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Exposure to noise is highly prevalent in the workplace, and an etiologic association with cardiovascular disease has been hypothesized. Although there is evidence of hypertension among noise-exposed workers, evidence of heart disease has been less conclusive.We identified a cohort of 27,464 blue-collar workers from 14 lumber mills in British Columbia who worked at least 1 year between 1950 and 1995 and who were followed up over the same period. Cumulative noise exposure was quantitatively assessed. Vital status was ascertained from the Canadian Mortality Database. We estimated standardized mortality ratios using the general population as referents, and we estimated relative risks using an internal low-exposure group as controls. To examine acute effects of noise, we assessed relative risks during subjects' working years in lumber mills. Because of the possibility of exposure misclassification as a result of hearing-protector use, we investigated a subgroup that had been employed before widespread use of protectors.During the follow-up period, 2510 circulatory disease deaths occurred. Relative risks for acute myocardial infarction mortality were elevated in the full cohort, with a stronger association in the subgroup without hearing protection. There was an exposure-response trend, with a relative risk in the highest exposed group of 1.5 (95% confidence interval=1.1-2.2). The highest relative risks (2.0-4.0) were observed during subjects' working years. Smoking did not appear to confound these associations.Chronic exposure to noise levels typical of many workplaces was associated with excess risk for acute myocardial infarction death. Given the very high prevalence of excess noise exposure at work, this association deserves further attention.

Senile cataract may be a marker of generalized tissue aging. We examined this hypothesis using population-based linked health data. We hypothesized that any such association would diminish with increased use of cataract surgery. Mortality rates of those 50-95 years of age undergoing cataract surgery in British Columbia during either 1985 or 1989 were compared with the provincial population of comparable age who did not undergo cataract surgery during the study period. The 1985 cohort included 8,262 patients undergoing surgery and a comparison population of 804,303, and the 1989 cohort included 11,952 patients and a comparison population of 839,393. Using Cox regression, for the 1985 cohort, the hazard ratios for dying during follow-up were 3.2 for males 50-54.9 years of age [95% confidence limits (CL) = 2.0, 5.0] and 3.3 for females (95% CL = 1.9, 5.7). Hazard ratios for older age groups decreased with age. We also fit an additive risk model that produced excess mortalities that were less age dependent. In the 1985 analysis, these ranged from +7.1 per 1,000 (95% CL = +0.44, +13.76) to +20.3 (95% CL = +13.24, +27.36) for males and -17.5 (95% CL = -28.28, -6.72) to +2.0 (95% CL = -2.12, +6.12) for females. Findings for the 1989 analyses were similar, indicating that the association between cataracts and generalized aging remained constant despite a large increase in the use of cataract surgery.

We examined the effect of decision latitude and work demand on risk of myocardial infarction in a former Soviet Bloc country and analyzed whether these factors contributed to the educational gradient in myocardial infarction in this population. We conducted a case-control study among full-time working men in the general population of five districts of the Czech Republic. Cases were 179 men 25-64 years of age with a first nonfatal myocardial infarction diagnosed in selected districts over a 1-year period, and controls were 784 men in the same age group randomly selected from the population register. We used logistic regression to estimate the odds of developing myocardial infarction in relation to self-reported work demand and decision latitude at work and the contribution of these factors as well as standard risk factors to socioeconomic differences in the risk of myocardial infarction. Cases reported lower decision latitude and lower work demand than controls. Age-adjusted odds ratios for the highest vs lowest quartiles of decision latitude and work demand were 0.43 (95% confidence interval = 0.25-0.75) and 0.54 (95% confidence interval = 0.31-0.93), respectively. Further adjustment for coronary risk factors and education did not change these estimates. Decision latitude accounted for part of the association between education and myocardial infarction, and decision latitude and risk factors jointly explained virtually all of it. The association between decision latitude at work and myocardial infarction found in our study is consistent with research in western populations and may partly explain the socioeconomic gradient in myocardial infarction.

The purpose of this study was to determine whether exposure to chlorophenate fungicides and their dioxin contaminants is associated with male infertility among sawmill workers. The study was conducted using fertility data compiled from 26,487 sawmill workers in 14 British Columbian sawmills. Our analysis was restricted to workers who had been employed for at least 1 continuous year between 1950 and 1985 and to live-births born at least 1 year after the initiation of employment in the period 1955-1988. We assessed fertility trends by internal comparison using Mantel-Haenszel rate ratios and by calculating standardized fertility ratios using an external and an internal reference population. We identified 19,684 births in the study period. Initially, both external and internal analyses showed that sawmill workers from mills using chlorophenates had lower fertility than workers employed in mills not using chlorophenates. After controlling for time since first hire, however, we found no inverse relation between cumulative exposure to chlorophenate fungicides and fertility. Based on the results of our study, there is little evidence for a reduction in fertility among chlorophenate-exposed sawmill workers in British Columbia. The analyses indicate the importance of time since hire as a potentially strong confounder in this type of investigation.