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LEA Advisory #46 - Evaluation of Employee Health Risk from Open Tire Burning Page 5 of 8 Laboratory analysis of soil samples taken from a tire fire in Bakersfield indicated the total concentration of zinc exceeded the total threshold limit concentration (TTLC) [7800 mg/kg and 15800 mg/kg]. The TTLC for zinc is 5,000 mg/kg. Zinc concentrations at the Panoche Waste Tire Site were also found to be extremely high (32,800-156,000 mg/kg). Background zinc soil concentrations for the site averaged 64 mg/kg while underlying soil beneath the ash concentrations ranged from 74 to 179 mg/kg. At the Rhinehart Tire Site elevated levels of zinc were identified in surface water samples and on site soils. A comparison of zinc levels in background sediments (93 ppm) with the highest zinc level found on the site (2880 ppm) showed a significant increase. (See reports for more specific emission data information.) The fire at a used tire facility near Hagersville in Ontario, Canada was monitored by the Ontario Ministry of Environment and Energy (MOEE) for impacts on the site and surrounding environment. Soil samples collected during the fire did not show elevated PCDD or PCDF concentrations. However, low concentrations of both compounds were detected in vegetation collected at 100 meters and 200 meters from the site. PCDD and PCDF concentrations in the foliage decreased with time but was still detectable for at least 200 days after the fire started. Potential Health Hazards To evaluate worker protection at tire fires, two cases must be considered: potential exposure while the fire is burning and potential exposure after the fire is out. This evaluation considers what activities will be performed at the site and what substances are present. A decision as to whether a health hazard exists is based on comparing emissions estimates with established safe levels for those compounds. Based upon available information, the following chemical hazards are of occupational concern. While the fire is still burning, the smoke plume may contain hazardous substances that should not be inhaled or allowed to contact the skin. The two substances for which excessive exposure risk exists are believed to be polycyclic aromatic hydrocarbons and carbon monoxide. Polycyclic aromatic hydrocarbons (PAH) are a class of compounds consisting of various arrangements and substitutions of multiple benzene rings. PAHs result mainly from the incomplete combustion or high-temperature treatment of coal-derived materials. Since there are no published exposure limits to PAHs, coal tar pitch volatile exposure values are used. The coal tar pitch volatile (CTPV) is a "benzene-soluble" fraction of total particulates that generally contains substances that have carcinogenic potential.Epidemiological studies of the cancer mortality rates among those workers that have high PAH exposure show an association with increased mortality from lung cancer. Benzene compounds may be produced as part of the thermal breakdown and reformation of molecules in the cooling process. Benzene may cause adverse health effects through inhalation, ingestion, or dermal contact. Acute exposure symptoms include dizziness, euphoria, giddiness, headache, nausea, weakness, drowsiness, respiratory irritation, pulmonary edema, and pneumonia. Benzene can also cause irritation to the skin, eyes, and mucous membranes. Allowable Employee Exposure Levels http://www.clwmb.ca.gov/pe/advisory/46/46.htm 8/11/98