Assessing Human Exposure to Benzene at Petroleum-Contaminated Site

Abstract

Entry of volatile organic compounds into buildings is often considered when evaluating air exposure pathways during remedial investigation of petroleum-contaminated sites. This paper presents two approaches used to evaluate human exposure to benzene inside a former gasoline station converted into a strip mall in Manitoba, Canada. Passive air sampling was used to measure benzene in indoor air several times over a two-week period. Soil-to-indoor air vapor transport and worker exposure were modeled to evaluate the potential impact from entry of benzene into the mall. Because these transport models lack field validation and their results can be highly dependent on the sophistication of the models, several models were used. Benzene levels inside the mall were comparable to average levels observed inside Canadian residences. It was not apparent that air inside the mall had been impacted by subsurface contamination at the time of sampling. Modeling of benzene exposure arising from soil vapor entry suggested low incremental exposure for workers compared to what they would receive by inhalation of air inside typical residences. Soil contamination was allowed to remain in place based on these findings.