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Lead Toxicity Among Bridge Workers, 1994

Following publication of blood lead level (BLL) surveillance results from the Connecticut Road Industry Surveillance Project (CRISP) * (1) in February 1995, CRISP staff were contacted by a primary-care physician in another state who monitors BLLs in bridge painters. After noting that some bridge workers with elevated BLLs had been evaluated in his clinic, the physician established a medical program to monitor lead-exposed bridge workers; all blood lead determinations were performed by an Occupational Safety and Health Administration (OSHA)-certified medical laboratory. This report summarizes BLL results from the physician's medical monitoring for March-December 1994, compares these findings with CRISP data, and indicates that the prevalence of elevated BLLs in bridge workers remains substantial.

During March-December 1994, the physician's monitoring database recorded BLLs from 373 bridge workers employed by 35 painting contractors in eight states **. Of the 225 bridge workers for whom information about specific occupation was available, 146 (65%) were employed as painters/sandblasters. Most (369 {99%}) of the 373 monitored workers were men. Of the 269 (72%) workers for whom age data were available, mean age was 35.7 years (range: 17-64 years). During this period, 168 (45%) of the workers had one BLL recorded, 84 (23%) had two, 65 (17%) had three, and 56 (15%) had four or more. The mean of the most recent BLL for these 373 workers was 27.2 ug/dL (standard deviation: 16.1 ug/dL; range: less than 2-72 ug/dL). More than half (194 {52%}) of the workers had a BLL greater than 25 ug/dL, and 35 (9%) had a level greater than or equal to 50 ug/dL (Table_1, page 919).

One of the national health objectives for the year 2000 is the elimination of occupational lead exposures associated with BLLs greater than 25 ug/dL (objective 10.8) (2). The OSHA Interim Final Standard for Lead in Construction requires medical removal from further exposure of any employee with a BLL greater than or equal to 50 ug/dL (3); the most recent BLL of 35 workers equaled or exceeded this level. The physician reported these levels to the respective employers and recommended medical removal of these workers.

Reported by: KF Maurer, MD, MR Cullen, MD, ME Garcia, MPH, Occupational and Environmental Medicine Program, Yale Univ School of Medicine, New Haven; M Erdil, MD, Occupational Medicine Svcs of Immediate Medical Care Center, Wethersfield, Connecticut. SK Hammond, PhD, School of Public Health, Univ of California, Berkeley. Industrywide Studies Br, Div of Surveillance, Hazard Evaluations, and Field Studies, National Institute for Occupational Safety and Health, CDC.

Editorial Note

Editorial Note: An estimated 90,000 bridges in the United States are coated with lead-based paints (4), which become a hazard to workers when these structures are refurbished or demolished. High exposures to lead among bridge workers were first documented in 1982 (5), and in 1992, personal exposures of a cohort of bridge workers to airborne lead ranged from 3690 ug/m3 to 29,400 ug/m3 for abrasive blasters and from 5 ug/m3 to 6720 ug/m3 for workers in other job categories (6). Despite such high exposures, bridge workers have typically accounted for only a small proportion of workers with elevated BLLs who are reported to lead registries, probably reflecting both a lack of medical monitoring of this worker population and underreporting of elevated results (7). In contrast, in Massachusetts, where blood lead monitoring has been required for workers involved in lead paint removal and structural painting since 1990, bridge painters have accounted for approximately one third of workers with BLLs greater than or equal to 60 ug/dL and for whom specific industry/occupation information was available (8).

CRISP was initiated in 1990 to reduce lead exposure and toxicity in Connecticut bridge workers through the incorporation of worker protection measures into road construction contracts. During 1991-1994, mean BLLs among painters/blasters in Connecticut declined from 41.8 ug/dL to 16.6 ug/dL (1). However, in May 1993, OSHA promulgated the Interim Final Standard for Lead in Construction (3), which lowered the permissible lead exposure limit in the construction industry from 200 ug/m3 to 50 ug/m3 and implemented requirements for exposure assessment, respiratory protection, protective clothing and equipment, hygiene facilities and practices, medical surveillance, medical-removal protection, employee training, signs, and record keeping. Because of the overlap in the periods of implementation of CRISP and the OSHA Interim Standard, the independent effects of these interventions in reducing BLLs among Connecticut bridge workers cannot be determined.

The findings in this report indicate that, in other states, lead exposure and elevated BLLs are problems among bridge workers that persist despite the regulatory requirements of the OSHA standard. In contrast to the elevated BLLs observed among these workers, only a small proportion of the 949 Connecticut bridge workers monitored by CRISP during the same period had elevated BLLs (Table_1). The mean of the most recent BLL in Connecticut bridge workers monitored by CRISP during March-December 1994 was 11.7 ug/dL (standard deviation: 9.5 ug/dL; range: less than 5-56 ug/dL), less than half the mean *** among the group of bridge workers in this report.

Data from CRISP differ from the data in this report because CRISP data are comprehensive and represent nearly all lead-exposed bridge workers in Connecticut, while the data in this report are not comprehensive, were not collected according to a specific sampling scheme, and may not be representative of all bridge workers in the eight states from which the specimens were obtained or generalizable to bridge workers in other states. Despite this limitation, the substantially lower proportion of workers with elevated BLLs -- and generally lower BLLs -- in the CRISP program suggests that a strategy like CRISP, which uses contract health and safety language that requires medical management with centralized data reporting and intervention, is independently effective in lowering BLLs. NIOSH and CRISP have initiated efforts to adapt the CRISP approach for implementation in other states.

References

  1. CDC. Controlling lead toxicity in bridge workers -- Connecticut, 1991-1994. MMWR 1995;44:76-9.

  2. Public Health Service. Healthy people 2000: national health promotion and disease prevention objectives -- full report, with commentary. Washington, DC: US Department of Health and Human Services, Public Health Service, 1991; DHHS publication no. (PHS)91-50212.

  3. Occupational Safety and Health Administration. Lead exposure in construction: interim final rule. Federal Register 1993;58:26590-649.

  4. Katauskas T. R&D special report: DOT coats rusting bridges with layers of problems. R&D Magazine, May 1990:42-8.

  5. Landrigan PJ, Baker EL Jr, Himmelstein JS, Stein GF, Weddig JP, Straub WE. Exposure to lead from the Mystic River Bridge: the dilemma of deleading. N Engl J Med 1982;306: 673-6.

  6. Sussell A, Tubbs R, Montopoli M. Occupational exposures during abrasive blasting removal of lead-based paint on a highway bridge. Appl Occup Environ Hyg 1992;7:497-9.

  7. Rabin R, Brooks DR, Davis LK. Elevated blood lead levels among construction workers in the Massachusetts Occupational Lead Registry. Am J Public Health 1994;84:1483-5.

  8. Rabin R, Davis L, Brooks D. Lead at work: elevated blood lead levels in Massachusetts workers, April-October, 1991. Boston, Massachusetts: Massachusetts Department of Public Health, 1992.

CRISP is an ongoing statewide medical surveillance system in Connecticut, which is funded by CDC's National Institute for Occupational Safety and Health (NIOSH) and designed to prevent lead toxicity in bridge workers. ** Arkansas, Florida, Georgia, Kentucky, New Jersey, New York, Ohio, and Tennessee. *** The limit of detection for lead for BLLs obtained from the group of bridge workers in this report (2 ug/dL) was lower than that for workers monitored by CRISP (5 ug/dL). If the CRISP limit of detection had applied to BLLs obtained from the bridge workers in this report, their mean BLL would have changed only from 27.2 ug/dL to 27.3 ug/dL.



Table_1
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TABLE 1. Blood lead levels (BLLs) in bridge workers monitored by a primary-care
physician and the Connecticut Road Industry Surveillance Project (CRISP),
March-December, 1994
===============================================================================================
                   Primary-care
              physician's database *            CRISP data
BLL           ----------------------        ------------------
 (ug/dL)         No.           (%)          No.           (%)
--------------------------------------------------------------
  <20            133          ( 36)         775          ( 82)
20-29             80          ( 21)         109          ( 11)
30-39             70          ( 19)          48          (  5)
40-49             55          ( 15)          12          (  1)
 >=50             35          (  9)           5          (  1)

Total            373          (100)         949          (100)
--------------------------------------------------------------
* Worker population obtained from Arkansas, Florida, Georgia, Kentucky, New Jersey, New York,
  Ohio, and Tennessee.
===============================================================================================



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