Rubber carcinogenic compounds

The presence of carcinogenic compounds within the rubber industry has been a controversial issue in the field of occupational medicine (Conde-Salazar 1987, 1990a). Both 1,3-butadiene and styrene, which are used extensively in synthetic rubber, are known carcinogens (reviewed in Fishbein 1992). Significant levels of butadiene (0.06-39 Ppm [National Institute for Occupational Safety and Health 1984 International Agency for Research on Cancer 1986 de Meester 1988]) and styrene (2.4 ppm [World Health Organization 1983]) can be found in factories where these synthetic rubbers are produced however, due to automation and safety precautions, workers are not routinely exposed to... 

Buta-1,3-diene (10.101, Fig. 10.24) is a gaseous chemical used heavily in the rubber and plastics industry, the presence of which in the atmosphere is also a concern. Butadiene is suspected of increasing the risks of hematopoietic cancers, and it is classified as a probable human carcinogen. Butadiene must undergo metabolic activation to become toxic the metabolites butadiene monoepoxide (10.102, a chiral compound) and diepoxybutane (10.103, which exists in two enantiomeric and one meso-form) react with nucleic acids and glutathione [160 - 163], as does a further metabolite, 3,4-epoxybutane-l,2-diol (10.105). Interestingly, butadiene monoepoxide is at least tenfold more reactive than diepoxybutane toward nucleic acids or H20. Conjugation between the C=C bond and the oxirane may account for this enhanced reactivity. 

Greim H (ed) Occupational Toxicants, Vol 15, Critical data evaluation for MAK values and classification of carcinogens. Commission for the investigation of health hazards of chemical compounds in the work area. Natural rubber latex, p 141, New York, VCH, 2001... 

An example of this type of a safer chemical is methacrylonitrile (1) compared with acrylonitrile (2) (Figure 1.1). Both compounds are a, 3-unsaturated aliphatic nitriles, and structurally very similar, but 2 causes cancer whereas 1 does not appear to do so. Among other applications, 2 is used in the production of acrylic and modacrylic fibers, elastomers, acrylonitrile-butadiene-styrene and styrene-acrylonitrile resins, nitrile rubbers, and gas barrier resins. In a study conducted by the US National Toxicology Program (NTP) in which 2 was administered orally to mice for 2 years, there was clear evidence that it caused cancer in the treated mice (in addition to causing other toxic effects), and is classified by the NTP as a probable human carcinogen [26]. 

Aromatic compounds are the most widely used and one of the most important classes of petrochemicals. They are still an important constituent of high-octane gasoline, although because of their carcinogenic nature their application will decrease. FCC gasoline contains about 29% aromatics, whereas the aromatic content of reformates is about 63%. They also are excellent solvents and constitute an important component of synthetic rubbers and fibers. 

In 1981 a study was undertaken in Poland on 680 samples of rubber products used in food processing plants. In 35% of the samples migration of metals/ metalloids into 3% acetic acid was reported (14% of the samples contained lead, 2.6% arsenic and 3% barium). The known carcinogen phenyl-feeto-naphthylamine was found in 15.1% of the compounds, with amino type antioxidants being detected in 23% of the compounds in total. Poor organoleptic properties were found in 22.1% of the samples. Migration of accelerators... 

SAFETY PROFILE Confirmed carcinogen with experimental carcinogenic and neoplastigenic data. Poison by intravenous and subcutaneous routes. Moderately toxic by other routes. An experimental teratogen. Other experimental reproductive effects. Mutation data reported. See also ANTIMONY COMPOUNDS. When heated to decomposition it emits toxic Sb fumes. Incompatible with chlorinated rubber and heat of 216° and with BrFs. 

SAFETY PROFILE Confirmed carcinogen of the lung, nasal sinus, brain, esophagus, stomach, liver, bladder, and kidney. They are often produced in food as by-products from processing and preparadon. They are found in whiskey, herbicides, and cosmetics, as well as in tanneries, rubber factories, and iron foundries. They can be formed within the body by reaction of amine-containing foods or drugs with the nitrites resulting from bacterial conversion of nitrates. See also N-NITROSO COMPOUNDS. 

SAFETY PROFILE Human poison by an unspecified route. Experimental poison by ingestion, intraperitoneal, intravenous, subcutaneous, and parenteral routes. Moderately toxic by inhalation and skin contact. Experimental teratogenic and reproductive effects. Questionable carcinogen with experimental carcinogenic data. Mutation data reported. Lead compounds are particularly toxic to the central nervous system. It is a solvent for fatty materials and has some solvent action on rubber as well. The fact that it is a lipoid solvent makes it an industrial hazard because it can cause intoxication not only by inhalation but also by absorption through the skin. Decomposes when exposed to sunlight or allowed to evaporate forms triethyl lead, which is also a poisonous compound, as one of its decomposition products. May cause elemental lead intoxication by coming in contact with the skin. 

Botli ((-naphthylamine and f-naphlhylamine have been important industrial compounds with W-phenyl-1 -naphthylamine being a rubber anti-oxidant and -naphthylamine being used in the azo dyestuffs industry. Urifortunately, the latter is strongly carcinogenic and tite use of both naphthylamines has now been discontinued. 

Similar considerations apply to all aryl amine bladder carcinogens employed in the dye, rubber and leather industries51. Between 1930 and 1960, the toxic natures of many other coal-tar (aromatic) amino compounds, particularly azo dyes, were revealed52. 

Although the amounts of carcinogenic AAs produced in dyestuff, chemical, and rubber factories have been greatly reduced, exposure to AAs and their oxidized nitroaromatic derivatives still occurs. Some of these compounds can be found in various color additives [9, 10], paints [11], food colors [12], leather and textile dyes [13, 14], fumes from heated cooking oils [15] and fuels [16], and tobacco smoke [17]. Several AAs have also recently been identified at trace levels in commercial hair dyes [18, 19]. 

Forms impact-sensitive explosive mixtures with dichloromethylsilane, May attack, plastics, coatings, and chlorinated rubber materials such as Hypalon , Parlon , Rutile , and fluorinated rubbers such as Viton . Inorganic lead compounds are known human carcinogens. 

There is sufficient evidence for the carcinogenicity of ETU in experimental animals. When administrated in the diet, ETU induced increased incidences of thyroid follicular cell carcinomas and papillary carcinomas with some metastases and liver hyperplastic nodules in rats of both sexes. There is inadequate evidence fw the carcinogenicity of ETU in humans [42]. ETU is used primarily as an accelerator for vulcanizing polychloropene and polyacrylate rubbers. The primary routes of potential human exposure to ETU are inhalation, ingestion and dermal contact. Potential occupational exposure also occurs during the manufacture of Cumulation and rqrplication of fungicides and insecticides prepmed from ETU. Residues of the compound have been found in 28 different commercial ethylenebisdithiocarbamates products [59]. 

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