and biodegradable, in the environment is a problem which is both significant and potentially dangerous to humans. An index of biodegradability is presented which is based on the correlation between environmental stability and fat solubility. Halogenated pesticides are, therefore, both more fat soluble and more resistant to biodegradation, while methylated pesticides are more water soluble and, therefore, more biodegradable. Three methods for detecting low-levels of halogenated pesticides are presented: the Macro, the Micro "Florisil," and the Micro "Silica." A method is also presented to detect these chemicals in blood. Two methods for the detection of nonpersistent, organophosphorus and carbamate insecticides, Cholinesterase inhibition and urinary metabolites, are described. Finally, methods of monitoring human exposure through the detection of phenols, phenoxy acids, alkyl phosphates, and anilines are presented.

A multiclass, multiresidue analytical method for determining pesticide residues in air.

A multiresidue method for chlorinated, organophosphate and N-methyl carbamate insecticides has been developed for use in the National Air Monitoring Program. The method involves partitioning and extracting the pesticides from the ethylene glycol trapping solvent with methylene chloride followed by fractionation and cleanup by elution through a silica gel column. The chlorinated compounds are determined by electron capture GC, phosphate compounds by flame photometric GC, and carbamates by electron capture GC after derivatization with pentafluoropropionic anhydride. Recovery data and limits of detectability are presented for 11 chlorinated, 7 phosphate, and 7 carbamate pesticides at high and low levels. It is expected that the method will be applicable to many other compounds not successfully determined by the present analytical procedure, and that it may be adaptable for the analysis of pesticide residues in foods and other environmental samples.

Concentrations of propoxur in air following repeated indoor applications.

The insecticide propoxur was applied as 2 non-overlapping bands approximately 1 m wide to the interior of houses in El Salvador once every 35 days for a period of 9 months. Air samples were collected from the interior of the houses once every seventh day during the entire period. In the study area, air temperatures remain relatively constant, while rainfall varies seasonally. It was found that volatilization of propoxur, as determined by the amounts detectable in air, represented release of the chemical from the treated surface and that the volatilization process was most influenced by the amount of moisture present in the air. Higher air concentrations of propoxur occurred during periods of high relative humidity than in periods of low relative humidity. The principles involved in this process and its bearing on the value of propoxur in malaria control programmes are discussed.