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EC number: 202-905-8 | CAS number: 100-97-0
- Life Cycle description
- Uses advised against
- Endpoint summary
- Appearance / physical state / colour
- Melting point / freezing point
- Boiling point
- Density
- Particle size distribution (Granulometry)
- Vapour pressure
- Partition coefficient
- Water solubility
- Solubility in organic solvents / fat solubility
- Surface tension
- Flash point
- Auto flammability
- Flammability
- Explosiveness
- Oxidising properties
- Oxidation reduction potential
- Stability in organic solvents and identity of relevant degradation products
- Storage stability and reactivity towards container material
- Stability: thermal, sunlight, metals
- pH
- Dissociation constant
- Viscosity
- Additional physico-chemical information
- Additional physico-chemical properties of nanomaterials
- Nanomaterial agglomeration / aggregation
- Nanomaterial crystalline phase
- Nanomaterial crystallite and grain size
- Nanomaterial aspect ratio / shape
- Nanomaterial specific surface area
- Nanomaterial Zeta potential
- Nanomaterial surface chemistry
- Nanomaterial dustiness
- Nanomaterial porosity
- Nanomaterial pour density
- Nanomaterial photocatalytic activity
- Nanomaterial radical formation potential
- Nanomaterial catalytic activity
- Endpoint summary
- Stability
- Biodegradation
- Bioaccumulation
- Transport and distribution
- Environmental data
- Additional information on environmental fate and behaviour
- Ecotoxicological Summary
- Aquatic toxicity
- Endpoint summary
- Short-term toxicity to fish
- Long-term toxicity to fish
- Short-term toxicity to aquatic invertebrates
- Long-term toxicity to aquatic invertebrates
- Toxicity to aquatic algae and cyanobacteria
- Toxicity to aquatic plants other than algae
- Toxicity to microorganisms
- Endocrine disrupter testing in aquatic vertebrates – in vivo
- Toxicity to other aquatic organisms
- Sediment toxicity
- Terrestrial toxicity
- Biological effects monitoring
- Biotransformation and kinetics
- Additional ecotoxological information
- Toxicological Summary
- Toxicokinetics, metabolism and distribution
- Acute Toxicity
- Irritation / corrosion
- Sensitisation
- Repeated dose toxicity
- Genetic toxicity
- Carcinogenicity
- Toxicity to reproduction
- Specific investigations
- Exposure related observations in humans
- Toxic effects on livestock and pets
- Additional toxicological data
Endpoint summary
Administrative data
Description of key information
The degradation of methenamineis strongly dependent on the pH where abiotic and biotic pathways are possible. With decreasing pH abiotic degradation (mainly hydrolysis) increases. In a new state of the art study (Muckle, 2009)Methenaminewas shown to be not ready biodegradable at neutralpH.The following data were determined for the test item: 10-day-window: day 8 - 18 degradation at the end of 10-day-window: 22% degradation at the end of the test: 35% However, other studies clearly indicate a good biodegradation on the chosen test conditions. Taken all together, hydrolysis seems to be the major degradation pathway formethenaminein the environment. At acidic pH-levels,methenamineis quickly degraded hydrolytically. At neutral and basic pH, the rate of hydrolysis decreases, and degradation is supported by microbial activity. Consequentlymethenaminecan be regarded as degradable but not as “ready biodegradable”.
Additional information
In aqueous systems, methenamine is susceptible to hydrolysis. The process is strongly pH dependent. At acidic pH-levels the substance is degraded in a few hours, at neutral and basic pH-levels the half life increases to several days. For environmental relevant conditions, hydrolytical degradation can last several days – weeks, e.g. in surface water with pH > 7.
The available tests on biodegradation revealed different results. In a new state of the art ready biodegradabability study methenamine did not meet the criteria for ready biodegradable although some degradation was noted. In other standard screening tests on ready biodegradation, degradation levels between 28 % and > 100 % were determined depending on the selected experimental conditions e.g. pH. In sewage treatment plant simulation studies the elimination rate was between 12 % and 53 %, depending on the test conditions e.g. the aging of the sludge. These differences might also be explained by the susceptibility to hydrolysis at different pH-levels, because hydrolysis is expected to be the decisive step also in the available biodegradation tests. In addition, the rate biological degradation might depend on the amount of protonated methenamine. At acidic pH-levels, most of the substance is protonated while in a more basic environment the amount of protonated methenamine is decreasing. The neutral molecule is considered to be more bioavailable and therefore subject to microbial degradation.
Taking these findings together, hydrolysis seems to be the major degradation pathway for methenamine in the environment. At acidic pH-levels, methenamine is quickly degraded hydrolytically. At neutral and basic pH, the rate of hydrolysis decreases, and degradation is supported by microbial activity.
No information about degradation of methenamine in soil is available. Since releases of methenamine into the soil compartment can be excluded due to fast hydrolysis and controlled conditions during manufacturing and processing of the substance. Further information is not required.
Consequently, methenamine can be regarded as degradable but not as “ready biodegradable”.
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