Monitoring exposure to field applicators

One essentially unexplored area for hair analysis is its application to the investigation of environmental toxin exposure. We received a research grant during 1979 from the National Institute of Occupational Safety and Health to explore the possibility of using hair analysis for monitoring exposure to polychlorinated biphenyl compounds (PCBs). Although the analytical chemical problems of this project were successfully solved, we were unable to mount successful field studies with human subjects. 

Issue The mineral processing industry and the end-users of their products need to agree on (1) realistic exposure scenario(s) (2) valid emission models (3) field monitoring methods for the application, use and disposal of biocidal products. 

Bystanders. The bystander had the lowest exposure to carbaryl of all the workers monitored. In keeping the bystander within 100 feet and downwind of the ground applicator, the bystander often had to walk into the field while it was being treated. This practice resulted in exposure when the hands of the bystander touched the crop foliage. Thus, with peas, there was no exposure because the plants were too small at the time of spraying for any inadvertent contact, but with relatively mature potatoes, measurable residues were deposited on the bystander. For example, when 80S was applied to this crop, the bystander had a total HDE of 0.5 mg/h... 

The exposure periods required to obtain sufficient sensitivity to measure VOCs in low pg/m concentrations using diffusive samplers are typically several days or weeks. It would be a major task to apply the laboratory and field tests required by protocols to evaluate diffusive monitors used in the workplace for these long exposure periods. At present the uncertainty associated with measurement by diffusive samplers requires further investigation, but a number of studies have shown them to be applicable to the measurement of VOCs in indoor air. 

Research into biomarkers for environmental contaminant exposure, an important area in impact-based monitoring, is unfortunately not covered in any detail in this volume. Biomarkers are applicable both to toxicological studies conducted in the laboratory and to field studies of exposed populations, including human populations (56). Potential biomarkers include tissue burdens of contaminants, molecular changes, e.g. creation of DNA adducts by genotoxic substances (57) that can be detected in vitro in the tissues of exposed organisms,... 

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