by Ronald White, 9/10/2013
On Aug. 21, the U.S. Environmental Protection Agency (EPA) published a draft revised health assessment of the toxic chemical benzo(a)pyrene (BaP). This chemical is widely found in the environment and in a number of workplaces, and in its assessment, EPA declared that BaP causes cancer.
BaP is released into the atmosphere from industrial production processes such as coal gasification, coal-tar distillation, coke production, and iron and steel founding; from construction sites where coal tar pitch is used for paving and roofing; and from burning petroleum products (e.g., vehicle exhaust), cigarettes, wood, and coal. The most common source of exposure to BaP is breathing in carbon-containing particles (e.g., soot, diesel particles), but BaP can also be ingested in food grown in areas with air or soil contaminated with BaP or by eating certain food products, such as charred meats, where BaP is formed during the cooking process. People can also be exposed to BaP through the skin after coming into contact with soils or materials that contain soot, tar, or crude petroleum products or by using certain pharmaceutical products containing coal tars, such as those used to treat the skin conditions eczema and psoriasis. In other words, exposure to BaP is ubiquitous in modern life.
The long-term health effects of BaP were last assessed by the federal government in 1987. At that point, it was classified as a “probable human carcinogen”; the new assessment upgrades BaP’s cancer classification to “carcinogenic to humans” and sets a limit on the amount of BaP a human can breathe without the risk of developing cancer and other serious illnesses; it also sets a limit on the amount of BaP that can be safely ingested and, for the first time for any EPA chemical assessment, estimates the risk of cancer when human skin is exposed to the chemical.
Research Shows Links to Cancer, Developmental Damage, and Low Birth Weight
Since 1987, the scientific literature examining the health effects of BaP has grown significantly. Studies have shown that BaP is associated with cancer, as well as developmental damage and immunological effects. Epidemiology studies involving exposure to BaP have reported associations with decreased fertility, low birth weight, postnatal body weight, and smaller head circumference in children. Animal studies show exposure to BaP to be linked to a variety of cancers, including alimentary tract, liver, kidney, respiratory tract, pharynx, and skin cancers. Workers exposed to BaP over long periods have been found to have a significantly increased risk of lung cancer.
Changes in the Assessment Process
The EPA’s Integrated Risk Information System (IRIS) program provides information about the health risks associated with exposure to approximately 550 chemicals. These health assessments are based on an accumulation of high-quality scientific studies and are used to inform decisions about allowable exposure levels made by EPA, states, localities, and other nations.
Public interest organizations and industry have criticized the IRIS program for long delays in the development and modernization of its chemical risk assessments. The IRIS assessment process has undergone several revisions over the past decade, but a series of Government Accountability Office (GAO) reports – 2008, 2011, and most recently in early 2013 – point out that significant work remains to be done.
Reforms made to the IRIS process in 2009 restored control of the interagency review and discussion steps of the assessment process to EPA after the Office of Management and Budget (OMB) took it over in 2005 under the Bush administration. This change provided EPA with the ability to interact directly with other agencies to address their comments and concerns, rather than needing to operate through the filter of OMB. Those reforms also improved transparency by making other federal agency comments on chemical assessments available to the public. However, the 2013 GAO report laments the recent pace of completion of IRIS assessments, noting that only four assessments were completed in each of fiscal years 2011 and 2012.
A 2011 report by the National Research Council (NRC) of the National Academy of Sciences provided EPA with a series of recommendations for improving the IRIS process in a report on EPA’s draft assessment of formaldehyde health risks. These recommendations included: 1) shortening the IRIS assessment documents to make them more readable; 2) providing clear information on the criteria used to include studies in EPA’s review of the science; 3) describing the rationale for selecting the key studies used to develop the assessment results, as well as discussing their methodological strengths and weaknesses; and 4) improving discussion of the basis for EPA’s overall assessment of the scientific studies reviewed.
Most recently, on July 31, EPA announced several changes to improve the IRIS process. EPA will now release preliminary materials and hold a public meeting early in the assessment process to explain the criteria for selecting health science studies to include in its review and to ensure that critical research is not omitted. These changes will provide early opportunities for public input into the assessment process and will allow citizens to comment on the quality of the information used to examine each chemical assessed.
EPA is also using a new structure for IRIS assessment documents, which is supposed to make the information involved clearer, more concise, more systematic, and more accessible. The draft BaP assessment is EPA’s first IRIS report to adopt this revised document structure. We found this new format to be a significant improvement in both content and readability.
EPA’s draft revised BaP health assessment represents a significant advance in understanding the scope and severity of the health risks associated with BaP exposure. When finalized, this document will serve as an important source of information for future federal and state efforts to regulate exposure from the myriad of places and processes where this chemical is found.
Unfortunately, given the health damage from exposure to this chemical, the completion and posting of the final document is likely to extend well into 2014 or beyond. The draft assessment must undergo peer review and public comments and will then be revised by EPA and go through a final EPA internal review, review by other federal agencies, and review by the OMB’s Office of Information and Regulatory Affairs (OIRA) before its exposure limits can be enforced and it can begin to improve the health of the nation.
Comments on the draft BaP assessment may be submitted and reviewed at Regulations.gov through Oct. 21, 2013. From the site, select Environmental Protection Agency and the key word EPA-HQ-ORD-2011-0391 (for the docket ID).