Review Of The Environmental Protection Agency S Draft Iris Assessment Of Tetrachloroethylene

Tetrachloroethylene is a volatile, chlorinated organic hydrocarbon that is widely used as a solvent in the dry-cleaning and textile-processing industries and as an agent for degreasing metal parts. It is an environmental contaminant that has been detected in the air, groundwater, surface waters, and soil. In June 2008, the U.S. Environmental Protection Agency released its draft Toxicological Review of Tetrachloroethylene (Perchloroethylene) (CAS No. 127-18-4) in Support of Summary Information on the Integrated Risk Information System (IRIS). The draft IRIS assessment provides quantitative estimates of cancer and noncancer effects of exposure to tetrachloreothylene, which will be used to establish airquality and water-quality standards to protect public health and to set cleanup standards for hazardous waste sites. At the request of EPA, the National Research Council conducted an independent scientific review of the draft IRIS assessment of tetrachloroethylene from toxicologic, epidemiologic, and human clinical perspectives. The resulting book evaluates the adequacy of the EPA assessment, the data and methods used for deriving the noncancer values for inhalation and oral exposures and the oral and inhalation cancer unit risks posed by tetrachloroethylene; evaluates whether the key studies underlying the draft IRIS assessment are of requisite quality, reliability, and relevance to support the derivation of the reference values and cancer risks; evaluates whether the uncertainties in EPA's risk assessment were adequately described and, where possible, quantified; and identifies research that could reduce the uncertainty in the current understanding of human health effects associated with tetrachloroethylene exposure.

Formaldehyde is ubiquitous in indoor and outdoor air, and everyone is exposed to formaldehyde at some concentration daily. Formaldehyde is used to produce a wide array of products, particularly building materials; it is emitted from many sources, including power plants, cars, gas and wood stoves, and cigarettes; it is a natural product in come foods; and it is naturally present in the human body as a metabolic intermediate. Much research has been conducted on the health effects of exposure to formaldehyde, including effects on the upper airway, where formaldehyde is deposited when inhaled, and effects on tissues distant from the site of initial contact. The U.S. Environmental Protection Agency (EPA) released noncancer and cancer assessments of formaldehyde for its Intergated Risk Information System (IRIS) in 1990 and 1991, respectively. The agency began reassessing formaldehyde in 1998 and released a draft IRIS assessment in June 2010. Given the complexity of the issues and the knowledge that the assessment will be used as the basis of regulatory decisions, EPA asked the National Research Council (NRC) to conduct an independent scientific review of the draft IRIS assessment. In this report, the Committee to Review EPA's Draft IRIS Assessment of Formaldehyde first addresses some general issues associated with the draft IRIS assessment. The committee next focuses on questions concerning specific aspects of the draft assessment, including derivation of the reference concentrations and the cancer unit risk estimates for formaldehyde. The committee closes with recommendations for improving the IRIS assessment of formaldehyde and provides some general comments on the IRIS development process.

The Integrated Risk Information System (IRIS) is a program within the US Environmental Protection Agency (EPA) that is responsible for developing toxicologic assessments of environmental contaminants. An IRIS assessment contains hazard identifications and dose-response assessments of various chemicals related to cancer and noncancer outcomes. Although the program was created to increase consistency among toxicologic assessments within the agency, federal, state, and international agencies and other organizations have come to rely on IRIS assessments for setting regulatory standards, establishing exposure guidelines, and estimating risks to exposed populations. Over the last decade, the National Research Council (NRC) has been asked to review some of the more complex and challenging IRIS assessments, including those of formaldehyde, dioxin, and tetrachloroethylene. In 2011, an NRC committee released its review of the IRIS formaldehyde assessment. Like other NRC committees that had reviewed IRIS assessments, the formaldehyde committee identified deficiencies in the specific assessment and more broadly in some of EPA's general approaches and specific methods. Although the committee focused on evaluating the IRIS formaldehyde assessment, it provided suggestions for improving the IRIS process and a roadmap for its revision in case EPA decided to move forward with changes to the process. Congress directed EPA to implement the report's recommendations and then asked the National Research Council to review the changes that EPA was making (or proposing to make) in response to the recommendations. Review of EPA's Integrated Risk Information System (IRIS) Process provides an overview of some general issues associated with IRIS assessments. This report then addresses evidence identification and evaluation for IRIS assessments and discusses evidence integration for hazard evaluation and methods for calculating reference values and unit risks. The report makes recommendations and considerations for future directions. Overall, Review of EPA's Integrated Risk Information System Process finds that substantial improvements in the IRIS process have been made, and it is clear that EPA has embraced and is acting on the recommendations in the NRC formaldehyde report. The recommendations of this report should be seen as building on the progress that EPA has already made.

Tetrachloroethylene is a volatile, chlorinated organic hydrocarbon that is widely used as a solvent in the dry-cleaning and textile-processing industries and as an agent for degreasing metal parts. It is an environmental contaminant that has been detected in the air, groundwater, surface waters, and soil. In June 2008, the U.S. Environmental Protection Agency released its draft Toxicological Review of Tetrachloroethylene (Perchloroethylene) (CAS No. 127-18-4) in Support of Summary Information on the Integrated Risk Information System (IRIS). The draft IRIS assessment provides quantitative estimates of cancer and noncancer effects of exposure to tetrachloreothylene, which will be used to establish airquality and water-quality standards to protect public health and to set cleanup standards for hazardous waste sites. At the request of EPA, the National Research Council conducted an independent scientific review of the draft IRIS assessment of tetrachloroethylene from toxicologic, epidemiologic, and human clinical perspectives. The resulting book evaluates the adequacy of the EPA assessment, the data and methods used for deriving the noncancer values for inhalation and oral exposures and the oral and inhalation cancer unit risks posed by tetrachloroethylene; evaluates whether the key studies underlying the draft IRIS assessment are of requisite quality, reliability, and relevance to support the derivation of the reference values and cancer risks; evaluates whether the uncertainties in EPA's risk assessment were adequately described and, where possible, quantified; and identifies research that could reduce the uncertainty in the current understanding of human health effects associated with tetrachloroethylene exposure.

Formaldehyde is ubiquitous in indoor and outdoor air, and everyone is exposed to formaldehyde at some concentration daily. Formaldehyde is used to produce a wide array of products, particularly building materials; it is emitted from many sources, including power plants, cars, gas and wood stoves, and cigarettes; it is a natural product in come foods; and it is naturally present in the human body as a metabolic intermediate. Much research has been conducted on the health effects of exposure to formaldehyde, including effects on the upper airway, where formaldehyde is deposited when inhaled, and effects on tissues distant from the site of initial contact. The U.S. Environmental Protection Agency (EPA) released noncancer and cancer assessments of formaldehyde for its Intergated Risk Information System (IRIS) in 1990 and 1991, respectively. The agency began reassessing formaldehyde in 1998 and released a draft IRIS assessment in June 2010. Given the complexity of the issues and the knowledge that the assessment will be used as the basis of regulatory decisions, EPA asked the National Research Council (NRC) to conduct an independent scientific review of the draft IRIS assessment. In this report, the Committee to Review EPA's Draft IRIS Assessment of Formaldehyde first addresses some general issues associated with the draft IRIS assessment. The committee next focuses on questions concerning specific aspects of the draft assessment, including derivation of the reference concentrations and the cancer unit risk estimates for formaldehyde. The committee closes with recommendations for improving the IRIS assessment of formaldehyde and provides some general comments on the IRIS development process.

Formaldehyde is widely present in the environment and is one of the highest production chemicals by volume, used in manufactured goods including wood products, permanent press fabrics, and household products. It is also formed by combustion sources and is present in smoke from cigarettes and other tobacco products, and in emissions from gas stoves and open fireplaces. In carrying out its mission to protect human health, the U.S. Environmental Protection Agency (EPA) identifies and characterizes the health hazards of chemicals found in the environment through its Integrated Risk Information System (IRIS) Program, which has reviewed the human health hazards resulting from formaldehyde exposure in several assessments. This report is a continuation of guidance from the National Academies on draft IRIS assessments of formaldehyde and other aspects of the IRIS program. This report reviews the 2022 Draft Assessment with regard to its adequacy and transparency in evaluating the scientific literature, use of appropriate methods to synthesize the current state-of-the science, and presentations of conclusions that are supported by the scientific evidence. The report concludes that the 2022 Draft Assessment follows the advice of prior National Academies reports and that its findings on hazard and quantitative risk are supported by the evidence identified. However, revisions are needed to ensure that users can find and follow the methods used in each step of the assessment for each health outcome.

Over the past several years, the US Environmental Protection Agency (EPA) has been transforming the procedures of its Integrated Risk Information System (IRIS), a program that produces hazard and doseâ€'response assessments of environmental chemicals and derives toxicity values that can be used to estimate risks posed by exposures to them. The transformation was initiated after suggestions for program reforms were provided in a 2011 report from the National Academies of Sciences, Engineering, and Medicine that reviewed a draft IRIS assessment of formaldehyde. In 2014, the National Academies released a report that reviewed the IRIS program and evaluated the changes implemented in it since the 2011 report. Since 2014, new leadership of EPA's National Center for Environmental Assessment (NCEA) and IRIS program has instituted even more substantive changes in the IRIS program in response to the recommendations in the 2014 report. Progress Toward Transforming the Integrated Risk Information System Program: A 2018 Evaluation reviews the EPA's progress toward addressing the past recommendations from the National Academies.

Potential health effects from chemicals that disrupt endocrine function pose an environmental health concern because of their ability to interfere with normal hormone function in human and wildlife populations. The endocrine system regulates biological processes throughout the body and is sensitive to small changes in hormone concentrations. Endocrine-disruptor research has focused primarily on chemicals that affect three hormone pathways that play important roles in reproduction and development - the estrogen, androgen, and thyroid hormone pathways. Some of this research has identified dose-response relationships that have nonmonotonic curves. Nonmonotonic dose-response curves (NMDRs) are of concern because they do not follow the usual assumption made in toxicology that as dose decreases the response also decreases. The existence of NMDRs has been a controversial topic for decades, and there has been considerable debate about their implications for how chemicals are tested and for how risks from such chemicals are assessed. Toxicity tests are designed to identify hazards and to characterize dose-response relationships, so tests are aimed at finding a (high) dose that elicits a response, and dose-response is explored by testing lower doses spaced to identify statistically a no- or lowest-observed-adverse-effect level. The concern for NMDRs is that such studies, as currently designed, might not detect the inflection of the dose-response curve if only a few doses are tested or if the change in inflection occurs below the range of doses tested. Another concern is that some NMDRs are found for biological effects that are not usually evaluated in toxicity tests. If current testing strategies are inadequate to account for NMDRs, changes to risk assessment practices might be necessary. To help address these issues, the U.S. Environmental Protection Agency (EPA) developed a draft State-of-the-Science Evaluation: Nonmonotonic Dose Responses as they Apply to Estrogen, Androgen, and Thyroid Pathways and EPA Testing and Assessment Procedures. EPA asked the National Research Council to conduct an independent review of this evaluation to ensure that it is scientifically sound and of high quality. Review of Environmental Protection Agency's State-of-the-Science Evaluation of Nonmonotonic Dose-Response as they Apply to Endocrine Disrupters evaluates whether EPA's evaluation presents a scientifically sound and high-quality analysis of the literature on NMDRs. This report reviews how well the EPA evaluation described how the assessment was performed, whether consistent methods and criteria were applied in the analysis of different evidence streams, and whether appropriate methods were applied to evaluating the evidence. The report makes recommendations to improve EPA's process and strengthen the evaluation.