Dr. Paul Price has a B.A. in chemistry, M.S, in environmental engineering, and PhD in environmental studies. He has been an exposure and risk assessor for more than forty-five years. He is the author of more than 90 papers and book chapters. Dr. Price is an adjunct professor at the University of Iowa. He has worked for a wide range of organizations including, trade associations, state and federal governments, consulting companies, large chemical manufactures, and non-profit organizations. His work has included pure research, applied research, regulatory affairs, and policy analysis. Areas of research includes the integration of mechanistic toxicity and exposure data into chemical risk assessments, modeling chemical exposures from the use of multiple consumer products, determination of variation in aggregate and cumulative exposures from near- and far-field sources using probabilistic models. For the last fifteen years he has been investigating mixture risk assessments and how advances in single chemical exposure and risk assessment can improve such assessments.
Combined exposure to multiple chemicals: assessing risks across regulatory silosSee more
22/06 - 14:00Visit the agenda
Title of talk
Possibilities for assessing multiple chemicals across regulatory domains through tiered approaches
22/06 - 15:15
Abstract of talk
The assessment of risks from unintentional mixtures (i.e., those that result from multiple sources covered by different regulatory programmes) are a challenge, but not an insurmountable challenge. Recent advances in exposure assessments make it possible to assess the potential for co-exposure between chemicals on a systematic basis and use such predictions to direct regulatory programmes to control exposures to those chemicals that in combination are a concern. Combined exposures to multiple substances in European populations are complex, but not random. Such exposures are a function of 1) the physical and chemical properties of a substance, 2) its use in commercial products, and 3) the exposure-related behaviours of individuals. In addition, the potential for co-exposures of concern for substances can be predicted based on the level of interindividual variation in exposure. This suggests that a tiered approach could be developed for identifying unintentional mixtures of concern. An initial tier of such a programme would be an exposure assessment that would evaluate the potential for a chemical to 1) reach any of a series of specific demographics (defined by time, location, age, and socio-economic status), 2) occur by a specific route, and 3) be linked to a specific source, 4) and interindividual variation in the magnitude of the doses received in the demographics. Such an approach could take a form similar to the USEPA ‘Chemical Dashboard’ that organises existing exposure data and structure-based predictions of exposure-related characteristics of a substance. A second tier would use structure-based models of adsorption, distribution, metabolism, and excretion to determine if the chemicals (or their metabolites) are likely to cooccur internally. In the third tier, mechanistic data would be used to determine if the chemicals are likely to initiate molecular events on common networks of Adverse Outcome Pathways. Throughout the process, chemicals with a limited potential for co-exposure, poor absorption, or lack of a common pathway would be screened out. The result would be groupings of chemicals with a high probability of causing combined effects. In the fourth tier, combined risk assessments would be performed for such groupings based on screening and, if necessary, refined risk assessment models. Chemicals that are found to drive combined effects of concern would then be flagged for control under the appropriate regulatory programmes.