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  Water and streambed-sediment samples were collected on March 9 and 10,1987 from one site upstream and three sites downstream of the discharge from a municipal wastewater-treatment plant on Rowlett Creek near Dallas, Texas. To extract and separate organic compounds, purgeand-trap, closed-loop stripping, and pH-adjusted solvent extraction methods were used for water samples; and a Soxhlet-solvent extraction method was used for streambed sediment. These methods were combined with gas chromatography/mass spectrometry to identify organic compounds in Rowlett Creek. Results from this study confirm the persistence of many organic compounds in water as far as 13.5 kilometers downstream of the wastewater discharge. These include: (1) the volatile organic compounds chloroform, 1,2-dichlorobenzene, 1,4-dichlorobenzene, tetrachloroethene, and trichloroethene; (2) several linear alkylbenzene compounds, octyl phenol, and a tetramethylbutyl phenol isomer that are related to detergent use; (3) 9-phenyl-9H-carbazole, a compound related to coal tars and coal combustion residues; and (4) caffeine. The only compound present in water in concentrations greater than U.S. Environmental Protection Agency maximum contaminant levels for drinking water was tetrachloroethene (6.0 micrograms per liter) in a sample collected 13.5 kilometers downstream from the waste water discharge. Compounds identified from the streambed-sediment samples include a xylene isomer at 7.7 kilometers downstream and chrysene, fluoranthene, pyrene, and a xylene isomer at 13.5 kilometers downstream from the wastewater discharge. Comparison of instantaneous flux values of selected organic compounds in water from downstream sites indicates: (1) the formation of chloroform in the stream following the discharge of the treated effluent, and that (2) instream biodegradation may be decreasing concentrations of linear alkylbenzene compounds in water. The relative persistence of many of the selected organic compounds in Rowlett Creek downstream from the municipal wastewater-treatment plant indicates that they could be transported into Lake Ray Hubbard, a source of municipal water supply.