Health hazard evaluation report: HETA-2001-0081-2877, Glass Masters Neon, Savannah, Georgia.
On November 11, 2000, the National Institute for Occupational Safety and Health (NIOSH) received a request for a health hazard evaluation from the owner of Glass Masters Neon in Savannah, Georgia, a small business which manufactures and repairs neon tubes for commercial signs and artwork. The owner, who was also the sole worker, was concerned about the health risks of his exposures to mercury, lead, and cadmium. In response to this request, a NIOSH industrial hygienist conducted a site visit on January 23, 2001. Full-shift, personal-breathing zone (PBZ) air samples for mercury vapor, lead, and cadmium were collected. Real-time air monitoring for mercury vapor was conducted throughout the shop area. Surface wipe samples of the work-tables were collected using moist cloth wipes for analysis of lead and other elements. In addition to the site visit, the owner's medical records were reviewed by a NIOSH physician. The worker's full-shift time-weighted average (TWA) PBZ air sample was 0.03 milligrams per cubic meter (mg/m3) for mercury, which is below the Occupational Safety and Health Administration (OSHA) 8-hour TWA permissible exposure limit (PEL) of 0.1 mg/m3 and the NIOSH recommended exposure limit (REL) of 0.05 mg/m3 , but it is above the American Conference of Governmental Industrial Hygienists' (ACGIH® ) threshold limit value (TLV®) 8-hour TWA of 0.025 mg/m3 . Lead and cadmium were not detected in the 8-hour PBZ air sample. Real-time monitoring indicated that mercury contamination was present in the neon glass room, especially in areas where mercury was added to glass tubes. Particularly high air concentrations of mercury were found above a floor mat. A difference existed between the amount of metals found on two work surfaces from which wipes samples were collected. The location designated as side A in this report was an area where cutting, heating, and other manipulations of the glass were performed; side B was an area where primarily glass cutting occurred. Side A had a much higher range of lead levels (120-170 micrograms per square foot (microg Pb/ft2 ) of surface wiped) than side B (16-21 microg Pb/ft2 of surface wiped). Cadmium levels were also elevated over background (side A = 1.1-2.9 microg Cd/ft2 of surface wiped; side B = 0.43-0.69 microg Cd/ft2 of surface wiped.). No occupational standards or recommendations exist for lead or cadmium or the other elements on surfaces. A medical record of the worker's urine, collected by his private physician, reported a mercury level of 22 micrograms per gram creatinine (microg/g creat.), which is below the ACGIH's biological exposure index (BEI® ) of 35 microg/g creat. No lead was detected in the worker's urine. Urinary cadmium was 0.9 microg/g creat., which is consistent with levels found in the general population. Airborne mercury concentrations exceeded the ACGIH-TLV® . Mercury in the air samples was largely the result of volatization of mercury from surface contamination rather than process aerosolization. Air concentrations of lead and cadmium were low, although there was lead and cadmium contamination of work surfaces. Recommendations were made to clean the shop and prevent further contamination by installing a hood with local exhaust ventilation, adding mercury trapping devices, and improving work practices.