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Objectives: To identify potential occupational risk factors, this study examined the occupational occurrence of various neurodegenerative diseases., Methods: Death certificates from 27 states in the National Occupational Mortality Surveillance System were evaluated for 1982 to 1991. Proportionate mortality ratios were calculated by occupation for presenile dementia, Alzheimer's disease, Parkinson's disease, and motor neuron disease., Results: Excess mortality was observed for all four categories in the following occupational categories: teachers; medical personnel; machinists and machine operators; scientists; writers/designers/entertainers; and support and clerical workers. Clusters of three neurodegenerative diseases were also found in occupations involving pesticides, solvents, and electromagnetic fields and in legal, library, social, and religious work. Early death from motor neuron disease was found for firefighters, janitors, military personnel, teachers, excavation machine operators, and veterinarians, among others., Conclusions: Neurodegenerative disease occurs more frequently in some occupations than in others, and this distribution, which may indicate occupational risk factors, should be further investigated.

Women comprise the majority of workers exposed to ethylene oxide during sterilization of medical instruments and supplies. This article evaluates molecular, cytogenetic, and hematologic effects of ethylene oxide on 68 women workers employed in nine hospitals in the United States and one hospital in Mexico. Workers were classified by three exposure categories: none (0), low (> 0-32 ppm-hrs), and high (> 32 ppm-hrs). Hematologic effects were evaluated using complete blood count with differential, which has been questioned as a test for screening ethylene oxide-exposed workers. A statistically significant decrease in hematocrit (n = 0.02) and hemoglobin (P = 0.03) levels, an increase in lymphocyte percentages (P = 0.04), and a relative decrease in neutrophil percentages (P = 0.03) with exposure were observed in US workers. The absolute number of lymphocytes, however, showed no relationship with exposure. No statistically significant results were seen for Mexican workers, although hematocrit decreased with exposure. An exposure-response relationship for the percentage for lymphocytes (positive) and neutrophils (negative) in US subjects and for neutrophils (positive) in Mexican subjects was seen. No overall relation with exposure was observed for total number of white cells. Molecular and cytogenetic results are also reported for the 68 women, who constitute a subgroup from a previous report. US women workers showed a statistically significant exposure-response relationship for ethylene oxide and hemoglobin adducts (P = 0.0002) and sister chromatid exchanges (P = 0.001). For micronuclei, the difference (P = 0.02) between low and high exposure was statistically significant. In Mexican workers, an exposure-response relationship was observed (P = 0.002) for hemoglobin adducts but not for sister chromatid exchanges or micronuclei.

Operators of hospital sterilizers that use ethylene oxide were studied to determine if there was a relationship between exposure and a battery of biological markers. A total of 73 workers from nine hospitals in the United States (U.S.) and one hospital in Mexico City was evaluated for ethylene oxide exposure during four months prior to collection of peripheral blood. The frequency of hemoglobin adducts (p = 0.0006) and sister-chromatid exchanges (SCEs) (p = 0.002) increased with cumulative exposure to ethylene oxide in U.S. subjects when controlling by regression analysis for various confounding factors, including cigarette smoking. Hemoglobin adducts, but not SCEs, were also increased in Mexican subjects (p = 0.0012). Chromosomal micronuclei showed no consistent relationship with exposure. The U.S. study participants were classified by four-month cumulative exposure levels of 10 ppm-h (n = 8), greater than 0 to 32 ppm-h (n = 32) and greater than 32 ppm-h (n = 11) of ethylene oxide exposure. The group with an exposure of greater than 32 ppm-h had an increased frequency of hemoglobin adducts (p = 0.002) and SCEs (p = 0.0001) compared to the nonexposed group. The estimated mean of the 8-h time-weighted average (8-h TWA) exposure levels for the highest U.S. exposure group (greater than 32 ppm-h) was 0.16 +/- 0.007 ppm (mean +/- SD). A similar exposure-related differential was observed in the Mexican subjects for hemoglobin adducts (p = 0.04) but not for SCEs. The latter finding may have been due to longer shipping times for the specimens in the cytogenetic assays. The estimated mean of the 8-h TWA exposure levels for the highest Mexican exposure group (greater than 32 ppm-h) was 0.48 +/- 0.08 ppm. This study is the third to suggest that exposures less than the U.S. OSHA standard of 1 ppm 8-h TWA result in biochemical and biologic changes. It is not known whether these changes may be indicative of increased risk of disease; however, they do appear to reflect exposure to relatively low levels of ethylene oxide. The exact meaning of these changes is unknown.

In conjunction with industrial hygiene surveys, mutagenicity studies were performed for the airborne contaminants in three polyurethane manufacturing plants. Airborne particles were collected on glass-fiber filters with Hi-Vol pumps from different locations in each plant. Gases were collected in multiple-sorbent cartridges. The collected airborne particles and sorbent cartridges were extracted with organic solvents. Each extract was tested for mutagenic activity using Salmonella typhimurium TA98 and TA100. The results showed that airborne particles from all three plants are mutagenic to TA98 with or without S9 activation. The mutagenicity with S9, however, was two to four times higher than that without S9. None of the samples of gases collected on sorbent cartridges showed mutagenic activity.