Registration Dossier
Registration Dossier
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EC number: 202-905-8 | CAS number: 100-97-0
Endpoint summary
Administrative data
Description of key information
Additional information
The available ecotoxicological studies demonstrate that methenamine is non-toxic at all for aquatic organisms in acute tests for numerous freshwarter and saltwater species.
When reaching the aqueous environment, methenamine is degraded hydrolytically to ammonium and formaldehyde. The rate of hydrolysis is strongly pH-dependent. While the substance is degraded rapidly at acidic pHs, it seems to be more stable to hydrolysis at pHs > 7 and may persist in the water phase for a few days, before being degraded biologically. Since this effect might occur under environmental relevant conditions, a long term exposure of aquatic systems and organisms in theory is possible but not likely. No studies are available concerning the long-term effects on fish and invertebrates. However, the following aspects clearly demonstrate that such data tests are not needed:
- methenamine was shown to be degradable (mainly hydrolysis, but also biodegradation)
- methenamine was non-toxic in the available tests using aquatic organism (up to 100 times above recommended limit concentrations)
- log Pow of -2.18 does not indicate a potential for bioaccumulation
- one degradation product, formaldehyde, is ready biodegradable, the other degradation product, ammonia, is a naturally occurring substance known for many metabolic pathways in organisms. The environmental levels of both due to degradation of methenamine are very low compared to releases from other sources.
Taking these findings together, a long-term exposure of aquatic organisms to ecotoxicological relevant concentrations of methenamine can be excluded. Hence, further information concerning long-term effects on aquatic organisms is dispensable.
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