William J. Popendorf

Preliminary Survey of Factors Affecting the Exposure of Harvesters to Pesticide Residues

A survey was conducted in the Central Valley of California among harvesters of grapes, oranges and peaches. A comparison was made among factors which might affect their exposure to pesticide residues, such as the age and sex distribution of work crews, their apparel and work practices as related to foliar contact, and exposure to airborne particulates. Recurring high values of airborne particulates suggest that contaminated dust is the primary vehicle for residue exposure.

Exploring citrus harvesters' exposure to pesticide contaminated foliar dust

The results of measurements in 32 citrus groves indicate that available and dislodgeable foliar dust measurements can predict aerosol mass concentrations produced during harvest with regression r2 values of 0.41 and 0.25, respectively. The pesticide content of these foliar measurements correlates with whole-body dermal dosing via the deposition of pesticide containing aerosols with similar regression r2 values of 0.63 and 0.75. Several lines of argument suggest that the wide range of particle size (< 1 microns to > 200 microns) underlies differences in foliar residue, aerosol, and dermal pesticide measurements. Significant implications of this report include the magnitude of the aerosols to which these workers are exposed (10-80 mg/m3) and the potential ability to set re-entry intervals based upon these predictable dermal dose estimates.

Predicting relative vapor ratios for organic solvent mixtures

This report describes the theory and experimental measurements related to the ability of both the current ACGIH recommended method and an alternative approach called VAPRAT to predict the ratios of vapors evaporating from multicomponent solvent mixtures. The current ACGIH “approximate solution” does not account for nonideal effects common in many organic solvent mixtures nor for differences in the relative volatilities of individual components. It was concluded that errors ranging between 10 and 1000% using the ACGIH method are unacceptable for many occupational health programs. Laboratory tests with VAPRAT (an acronym for VAPor RATios) resulted in maximum errors of 20%. VAPRAT promises to be a useful alternative in the future for such applications as predicting the solvent mixture concentration from the measurement of a single component, adjusting TLVs for the presence of these other vapors, or for predicting the effects of solvent substitution.