Occupational and Paraoccupational Lead Exposure to Lead -- Colorado

On December 10, 1987, the Environmental and Occupational Disease Surveillance Project of the Colorado Department of Health (CDH) received a report that a 29-year-old man had a blood-lead level of 170 ug/dL, a level almost seven times the blood-lead concentration required to be reported to CDH (greater than or equal to 25 ug/dL). The patient had been hospitalized on November 15, 1987, for increasingly severe chronic abdominal pain and cramping. He had been hospitalized in 1986 for similar complaints and had been treated with cimetidine for a presumptive diagnosis of peptic ulcer disease.

The patient was discharged on November 17, 1987, after symptoms subsided. Later, his physician received reports of both an excessive blood-lead level (ob tained during hospitalization) and a free erythrocyte protoporphyrin (FEP) level of 166.3 ug/dL (normal: less than 35 ug/dL). The patient was readmitted December 5, 1987, for chelation therapy with the use of ethylenediaminetetraacetic acid (EDTA), and he was discharged after his blood-lead level had fallen to 55 ug/dL. He was readmitted in January 1988 with a blood-lead level of 78 ug/dL and was again chelated with EDTA. Follow-up testing later that month showed his blood-lead level to be 20 ug/dL.

An occupational history revealed that since 1981 the patient had worked at a company that produces belt buckles, plaques, and awards. The patient was specifically involved in the manufacture of lead belt buckles and other lead products. His duties included pouring molten lead into a mold, removing the buckles from the mold, and grinding and smoothing imperfections in the product. In February 1988, the Tri-County Health Department (TCHD) conducted an environmental investigation of the patient's worksite. Investigators found that during the patient's 6-year employment at the company, ventilation for the melting and grinding areas was inadequate. A half-face respirator was available to the patient but was rarely used; furthermore, no routine maintenance was performed on the equipment, and inappropriate respirator filters were provided. During the site investigation, the grinding operation produced a visible cloud of particulate in the breathing zone of the operators, and a fine dust was found throughout the facility. Although environmental sampling was not done, the sampling of a similar operation in Colorado Springs (1) indicated that this type of grinding operation may produce lead exposures as high as 1900 ug/m3 (Occupational Safety and Health Administration (OSHA) permissible exposure limit (PEL): 50 ug/m3 (2)).

In November 1987, after the discovery of this employee's elevated blood-lead level, the company terminated its lead-pouring operation. The company did not have a blood-lead-monitoring program; however, three of the five employees tested by CDH and TCHD in February 1988 had blood-lead levels exceeding 50 ug/dL (range, 14-58 ug/dL).* Seven employees at the facility, including the owners, refused blood-lead testing. Breathing-zone air samples collected in February 1988 contained lead particulate levels ranging from 35 ug/m3 in the polishing room to 1121 ug/m3 in the grinding area. These elevated lead levels were attributed to residual lead contamination from the terminated production process and to lead present in the copper, zinc, and nickel alloys used in other processes.

Between February and August 1988, TCHD assisted the company in decreasing workplace lead exposures by introducing local exhaust ventilation at the grinding, polishing, and soldering operations. Follow-up blood sampling indicated that the blood-lead level of the employee who had the highest level during the first sampling (58 ug/dL) had dropped to 27 ug/dL, but another employee's blood-lead level remained elevated (52 ug/dL). Four air samples collected in the facility in August 1988 contained lead concentrations below the OSHA PEL (range, 20-44 ug/m3). A fifth sample, obtained in the melting and grinding area, had a lead concentration of 140 ug/m3; planned modifications to the ventilation system may reduce lead exposure to permissible levels.

The index patient's wife and three daughters were also screened for evidence of "paraoccupational exposure," which may occur when workers exposed to hazardous substances in their jobs carry the toxic materials home, usually on work clothing, thus exposing family members (3). The patient's children had blood-lead and/or FEP levels that exceeded CDC-recommended concentrations (4) (Table 1). Radiographs of his 4-year-old daughter showed dense metaphyses adjacent to the epiphyseal plates at the distal ulna and radius. (Increased metaphyseal density in long bones is indicative of excessive lead absorption in growing children (4).) All three children were given penicillamine chelation therapy. When retested, the 4-year-old girl had a blood-lead level of 41 ug/dL and was retreated.

None of the other employees who agreed to blood-lead screening had children at risk of paraoccupational exposure. Reported by: D Johnson, MD, K Houghton, MD, Mercy Family Medical Clinic, Mercy Hospital, C Siegel, MD, Eastside Clinic, Denver Health and Hospitals, Denver; J Martyny, PhD, Tri-County Health Dept; L Cook, MS, EJ Mangione, MD, Div of Epidemiology, Colorado Dept of Health. Office of the Director, National Institute for Occupational Safety and Health, CDC.

Editorial Note

Editorial Note: This report emphasizes the importance of occupational disease surveillance of sentinel health events, i.e., an unnecessary disease, disability, or untimely death that is occupationally related and whose occurrence may 1) provide the impetus for epidemiologic or industrial hygiene studies or 2) serve as a warning that materials substitution, engineering control, personal protection, or medical care may be required (6).

In February 1985, CDH instituted a network for surveillance of selected sentinel health events. This activity, which began as part of a cooperative agreement among CDH and CDC's National Institute for Occupational Safety and Health (NIOSH) and Center for Environmental Health and Injury Control, was designed to improve CDH's surveillance capacity. In this investigation, one case of lead poisoning reported through the CDH surveillance system resulted in the identification of other persons at risk for lead exposure and the implementation of workplace controls to reduce lead exposure among employees and their families. Sentinel occupational health events such as the one reported here demonstrate the value of state programs that mandate routine reporting of elevated blood-lead levels by laboratories and physicians. They also illustrate the continuing problem of occupational and subsequent paraoccupational lead exposure (5).

The importance of obtaining an occupational history as part of a medical record is demonstrated by the index patient's first hospitalization and treatment for a presumed peptic ulcer. Recognition of the patient's occupational exposure to lead at that time may have accelerated diagnosis and treatment of lead poisoning and decreased his children's exposure to lead and its attendant risks of long-term neurobehavioral effects. Blood-lead levels of children exposed to lead through a parent's occupation are higher than those of unexposed controls (3,7). In this instance, clinical lead toxicity (CDC definition: greater than or equal to 25 ug/dL blood lead, greater than or equal to 35 ug/dL FEP (4)) developed in two children as a consequence of their father's occupational lead exposure. Recent evidence suggests that adverse health effects of lead exposure are associated with lower blood-lead levels than was previously believed, particularly in children less than 6 years old (8). Thus, the levels of lead in the children in this investigation place them at increased risk for persistent neurobehavioral dysfunction.

This investigation illustrates how state and local public health agencies and employers can collaborate to control an occupational health problem. As a result of continued public awareness that many occupational illnesses and injuries can be prevented, state and local health departments have intensified their occupational health surveillance, including programs directed at specific hazards. Through a new program, the Sentinel Event Notification System for Occupational Risks (SENSOR), NIOSH supports demonstration projects in 10 state health departments** to improve state and local capacity to detect and investigate events such as the one described here. The SENSOR program has targeted specific conditions (lead poisoning, carpal tunnel syndrome, occupational asthma, hypersensitivity pneumonitis, silicosis, pesticide poisoning, pneumoconiosis, and occupational burns) for surveillance and follow-up. Information about this program is available from Surveillance Coordinating Activity, Office of the Director, NIOSH, Mailstop D26, CDC, Atlanta, GA 30333.

References

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