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APHA Scientific Session and Event Listing

Robert M. Park, MS, Risk Evaluation Branch, NIOSH, 4676 Columbia Pkwy, ms C-15, Cincinnati, OH 45226, 513-533-8572, rhp9@cdc.gov, Rosemarie Bowler, PhD, Department of Psychology, San Francisco State University, 8371 Kent Drive, El Cerrito, CA 94530, Donald E. Eggerth, PhD, Education and Information Division, NIOSH, 4676 Columbia Pkwy, Cincinnati, OH 45226, Emily Diamond, PhD, The Wright Institute, 2728 Durant Avenue, Berkeley, CA 94704, and Katie J. Spencer, MS, Math Stat Dept, Miami University, Rte 27, Oxford, OH 45056.

Risk assessment estimates excess life-time risk for disabling or fatal health outcomes in relation to a fixed life-time workplace exposure. For sub-clinical health effects such as neurobehavioral changes measured as continuous variables, the Benchmark Dose (BMD) method poses issues: one must define a threshold for impairment (often the 5th percentile of performance in an unexposed population) and then calculate at what exposure there is 1, 5, or 10% excess impairment. But individuals falling below the 5th percentile may have other identifiable risk factors that themselves merit preventive; and allowing an increase of 5% impairment (above a background 5%) is equivalent to permitting a relative risk of 2.0 or 50/1000 excess risk. Neurobehavioral assessments were conducted for 48 California bridge welders exposed to manganese for up to two years in confined spaces. Exposures ranged 0.1-0.4 mg/m3. Results for four tests (Rey-Osterrieth Complex Figure Test, Working Memory Index, Stroop Color Word Test and Auditory Consonant Trigrams Test) were used in the benchmark dose procedure. Based on environmental sampling results, benchmark dose estimates were generally within a factor of 2.0 across the four outcomes, and decreased as the percentile of normal performance defining impairment increased. Estimated excess impairment, defined as performance below the 5th percentile of normal, at the current Cal OSHA standard (0.2 mg/m3, 8 hr TWA), ranged 15 - 32%. These results indicate unacceptable risks of a possible parkinsonian syndrome at the current OSHA PEL for manganese (5.0 mg/m3, 15 min) and likely at the Cal OSHA PEL as well.

Learning Objectives:

• Participants will gain some understanding of risk assessment methods applied to health effects with continuous outcomes, in this case neurological. Neurobehavioral clinical data from a study population of welders will be used to demonstrate assessing neurological deficits arising from exposure to manganese fume. The steps from exposure characterization and modeling exposure response through determination of risks associated with specified levels will be presented. Participants will be better able to assess the capabilities and limitations of risk assessment methods in a variety of settings.

Keywords: Risk Assessment, Workers' Compensation

Presenting author's disclosure statement:

Not Answered

Handout (.ppt format, 1921.5 kb)