Abstract  This draft risk evaluation for methylene chloride was performed in accordance with the Frank R. Lautenberg Chemical Safety for the 21st Century Act and is being disseminated for public comment and peer review. The Frank R. Lautenberg Chemical Safety for the 21st Century Act amended the Toxic Substances Control Act (TSCA), the Nation’s primary chemicals management law, in June 2016. As per EPA’s final rule, Procedures for Chemical Risk Evaluation Under the Amended Toxic Substances Control Act (82 FR 33726), EPA is taking comment on this draft, and will also obtain peer review on this draft risk evaluation for methylene chloride. All conclusions, findings, and determinations in this document are preliminary and subject to comment. The final risk evaluation may change in response to public comments received on the draft risk evaluation and/or in response to peer review, which itself may be informed by public comments. The preliminary conclusions, findings, and determinations in this draft risk evaluation are for the purpose of identifying whether the chemical substance presents unreasonable risk or no unreasonable risk under the conditions of use, in accordance with TSCA section 6, and are not intended to represent any findings under TSCA section 7.

Abstract  The analysis of the water quality response of a stream receiving intermittent storm runoff is addressed within a probabilistic framework. Lognormally distributed runoff and stream flows and concentrations are assumed and cross correlations are explicitly included in the exact solution method. An approximate moment method is suggested which is suitable for rapid screening analyses. Both solutions can be used to provide a first level of analysis before embarking upon detailed time variable or Monte Carlo simulations.

Abstract  We report the results of the first prospective, multicenter study of acute carbon monoxide (CO) poisoning in pregnancy. We collected and followed cases of CO poisoning occurring during pregnancy between December 1985 and March 1989. The sources of CO were malfunctioning furnaces (n = 16), hot water heaters (n = 7), car fumes (n = 6), and methylene chloride inhalation (n = 3). Pregnancy outcome was adversely affected in 3 of 5 pregnancies with severe toxicity; two stillbirths, and one cerebral palsy with tomographic findings consistent with ischemic damage. All adverse outcome occurred in cases treated with high flow oxygen, whereas the 2 cases of severe toxicity with normal outcomes followed hyperbaric oxygen therapy. All 31 babies exposed in utero to mild or moderate CO poisoning exhibited normal physical and neurobehavioral development. Severe maternal CO toxicity was associated with significantly more adverse fetal cases when compared to mild maternal toxicity (P less than 0.001). It is concluded that while severe CO poisoning poses serious short- and long-term fetal risk, mild accidental exposure is likely to result in normal fetal outcome. Because fetal accumulation of CO is higher and its elimination slower than in the maternal circulation, hyperbaric oxygen may decrease fetal hypoxia and improve outcome.

Abstract  This review article aims to anatomize sources of the healthy worker effect (HWE) and to summarize advantages and limitations of several approaches frequently proposed to eliminate the HWE. Although the HWE is frequently addressed in the context of selection bias, our review suggests that the selection of occupational cohorts with advantageous health status would preferably be addressed as a source of confounding biases. The authors also conclude that the exclusion of unhealthy workers at employment and the study of active workers are the two main sources of HWE, and that the use of the general population as a comparison group in occupational epidemiology should be avoided if possible. The authors encourage investigators to make distinctions between the underlying factors related to the use of the general population as the comparison group in occupational epidemiology

Abstract  These guidelines revise and replace the U.S. Environmental Protection Agency’s (EPA’s, or the Agency’s) Guidelines for Carcinogen Risk Assessment, published in 51 FR 33992, September 24, 1986 (U.S. EPA, 1986a) and the 1999 interim final guidelines (U.S. EPA, 1999a; see U.S. EPA 2001b). They provide EPA staff with guidance for developing and using risk assessments. They also provide basic information to the public about the Agency's risk assessment methods.