Carcinogens mixtures

Phosphorus (white) [7723-14-0] M 31.0, m 590, d 1.82. Purified by melting under dilute H2S04" dichromate (possible carcinogen) mixture and allowed to stand for several days in the dark at room temperature. It remains liquid, and the initial milky appearance due to insoluble, oxidisable material gradually disappears. The phosporus can then be distilled under vacuum in the dark [Holmes Trans Faraday Soc 58 1916... 

Keywords Alternative methods, Chemical carcinogenicity, Mixtures, Toxicological profile... 

Virtually all of these occupations entail exposure to mixtures of chemicals with the carcinogenic agent(s) unidentified. Indeed, it is the mixtures, and not any particular components of them, that are cancer causing. Examples of carcinogenic mixtures of occupational chemicals are given in the next section. 

Following are examples of carcinogenic mixtures described in the literature. Most of the mixtures are composed of lipophilic and hydrophilic components. Kovi/ values are given for single compounds where available. The designations [L] and [H] are used for lipophilic and hydrophilic mixtures, respectively, for which individual compounds are not discernable. 

In a manner analogous to the hazard index approach for noncarcinogens, hazard quotients for carcinogenic mixture components can be estimated by dividing chemical exposure levels by doses (DR) associated with a set level of cancer risk the HI is the sum of the HQ values [9,16] ... 

Fears, T.R., R.M. Elashoff, and M.A. Schneiderman. 1989. The statistical analysis of carcinogen mixture experiment. 111. Carcinogens with different target systems, aflatoxin Bl, N-butyl-N-(4-hydroxybutyl) nitrosamine, lead acetate, and thiourcil. Toxicol. Ind. Health 5(1) 1-23. 

It is very difficult to treat MDA as a single entity because the manufacturing processes of PMDA and MDA are essentially identical, with the exception of a separation step. This article focuses on the technology of 4,4 -MDA, and it also includes properties of isomers and oligomeric mixtures when they are of commercial importance. The 4,4 -MDA is a suspected human carcinogen, and therefore special handling of this material is required. AH of the MDA and PMDA produced is consumed in industries that are "destmctive" of MDA s chemical identity. Thus MDA loses its unique chemical identity and is not encountered by household consumers. 

Abbott Laboratories, which has conducted additional toxicity and carcinogenicity studies with cyclamate, a 10 1 mixture of cyclamate—saccharin, and cyclohexylamine, claimed to be unable to confirm the 1969 findings. Abbott then filed a food additive petition for cyclamate in 1973, which was denied by the FDA in 1980. In 1982, the Calorie Control Council and Abbott Laboratories filed a second food additive petition containing the results of additional safety studies (73). That petition was stiU pending as of 1996. Cyclamate is, however, allowed for use in any or all three categories, ie, food, beverage, and tabletop, in about 50 countries. Sweet n Low, known in the United States as a saccharin-based table-top sweetener, contains exclusively cyclamate in Canada. 

Semicarbazide hydrochloride (hydrazine carboxamide hydrochloride) [563-41-7] M 111.5, m 173 (dec), 175 (dec), pK " 3.66. Crystd from aqueous 75% EtOH and dried under vacuum over CaS04. Also crystd from a mixture of 3.6 mole % MeOH and 6.4 mole % of water. [Kovach et al. J Am Chem Soc 107 7360 1985.] IR v 700, 3500 cm" [Org Synth Coll Vol I 485 I94I-, Davison and Christie J Chem Soc 3389 I955 -, Thiele and Stange Chem Ber 27 33 I894 pK Bartlett J Am Chem Soc 54 2853 1923]. The free base crystd as prisms from abs EtOH, m 96° [ Curtius and Heidenreich Chem Ber 21 55 1894]. TOXIC ORALLY, possible CARCINOGEN and TERATOGEN. 

Group 1 The agent (mixture) is carcinogenic to humans. The exposure circumstance entails exposures dial are carcinogenic to humans. 

Group 3 The agent (mixture, or exposure circumstance) is unclassifiable as to carcinogenicity in humans. 

De Minimis Limitation. A listed toxic chemical does not have to be considered if it Is present in a mixture at a concentration below a specified de nvnimis level. The de minimis level is 1.0%, or 0.1% if the chemical meets the OSHA carcinogen standard. See Table II for the de minimis value associated with each listed toxic chemical. For mixtures that contain more than one member of a listed chemical category, the de minimis level applies to the aggregate concentration of all such members and not to each individually. EPA included the de minimis exemption In the njle as a burden reducing step, primarily because facilities are not likely to have information on the presence of a chemical in a mixture or trade name product beyond that available in the product s MSDS. The de minimis levels are consistent with OSHA requirements lor development of MSDS information concerning composition. 

Polycyclic aromatic hydrocarbons have been classified as human carcinogens because they induce cancers in experimental animals and because smoking and exposure to mixtures of chemicals containing polycyclic aromatic hydrocarbons in the workplace increase the risk of lung cancer in exposed individuals. In experimental animals, benzo(a)pyrene induces cancer in different organs depending on the route of administration.Furthermore, exposure to polycyclic aromatic hydrocarbons commonly occurs in occupations related to traffic (use of diesel engines in transportation and railways). 

Chemical and common names of carcinogens must be listed if they are present in the mixture at levels of 0.1 percent or greater. 

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