PRODUCTION AND SURVEILLANCE OF MERCURY EXPOSURE OVER 40 YEARS AT A CHLORALKALI PLANT

Mercury vapour exposure was studied for 40 years in 419 chloralkali wo rkers. The concentration of mercury was measured in the work room (sta tionary) from 1953 and in urine from 1948. There were major difference s in the mean urinary concentrations between different types of job. T he mean urinary mercury concentration, uncorrected for urinary dilutio n, for all subjects varied between 30 and 250 mu g 1.(-1) during the s tudy period. For workers in the cell-room the correlation (I) between urinary mercury and mercury in the work room was r = 0.74 (P < 0.001), and for repair men/mechanics it was r = 0.70 (P < 0.001). The introdu ction of new cells and stabilizing the volume of production may have b een important for reducing air-Hg and U-Hg, whereas other changes in t he production process, or actions to reduce the release of mercury to the work environment, had no detectable effect. The urinary mercury co ncentration among all workers was related to the relative energy consu mption (r = 0.83, P < 0.001).