Characterizing Lead Exposure at a U.S. Coast Guard Indoor Firing Range
Torres, Melvin Alexis
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Exposure to airborne and settled dust at firing ranges is a well-known hazard that puts employees at risk for lead poisoning. Nine firearms instructors (FAIs) were studied over a 4-week period while working at a U. S. Coast Guard indoor firing range to determine if their work placed them at risk of overexposure to lead. Blood was collected at the beginning and end of the study to determine if a change in blood lead levels (BLLs) had occurred throughout the study. Questionnaires were also issued to obtain demographic, occupational, & extracurricular activity information to determine any other potential sources of lead exposure. Personal air lead exposures were measured for the instructors during weaponry qualification. To determine the effectiveness of range cleaning, surface wipes of lead dust before and after cleaning were collected from the floor. Mean BLLs from FAIs at baseline was 2.4 µg/dL compared to 2.3 µg/dL at the end of the study, more than 20 times below OSHA's standard of 40 µg/dL. Furthermore, the mean airborne lead was 2.7 µg/m3, also more than 20 times below OSHA's standard of 50 µg/m3. One of our hypotheses was to find a relationship between changes in BLL and mean airborne lead; however, no correlation was found. We also found no relationship between changes in BLL, mean airborne lead, the number of hours per month spent inside the range and the number of lead and jacketed rounds fired at the range. When evaluating the cleaning methods, paired t-tests were used to measure the post- to pre-cleaning differences for weekly and monthly cleaning practices. Statistically significant differences were found (p<0.01) for both, though weekly cleaning had lower surface concentrations after cleaning than before cleaning, while monthly cleaning had higher concentrations after cleaning than before. Our results show that a combination of controls, using jacketed bullets instead of lead and a well-functioning ventilation system, can be used to keep air and blood lead levels low. Additionally, although OSHA's surface contamination recommendation level of 21.5 µg/100 cm2 was not reached (highest value was 4.4 µg/100 cm2), we found that weekly cleaning is more effective than monthly cleaning at removing lead from the floor. A more robust cleaning procedure should be implemented to improve removal of lead from the range.
- Environmental health