- Challenge: Exxon Mobil asked Cardno ChemRisk to characterize historical workplace concentrations of benzene at their refineries over time.
- Approach: Cardno ChemRisk scientists conducted a historical exposure assessment for airborne benzene exposures to workers at four Exxon refineries (and their dock facilities) in the U.S., based on available industrial hygiene sample analyses collected since the 1970s. Over 20,000 samples were analyzed to quantify benzene exposures of workers in various jobs, locations and tasks within the refineries.
- Findings: Cardno ChemRisk found that airborne benzene concentrations for most job and task levels were lower than contemporaneous industry-wide surveys, and decreased with time. Although concentrations were generally low, they likely overestimated worker exposure because samples were usually collected in a targeted manner (e.g., focus on activities with greatest potential for exposure) and workers often wore respirators.
- Value: This was the most comprehensive analysis of historical benzene data conducted for Exxon to date. Results were published in peer-reviewed literature and can be used to answer questions about exposure risk.