Cohort Observation of Blood Lead Concentration of Storage Battery Workers

Kim, Chang Yoon; Kim, Jung Man; Han, Gu Wung; Park, Jung Han

Abstract

To assess the effectiveness of the interventions in working environment and personal hygiene for the occupational exposure to the lead, 156 workers (116 exposed subjects and 40 controls) of a newly established battery factory were examined for their blood lead concentration (Pb-B) in every 3 months up to 18 months. Air lean concentration (Pb-A) of the workplaces was also checked for 3 times in 6 months interval from August 1987. Environmental intervention included the local exhaust ventilation and vacuum cleaning of the floor. Intervention of the personal hygiene included the daily change of clothes, compulsory shower after work and hand washing before meal, prohibition of cigarette smoking and food consumption at the work site and wearing mask. Mean Pb-B of the controls was 21.97 +/- 33.6 microgram/dl at the preemployment examination and slightly increased to 22.75 +/- 3.38 microgram/dl after 6 months. Mean Pb-B of the workers who were employed before the factory was in operation (Group A) was 20.49 +/- 3.84 microgram/dl on employment and it was increased to 23.90 +/- 5.30 microgram/dl after 3 months <(P<0.01). Pb-B was increased to 28.84 +/- 5.76 microgram/dl 6 months after the employment which was 1 month after the initiation of intervention program. It did not increase thereafter and ranged between 26.83 microgram/dl and 28.28 microgram/dl in the subsequent 4 tests. Mean Pb-B of the workers who were employed after the factory had been operation but before the intervention program was initiated (Group B) was 16.58 +/- 4.53 microgram/dl before the exposure and it was increased to 28.82 +/- 5.66 microgram/dl (P<0.01) in 3 months later (1 month after the intervention). The values of subsequent 4 tests remained between 26.46 and 28.54 microgram/dl. Mean Pb-B of the workers who were employed after intervention program had been started (Group C) was 19.45 +/- 3.44 microgram/dl at the preemployment examination and gradually increased to 22.70 +/- 4.55 microgram/dl after 3 months (P<0.01), 23.68 +/- 4.18 microgram/dl after 6 months, and 24.42 +/- 3.60 microgram/dl after 9 months. Work stations were classified into 4 parts according to Pb-A. The Pb-A of part I, the highest areas, were 0.365 mg/m3, and after intervention the levels were decreased to 0.216 mg/m3 and 0.208 mg/m3 in follow-up tests. The Pb-A of part II was decreased from 0.232 mg/m3 to 0.148 mg/m3, and 0.120 mg/m3 after the invention. Pb-A of part III and IV was tested only after intervention and the Pb-A of part III were 0.124 mg/m3 in January 1988 and 0.081 mg/m3 in August 1988. The Pb-A of part IV, not stationed at one place but moving around, was 0.110 mg/m3 in August 1988. There was no consistent relationship between Pb-B and Pb-A. Pb-B of the group A and B workers in the part of the highest Pb-A were lower than those of the workers in the parts of lower Pb-A. Pb-B of the workers in the part of the lowest Pb-A increased more rapidly. Pb-B of group C workers was the highest in part I and the lowest in part IV. These findings suggest that Pb-B is more valid method than Pb-A for monitoring the health of lead workers and intervention in personal hygiene is more effective than environmental intervention.