Abstract  Environmental and medical surveys were conducted on December 12 and 13, 1977, and February 22 to 24, 1978, to evaluate employee exposure to chlorofluorocarbons at Allied Chemical Corporation (SIC-2869) in Danville, Illinois. The evaluation was requested by an authorized representative of the International Chemical Workers Union, Local 617, on behalf of the approximately 45 affected employees. Seven persons had at least one abnormal liver function test result and fifteen had at least one abnormal kidney function test result. Four workers had a lowered hemoglobin or hematocrit. All environmental sample chemical concentrations were below the current standards. Based on the excessive percentage of workers with abnormal results on kidney tests, the authors conclude that a health hazard does exist. A hazard also is indicated by the high rate of abnormal liver function tests in packagers and laboratory technicians. The authors recommend that the planned changes in the medical program be implemented, that the company provide annual liver function tests for all workers previously exposed to vinyl-chloride (75014), and that workers be educated about the potential hazards and toxic symptoms associated with the chemicals used in the facility.

Abstract  In response to a request from the Superintendent of the Bethlehem-Center School District, an investigation was undertaken of possible hazardous conditions due to materials used during a roofing project at the Bethlehem-Center Elementary School (SIC-8211), Fredericktown, Pennsylvania. In November, 1990 a contractor repaired and treated the tar buildup roof of the school with resaturant. Approximately 7680 gallons of the material was applied to the roof. During this period numerous children complained of headaches, nausea, burning eyes, and respiratory difficulties. Officials closed the school for 4 day. Classes then resumed until April of the following year when unusually warm weather caused another episode of a tar like odor and several students became ill. Hydrocarbon analysis in April 1991 indicated only trace amounts of carbon-tetrachloride (56235) in one of the samples. Carbon-tetrachloride was not identified in any of the other samples nor was it detected in the analysis of the bulk roof material. In June, trace levels of polynuclear aromatic hydrocarbons were found, ranging from 0.001 to 0.055mg/m3 benzene soluble fraction. Naphthalene (91203) comprised the majority of the sample, ranging from 0.001 to 0.046mg/m3. The author concludes that no specific hazard was identified at the school, but the odor had brought to light a preexisting situation where there was inadequate intake of outside air and poor circulation of existing air in the building. The author recommends that the ventilation system be improved.

Abstract  The neurotoxic effects of organic solvents are reviewed. Organic solvents have been used in extraction, dissolution or suspension of fats, waxes and resins. Studies have shown that acute neurotoxicity is similar for human and laboratory animal exposures and is characterized by narcosis, anesthesia, central nervous system depression, respiratory arrest, loss of consciousness and death. Chronic effects have been studied to a limited extent in animals and have been documented epidemiologically for workers and solvent abusers. Reported effects included peripheral neuropathy and mild toxic encephalopathy. Three severity levels were defined for chronic human exposures: minimal, organic affective syndrome; moderate, mild, chronic toxic encephalopathy; and pronounced, severe, chronic toxic encephalopathy. Neurophysiological effects (electromyogram or electroencephalogram abnormalities, decreased nerve conduction velocities) have also been reported in exposed workers. Neurobehavioral effects such as reversible subjective symptoms, prolonged personality or mood changes and intellectual impairment have been studied epidemiologically and in volunteers. Severe exposure has produced irreversible impairment of intellect and memory (dementia) and structural central nervous system damage. Metabolic aspects of organic solvent exposure were discussed. Guidelines for minimizing worker exposure are discussed in relation to exposure monitoring; control of exposure through contaminant control, worker isolation, use of personal protective equipment and worker education; and medical surveillance. A table containing a summary of NIOSH recommended exposure limits for organic solvents is presented. Examples of solvents neurotoxic to humans discussed include carbon-disulfide (75150), n-hexane (110543), methyl-n-butyl-ketone (591786), trichloroethylene (79016), perchloroethylene (127184) and toluene (108883)

Abstract  The ATSDR toxicological profile succinctly characterizes the toxicologic and adverse health effects information for the hazardous substance described here. Each peer-reviewed profile identifies and reviews the key literature that describes a hazardous substance's toxicologic properties. Other pertinent literature is also presented, but is described in less detail than the key studies.

Abstract  Narrative The Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) [42 U.S.C. 9604 et seq.], as amended by the Superfund Amendments and Reauthorization Act (SARA) [Pub. L. 99 499], requires that the Agency for Toxic Substances and Disease Registry (ATSDR) develop jointly with the U.S. Environmental Protection Agency (EPA), in order of priority, a list of hazardous substances most commonly found at facilities on the CERCLA National Priorities List (NPL) (42 U.S.C. 9604(i)(2)); prepare toxicological profiles for each substance included on the priority list of hazardous substances, and to ascertain significant human exposure levels (SHELs) for hazardous substances in the environment, and the associated acute, subacute, and chronic health effects (42 U.S.C. 9604(i)(3)); and assure the initiation of a research program to fill identified data needs associated with the substances (42 U.S.C. 9604(i)(5)). The ATSDR Minimal Risk Levels (MRLs) were developed as an initial response to the mandate. Following discussions with scientists within the Department of Health and Human Services (HHS) and the EPA, ATSDR chose to adopt a practice similar to that of the EPA's Reference Dose (RfD) and Reference Concentration (RfC) for deriving substance specific health guidance levels for non-neoplastic endpoints. An MRL is an estimate of the daily human exposure to a hazardous substance that is likely to be without appreciable risk of adverse non-cancer health effects over a specified duration of exposure. These substance specific estimates, which are intended to serve as screening levels, are used by ATSDR health assessors and other responders to identify contaminants and potential health effects that may be of concern at hazardous waste sites. It is important to note that MRLs are not intended to define clean up or action levels for ATSDR or other Agencies. The toxicological profiles include an examination, summary, and interpretation of available toxicological information and epidemiologic evaluations of a hazardous substance. During the development of toxicological profiles, MRLs are derived when ATSDR determines that reliable and sufficient data exist to identify the target organ(s) of effect or the most sensitive health effect(s) for a specific duration for a given route of exposure to the substance. MRLs are based on non-cancer health effects only and are not based on a consideration of cancer effects. Inhalation MRLs are exposure concentrations expressed in units of parts per million (ppm) for gases and volatiles, or milligrams per cubic meter (mg/m3) for particles. Oral MRLs are expressed as daily human doses in units of milligrams per kilogram per day (mg/kg/day). Radiation MRLs are expressed as external exposures in units of millisieverts. ATSDR uses the no observed adverse effect level/uncertainty factor (NOAEL/UF) approach to derive MRLs for hazardous substances. They are set below levels that, based on current information, might cause adverse health effects in the people most sensitive to such substance-induced effects. MRLs are derived for acute (1 14 days), intermediate (>14 364 days), and chronic (365 days and longer) exposure durations, and for the oral and inhalation routes of exposure. Currently MRLs for the dermal route of exposure are not derived because ATSDR has not yet identified a method suitable for this route of exposure. MRLs are generally based on the most sensitive substance-induced end point considered to be of relevance to humans. ATSDR does not use serious health effects (such as irreparable damage to the liver or kidneys, or birth defects) as a basis for establishing MRLs. Exposure to a level above the MRL does not mean that adverse health effects will occur. MRLs are intended to serve as a screening tool to help public health professionals decide where to look more closely. They may also be viewed as a mechanism to identify those hazardous waste sites that are not expected to cause adverse health effects. Most MRLs contain some degree of uncertainty because of the lack of precise toxicological information on the people who might be most sensitive (e.g., infants, elderly, and nutritionally or immunologically compromised) to effects of hazardous substances. ATSDR uses a conservative (i.e., protective) approach to address these uncertainties consistent with the public health principle of prevention. Although human data are preferred, MRLs often must be based on animal studies because relevant human studies are lacking. In the absence of evidence to the contrary, ATSDR assumes that humans are more sensitive than animals to the effects of hazardous substances that certain persons may be particularly sensitive. Thus the resulting MRL may be as much as a hundredfold below levels shown to be nontoxic in laboratory animals. When adequate information is available, physiologically based pharmacokinetic (PBPK) modeling and benchmark dose (BMD) modeling have also been used as an adjunct to the NOAEL/UF approach in deriving MRLs. Proposed MRLs undergo a rigorous review process. They are reviewed by the Health Effects/MRL Workgroup within the Division of Toxicology and Human Health Sciences; an expert panel of external peer reviewers; the agency wide MRL Workgroup, with participation from other federal agencies, including EPA; and are submitted for public comment through the toxicological profile public comment period. Each MRL is subject to change as new information becomes available concomitant with updating the toxicological profile of the substance. MRLs in the most recent toxicological profiles supersede previously published levels. To date, 158 inhalation MRLs, 279 oral MRLs and 8 external radiation MRLs have been derived. A listing of the current published MRLs by route and duration of exposure is provided as follows.