Aromatic Amines An Assessment of the Biological and Environmental Effects (1981) / Chapter Skim
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4,4'-Methylene-Bis(2-Chloroaniline)
4,4'-Methylene-Bis(2-Chloroaniline)
Pages 168-197
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From page 168... ...
, commonly referred to as MOCA (a req istered trade name) , is a nearly odorless, crystalline solid that is yellow to tan in color (du Pont, 1977~.
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Some unknown quantity of MOCA is probably imported. USES MOCA is applied principally as a curing agent for polyurethanes and epoxy resins which are then used in the manufacture of specialized products, particularly integral-skin polyurethane semirigid foam (used for crash padding)
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International Trade Commision, 1979 a Actual rates are not reported because of company con f identiality.
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In the automotive industry, they have been used in dashboard padding and in numerous small parse. Other reported uses include shoe soles; rolls for postage stamp machines; cutting bars in plywood manufacture; rolls and belt drives on ca'Qeres, computers, and reproducing equipment; and wheels and pulleys for escalators and elevators.
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Surface soil samples from public roads as far as 1.6 km from the plant contained up to 2 ppm MOCA; those adjacent to the plant, up to 590 ppm; garden and yard samples from the local residences contained, up to 55 ppm; and house dust from vacuum cleaners, up to 18 ppm (Michigan Department of Natural Resources, 1979~. According to Parris et al.
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Available MOCA metabolism data indicate that the substance behaves as a polymorphic substrate for the acetyl CoA-dependent N-acetyltransferase of both rabbit and human liver (Glowinski et al., 1978~. The genetically determined levels of this enzyme may, in fact, determine the rapidity with which MOCA is excreted and/or converted to the reactive species involved in the carcinogenic process.
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me preschool children were presumed to have been emoted while playing in MOCA-contaminated soil; older neighborhood children did not have detectable levels of MOCA {i.e., ~ 0.3 ppt'} in urine. The workers were found to have up to 59 ppm MOCA in their urine; the members of the workers' families had urine MOCA levels of up to 15 ppb; ne ighborhood chi ldren had up to 2 ppb.
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H) has adopted a threshold limit value, time-weighted average concentration of 0.02 ppm for MOCA (American Conference of Governmental Industrial Hygienists, 19791.
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mg/m3) Near the blend ing reactor 180 0 .0400 where MOCA is mixed manu ally Near another reactor 180 0.110 where MOCA is mixed automatically Above the oven in wh ich the 140 O .
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Sect ions of the tube pack ing were then extracted with 0.5 ml of acetone and analyzed by direct injection into ~ gas chromatograph equipped with a 30-cm long, 2.3 mm (internal diameter) stainless steel column packed with 10% Dexsil 300 GO coated on 80/90 mesh Anak rom ABS.
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The gas chromatograph was equipped with a 1.8 m long, 0.32 cm (internal diameter) glass column packed with 3% OV-1 on Gas Chrom Q and a flame ionization detector (FID}.
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Evidence for the oxidation of the aromatic ring is supported by the report that S-hydroxy-MOCA is urinary metabolite of the parent amine in dogs (Barnes, 1964~. By analogy to other aromatic amides, transformation of MOCA to derivatives capable of reacting with tissue macromolecules can be expected to occur as a consequence of the production of an Nonoxidized derivative and a subsequent activation step.
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Rabbits appear to be less susceptible to the acute toxic affects of MOCA: the acute lethal dose by skin application was < 5 g/kg. The protection afforded rabbits by their effective N-acetylation of MOCA may reduce methemoglobin formation as compared to its formation in rats, which are less effective acetylators of aromatic amines, or dogs, which are unable to acetylate aromatic amines.
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Chronic Toxicity Carc inooen ic sty MOCA is of pr imary concern because of its demonstrated carcinogenicity in animals, and its structural relationship to aromatic amines known to be capable of inducing bladder cancer in humans. It is carcinogenic in mice, rats, and dogs (Table 7-31.The evidence for tumor development is less strong in mice (Russfield et al., 1975~.
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TABLE 7-3 Tumor Induction by MOCA Species Tumor Mouse Rat DC9 . Lung adenocarcinoma Mammary adenocarcinoma Zymbal gland adenocarcinoma Hepatocellular carcinoma Hepatoma Hemangiosarcoma Bladder + + + + + 182 +
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TABLE 7-4 Comparative Carcinogenicity of (Orally Administered) Aromatic Amines in the Lower Urinary Tract of DO9a Total Intake Treatment Total Tumor Compound Per Dog (Mbl)
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It seems very likely that, if a similar experiment were to be conducted with female rats, the mammary incidence of mammary gland tumors would be signif icantly higher than it was in the male animals used in this experiment. Although Stula et al.
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TABLE 7-5 Incidence (Percentage) of Predominant Neoplesms in Male Rats Fed FOCAL MOCA (ppm)
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However, MOCA was positive in bacterial DNA repair tests, phase induction tests, the Salmonelia/microsome tests, the Salmonella fluctuation test, and in E cold WP-2.
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cold mutagenesis, Drosophila, and cell transformation _ vivo. Mixed results were observed with yeast, chromosomal effects in cultured cells.
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RECOMMENDATIONS The MOCA-exposed population in and around Adr fan, Mich . and ind ividua Is exposed as a consequence of the use of COCA should be studied further to learn whether or not the compound is carcinogenic in humans.
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1979. TLVa: Threshold Limit Values for Chemical Substances and Physical Agents in the Workroom Environment with Intended Changes for 1979.
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1979. Toxic Substance Control Commission.
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Michigan Depar tment of Natural Resources, Air Quality Division, Lansing, Michigan . National Institute for Occupational Safety and Health.
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. Interna tional Trade Commission .
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Division of Environmental Epidemiology, Michigan Department of Public Health, Lansing, Michigan.
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12: 415-418 . Van Roosmalen, P.B., A.L.
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1979 . Compara tive mutagen ic i ty study of potentially carcinogenic industrial compounds.
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Linch, A.L., C.B. O'Conner, J.R.
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Stula, E.~., J.R. Barnes, H
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