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Current Trends Controlling Lead Toxicity in Bridge Workers -- Connecticut, 1991-1994

Workers involved in the repair of infrastructure -- including bridges and roads -- are at risk for exposure to lead and lead poisoning (1,2). Because of these risks, in 1990, the Yale University School of Medicine, the Connecticut Department of Public Health and Addiction Services (CDPHAS), the Connecticut Department of Transportation (CONNDOT), and CDC's National Institute for Occupational Safety and Health (NIOSH) initiated the Connecticut Road Industry Surveillance Project (CRISP) * to reduce lead toxicity in bridge workers through the incorporation of protective measures into contracts in addition to the use of regulatory measures. This report describes an assessment of the impact of this program.

The two principal elements of CRISP are 1) detailed medical and environmental specifications (e.g., medical examinations and industrial hygiene) for monitoring and reducing occupational lead exposures at bridge sites -- these specifications are included in the construction contracts and are paid for by CONNDOT under the terms of the contract; and 2) a centralized, statewide surveillance system to monitor blood lead levels (BLLs) in workers -- this system is based in CDPHAS.

Since 1993, CONNDOT has mandated that, for jobs associated with potential lead exposures, both the bids and contracts explicitly address lead-control activities, including the need for an industrial hygienist to monitor every project, personal and ambient airborne lead sampling, minimum standards for protective equipment, and standardized comprehensive medical monitoring (using the CRISP protocol). Medical examinations must be conducted at designated CRISP-affiliated clinics and blood lead specimens analyzed at a single, specified Occupational Safety and Health Administration (OSHA)-approved laboratory. CRISP centralizes the collection and review of comprehensive medical data for exposed workers and the response when workers' BLLs exceed specific action levels. Lead-control specifications were fully implemented in all CONNDOT contracts in February 1993. CRISP had enrolled some workers before 1993; however, most of these workers were employed by construction companies that were voluntarily and independently attempting to protect workers from lead exposures. ** However, since February 1993, all workers potentially exposed to lead at CONNDOT bridge repair sites have been enrolled in CRISP.

From July 1991 through December 1994, a total of 1421 workers were enrolled in the CRISP database; 34 workers were monitored in 1991, 108 in 1992, 669 in 1993, and 959 in 1994 ***. These workers were employed by 90 contractors and other companies and were assigned to projects at 68 CONNDOT sites.

BLLs for the most highly exposed work categories declined substantially during 1991-1993 and remained relatively stable during 1994 Table_1. Average BLLs in painters/blasters declined from 41.8 ug/dL and 28.2 ug/dL in 1991 and 1992, respectively, to 16.4 ug/dL and 16.6 ug/dL in 1993 and 1994, **** respectively. Similarly, average BLLs for iron workers/welders declined steadily from 20.6 ug/dL in 1991 to 10.9 ug/dL in 1994, and those for carpenters from 14.0 ug/dL in 1992 ***** to 7.5 ug/dL in 1994. Reported by: KF Maurer, MD, MR Cullen, MD, Occupational and Environmental Medicine Program, Yale Univ School of Medicine, New Haven; M Erdil, MD, Immediate Medical Care Center, Weathersfield; CJ Dupuy, MS, BC Jung, MPH, JL Hadler, MD, State Epidemiologist, Connecticut Dept of Public Health and Addiction Svcs; B Castler, Connecticut Dept of Transportation. SK Hammond, PhD, School of Public Health, Univ of California, Berkeley. Div of Surveillance, Hazard Evaluations, and Field Studies, National Institute for Occupational Safety and Health, CDC.

Editorial Note

Editorial Note: Although the potential for high exposures to lead among bridge repair workers was well documented in 1982 (3), limited progress has been made in controlling exposures. In 1991, NIOSH reported elevated airborne lead exposures and BLLs in bridge repair workers at eight sites in five states and recommended improved surveillance for and more effective control of lead exposures at such sites (4). During 1988-1991, efforts by clinicians and industrial hygienists in Connecticut confirmed high lead exposures and high BLLs among bridge workers in certain job categories (5). In May 1993, OSHA lowered the permissible exposure level for lead in the construction industry (previously 200 ug/m superscript 3) to that established for general industry (50 ug/m superscript 3) (6). One of the national health objectives for the year 2000 is to eliminate exposures associated with BLLs greater than 25 ug/dL in workers (objective 10.8) (7).

In Connecticut, extensive bridge repair and rehabilitation began statewide in 1983 after the collapse of an interstate highway bridge. The presence of lead-containing paints on most bridges created the potential for high exposures to lead for many workers. CRISP is an innovative approach for workers and their employers to control lead exposures on bridge repair jobs and, compared with traditional surveillance and regulatory approaches, is unique in its routine use of health-related contract language and its focus on medical surveillance -- an approach that emphasizes a collaborative, nonadversarial strategy for exposure control.

The use of contract language as a foundation for health and safety activity in the construction industry ensures worker protection through direct, day-to-day enforcement by the contracting parties. For example, for bridge repair projects, CONNDOT inspectors and field engineers enforce the requirements of the "Lead Health Protection Program" (as it is termed in the contracts) just as they do the thickness of paint applied or other construction specifications.

The medical focus and regional organization of CRISP were designed to address the specific circumstances of the construction industry, in which workers frequently transfer sites, change employers, or move to different regions. The requirement that all clinics adhere to a standard medical protocol and the centralization of all medical decision making for bridge workers ensures that CONNDOT's contractors and their employees receive a consistent standard for medical care and work- and exposure-related decisions. In addition, because medical data are relayed to the central CRISP office within 48-72 hours of medical evaluation and testing for BLL, CRISP staff can respond rapidly to reports of elevated BLLs with recommendations to reduce or eliminate further exposures to the affected worker or to address adverse exposure-related health effects.

The findings in this report indicate that after implementation of CRISP, BLLs decreased substantially among Connecticut bridge workers. Evaluation of these results is complicated by the concurrent promulgation (in 1993) by OSHA of the Interim Final Standard for Lead in Construction (29 CFR 1926.62) (6), a comprehensive standard for lead control in the construction industry. The relative contributions of these efforts in reducing BLLs are even more difficult to clarify because some provisions of the CONNDOT "Lead Health Protection Program" contain more aggressive worker exposure-control requirements than does the OSHA standard (e.g., CRISP mandates more frequent BLL monitoring during the initial months of a project than does OSHA). In addition, CRISP, CONNDOT, and OSHA allow CRISP-enrolled employers 30 days to correct problems on their sites before a formal referral to OSHA is made from CRISP/CONNDOT; this agreement assists CRISP in encouraging compliance from companies and enables OSHA to more effectively target problem sites for inspection.

References

  1. CDC. Lead poisoning in bridge demolition workers -- Massachusetts. MMWR 1989;38:687-8,693-4.

  2. CDC. Lead poisoning in bridge demolition workers -- Georgia, 1992. MMWR 1993;42:388-90.

  3. 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.

  4. NIOSH. Request for assistance in preventing lead poisoning in construction workers. Cincinnati: US Department of Health and Human Services, Public Health Service, CDC, 1990; DHHS publication no. (NIOSH)91-116a. (Revised 1992).

  5. Maurer KF, Smith IK, Cullen MR. Controlling lead toxicity in bridge workers: preliminary findings of the Connecticut Road Industry Surveillance Project. Journal of Protective Coatings and Linings 1993;10:37-43.

  6. Occupational Safety and Health Administration, US Department of Labor. Lead exposure in construction: interim final rule. Federal Register 1993;58:26590-649. (29 CFR 1926).

  7. 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, 1991; DHHS publication no. (PHS)91-50212.

* CRISP is funded through a cooperative agreement between NIOSH and the Yale University School of Medicine. 

** For this reason, CRISP data from 1991 and 1992 may not be representative of all Connecticut lead-exposed bridge workers during that time; however, comparison of CRISP data from subsequent years with these data would most likely underestimate reductions in BLLs resulting from CRISP activities. 

*** The same worker may have been monitored in greater than 1 year and would, therefore, be counted in the total for each year in which he or she was monitored. 

**** BLL data for 1994 are complete through September 30, 1994. 

***** No carpenters were enrolled in the system in 1991.



Table_1
Note: To print large tables and graphs users may have to change their printer settings to landscape and use a small font size.

TABLE 1. Mean blood lead levels (BLLs) for hands-on bridge workers,
by job category and year -- Connecticut Road Industry Surveillance
Project (CRISP), 1991-1994
====================================================================
Job category/                        Mean BLL    Standard
  Year               No. workers      (ug/dL)   deviation
--------------------------------------------------------------------
Carpenters
  1991                    -- *           --          --
  1992                     1           14.0           0
  1993                    52            6.8         3.6
  1994 +                  28            7.5         5.9

Iron workers/
  Welders
  1991                    10           20.6        15.1
  1992                    22           19.1         8.8
  1993                   103           13.6         8.9
  1994 +                 116           10.9         5.8

Painters/Blasters
  1991                    19           41.8        18.6
  1992                    30           28.2        17.3
  1993                   122           16.4        10.6
  1994 +                 261           16.6        10.4

Laborers/
  Groundsmen
  1991                     1            9.0           0
  1992                    31           17.1         8.8
  1993                   160            7.1         4.2
  1994 +                 226            9.2         7.4
--------------------------------------------------------------------
* No carpenters were enrolled in CRISP in 1991.
+ Data for 1994 are complete through September 30, 1994.
====================================================================


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