Epidemiologic Notes and Reports Lead Poisoning in a Capacitor and Resistor Plant -- Colorado

In July 1984, the Mesa County, Colorado, Health Department was notified of a local electrical component manufacturing plant worker who had a blood lead level of 105 ug/dl. At the plant, fritted leaded glass was used in a vitreous enameling process to coat capacitors and resistors, and during the dipping, sandblasting, and sanding processes, a fine dust containing lead borosilicate was produced. The Occupational Safety and Health Administration (OSHA) began an investigation at the component plant July 30, 1984. The plant was found to be heavily contaminated, with air lead levels ranging from 61 ug/m((3)) to 1,700 ug/m((3)), in excess of the OSHA Permissible Exposure Level (PEL) of 40 ug/m((3)) per 10-hour working day.

Eighty-one of approximately 94 additional workers from the plant were tested and found to have blood lead levels ranging from 3 ug/dl to 135 ug/dl. Among these were two pregnant woman, one of approximately 8 weeks' gestation with a blood lead level of 61 ug/dl, and a second of 8-13 weeks' gestation with a blood lead level of 27 ug/dl. Thirty-eight (42%) of 94 workers were removed from the workplace because of elevated blood lead levels 50 ug/dl or greater. Nineteen of the workers received chelation therapy. Fourteen (58%) of 24 workers with elevated blood lead levels who were sent for additional testing were found to have evidence of possible neurologic impairment on the basis of the Halstead-Reitan Neuropsychological Test Battery; these workers have been removed from the exposure site.

Although the plant's management was apparently unaware of lead in the raw material, the process in question required the low-melting-point leaded glass for adequate coating of the components. The plant was cited and fined for violations of numerous regulations; OSHA made engineering recommendations and enforced requirements for respirators, protective clothing, and periodic air and blood lead monitoring.

In addition, children of workers were potentially exposed to lead dust brought home on workers' clothes. The mean lead level in 20 exposed children under 6 years old (13.4 ug/dl) was significantly above that in 31 unexposed comparison children under 6 years of age (7.1 ug/dl) by Student's t-test. No children were found to be above the CDC guideline for lead toxicity in children (25 ug/dl of blood lead and erythrocyte protoporphyrin level 35 ug/dl or greater) (1), but a repeat screening of workers' children in November 1984 found three with blood lead levels above this new guideline. The children were referred for CaNa((2)) EDTA mobilization tests and were not found to have elevated total body burdens of lead. Chelation therapy was not necessary (2). Reported by I Alkes, MD, St. Mary's Family Practice Residency, Grand Junction, D Teitelbaum, MD, Denver Clinic, PC, F Kadushin, PhD, Colorado Neurobehavioral Institute, K Lampert, MD, Mesa County Health Dept, R Hopkins, MD, Colorado Dept of Health; J Ryan, Occupational Safety and Health Administration Region VIII; Div of Field Svcs, Epidemiology Program Office, Special Studies Br, Chronic Diseases Div, Center for Environmental Health, CDC.

Editorial Note

Editorial Note: This type of plant and process represents a new source of lead poisoning in workers and potential exposure for their families. OSHA standards were violated, but with consultation and enforcement of existing rules, the plant has been able to maintain operations while bringing this exposure problem under control, as shown by repeated monitoring of blood lead levels and area air samples.

The blood lead test is one measure of the amount of lead in the body and is the best available measure of recent lead absorption. Adults not exposed to lead at work usually have a blood lead level less than 30 ug/dl; the average is less than 15 ug/dl (3,4). For purposes of compliance with the OSHA lead standard, a blood lead level averaging 50 ug/dl or more represents excessive lead exposure, and the affected employee must be removed from further lead exposure until his blood lead level is less than 40 ug/dl. The standard protects the earnings, seniority, and other benefits of employees who, because of excessive lead absorption, are removed from jobs involving lead exposure (5).

A World Health Organization study group recommended that blood lead levels not exceed 30 ug/dl in occupationally exposed women of childbearing age and not exceed 40 ug/dl in other workers (6). In a pregnant woman, lead crosses the placenta, and lead concentrations in umbilical cord blood are nearly equal to those in maternal blood (7). Since the growing brain of the fetus is likely to be at least as sensitive to the neurologic effects of lead as the brain of a young child, umbilical cord levels should be at least below 25 ug/dl (2).

Lead dust can cling to the skin, shoes, clothing, and vehicles of workers and can thus be carried from workplace to home. Previous studies have demonstrated the potential for elevated blood lead levels in children of workers (8). It is important, therefore, when high levels are seen in workers, to evaluate potential familial exposure, as was done in this instance. Strict compliance with OSHA standards is quite effective in decreasing this type of exposure. These standards provide that employees exposed to lead levels above the PEL be provided with the following at the employer's expense: protective work clothing and equipment, cleaning of work clothing, change rooms, showers, and filtered-air lunchrooms. However, many occupational exposures to lead are not covered by the OSHA standards. Companies with fewer than 10 employees (cottage industries, "hobby" production of pottery and stained glasswork, and home manufacturing of bullets and fishing sinkers) are excluded from the OSHA standards.

References

1. CDC. Preventing lead poisoning in young children: a statement by the Centers for Disease Control: January 1985. Atlanta, Georgia: U.S. Department of Health and Human Services, 1985.

2. Piomelli S, Rosen JF, Chisolm JJ, Graef JW. Management of childhood lead poisoning. J Pediatr 1984:105:523-32.

3. Mahaffey KR, Annest JL, Roberts J, Murphy RS. National estimates of blood lead levels: United States, 1976-1980: association with selected demographic and socioeconomic factors. N Engl J Med 1982;307:573-9.

4. Annest JL, Pirkle JL, Makuc D, Neese JW, Bayse DD, Kovar MG. Chronological trend in blood lead levels between 1976 and 1980. N Engl J Med 1983;308:1373-7.

5. U.S. Department of Labor. General industry OSHA safety and health standards (29 CFR 1910). Washington: U.S. Department of Labor, 1983 (OSHA 2206) (29 CFR 1910.1025).

6. World Health Organization. Recommended health-based limits in occupational exposure to heavy metals. Geneva: World Health Organization, 1980 (Technical report series, no. 647).

7. Barltrop D. The prevalence of pica. Am J Dis Child 1966;112:116-23.

8. Baker EL, Folland DS, Taylor TA, et al. Lead poisoning in children of lead workers: home contamination with industrial dust. N Engl J Med 1977;296:260-1.

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