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EC number: 205-840-3 | CAS number: 155-04-4
- 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
Additional information
Only very limited aquatic ecotoxicity data are available with ZMBT as test substance.
Short-termToxicity to Fish:
ZMBT: LC50 geometric mean = 22.4 mg/l
MBT: In a flow-through toxicity test on rainbow trout a 96-hour LC50 of 0.73 mg/l was obtained.
Comparing these two LC50 values indicates, that the short term toxicity to fish of MBT exceeds the that of ZMBT by a factor exceeding 30.
Toxicity to microorganisms:
The toxicity of ZMBT to activated sludge was studied and effect concentration was reported as 3h-EC50 of 1220 mg/l. For the assessment of microorganisms in biological treatment plants, Tomlinson (1966) studied the inhibition of MBT on the first nitrification step (oxidation of NH4 to NO2) and obtained after 2-4 h exposure an EC75 value of 3mg/l for non-adapted sludge.
Again, the two results for ZMBT and MBT indicate a much higher toxicity to microorganisms for MBT. Although not directly comparable (EC50 vs. EC75) a higher toxicity by a factor exceeding 300 is deemed realistic.
ZMBT is an organic complex, in which the MBT structure is present. MBT is found as impurity in ZMBT with variable percentage. The MBT impurity in the substance as manufactured as well as dissociation of ZMBT determine the hazard profile of ZMBT aqueous solution. Dissociation of ZMBT is as a minimum expected as a result of ADME (adsorption, distribution, metabolism, excretion) processes in the fish, at least as soon as ZMBT reaches the stomach.
Comparing short-term Toxicity Fish data for ZMBT and MBT with Toxicity to microorganisms data for ZMBT and MBT, the hypothesis that in fact, aquatic toxicity is driven by the impurity MBT plus dissociation of ZMBT to MBT and Zn2+, appears to be supported.
Available data on ZMBT and MBT suggest that the impurity MBT is the driver for aquatic toxicity already at concentrations of about 3%. Hence a read-across approach from MBT is used to support the risk assessment of ZMBT as a worst-case, thus effectively also covering ZMBT grades containing less than 3% MBT impurity.
A respective Read-Across Strategy according to RAAF Category 1 ((Bio)transformation to common compound(s); Property of the target substance predicted to be quantitatively equal to those of the source substance or prediction based on a worst-case approach.), RAAF Category 2 (Different compounds have qualitatively similar properties; Properties of the target substance predicted to be quantitatively equal to those of the source substance or prediction based on a worst-case approach.) or a combination of both may be applicable. An update of the ZMBT dossier at ECHA with the RAAF document covering ecotoxicity and fate will be submitted in due course.
For the purpose of the risk asssessment of ZMBT, a read-across approach from MBT is used as a worst-case.
The most sensitive acute toxicity of MBT is to aquatic algae (Selenastrum capricornutum) tested according to OECD TG 201 "Alga, Growth Inhibition Test". After 72 hours of exposure, an ECr50 of 0.5mg/L was obtained (MITI, 1999). Besides the results from acute tests, the ecotoxicity of MBT was also determined in long-term tests to three trophic levels. Anembryo-larval test to Oncorhynchus mykiss carried out in a flow-through system resulted in a NOEC of 0.041 mg/l (CMA, 1989), which is the most sensitive one in three trophic levels and hence used for further risk assessment. The described metabolites of MBT are less toxic to aquatic organisms than MBT itself.
The toxicity of ZMBT to activated sludge was studied and effect concentration was reported as 3h-EC50 of 1220 mg/l. For the assessment of microorganisms in biological treatment plants, Tomlinson (1966) studied the inhibition of MBT on the first nitrification step (oxidation of NH4 to NO2) and obtained after 2-4 h exposure an EC75 value of 3mg/l for non-adapted sludge. The effect concentration of MBT is lower than the one of ZMBT; and hence it is used as a worst case for the further risk assessment of ZMBT.
Information on Registered Substances comes from registration dossiers which have been assigned a registration number. The assignment of a registration number does however not guarantee that the information in the dossier is correct or that the dossier is compliant with Regulation (EC) No 1907/2006 (the REACH Regulation). This information has not been reviewed or verified by the Agency or any other authority. The content is subject to change without prior notice.
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