Exposure assessment and longitudinal pulmonary function of electric utility power plant maintenance welders

Abstract

An exposure assessment and longitudinal pulmonary function study of electric utility power plant maintenance welders involved industrial hygiene surveys, air monitoring and exposure evaluation in eleven power plants for a six-year period. Eight-hour timeweighted exposures exceeded occupational exposure limits on an intermittent, but not routine basis. Overexposures to fume regularly occurred during all thermal cutting processes. Exposures over the ACGIH TLV for manganese and over both the TLV (soluble form) and OSHA PEL (ceiling) for hexavalent chromium often resulted during flux-cored arc welding on mild steel and shielded metal arc welding on high alloy steel, respectively. The longitudinal pulmonary function study involved 43 welders in nine power plants, resulting in 195 test results each for FEV1, and FVC, over periods of time from first to last test ranging from 1.7-19.9 years. Medical surveillance questionnaires, administered at the times of testing, were used to determine potential confounders such as smoking status, smoking consumption in packyears, years in a plant containing asbestos insulation, age at spirometry, change in weight, years of follow-up, and number of tests per subject. The mean annual decline was 49.4 ml (95% Cl 23.3-75.5) for height-adjusted FEV1, and 70.8 ml (95% Cl 40.4-101.2) for height-adjusted FVC. This rate of decline appears higher than the annual expected age-related decline in a general population that is reported to be 25-30 ml for FEV1 and FVC. Multiple linear regression was used to evaluate changes in FEV1 and FVC with the covariates, and the only significant association (95% confidence level) was annual change in body weight for height-adjusted FEV1 (p-value = .0148) and height-adjusted FVC (p-value = .0101).