Exponent complements this strong and diverse depth of scientific experience with its considerable knowledge base regarding current government and international standard-setting organizations’ activities regarding risk assessment, mathematical modeling, and exposure limits. Our work is supported and supplemented by our close ties with analytical laboratories for fast turnaround time on samples and our ability to design, construct, and operate exposure-testing chambers.
What is Exposure Assessment?
Characterizing and estimating the magnitude, frequency, and duration of potential exposures is an essential component for evaluating health risks posed by a particular chemical or physical agent.
Exposure assessment is an integral part of health risk assessment and is applied to assess:
- Exposure at contaminated sites and environments
- Exposures in the work place
- Exposures in the home
- Exposure to consumer products
- Exposures in the environment
Exposure assessment is also used to support epidemiological studies, toxicity assessments, and medical monitoring.
Exposure assessment incorporates information on the physical setting, potentially exposed populations, potential exposure pathways (generally inhalation, dermal and/or ingestion intake) and exposure concentrations to estimate intake or dose of the chemical or agent.
Exposure depends on various characteristics of the agent, such as particle shape or fiber size (for inhalation), form of radiation (for example) or chemical species, chemical composition, environmental fate and transport of the chemical, bioavailability, human behavior and use/misuse, whether natural barriers or personal protective equipment prevent actual exposure, and whether the substance is transformed (or adsorbed, retained, metabolized, or excreted) within the body.
The Challenges of Exposure Assessment
Characterizing historical occupational, environmental, or consumer product exposures is especially challenging because there are frequently few or no chemical concentration data specific to the historical exposure event(s), and in many cases, the occupational or environmental conditions have changed or the consumer product is no longer produced or has been reformulated. If data is available, it is usually scant or collected using outdated methods that are not specific for particular chemicals of interest (e.g., dust concentrations vs. asbestos fiber concentrations).
Over the past decade, there has been growing interest in historical exposure(s) that individuals or groups experienced as part of their activities. Exponent has significant experience in this area, and has helped clients assess exposures from various consumer products using techniques such as exposure simulation, where industrial hygiene (exposure) data are collected during testing of re-formulated, and in some cases existing but historical, products. The term coined for historical exposure assessments where specific doses are calculated on a job-, task- or person-specific basis is “exposure reconstruction” or “dose reconstruction.”
Recent Related Publications and Presentations
Sheehan P, Bogen K, Posson M, Singhal A, Glomski M, Hellerstein J. Assessing anthraquinone (AQ) exposure from food packaging: a product stewardship challenge in Europe. Presented at the American Industrial Hygiene Conference and Expo, San Antonio, TX, May 31-June 5, 2014.
Bogen KT, Sheehan PJ. Dermal versus total uptake of benzene from mineral spirits solvent during parts washing. Risk Analysis 2014; 34(7):1336–1358.
Bogen KT. Dermal uptake of 18 dilute aqueous chemicals: In vivo disappearance-method measures greatly exceed in vitro-based predictions. Risk Analysis 2013; 33(7):1334–1352.
Brattin W, Drexler J, Lowney Y, Griffin S, Diamond G, Woodbury L. An in vitro method for estimation of arsenic relative bioavailability in soil. Journal of Toxicology and Environmental Health 2013; 76:7:458–478.
Sheehan P, Kalmes R, Turnham P, Anderson E. Simulation study of potential historical user asbestos fiber exposure from cosmetic body talc use. Presented at the American Industrial Hygiene Conference and Expo, Montreal, Canada May 18-23, 2013.