108-31-6 - SIAM 18, 20-23 April 2004 SIDS INITIAL...

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SIAM 18, 20-23 April 2004 US/ICCA SIDS INITIAL ASSESSMENT PROFILE CAS No. 108-31-6 110-16-7 Chemical Name Maleic Anhydride Maleic Acid Structural Formula Maleic Anhydride: C 4 H 2 O 3 Maleic Acid: C 4 H 4 O 4 SUMMARY CONCLUSIONS OF THE SIAR Category/Analogue Rationale Maleic anhydride is readily hydrolyzed to maleic acid under aqueous conditions. As a result, these two chemicals are presented because of the conditions used to test their toxicity. The only difference may be due to the potential for maleic anhydride to form haptens by acylating with amino acids, resulting in an immunological response (dermal and respiratory sensitization). Human Health Maleic anhydride and maleic acid exhibit relatively low acute toxicity by the oral and dermal routes, with the oral LD 50 of about 1.0 g/kg in rats and an acute dermal LD 50 in the range of 1.6 to 2.6 g/kg in rabbits. Maleic anhydride and maleic acid have been reported to be severely irritating to the skin and eyes of rabbits. Maleic anhydride has been shown to be a skin sensitizer to guinea pigs and a possible respiratory sensitizer to rats. There have been a few published human cases suggesting that maleic anhydride provokes asthma in a relatively small proportion of exposed workers; however, questions have been raised about whether the asthma was related to maleic anhydride exposure. Although no sensitization data exist for maleic acid, it is not predicted to be either a skin or respiratory sensitizer. Repeated exposure of maleic anhydride by inhalation to rats, hamsters, and monkeys have resulted in effects that were limited to the respiratory tract and eye irritation. In a four-week study, rats exposed six hours/day to 0, 12, 32, and 84 mg/m 3 (0, 3, 8, 21 ppm) maleic anhydride showed evidence of nasal, trachea, and lung irritation at all exposure levels. These effects were concentration-related and included epithelial hyperplasia and the presence of inflammatory exudates in the nasal turbinates and trachea; and epithelia hyperplasia, squamous metaplasia, and intra-alveolar hemorrhage in the lung. Increased incidence of hemorrhagic lung foci were also observed in the 32 and 86 mg/m 3 exposed groups. The LOAEL was 12 mg/m 3 (3 ppm). In a six-month inhalation study in which rats, hamsters, and monkeys were exposed to 0, 1.1, 3.3, or 9.8 mg/m 3 (0, 0.3, 0.8, or 2.4 ppm), respiratory tract and eye irritation were observed in rats and hamsters exposed to 3.3 or 9.8 mg/m 3 (0.8 or 2.4 ppm) and monkeys to 9.8 mg/m 3 (2.4 ppm),
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SIAM 18, 20-23 April 2004 US/ICCA 2 with body weight reductions only in male rats from the high-exposure group at study termination. Hyperplastic changes in the nasal tissues, which ranged in severity from trace to mild, were present in rats at all exposure levels and in hamsters in the mid- and high-exposure levels. Metaplastic changes in the nasal tissues occurred in both rats and
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This note was uploaded on 04/12/2010 for the course CHE che 432 taught by Professor Hmad during the Spring '10 term at Aberystwyth University.

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108-31-6 - SIAM 18, 20-23 April 2004 SIDS INITIAL...

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