Fibers carcinogenicity

Wylie AG, Bailey KF, Kelse JW, et al Tbe importance of width in asbestos fiber carcinogenicity and its implications for public policy. Am Ind Hyg Assoc J 54 239-252, 1993... 

Eastes W, Hadley JG. 1996. A mathematical model of fiber carcinogenicity and fibrosis in inhalation and intraperitoneal experiments in rats. Inhal Toxicol 8 323-343. 

THPOH—Ammonia—Tris Finish. By far the most effective finish for polyester—cotton textiles was a system based on the THPOH—NH treatment of the cotton component either foUowed or preceded by the appUcation of Tris finish to the polyester component. This combined treatment appeared to be effective on almost any polyester—cotton blend. A large amount of fabric treated in this way was sold throughout the United States and much of the rest of the world. Shortly after the introduction of Tris finishing, Tris was found to be a carcinogen. Most of the Tris treated production was in children s sleepwear, and this created a situation in which almost aU chemical fire-retardant-treated textiles were unfairly condemned as dangerous. Manufacturers mshed to replace chemically treated textiles with products produced from inherently flame-resistant fibers. Nowhere was the impact more severe than in the children s sleepwear market. New, safer materials have been introduced to replace Tris. Thus far none has been as completely effective. 

Other fibrous and porous materials used for sound-absorbing treatments include wood, cellulose, and metal fibers foamed gypsum or Pordand cement combined with other materials and sintered metals. Wood fibers can be combined with binders and dame-retardent chemicals. Metal fibers and sintered metals can be manufactured with finely controlled physical properties. They usually are made for appHcations involving severe chemical or physical environments, although some sintered metal materials have found their way into architectural appHcations. Prior to concerns regarding its carcinogenic properties, asbestos fiber had been used extensively in spray-on acoustical treatments. 

Curing the treated fibers with ammonia chemically attaches the compound to the cloth. The corresponding sulfate has replaced much of the hydroxide because under certain conditions of manufacture or use the carcinogen bis(chloromethyl) ether may form. 

Sihca and aluminosihcate fibers that have been exposed to temperatures above 1100°C undergo partial conversion to mullite and cristobaUte (1). Cristobahte is a form of crystalline siUca that can cause siUcosis, a form of pneumoconiosis. lARC has deterrnined that cristobaUte should be classified as 2A, a probable carcinogen. The amount of cristobahte formed, the size of the crystals, and the nature of the vitreous matrix in which they are embedded are time- and temperature-dependent. Under normal use conditions, refractory ceramic fibers are exposed to a temperature gradient, thus only the hottest surfaces of the material may contain appreciable cristobahte. Manufacturers Material Safety Data Sheets (MSDS) should be consulted prior to handling RCF materials. 

A further consensus developed within the scientific community regarding the relative carcinogenicity of the different types of asbestos fibers. There is strong evidence that the genotoxic and carcinogenic potentials of asbestos fibers are not identical in particular mesothelial cancer is mostiy, if not exclusively, associated with amphibole fibers (43). 

Direct dyes are defined as anionic dyes substantive to ceUulosic fibers (cotton, viscose, etc), when applied from an aqueous bath containing an electrolyte. Before the discovery of Congo Red in 1884, only mordanted cotton could be dyed. Congo Red [573-58-0] (62) (Cl Direct Red 28 Cl 22120) a primary symmetrical disazo dye, which is made readily from bisdiazotized benzidine and naphthionic acid [84-86-6] (4-arnino-l-naphthalenesulfonic acid), was the precursor of a most important line of dyes, including all shades, derived from benzidine and its homologues. Today, no benzidine dye is produced because benzidine is carcinogenic. 

Five recent studies investigated the potential toxic risk if CNTs reach the pleural cavity after inhalation exposure [6,88-91]. Three of these in vivo studies revealed that if CNTs are delivered to the abdominal cavity of mice or rats, they could induce a serious potential carcinogenic risk resembling that associated with exposure to certain asbestos fibers [6,88,89]. The other two studies described nontoxic responses [90,91]. 

The mechanism of carcinogenesis by PAHs is believed to involve alkylation of an informational macromolecule in a critical, but at present unknown, manner. Such an interaction with a protein has been modelled by alkylation of a peptide this showed a conformational change occurred on alkylation. It has not yet been possible to study the structure of DNA alkylated by an activated carcinogen this is because DNA is a fiber and the structural order in it is not sufficient for a crystal structure determination. However the crystal structures of some alkylated portions of nucleic acids are described, particularly some nucleosides alkylated by chloromethyl derivatives of DMBA. In crystals of these alkylation products the PAH portion of the adduct shows a tendency to lie between the bases of other nucleoside... 

Nickel may be a factor in asbestos carcinogenicity. The presence of chromium and manganese in asbestos fibers may enhance the carcinogenicity of nickel (USEPA 1980), but this relation needs to be verified. Barium-nickel mixtures inhibit calcium uptake in rats, resulting in reduced growth (WHO 1991). Pretreatment of animals with cadmium enhanced the toxicity of nickel to the kidneys and liver (USPHS 1993). Simultaneous exposure to nickel and cadmium — an industrial situation... 

The effects of toxins are, generally, proportional to dosage. Well-controlled dosage, as in these cell systems, provides the best opportunity for relating carcinogenicity to levels of exposure. In live animal experiments, the amount administered is usually defined as the exposure. However, not all fibrous particles will ultimately reach a specific target tissue. Measurement of the fiber load at the tissue site and the pathologic response are tedious but necessary procedures to evaluate this aspect of the problem. 

Using in vivo techniques, natural and synthetic fibrous materials have been shown to induce fibrosis and carcinogenic responses that were directly related to dose, if the materials were placed on the target tissues. Chrysotile appeared to be more biologically active than the other UICC asbestos samples or fibrous glass, with particle size and shape having some influence on the response. In vitro experiments indicate that fibers can be cytotoxic and possibly mutagenic, increase the secretory activity of fibroblasts, and possibly initiate an immune cascade. 

Bertrand, R., and H. Pezerat (1980). Fibrous glass carcinogenicity and dimensional characteristics, pp. 901-911. In Wagner, J. C., ed. Biological Effects erf Mineral Fibers. Vol. 2, Pub. No. 30 of International Agency for Research on Cancer, Lyon, France. 

Stanton, M. F., M. Layard, A. Tegeris, E. Miller, M. May, and E. Kent (1977). Carcinogenicity of fibrous glass pleural response in the rat in relation to fiber dimension. J. Natl. Cancer Inst. 58 587—603. 

Wagner, J. C., G. Berry, and J. W. Skidmore. (1976). Studies of the carcinogenic effects of fiber glass of different diameters following intrapleural innoculation in experimental animals, pp. 193-197. In Proceedings of a symposium, HEW Publication Pub. No. 76-151 (National Instituion of Occupational Safety and Health), Washington, D.C. 

The levels of antifeedants can be raised safely only in plants such as forest trees or fiber crops, not in food plants for humans or livestock. Such problems have arisen inadvertently. For instance, a new insect-resistant potato cultivarhad to be withdrawn from the market because it contained high levels of the carcinogens solanine and chaconine (Renwick etal, 1984). In another example, an insect-resistant celery had 10 times the usual concentration of the carcinogen 8-methoxypsoralen (and related psoralens), which caused dermatitis in produce handlers (Seligman etal, 1987). 

SVFs have been widely used as insulation material in places in which asbestos was used many years ago, and therefore the hazards have been compared. Because the three principal types of asbestos fibers types have caused lung cancer at high exposures, there is a widely held belief that all fibers are carcinogenic if inhaled in large enough doses." Hence, on a morpho-... 

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