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t 7 • CRA Chemical Safety Sheet • Benzene Applicable Regulations Cal-OSHA Benzene Standard,8 CCR 5218. Note that this standard does not apply to work operations where the only exposure to benzene is from liquid mixtures containing 0.1 percent or less of benzene by volume,or the vapors released from such liquids. General Locations and Forms Benzene is a liquid aromatic petroleum product found in gasoline. Current formulations include benzene at or below 1%,although older formulations could have contained benzene up to 5%. Benzene has a vapor pressure of 75 mm Hg and evaporates readily. On project sites it is typically found as a fraction of gasoline contamination on soil and groundwater. Routes of Exposure Benzene may be inhaled,absorbed through skin,or ingested. Potential Hazards Benzene is flammable,with a flash point of 12oF. It is incompatible with corrosives and oxidizers. Benzene may cause eye and skin irritation on contact. It is a central nervous system depressant that may cause narcosis,dizziness,headaches,and nausea. Benzene may - also damage the liver,and may cause leukemia. Permissible Exposure Limit 8-Hour Time-Wei hted Average TWA Action Level 0.5 ppmv 8-Hour Time-Weighted Average TWA Permissible Exposure Limit 1 ppmv 15-minute Short-Term Exposure Limit STEL 5 ppmv Medical Monitoring Medical monitoring for benzene consists of testing the blood for the metabolites of benzene shortly afterpotential exposure(within a few days). Medical monitoring is only required if employee exposures are at or above the Action Level for 30 or more days per year,or at or above the PEL and/or STEL for 10 or more days per year. Based on testing results,re-testing or medical removal may be required. Exposure Assessment Air monitoring is the primary method of exposure assessment. Monitoring on project sites is typically performed with an organic vapor meter such as a Photoionization Detector(PID). The PID responds well to benzene,and when calibrated to isobutylene,will respondat roughly double the actual ambient benzene concentrations(i.e.,will read 2 ppmv when ambient concentrations are I ppmv). However, when monitoring gasoline vapors,all PID readings will be a mixture of responses to the various gasoline components. The benzene fraction of such readings is expected be quite low. As such,a site PID Action Level of 50 ppmv sustained for 5 minutes should provide adequate protection to keep employee exposures below the benzene Action Level of 0.5 ppmv. This rationale will be verified periodically through the use of NIOSH-method sampling(either passive badge samplers or charcoal tube monitoring). If planning for the excavation of gasoline-bearing soils,where the greatest risk of inhalation exposure is likely to occur,the employee should bring benzene-specific colorimetric tubes and a pump to thejob site.If the PID readings exceed 50 ppmv in the breathing zone,the breathing zone should be checked specifically for benzene using the colorimetric tubes to determine the actual benzene concentration. If benzene concentrations are below Action Levels,then work may proceed using the PID at the prescribed intervals. If not,employees should leave the area immediately, and utilize engineering or work practice controls to further reduce benzene concentrations. CRA employees are prohibited from working in environments with concentrations equal to or exceeding 5 ppmv based on colorimetric tubes even with air-purifying respiratory protection. For non-excavation projects,site personnel should follow the monitoring procedures and corresponding actions outlined below. Include off-site and downwind concentration monitoring in the monitoring program in addition to on-site breathing zones. Monitor breathing zone of work area with a PID at the start of work and at least every two hours thereafter. If you smell hydrocarbons,increase monitoring to 15-minute intervals. If peak concentrations are 50 ppmv or more, monitor continuously for 5 minutes. If the estimated average is less than 50 ppmv, no respiratory protection is required. If concentrations average 50 ppmv or more up to 100 ppmv,employ engineering or work practice controls(more ventilation,moving upwind,etc.)to reduce concentrations back below 50 ppmv. If these controls are not adequate,''/z-face (air-purifying)respirators with organic vapor cartridges are to be used and monitoring must continue at 15-minute intervals. Work may continue up to 8 hours with concentrations between 50 and 100 ppmv while using air-purifying respiratory protection. If eye irritation is experienced,employees should leave the area immediately,and utilize engineering or work practice controls to further reduce vapor levels. If peak PID concentrations are 100 ppmv or more, monitor continuously for 5 minutes. If average is 100 ppmv or more, employ engineering controls to reduce concentrations back below 100 ppmv. CRA employees must discontinue working in environments of 100 ppmv or more until specifically authorized by a Safety Committee member to continue work in that environment. This authorization may be in the form of specific Site Safety procedures or determined in real time with the Safety Committee representative.