Retrospective Estimation of Exposures to Confirmed or Suspected Carcinogens in an Electrical Utility

Abstract

As part of a study of the association between cancer and long-term exposure to electric and magnetic fields among electrical utility workers, we estimated exposures to potentially confounding chemical and physical agents. Past inhalation and dermal exposure to 47 confirmed or suspected carcinogens was estimated semiquantitatively at Hydro-Québec through interviews with workers and visits to job sites. Inhalation exposures were estimated as the time-weighted average (TWA) intensity; dermal exposures were estimated based on average duration and frequency. With the exception of trades involved in equipment repair and maintenance, average TWA inhalation exposures to chemical agents were judged as generally low with respect to the 1990–91 American Conference of Governmental Industrial Hygienists threshold limit values (TLVs). Inhalation exposures were classified to the TWA classification scale in 164 cases; of these, 96 percent were judged as occasional, rare, or very low (estimated < 10% TLV), 2 percent as low (estimated 10 to 25% TLV), and 2 percent as moderate (estimated 25 to 100% TLV). No long-term exposures were judged to have exceeded the TLV. For dermal exposures, the hygienists classified 127 exposures to the duration scale; of these, 63 percent were estimated as occasional or rare, or occurring less than 5 percent of the time, 19 percent were estimated as occurring between 5 and 33 percent of the time, and 18 percent were estimated as occurring more than 33 percent of the time. Of all the exposures examined, dielectric oil was the most ubiquitous. Regular dermal contact with these oils was common for 21 of the job categories examined. Exposures to asbestos, diesel and gasoline exhaust, herbicides, soldering and welding fumes, solvents, paints, and wood treatment chemicals were also documented. Estimates were compiled into a job-exposure matrix for use in occupational hygiene programs seeking to eliminate or reduce exposures to confirmed or suspected carcinogens in electric utilities.