Reconstruction of occupational mercury exposures at a chloralkali plant

Persistence of mercury-induced motor and sensory neurotoxicity: systematic review of workers previously exposed to mercury vapor

Elemental mercury (Hg0) is a well-recognized neurotoxicant, but it is uncertain whether and for how long its neurotoxicity persists. Among studies that evaluated previously-exposed workers, only one examined workers during and also years after exposure had ceased. The objective of this review is to create a series of 'synthetic' longitudinal studies to address the question of persistence of Hg0 neurotoxicity in occupationally exposed workers. We systematically reviewed studies describing objective motor and sensory effects in previously-exposed mercury workers. Data from physical examination (PE), neurobehavioral (NB) tests, and electrophysiological studies (EPS) were extracted into structured tables and examined for their consistency and dose-relatedness and then compared with the corresponding results from studies of currently exposed workers. We identified six cohorts that described neurological findings in 1299 workers, examined an average of 4.8-30 years after the cessation of exposure. Historical group mean UHg levels ranged from 23 to >500 μg/L, with UHg levels >6000 μg/L in some individuals. Overall, few findings were significant; most were inconsistent across the previous-exposure studies, and in comparisons between studies of previously and currently exposed workers. The results of this systematic review indicate that Hg0-related neurotoxic effects detectable on PE, NB testing, and EPS are substantially reversed over time. To the extent that such effects do persist, they are reported principally in workers who have had very high-dose exposures. In addition, based on the limited available data, those effects reported to persist have been described as having little or no functional significance.

Sex, gender and women's occupational health: the importance of considering mechanism

A number of researchers have pointed out that less is known about occupational determinants of health in women than in men. The authors examine inventories of ongoing Canadian research and of recent scientific publications in order to identify trends in the approaches used to study women's occupational health (WOH). We also consider conceptual issues in the treatment of the sex and gender of subjects. We observe that women have been the subject of relatively few investigations of occupational health in the natural or biomedical sciences and that studies of WOH have concentrated on the health care professions and on psychosocial stressors, with a deficit in toxicological and physiological studies. We use recent studies of mercury exposure in chloralkali process plants and of musculoskeletal disorders among office workers to provide specific examples of problems in conceptualizing WOH. We propose that WOH be studied more often, especially by researchers in the natural and biomedical sciences, and that such studies include both women and men, where possible, and consider the complex relationships of gender and sex to the pathways involved. More interdisciplinary research would facilitate this process, since social researchers have tended to focus more on gender/sex issues. Our findings demonstrate that it is necessary to explore the implications of using sex routinely as an explanatory variable in occupational health research and to increase emphasis on the mechanisms involved in any sex or gender differences sought or found. From an equity perspective, it is also important to situate biological sex differences so as to prevent them from being used erroneously to justify job segregation or inequitable health promotion measures.