Medical and morbidity surveillance findings among employees potentially exposed to TCDD

Evaluation of cardiovascular outcomes among U.S. workers exposed to 2,3,7,8-tetrachlorodibenzo-p-dioxin

Some animal studies and some human studies suggest that exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) may be associated with adverse effects on the cardiovascular system. As part of a cross-sectional medical study comparing workers employed 15 years earlier in the manufacture of 2,4,5-trichlorophenol or one of its derivatives at two U.S. chemical plants with an unexposed comparison group, we examined the association between TCDD exposure and various cardiovascular outcomes. A total of 281 workers and 260 unexposed referents participated. The workers had substantial exposure to TCDD, as demonstrated by significantly elevated mean serum TCDD concentration of 220 pg/g of lipid, compared with 7 pg/g of lipid among the referents. No significant association was found between TCDD exposure and any of the cardiovascular outcomes including myocardial infarction, angina, cardiac arrhythmias, hypertension, and abnormal peripheral arterial flow. Although our study had sufficient statistical power to detect an elevated risk for cardiac arrhythmias, hypertension, and abnormal peripheral arterial flow, it had low power (approximately 50%) to detect an elevated risk for myocardial infarction and angina. Our review of the literature suggests that our negative findings are consistent with those from other cross-sectional medical studies. Although several mortality studies of TCDD-exposed cohorts found significantly increased risks for cardiovascular disease mortality, similar increased risks were not observed in other mortality studies. The data available do not provide definitive conclusions but indicate that further examination of the association between TCDD exposure and cardiovascular disease should be pursued.

Dioxin exposure and non-malignant health effects: a mortality study

OBJECTIVE

To investigate, in a population heavily exposed to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), the possible unusual occurrence of diseases other than cancer.

METHODS

Five year extension of the follow up of the cohort involved in the Seveso accident. Soil measurements identified three exposure zones: (A) highest contamination, (B) substantial, and (R) low but higher than background contamination. Blood TCDD measurements, although limited in number, confirmed zone exposure ranking. The 15 year mortality in the exposed cohort was compared with that of a large population in the surrounding non-contaminated territory. Relative risks (RRs) and 95% confidence intervals (95% CIs) were estimated with Poisson regression techniques.

RESULTS

The already noted increased occurrence of cardiovascular deaths was confirmed, in particular in zone A, among males for chronic ischaemic heart disease (five deaths, RR 3.0, 95% CI 1.2 to 7.3), and among females for hypertensive disease (three deaths, RR 3.6, 95% CI 1.2 to 11.4) and chronic rheumatic heart disease. Novel findings were the increase of chronic obstructive pulmonary disease, most notably among males in zone A (four deaths, RR 3.7, 95% CI 1.4 to 9.9) and females in zone B (seven deaths, RR 2.4, 95% CI 1.1 to 5.1); and from diabetes, which was significantly increased in females in zone B (13 deaths, RR 1.9, 95% CI 1.1 to 3.2). In zone R, chronic ischaemic heart disease (males and females), hypertension (females), and diabetes (females) showed less pronounced, although significant excesses.

CONCLUSIONS

As well as high TCDD exposure, the accident caused a severe burden of strain in the population. Both these factors might have contributed to the noted increased risks (in particular, circulatory and respiratory). The cardiovascular and immune toxicity of TCDD, as well as its complex interaction with the endocrine system, might be relevant to the explanations of these findings. These results, although not conclusive, concur with previous data in suggesting cardiopulmonary and endocrine effects in humans highly exposed to TCDD.

The relationship between work-related and non-work-related injuries

A case-control study of occupational injuries sustained by 914 male hourly workers employed in two Tenneco manufacturing divisions in 1987 was undertaken to examine the association between occupational and non-occupational injuries. Its aim was to evaluate whether employees who experienced a work-related injury were more likely to have sustained a previous non-work-related injury compared to individuals who did not experience a work-related injury. A statistically significant association between occupational injuries and past non-occupational injuries was seen when all workers compensation (WC) claims were analyzed (OR = 1.41) and when claims involving indemnity for lost time were analyzed (OR = 1.82). In addition, both workers who had occupational low-back injuries and workers who had occupational non-low-back injuries also had significantly higher risks of such injuries from a non-occupational origin (OR = 1.91 for low-back injuries and OR = 1.44 for non-low-back injuries). The findings suggest that elements other than workplace hazards (such as life-style and physical and psychological factors) may predispose an individual to both occupational and non-occupational injuries.

Health care utilization and costs for injury in a corporate setting

This article presents the incidence and costs for non-work-related injuries among 15,408 employees and their families based on health insurance claims data analysis. The treatment of injuries accounted for 11.3% of the plan's total health care costs ($31 million) for the 1986 policy year. For adults, women had a higher incidence rate than men; but for children, males had a higher incidence rate than females. A disproportionately high share of claims and charges for adults were attributed to low back disorders. Hospital admissions, length of stay and hospital days per 1,000 persons were similar for males and females, but much higher for adults than for children. This article provides an example of the utility of health insurance claims data as a source of morbidity information for disease surveillance and epidemiologic research. The analysis of claims data can be seen as a prerequisite to the development of preventive programs aimed at reducing injury rates and health care costs for injuries in a corporate setting.