Lead Exposure from Indoor Firing Ranges Among Students on Shooting Teams --- Alaska, 2002--2004

CDC recognizes blood lead levels (BLLs) of >25 µg/dL in adults and >10 µg/dL in children aged <6 years as levels of concern; no similar level has been set for older children and adolescents (1,2). During 2002--2004, the Alaska Environmental Public Health Program (EPHP) conducted lead-exposure assessments of school-based indoor shooting teams in the state, after a BLL of 44 µg/dL was reported in a man aged 62 years who coached a high school shooting team in central Alaska. This report summarizes the results of the EPHP investigation of potential lead exposure in 66 members of shooting teams, aged 7--19 years, who used five indoor firing ranges. The findings suggest that improper design, operation, and maintenance of ranges were the likely cause of elevated BLLs among team members at four of the five firing ranges. Public health officials should identify indoor firing ranges that have not implemented lead-safety measures and offer consultation to reduce the risk for lead exposure among shooters, coaches, and employees.

The shooting-team coach was asymptomatic for lead exposure; in January 2002, he sought BLL testing from his health-care provider after reading about potential lead exposure at firing ranges. The BLL test result of 44 µg/dL was reported to EPHP in accordance with the Alaska lead surveillance system, which requires laboratories to report all BLLs >10 µg/dL. An epidemiologic investigation by EPHP revealed that the man was the chief range officer and shooting-team coach for firing range A, which was used primarily by adolescents. In February 2002, EPHP tested BLLs for all seven members of the shooting team, who were aged 15--17 years. The mean BLL was 24.3 µg/dL (range: 21.0--31.0 µg/dL). BLLs for 14 nonshooting family members were significantly (p<0.05) lower (mean: 3.5 µg/dL; range: 1.0--7.0 µg/dL) (Table). EPHP advised parents of the team members that their children should discontinue use of the firing range.

Range A, an indoor firing range, was used by the shooting team on school property in a multipurpose building that also housed a hockey rink. A utility fan located near the bullet backstop ventilated the range; no formal range maintenance protocol was observed. An environmental evaluation performed in May 2002 by an independent environmental and engineering consulting firm concluded that the range and its ventilation system were contaminated with lead dust. Three months after their initial testing, the four shooting-team members available for retesting all had lower BLLs; their levels declined from 29 to 16 µg/dL, 23 to 11 µg/dL, 22 to 16 µg/dL, and 21 to 14 µg/dL (retest mean: 14.3 µg/dL; range: 11--16 µg/dL) (Table). Range A was closed for 1 year, during which time the building was renovated, and a new ventilation system was installed.

Because of the potential for similar lead exposures, during October 2002--January 2004, EPHP investigated four additional indoor firing ranges used by school-based shooting teams in central and southwest Alaska. Range B was a commercial range with paid employees. Ranges C and E were operated by volunteer-run sport associations. Range D was a school-operated range located in a multipurpose room that was also used for lunches, physical education, wrestling practice, and meetings.

Range B had a written maintenance protocol that specified daily, weekly, 6-month, and annual maintenance tasks; range surfaces were cleaned with wet mops and vacuums equipped with high-efficiency particulate air (HEPA) filters. Ranges C, D, and E had no written maintenance protocols; dry sweeping, which aerosolizes lead dust particles, was used to clean floors (Table). Independent assessments by certified industrial hygienists were performed at ranges B, C, and D. The ventilation system at range B was determined adequate in both design and function for the firing range. Ventilation systems for ranges C and D were determined inadequate. Range E ventilation was not assessed; however, EPHP advised the operators to seek an independent assessment.

BLLs of all eight shooting team members tested at range B were <5.0 µg/dL. Twenty-two (43%) of 51 shooters had BLLs >10 µg/dL at ranges C, D, and E; eight (33%) of 24 shooters had BLLs >25 µg/dL at range C (Table). Among nonshooting family members tested, BLLs were lower than those for shooters at ranges C (p<0.05) and E (p=0.06); BLL testing was not performed for family members of shooters at ranges B and D. After 3 months away from ranges C and D, 19 (61%) of 31 shooters at those ranges were retested. Test results indicated that BLLs had declined in all but two of the 19 shooters; no further testing was conducted.

EPHP made no recommendations for range B because BLLs among shooters were not elevated and the range had an adequate ventilation system and maintenance practices. Ranges C and D voluntarily shut down. Range C later reopened after installing an improved ventilation system. Shooting practice for team members who used range D was moved to another location. EPHP recommended that range E discontinue dry sweeping, institute a regular maintenance schedule, and acquire the services of an industrial hygienist to evaluate the ventilation system.

Reported by: T Lynn, DVM, S Arnold, PhD, C Wood, MS, L Castrodale, DVM, J Middaugh, MD, Section of Epidemiology, Alaska Dept of Health and Social Svcs. M Chimonas, MD, EIS Officer, CDC.

Editorial Note:

Low levels of lead exposure can adversely affect the intellectual development of young children (1). Even BLLs <5 µg/dL can have deleterious effects on intelligence quotients for persons aged 6--16 years (3); however, no BLLs of concern have been set for children and adolescents in this age group. During 1999--2002, the geometric mean BLL in the United States was 1.6 µg/dL for persons aged >1 year and 1.1 µg/dL for persons aged 6--19 years (4). Findings in this report indicate that, at four of the five ranges investigated, BLLs among students on shooting teams were elevated, with mean BLLs ranging from 7.6 µg/dL at range E to 24.3 µg/dL at range A. None of the four ranges had written protocols for maintenance; three had inadequate ventilation systems, and ventilation at the fourth was not assessed. Range B, where all shooters had BLLs <5 µg/dL, had a modern, well-maintained ventilation system, followed a written maintenance protocol, and did not employ dry sweeping to clean the range.

Firing ranges have been recognized as potential sources of lead exposure since the 1970s (5). Lead-containing dust is produced by 1) the combustion of lead-containing primers, 2) the friction of bullets against the gun barrel, and 3) fragmentation as bullets strike the backstop (5). Lead dust inhaled into the lungs is highly bioavailable, with an absorption rate near 100% (6). The Occupational Safety and Health Administration (OSHA) has established acceptable standards for airborne lead exposure in the workplace, including indoor firing ranges, since 1979 (7). Guidelines for proper design and operation include use of a separate ventilation system for firing lanes, written protocol for range maintenance, use of wet mopping or HEPA vacuuming instead of dry sweeping to remove dust and debris, and use of copper-jacketed bullets (8,9).

The findings in this report are subject to at least three limitations. First, detailed shooting histories of the extent of indoor firing range use were not obtained for the students in the study. Second, persons using the firing ranges who were not members of the school shooting teams were not included in the analysis. Finally, limited information was obtained regarding other possible sources of lead exposure. However, other common causes of the elevated BLLs were unlikely because 1) BLL samples of nonshooting family members were not elevated, 2) BLLs decreased for 21 of 23 shooters retested after removal from the firing ranges, 3) lead paint is rare in Alaska (approximately 93% of houses were built since 1950) (1), 4) drinking water measurements were below the action level for lead for each community (10), and 5) the ammunition used by those in the study is not commonly homemade.

This investigation revealed that lead exposure can occur at indoor firing ranges despite federal regulations and specific guidelines pertaining to range design and operation. Because OSHA regulations were created to protect employees and not users of firing ranges, legal requirements for a lead-safety program and adequate range design and operation do not apply to volunteer-run ranges; moreover, schools with onsite shooting ranges likely are unaware of such requirements. Public health officials should identify volunteer-run or other firing ranges in their areas that do not fall under the jurisdiction of regulatory agencies. Lead-risk assessments should be conducted, and ranges with antiquated design and maintenance protocols should be encouraged to modernize and adopt published recommendations (8,9). Because children and adolescents are at risk for adverse effects from lower levels of lead exposure, they should not participate in range maintenance or clean-up. Periodic BLL testing should be considered for children and adolescents who use indoor firing ranges to ensure that they are not exposed to lead.

References

1. CDC. Screening young children for lead poisoning: guidance for state and local public health officials. Atlanta, GA: US Department of Health and Human Services, CDC; 1997.
2. CDC. Adult blood lead epidemiology and surveillance---United States, 1998--2001. In: Surveillance Summaries, December 13, 2002. MMWR 2002;51(No. SS-11):1--10.
3. Lanphear BP, Dietrich K, Auinger P, Cox C. Cognitive deficits associated with blood lead concentrations <10 µg/dL in US children and adolescents. Public Health Rep 2000;115:521--9.
4. CDC. Blood lead levels---United States, 1999--2002. MMWR 2005;54:513--6.
5. Fischbein A, Rice C, Sarkozi L, Kon SH, Petrocci M, Selikoff IJ. Exposure to lead in firing ranges. JAMA 1979;241:1141--4.
6. Klaassen CD, Amdur MO, Doull J, et al. Casarett & Doull's toxicology: the basic science of poisons. 5th ed. New York, NY: McGraw-Hill; 1996:703--9.
7. US Department of Labor, Occupational Safety and Health Administration. Final standard: occupational exposure to lead. Federal Register 1978;43:52952--3014. 29 CFR § 1910.1025.
8. Schaeffer DJ, Deem RA, Novak EW. Indoor firing range air quality: results of a facility design survey. Am Ind Hyg Assoc J 1990;51:84--9.
9. Navy Environmental Health Center. Indoor firing ranges industrial hygiene technical guide. Portsmouth, VA: Department of the Navy, Navy Environmental Health Center; 2002. TM6290.99-10 Rev. 1.
10. Division of Environmental Health. Drinking Water Program: drinking water lead level measurement records. Juneau, AK: Department of Environmental Conservation, Division of Environmental Health; July 2001--December 2003.

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Date last reviewed: 6/16/2005