Field exposure, worker, data base

A data base for predicting the chemical behavior of the bubbler was established. The generated data base is used to characterize the sensitivity and stability of the bubbler in the presence of known quantities of toxic vapors under ambient stress conditions. The data base is used to correlate the exact relationship between field sampling results and a worker s daily exposure. 

Of special interest recently Is the exposure to workers who mix, load and apply pesticides In the field. These work tasks are done by one, two or sometimes even three persons In a work crew. There have been numerous studies conducted and reported in the literature which characterize the exposure of this group under various application conditions. It Is this body of data which we have reviewed as a possible data base. 

Assessments of risks associated with the use of chlorpyrifos insecticide products for workers have been made. The assessments are based on the results of field studies conducted in citrus groves, a Christmas tree farm, cauliflower and tomato fields, and greenhouses that utilized both passive dosimetry and biomonitoring techniques to determine exposure. The biomonitoring results likely provide the best estimate of absorbed dose of chlorpyrifos, and these have been compared to the acute and chronic no observed effect levels (NOELs) for chlorpyrifos. Standard margin-of-exposure (MOE) calculations using the geometric mean of the data are performed however, probability (Student s f-test) and distributional (Monte Carlo simulation) analyses are deemed to provide more realistic evaluations of exposure and risk to the exposed population. 

The response submitted by The Dow Chemical Company included a more realistic evaluation of human exposure to 2,k,5-T (3) This evaluation relied on data from several studies in humans which showed that 2,1, 5-T was rapidly excreted in the urine with nearly complete clearance from the body within less than a week after exposure. Based on these data, the dose received by a person using a backpack sprayer was estimated to be less than 0.1 milligram per kilogram of body weight per day of exposure spraying brush. This estimate was subsequently confirmed by an extensive study conducted in forest workers applying 2,k,5-T under field conditions in Arkansas. 

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