Abstract  The industrial and commercial uses of carbon-tetrachloride (56235) and the methods of commercial preparation of the compound are described, with data from experiments in which human beings are exposed to the compound and physiological effects are measured. The modes of absorption are inhalation, alimentary system absorption from medicinal doses of the compound, and absorption by the skin and appendages especially during hair shampooing. Effects include headache, nervousness, loss of weight, jaundice, liver necrosis, visual disturbances, coma and death. Methods of prevention and treatment of poisoning by carbon-tetrachloride are described.

Abstract  This report, entitled, A Review of the Reference Dose and Reference Concentration Processes, summarizes the review and deliberations of the Risk Assessment Forum's RfD/RfC Technical Panel and its recommendations for improvements in the process of deriving reference values, including setting less than lifetime as well as chronic reference values. It discusses revisions to the overall framework for the derivation of reference values that broaden and expand the information considered in setting reference values. The document is a review, not guidance, and it evaluates the state-of-the-art for hazard characterization with a focus on protection of potentially sensitive subpopulations. The report makes a number of recommendations that should be considered in the implementation of changes in the current process and/or development of needed guidance. The Technical Panel views the RfD/RfC process as one that should be continually evolving as new information becomes available and as new scientific and risk assessment approaches are developed. This does not mean that current RfDs or RfCs are invalid, but these new scientific issues should be included in the process of re-evaluating current reference values. As a follow-up to the recommendation for deriving less-than-lifetime reference values, the report includes a review of current testing guideline protocols to determine what data are collected that could be used in setting these reference values. The Technical Panel has provided specific recommendations for deriving reference values and the development of guidance in some cases and more general conclusions and recommendations in others. Case studies are included to illustrate the recommendations of the Technical Panel.

Abstract  This report presents the re-evaluation of the raw data of previously published acute inhalation toxicity studies of some volatile industrial chemicals. In these studies both concentration and exposure time were varied. The raw data were obtained from an extensive literature search and were subjected to probit analysis. The results show that the product of concentration and exposure time (ct) is not always a good parameter for predicting the mortality response (Haber's rule). On the contrary, the term cnt, in which the exponent n is different from 1, often predicts the response very well.

Abstract  Extremely hazardous substances can be released accidentally as a result of chemical spills, industrial explosions, fires, or accidents involving railroad cars and trucks transporting EHSs. Workers and residents in communities surrounding industrial facilities where these substances are manufactured, used, or stored and in communities along the nation's railways and highways are potentially at risk of being exposed to airborne EHSs during accidental releases or intentional releases by terrorists. Pursuant to the Superfund Amendments and Reauthorization Act of 1986, the U.S. Environmental Protection Agency (EPA) has identified approximately 400 EHSs on the basis of acute lethality data in rodents. Acute Exposure Guideline Levels for Selected Airborne Chemicals, Volume 17 identifies, reviews, and interprets relevant toxicologic and other scientific data for selected AEGL documents for acrylonitrile, carbon tetrachloride, cyanogen, epichlorohydrin, ethylene chlorohydrin, toluene, trimethylacetyl chloride, hydrogen bromide, and boron tribromide in order to develop acute exposure guideline levels (AEGLs) for these high-priority, acutely toxic chemicals. AEGLs represent threshold exposure limits (exposure levels below which adverse health effects are not likely to occur) for the general public and are applicable to emergency exposures ranging from 10 minutes (min) to 8 h. Three levels - AEGL-1, AEGL-2, and AEGL-3 - are developed for each of five exposure periods (10 min, 30 min, 1 h, 4 h, and 8 h) and are distinguished by varying degrees of severity of toxic effects. This report will inform planning, response, and prevention in the community, the workplace, transportation, the military, and the remediation of Superfund sites.

Abstract  This document presents the scope of the risk evaluation to be conducted for carbon tetrachloride. If a hazard, exposure, condition of use or potentially exposed or susceptible subpopulation has not been discussed, EPA, at this point in time, is not intending to include it in the scope of the risk evaluation. As per the rulemaking, Procedures for Chemical Risk Evaluation Under the Amended Toxic Substances Control Act (TSCA), with respect to conditions of use in conducting a risk evaluation under TSCA, EPA will first identify “circumstances” that constitute “conditions of use” for each chemical. While EPA interprets this as largely a factual determination—i.e., EPA is to determine whether a chemical substance is actually involved in one or more of the activities listed in the definition—the determination will inevitably involve the exercise of some discretion.