Assessing Human Exposure to Polycyclic Aromatic Hydrocarbons (PAH) in a Petrochemical Region Utilizing Data from Environmental Biomonitors

Abstract

Polycyclic aromatic hydrocarbons (PAH) are toxic compounds that have been classified by the International Agency for Research on Cancer as probable or possible human carcinogens. Human exposure to PAH is usually assessed by considering data from a single air monitoring station as being representative of a large region; however, air pollution levels change on small spatial scales and thus also affect environmental exposure. The use of environmental biomonitors is a useful tool to assess the levels of PAH with high spatial resolution. The aims of this study were to (1) assess human exposure to PAH in a petrochemical region in Portugal, integrating data from environmental biomonitors (lichens), air, and soil in a regional area, and (2) determine the health risks associated with exposure to PAH with high spatial resolution. Bearing this in mind, benzo[a]pyrene (BaP) equivalent concentrations in samples of soil, air, and lichens collected in the study region were used to assess human exposure through different pathways, including inhalation of air and soil particles, ingestion of soil, and dermal contact with soil. Human health risk was calculated through the Incremental Lifetime Cancer Risk (ILCR). BaP equivalent concentrations found in the region ranged from 6.9 to 46.05 ng BaPeq/g in lichens, from 16.45 to 162.02 ng BaPeq/g in soils, and from 0.02 to 0.16 ng BaPeq/m³ in air, indicative of high variability in this regional area. Human exposure to PAH varied between 976 and 42,877 ng BaPeq/d. When considering all exposure pathways, ILCR values were between 10^-4 and 10^-3. Considering only inhalation, ILCR values were between 10^-6 and 10^-5. The main risk seemed to arise from soil (either ingestion or inhalation of resuspended soil particles). The high spatial resolution of our environmental data allowed for detection of critical exposure levels at unexpected sites. Our results identified important areas where health studies on local populations need to be focused, and where environmental levels of PAH need to be monitored over time in order to protect human health.

Acknowledgments

The authors are grateful for financial support from PPCDT/AMB/56120/2004, POCTI/AMB/56120/2004, GISA–Integrated Management of Health and Environment Project (http://www.gisaproject.org) and from the Scientific Doctoral Grant SFRH/BD/35308/2007. The authors are also grateful to the Portuguese Environmental Protection Agency (APA) and to the Regional Development and Coordinating Commission of Alentejo (CCDRA) for technical support.