BREAST CANCER RISK ASSOCIATED WITH ELECTROMAGNETIC FIELD EXPOSURE FROM COMPUTER WORK ASCERTAINED FROM OCCUPATIONAL HISTORY DATA

Abstract

ISEE-255 Introduction: Along with increasing breast cancer incidence in industrialized counties, women working in the latter half of the twentieth century were more likely to be exposed to electromagnetic fields (EMF) from computer use. This trend offers opportunities for occupational exposures that may play a role in breast cancer risk. Only a few occupational studies have presented data on female workers and breast cancer incidence, and findings have been inconsistent. Aim: We examined the relation between occupational exposure to EMF from computer use and breast cancer risk in a large, population-based, case-control, multi-state study in the United States. Methods: Female breast cancer cases 20-69 years of age and diagnosed in 1995-2000, were identified from statewide cancer registries in the states of Massachusetts, New Hampshire, and Wisconsin (n=6,422). Female controls of similar age were randomly selected from population lists (n=7,673). Lifetime occupational history, including job title, industry, duties, hours worked per week and length of employment were obtained through structured telephone interviews approximately one year after diagnosis. Individual occupations were coded according to the U.S. Department of Labour Occupational Information Network (O*NET) Content Model. The O*NET assigned level of work with computers was used as a measure of occupational EMF exposure. Total hours worked on a specific job were multiplied by the EMF exposure level for the respective occupation. Cumulative EMF exposure was obtained by adding individual occupational exposure over the period of time that was studied—in this case, the previous 10 years. Results: The risk for breast cancer was similar in the highest quartile of EMF-exposure from computer use (relative risk 1.05, 95% confidence interval (CI) 0.95 – 1.16) compared to the lowest quartile, after adjustment for numerous established risk factors, for all states combined. A similar pattern was observed when the analyses were stratified by menopausal status. When data were analyzed by state, Wisconsin women had an increased breast cancer risk (relative risk 1.18, 95% CI 1.03 – 1.35) for the highest quartile compared to the lowest. In contrast, the relative risk for New England women (New Hampshire and Massachusetts) was 0.90 (95% CI 0.77 – 1.04). Test for heterogeneity between the states (Wisconsin versus New Hampshire/Massachusetts) was statistically significant (p-value = 0.04). Conclusion: Breast cancer is one of the most successfully treated cancers when diagnosed early. Prevention programs directed towards high-risk occupational groups may increase early detection of the tumour, and potentially save lives. This analysis indicates no overall association of occupational EMF exposure from computer use with the risk of breast cancer. The modest though significant increase in risk among WI-only women merits a more in-depth analysis of EMF exposures in the workplace.