Workshop: Predicting Workplace Exposure to New Chemicals

Abstract

EPA's Office of Toxic Substances (OTS) recently held a Workshop entitled “Predicting Workplace Exposure to New Chemicals.” EPA and industry representatives divided into four cooperative “brainstorming” workgroups, which addressed the topics of inhalation exposure, engineering controls, respiratory protection, and dermal exposure, as these pertain to the Agency's risk assessment and risk management processes for new chemical substances. All four groups emphasized the need for better characterizations of workplace environments in order to strengthen the predictive power of many of the tools that are already used.

The inhalation workgroup made specific suggestions regarding fugitive emission estimations and OTS's current volatilization model, and emphasized their preference for engineering controls in lieu of personal protective equipment. The engineering control group suggested categorizing process facilities and operations by degree of containment, by ventilation system, and by range of concentration, in order to standardize the consideration of additional control measures. Participants in the respiratory protection session recommended that a target exposure level be established to facilitate the choice of an appropriate respirator or engineering control, and discussed which breathing apparatus is most suitable for certain use scenarios, including scenarios involving carcinogens. Finally, the dermal exposure workgroup encouraged more quantitative assessment techniques. They commented on the use of deposition rate versus absorption rate to calculate absorbed dose, and on both the physical state of a PMN chemical, and the function of carrier solvents in mixtures, as factors influencing absorption rate.