Probabilistic Risk Assessment for Atrazine and Simazine

Probability distributions have been used for the triazine herbicides, atrazine and simazine to more accurately characterize the uncertainty and variability associated with the individual components of exposure (e.g., drinking water concentrations, food residue concentrations, and pesticide handling exposures associated with different user subpopulations, crops, product formulations, techniques of mixing/loading and application, and types of protective clothing). Furthermore, distributional techniques have made it possible to more realistically combine exposures from multiple years, subpopulations, exposure pathways, and chemicals. Using new studies on potential human exposure through diet, drinking water and pesticide handling, safety margins and margins of exposure have been calculated for atrazine and simazine. Margins of safety calculated for potential exposure through diet and drinking water ranged from 25,000 to 1,000,000 depending on the exposure pathway. Margin of safety per pesticide handler ranged from 1,400 to 33,000. Results indicated that neither occupation exposure, dietary exposure nor environmental exposure to atrazine and simazine alone or to atrazine and simazine combined are likely to produce adverse health consequences.

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