Registration Dossier
Registration Dossier
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EC number: 203-571-6 | CAS number: 108-31-6
Endpoint summary
Administrative data
Description of key information
- 96-hour LC50 in fish = 75 mg/L
- 48-hour EC50 in daphnids = 37.9 mg/L
- 72-hour ErC50 in freshwater algae = 65.8 mg/L
Aquatic toxicity testing indicates a low level of toxicity for maleic anhydride. Acute values obtained with non-neutralized test solutions were:
Additional information
Studies on the acute aquatic toxicity of maleic anhydride are available for all three trophic levels. Since maleic anhydride rapidly hydrolyses in contact with water (half-life = 0.3 min), the breakdown product maleic acid was also considered in the assessment.
Two key studies, with representative freshwater fish (rainbow trout and bluegill sunfish), showed similar results:
LC50 (fish, 96 h) = 75 mg/L (test substance: maleic anhydride; non-neutralized test solution).
The pH values decreased with increasing test compound concentrations; the observed toxicity is mostly related to acidity.
The test organism most sensitive to maleic acid was Daphnia magna with an EC50 (48 h) of 42.8 mg/L (non-neutralized solution, toxicity partly attributable to pH effect), corresponding to 37.9 mg maleic anhydride/L.
Also a long-term test result (21 days) with maleic anhydride is available for Daphnia magna:
NOEC (Daphnia magna, 21 d) = 10 mg/L (reproduction rate),
EC50 (Daphnia magna, 21 d) = 77 mg/L (reproduction rate).
Due to very limited reporting, the study is considered not reliable hence is not used in the chemical safety assessment of maleic anhydride.
The 72-h ErC50 for growth inhibition in the alga Pseudokirchnerella subcapitata was determined at 74.35 mg maleic acid/L. This ErC50 corresponds to 65.78 mg maleic anhydride/L.
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