Occupational Health Management in the Lead Industry: The Korean Experience

In 1967, the problem of occupational lead exposure came to public attention in Korea. Since then, regular progress has been made in lowering workplace lead exposures, instituting new workplace controls, and implementing health examinations of exposed workers. Past serious lead poisoning episodes made it possible to introduce biological monitoring programs on a voluntary basis in high-lead-exposure facilities in Korea. Industry-specific occupational health services for lead workers in Korea during the last 22 years can be categorized into three phases. During the first phase (1988-1993), efforts were directed at increasing awareness among workers about the hazards of lead exposure, biological monitoring of blood zinc protoporphyrin began, and a respiratory protection program was introduced. During the second phase (1994-1997), a computerized health management system for lead workers was developed, blood-lead measurement was added to biologic monitoring, and engineering controls were introduced in the workplace to lower air-lead levels to comply with air-lead regulations. Finally, during the third phase (1998-present), a new biomarker, bone-lead measurement by X-ray fluorescence, was introduced. Bone-lead measurement proved to be useful for assessing body burden and to demonstrate past lead exposure in retired workers. Occupational health service practice for lead workers, including the industry-specific group occupational health system, has brought considerable success in the prevention of lead poisoning and in reducing the lead burden in Korean lead workers during the last several decades. The successful achievement of prevention of lead poisoning in Korea was a result of the combined efforts of lead workers, employers, relevant government agencies, and academic institutes.

Bone and Blood Lead Levels of Middle Aged Koreans not Occupationally Exposed to Lead / 대한산업의학회지

OBJECTIVES: In order to investigate the level and the association between bone lead and blood lead levels of non-occupationally, lead-exposed Koreans, the authors studied the lead biomarkers of 137 middle aged Koreans (86 males and 51 females) older than whose age were above 40 years. METHODS: The tibia lead level was selected as the bone lead indicator of cortical bone, and the blood lead level was also measured. The tibia lead level was measured by K-shell XRF with 30-minute measurement of each subjects. The blood lead level was analyzed by AAS method. RESULTS: The mean (SD) of the tibia lead level of the 137 study subjects was 3.49 (4.99) microgram/g, and tended to be higher. The mean (SD) of tibia lead level in male subjects (was 3.90 (4.88) microgram/g) and larger than in that of female subjects (2.80 (5.14) microgram/g), but without no statistical significance was observed. The mean (SD) of blood lead level of all total subjects was 3.70 (1.35)microgram/dl, and tended to be higher. The mean (SD) of blood lead level in male subjects (was 3.93 (1.25) microgram/dl) and larger than in that of female subjects (3.30 (1.42) microgram/dl), but without no statistical significance was observed. In multiple regression analysis of blood lead levels after adjusting for covariates, age was a significant independent variable. A weak association of age with tibia lead in female subjects was also observed in multiple regression analysis. CONCLUSION: The mean (SD) of tibia and blood lead levels of middle aged Koreans whose ages were over 40 years old were 3.49 (4.99) microgram/g and 3.70 (1.35) microgram/dl, respectively. Age and sex were positive predictors of blood lead level in multiple regression analysis after controlling for the covariates. However, in multiple regression analysis whereas age was weakly association with tibia lead level only in female subjects in multiple regression analysis.

The Effect of ALAD Polymorphism on the Relationship of Blood and Bone Lead with Hematologic Biomarkers in Lead Exposed Workers / 대한산업의학회지

OBJECTIVES: To evaluate the effect of ALAD polymorphism on the relationship of blood and bone lead with hematologic biomarkers in lead exposed workers, 450 lead exposed workers and 85 non-lead exposed workers were selected. METHODS: Blood lead and tibia bone lead were selected as parameters of lead exposure and blood ZPP, urinary ALA (ALAU), hemoglobin (Hb) and hematocrit (Hct) were chosen as parameters of hematologic effect of lead exposure. Genotype of each subject was assayed and expressed as ALAD1 and ALAD2. Demographic information such as sex, age and personal habit of smoking and drinking were collected. Job duration of lead exposed workers was also obtained. RESULTS: The overall prevalence of the variant allele, ALAD2 in lead exposed workers was 9.6 %(43 out of 450 lead workers) which was not differed from control workers (9.4 % : 8 out of 85). The means of tibial lead and blood ZPP in lead workers with ALAD2 were lower than those of lead workers with ALAD1, but the differences were not statistically significant. After adjusting for possible confounders (sex, job duration, BMI, drinking and smoking status) only blood lead and bone lead contributed negatively to the level of hemoglobin with statistical significance without any contribution of ALAD genotype. On the other hand, no significant effect of blood lead, bone lead and ALAD genotype were observed on the level of hematocrit after controlling possible confounder. ALAD genotype in the multiple regression analysis of blood lead and bone lead with log transformed urinary ALA (LogALAU) after adjusting for possible confounders showed significant main and interaction effect on LogALAU simultaneously, which resulted lower LogALAU in lead exposed workers of ALAD2 than ALAD1. It was also observed only main effect of ALAD gene type on blood ZPP after adjusting possible confounder resulting lower ZPP in lead workers of ALAD2 than ALAD1. CONCLUSIONS: With above results, it was found that ALAD polymorphism did not affect on the level of hemoglobin and hematocrit, but ALAD polymorphism made significant effect on the association of blood and bone lead with urinary ALA and blood ZPP. The lower urinary ALA and blood ZPP in ALAD2 lead workers suggested that ALAD2 genotype may be supportive for the protective effect of lead.