LEUKEMIA IN TELEPHONE LINEMEN

This case-control study examines potential associations between teleph one linework and the occurrence of leukemia except chronic lymphocytic leukemia in a primarily retired population of American Telephone and Telegraph Company (AT&T) workers. Cases died between 1975 and 1980. Ex posure is defined both by job title and, for workers with complete job histories, by a lifetime exposure score based on industrial hygiene p ersonal monitoring measurements of line and nonline jobs. When the tim e-weighted average mean for each job is accumulated into a lifetime ex posure score, workers with scores above the median for the population show an excess of leukemia 2.5 times higher than workers below the med ian (95% confidence interval (Cl) 0.7-8.6). Those individuals with lon g duration of employment in jobs with intermittent peak exposures may be at higher risk of leukemia than those with a constant exposure leve l. Analyses that allow for a latent period suggest the risk is associa ted with exposures that occurred 10 or more years before death. Worker s with peak exposure scores above the median have odds ratios of 2.4 ( 95% Cl 0.7-9.0) and 6.6 (95% Cl 0.7-58) for latent periods of 1 0 and 1 5 years, respectively. The data suggest an increasing risk with incr easing exposure (p for trend = 0.05) when cumulated scores are based o n peak exposure scores. Peak exposures tended to occur in cable splici ng work and in old telephone switching offices. The numbers in this st udy are small and observed differences may-be due to chance.