Industry Eyes Data Quality Challenge Of EPA Formaldehyde Risk Analysis
Posted: September 14, 2010
Industry is harshly criticizing EPA's strict draft risk assessment of formaldehyde, arguing that the risk estimates in the assessment are too conservative and raising the possibility of a future Data Quality Act (DQA) challenge if EPA does not substantially revise the assessment.
Comments filed with EPA by several trade associations, including the American Chemistry Council (ACC), American Forest & Paper Association (AFPA), American Petroleum Institute and others, question the assessment's compliance with the DQA and raise other issues about the document.
"EPA has failed to comport with the explicit [DQA] Guidelines as well as EPA Cancer Guidelines," according to ACC's Aug. 31 comments. An ACC source tells Risk Policy Report that while the association has not filed a DQA challenge regarding the assessment, raising the issue in public comments preserves the opportunity to do so at a later time.
The AFPA and other groups in their comments, further say the draft assessment falls "far short of meeting the Office Management and Budget's [DQA] guidelines as well as the agency's own specific guidelines. Among some of the serious deficiencies of the current draft assessment is its failure to consider the best available science, failure to use a sound weight-of-the evidence approach, and a lack of transparency and objectivity." Comments from the Methanol Institute and the American Coatings Association (ACA) raise similar concerns.
The questions come as industry is ramping up DQA challenges to EPA risk analysis and other risk-based decisions at the agency. For example, the ACC filed a petition questioning EPA's action plans for the plastic chemicals bisphenol-A and phthalate esters, the Methanol Institute filed a petition over the agency's assessment of methanol's risks, industry groups filed a petition questioning the agency's arsenic assessment and the ACA filed a petition regarding EPA's lead public service announcements.
The industry comments on the formaldehyde assessment reiterate questions also raised by other agencies, including the Agency for Toxic Substances & Disease Registry (ATSDR), Defense Department and National Aeronautics & Space Administration. The groups question the strength of the epidemiological evidence that EPA bases its cancer findings and cancer potency estimate on, as well as the agency's hypothesis for how formaldehyde can cause leukemia. The groups also question the inclusion of a new epidemiological study, known as the Zhang study, which EPA relied on in deciding that formaldehyde is a human carcinogen. The International Agency for Research on Cancer and a panel of expert advisers to the National Toxicology Program also used the study in similar decisions about carcinogenicity.
The industry comments also criticize EPA's inclusion of a mutagenic mode of action in the assessment, which requires the agency to use a strict, linear estimate of low-dose effects. The groups argue that the use of the conservative assessment practice results in an assessment that is unrealistic and risk standards that cannot be met because levels of formaldehyde in human breath exceed them.
The American Petroleum Institute (API) in Aug. 31 comments notes that EPA's inhalation unit risk factor, or estimate of cancer potency, is 0.13 parts per million (ppm), corresponding to an exposure criterion of 7.7 parts per trillion (ppt).
"Based on current levels of formaldehyde that humans are exposed to via inhalation of ambient, indoor, and work room air, the cancer risks estimated using EPA's draft unit risk factor are not plausible or realistic," according to the comments. "This brings into question the utility and technological feasibility of achieving an exposure criterion of 7.7 ppt for formaldehyde. EPA's cancer risk estimates are also not plausible if one considers the normal levels of formaldehyde present in human tissues."
'Typical Range' Indoors
API quotes studies indicating "overall" outdoor levels of formaldehyde ranging between 0.56 and 36.31 parts per billion (ppb) and a "typical range" of formaldehyde in houses in the United States of 11 and 285 ppb. "EPA's draft value of 7.7 ppt is 4,000-fold lower than the mean indoor level and 37,000-fold lower than peak indoor levels. EPA's cancer risk assessment is based on the assumption that a single peak formaldehyde exposure any time during one's lifetime can cause leukemia. Therefore, using the peak indoor exposure is a relevant comparison," according to API's comments.
Other comments quote a 2007 National Academy of Sciences report statistic that exhaled human breath contains 2 ppb formaldehyde.
Several of the industry groups also quote a study published last month in Toxicological Sciences by Lu et al, which compares endogenous and exogenous amounts of formaldehyde in the blood of rats exposed to the chemical. The study "casts serious questions as the biological plausibility of EPA's proposed" biological means of how the chemical could cause leukemia, according to API.
Both API and AFPA also raise concerns about EPA's non-cancer risk estimate, the reference concentration, or the amount of formaldehyde the agency considers safe to breathe on a daily basis over a lifetime. The groups question EPA's decision to use studies of occupants of mobile homes, rather than studies of human volunteers exposed to formaldehyde in chambers. The latter are more robust, the organizations argue.
"Chamber studies preclude confounding exposures, reduce or eliminate false positives, and provide for accurate measure of exposure, in addition to other study advantages," according to AFPA's Aug. 31 comments. "EPA's reasons for rejecting controlled chamber studies are without sound scientific merit, and need to be reexamined."
ACC urges EPA to consider the 0.3 ppm standard as "conservative and protective against sensory irritation" that it says authoritative international agencies have adopted, including the Organization for Economic Cooperation and Development, National Academy of Sciences, ATSDR, and World Health Organization, among others. -- Maria Hegstad