Air sampling and analysis in a rubber vulcanization area

Results of sampling and analysis of air in a rubber vulcanization area are described. Organic compounds were collected on activated charcoal, desorbed with carbon disulfide and analyzed by gas chromatography. Several previously identified substances were quantitated, including styrene, toluene, ethylbenzene, and several oligomers of 1,3-butadiene. Concentrations ranged from 0.007 to 1.1 ppm.

Aspects of the toxicology of chloroprene: immediate and long-term effects

The maximum permissible concentration (MPC) of chloroprene was set at 2 mg/m3 in the USSR in the 1940's. The existing MPC is 4 mg/m3. The threshold of systemic effects as a result of chronic chloroprene exposure is l.69 mg/m3. However, the threshold for embryotoxic and mutagenic effects is 0.15 mg/m3. In consideration of this information, setting a new MPC for chloroprene at 0.05 mg/m3 is recommended.

Hepato- and cardiotoxicity of xanthoascin, a new metabolite of A. candidus Link, to mice. I. Blood chemistry and histological changes in mice

Aspergillus candidus Link, one of the commonest constituents of cereal mycoflora, produces two kinds of mycotoxins, terphenyllin and xanthoascin, which show different chemical and toxicological properties. The latter, xanthoascin, caused severe hepatic injury with jaundice and focal or confluent necrosis of hepatocytes, when given to mice in doses of 6 mg/kg b.w. or higher by a single subcutaneous injection. With higher doses above 15 mg/kg, myocardial degeneration and necrosis was induced after a week or two in addition to the hepatic injury. Vacuolation of the nuclei of the alveolar interstitial cells of the lung and myocardial interstitial cells was another characteristic lesion caused by this mycotoxin. Other organs including the testicles and thymus were widely involved. The unique nature of lesions in the liver and heart may necessitate further investigations in the field of mycotoxicology in relation to human diseases such as nutritional hepatitis and primary myocardial degeneration.

Measurement of some potentially hazardous materials in the atmosphere of rubber factories

Two separate topics of work are outlined: methods for the measurement of chlorinated monomers in PVC and polychloroprene, and also methods for the measurement of these materials in factory air. Typical results which have been obtained in supplies of raw materials, in finished products, and in the working atmosphere at manufacturing operations are given. The second topic concerns the measurement of benzo[a]pyrene in the atmosphere of a tire manufacturing plant. This material is present in trace quantities in the mineral oils and carbon blacks used by the industry. The atmospheric concentrations present at various processes in this plant were measured on a daily basis over a period of two years, and the results obtained compared with results taken concurrently from an outside air station. It is shown that no significant quantities of benzo[a]pyrene are produced by tire manufacturing operations.

Determination of hexachloro-1,3-butadiene in spinach, eggs, fish, and milk by electron capture gas-liquid chromatography

Hexachloro-1,3-butadiene (HCBD), a waste product formed in the manufacture of perchloroethylene and trichloroethylene, has been found in fish from the lower Mississippi River basin. The AOAC official method for organochlorine pesticide residues in fatty and nonfatty foods has been modified for the determination of HCBD residues in selected food commodities. Acetonitrile extracts of nonfatty foods, or the combined acetonitrile extracts obtained in acetonitrile-petroleum ether partitioning of fat isolated from fatty foods, are diluted with water and extracted with petroleum ether. The petroleum ether extracts are chromatographed on Florisil and HCBD is eluted with petroleum ether. The elute is analyzed by gas-liquid chromatography with an electron capture detector. Average recoveries of HCBD from fortified samples of fatty and nonfatty foods were greater than 90% in the interlaboratory trials of the method.

Toxicological studies of photosensitizer agents and photodegradable polyolefins

The authors report the results of a series of toxicological tests conducted on plastic materials (polyethylene) activated with tetraphenylbutadiene (TPB) an additive recently proposed as a sensitizer capable of photodegrading plastic materials. The toxic effects of polyethylene, TPB, and TPB's degradation products were investigated in rabbits, mice and rats. The studies revealed these products to possess a very low toxicity.

Biochemical toxicology of unsaturated halogenated monomers

Previous inhalation toxicity studies from our laboratory have shown that 1,1-dichloroethylene (1,1-DCE), 1,1-dibromoethylene (1,1-DBE), and 2-chloro-1,3,-butadiene (2-CBD) are more toxic to fasted rats than to fed rats. Vinyl chloride monomer (VCM) and 1,1-difluoroethylene (1,1-DFE) were not acutely hepatotoxic at 46,500 and 82,000 ppm, respectively, in normal male rats, whether fed or fasted. On a molar basis, 1,1-DBE and 1,1-DCE have similar toxicities while 2-CBD is less toxic. All three compounds produce similar elevation of serum transaminase and bloody ascites, although at differing times following differing exposure concentrations. 1,1-DCE produces massive midzonal hepatic necrosis with hepatic thrombosis and chromatolysis within 2 hr after a 4 hr exposure of fasted rats to 200 ppm. Subsequent to formation of this midzonal lesion, the central portion of the lobule collapses, accompanied by congestion, ascites, and in increased hematocrit in the rat. Serum transaminase and sorbital dehydrogenase are greatly elevated at 6 hr. This effect in fasted rats is associated with glutathione (GSH) depletion. Diethyl maleate (DEM) which depletes GSH in fed rats potentiates the injury associated with 1,1-DCE exposure as well as that produced by 2-CBD. Rats fed ad libitum and exposed to 1,1-DCE or 2-CBD at night, a time of low hepatic GSH concentration, exhibit enhancement of hepatotoxic response when compared to animals exposed during the day when GSH is high.

Thermal oxidative decomposition studies of neoprene compositions

Four neoprene compositions--uncured gum, known cured rubber, cable insulation, and hose conduit, the latter two used in underground mining--were subjected to thermal oxidative degradation under static and dynamic environments, and the volatile products were quantitated on a milligrams-per-gram basis. In a quiescent system at 370 degrees C, no glow was observed, the extent of oxidation was low, up to 84% of the chlorine content was evolved as hydrogen chloride, and the sulfur present was released largely in the form of carbon disulfide. Under more drastic conditions (higher temperatures and flowing air), glow occurred in several instances resulting in an increased production oxidation products as represented by CO2, COS, SO2, HCOOH, and CH3COOH, among others. Thermogravimetric investigations of the neoprene compositions show the first weight loss to correlate closely with hydrogen chloride evolution; furthermore, the use of thermogravimetric curves as means of meterial differentiation appears to offer a definite promise.

Short-term inhalation toxicity of halogenated hydrocarbons: effects on fasting rats

Male rats, fasted overnight (18 hours), and exposed to various materials in inhalation were more sensitive to the hepatotoxic effects of carbon tetrachloride, 2-chlorobutadiene, 1,1-dibromoethylene, and 1,1-dichloroethylene (DCE). Vinyl chloride monomer and 1,1-difluoroethylene were not acutely hepatotoxic in fed or fasted rats at any concentration tested. Vinyl chloride monomer when administered simultaneously with DCE prevented the injury associated with DCE inhalation in fasted rats. This prevention of injury may be a result of a competitive interaction since the effect was concentration dependent.