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BENZO(A)PYRENE*
Characteristics
Pure Benzo(a)pyrene (BaP) is usually found as pale yellow crystals. It does not dissolve in water, but will dissolve in organic (carbon-containing) solvents. BaP is one of a group of compounds known as the Polycyclic Aromatic Compounds (PAHs). Only relatively small amounts of BaP are intentionally manufactured to be used in dyes.
Exposure to Benzo(a)pyrene
The vast majority of BaP is released to the environment when combustion is incomplete (usually because there is insufficient oxygen). Thus, most BaP is released from vehicle exhausts and domestic wood and coal fires. Trace amounts are found in cigarette smoke. BaP is also released naturally from volcanoes and forest fires, but the amounts are very small compared to those released from man-made combustion sources. BaP has very low solubility in water, but can be found in drinking water when groundwater or surface water sources are contaminated with BaP. BaP binds to particulate matter in water, which is often removed by filtration before reaching the tap. BaP partitions strongly to sediment, but will break down when exposed to UV in sunlight.
Effects on Health
Benzo(a)pyrene can enter the body either by inhalation of air containing benzo(a)pyrene, ingestion of water or food containing benzo(a)pyrene, or by dermal contact with benzo(a)pyrene, contaminated soil or products containing benzo(a)pyrene. Inhalation of benzo(a)pyrene may cause respiratory tract irritation. Exposure to benzo(a)pyrene may damage the reproductive system and cause cancer. Ingestion of benzo(a)pyrene may cause gastrointestinal irritation. Dermal contact with benzo(a)pyrene may lead to skin irritation. In the natural environment benzo(a)pyrene occurs as part of a mixture of Polycyclic Aromatic Hydrocarbons (PAHs). The full effects of benzo(a)pyrene on human health are unknown, however studies have shown that inhalation of PAHs or dermal contact with PAHs for long periods of time can cause cancer. However, exposure to benzo(a)pyrene at normal background levels is unlikely to have any adverse effect on human health. Lung cancer has been shown to be induced in humans by various mixtures of polycyclic aromatic hydrocarbons known to contain BAP including cigarette smoke, roofing tar and coke oven emissions. It is not possible, however, to conclude from this information that BAP is the responsible agent.
Effects on Children
Based on what is known about effects of BaP exposure, health concerns associated with BaP exposure for children are: formation of BaP-DNA adducts which may lead to errors in DNA replication and increased risk of cancer; also increased risk of cancer associated with BaP metabolite formation; persistent effects on the development and function of the immune system; and reduced fertility in offspring during adulthood following BaP exposure during pregnancy.
Concerns for BaP exposure of pregnant women and children are: ambient air contamination from mobile sources (e.g., cars) and industrial sources (e.g., coke ovens, metal processing plants); fetal exposure from maternal cigarette smoking; fetal and childhood exposure from second-hand cigarette smoke; and exposure from diet, including grilled and broiled food . Children may also have greater exposure than adults to contaminated soil in areas where BaP-contaminated soil from industrial contamination may be present, because of behavior patterns, particularly hand-to-mouth activity.
Recommendations
In view of the U.S. EPA Maximum Contaminant Level Goal (MCLG) of 0 for BaP (see Toxicity Summary and Reference Values in this Chemical Summary), caregivers may consider an alternate water supply where BaP contamination is impacting drinking water.
BaP is number 9 on the 2005 Priority List of Hazardous Substances for the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) section 104(i), as amended by the Superfund Amendments and Reauthorization Act (SARA).
* Compiled by Elizabeth Limbrick, New Jersey Institute of Technology Technical Assistance to Brownfield Communities (TAB) Program. Sources: http://apps.sepa.org.uk/spripa/Pages/SubstanceInformation.aspx?pid=22; http://www.epa.gov/iris/subst/0136.htm; http://www.epa.gov/teach/chem_summ/BaP_summary.pdf