Evaluating uncertainty to strengthen epidemiologic data for use in human health risk assessments.

Background: There is a recognized need to improve the application of epidemiologic data in human health risk assessment especially for understanding and characterizing risks from environmental and occupational exposures. Although there is uncertainty associated with the results of most epidemiologic studies, techniques exist to characterize uncertainty that can be applied to improve weight-of-evidence evaluations and risk characterization efforts.

Methods: This report derives from a Health and Environmental Sciences Institute (HESI) workshop held in Research Triangle Park, North Carolina, to discuss the utility of using epidemiologic data in risk assessments, including the use of advanced analytic methods to address sources of uncertainty.

Critical analysis of literature on low-dose synergy for use in screening chemical mixtures for risk assessment.

There is increasing interest in the use of tiered approaches in risk assessment of mixtures or co-exposures to chemicals for prioritization. One possible screening-level risk assessment approach is the threshold of toxicological concern (TTC). To date, default assumptions of dose or response additivity have been used to characterize the toxicity of chemical mixtures.

Modeling cholinesterase activity for human dietary risk assessment of carbamate insecticides.

This article demonstrates statistical models to quantify the interaction between a carbamate insecticide and acetylcholinesterase. Carbamates are a class of chemicals that inhibit the activity of acetylcholinesterase in humans, an enzyme involved in the regulation of the neurotransmitter acetylcholine. Following exposure to a carbamate insecticide, we specifically address (1) if acetylcholinesterase activity recovers to its level of preexposure activity; (2) the level of inhibition of acetylcholinesterase activity; (3) the recovery time of acetylcholinesterase activity to its preexposure level for a typical individual; and (4) the upper percentiles of the recovery time of acetylcholinesterase activity across individuals.

Health survey of workers exposed to mixed solvent and ergonomic hazards in footwear and equipment factory workers in Thailand.

A cross-sectional health study was performed at four footwear and one equipment factory in Thailand to evaluate the prevalence of chemical- and ergonomic-related symptoms in Thai factory workers and to investigate associations between these symptoms and exposures to organic solvents, isocyanates and ergonomic risks. A 10-page health questionnaire was administered to 1784 workers across the four footwear and equipment factories. A total of 1675 questionnaires were returned, yielding a 94% response rate.

A survey of airborne and skin exposures to chemicals in footwear and equipment factories in Thailand.

This research reports on a pilot industrial hygiene study that was performed at four footwear factories and two equipment factories in Thailand. Workers in these factories were exposed through inhalation and dermal contact to a large number of organic vapors from solvents and cements that were hand applied. In addition, these workers were exposed to highly toxic isocyanates primarily through the dermal route.

Derivation of single layer clothing penetration factors from the pesticide handlers exposure database.

Quantitative characterization of the penetration of chemical residues through various types and configurations of clothing is an important underpinning of mitigation strategies to reduce dermal exposure to occupational cohorts. The objective of the evaluation presented herein is the development of pesticide clothing penetration (or conversely protection) factors for single layer clothing (i.e.

Plutonium-related work and cause-specific mortality at the United States Department of Energy Hanford Site.

Background: Health effects of working with plutonium remain unclear. Plutonium workers at the United States Department of Energy (US-DOE) Hanford Site in Washington State, USA were evaluated for increased risks of cancer and non-cancer mortality.

Methods: Periods of employment in jobs with routine or non-routine potential for plutonium exposure were identified for 26,389 workers hired between 1944 and 1978.