Dose reconstruction is the determination of potential doses from historical chemical exposures, whether by inhalation, ingestion, or entry through the skin. Doses depend on the current concentration levels in air, water, soil, food, or products contacted, and duration and frequency of exposure. If concentration data are available for the time period and location at which exposure is being claimed (or to the product at issue), estimating exposure and dose for each chemical is straightforward. However, for exposures that occurred historically, often this information is not available or is unreliable as it is outdated and not specific.
Exponent has used a variety of assessment tools to gather data to reconstruct and characterize historical exposures. These include:
- Extrapolations to historical conditions based on current data and conditions or based on activity-based sampling
- Factors representing differences between historical and current conditions (e.g., use of differences in ventilation conditions and air exchange rates between the historical and current work facility conditions or, process changes)
- Mathematical modeling of historical exposure conditions (e.g., use of emission and dispersion models to estimate chemical concentrations in air under specific historical conditions)
- Exposure simulations of historical conditions and collection of industrial hygiene data (e.g., tests of chemical releases from historical products under controlled conditions).
Using these methods, Exponent has calculated the historical chemical dose to which persons that worked certain jobs or tasks or used specific products were exposed.
Recent Related Exponent Publications
Exponent has published and presented dose reconstruction assessments for automobile and truck mechanics, workers using solvents, persons using various commercial and consumer products and persons at contaminated sites.
Lewis RC, Evenson KR, Savitz DA, Meeker JD. Temporal variability of daily personal magnetic field exposure metrics in pregnant women. Journal of Exposure Science and Environmental Epidemiology 2015; 25(1):58–64.
Bogen KT, Sheehan PS. Dermal vs. total uptake of benzene from mineral spirits solvent during parts washing. Risk Analysis 2014; 34(7):1336–1358.
Richter RO, Kerger BD, Hoyt S, Fedoruk MJ. Total aromatic content in petroleum solvents modifies headspace benzene vapor concentrations: Implications for exposure assessments. Journal of Human Ecological Risk Assessment 2013; 19:354-373.
Brorby GP, Sheehan PJ, Berman DW, Bogen KT, Holm SE. Exposures from chrysotile-containing joint compound: evaluation of new model relating respirable dust to fiber concentrations. Risk Analysis 2013; 33(1):161-176.