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Diss Factsheets
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EC number: 216-653-1 | CAS number: 1634-04-4
- 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
Biodegradation in water: screening tests
Administrative data
Link to relevant study record(s)
Description of key information
Key value for chemical safety assessment
- Biodegradation in water:
- under test conditions no biodegradation observed
- Type of water:
- freshwater
Additional information
Three closed bottle tests (OECD 301D) are available (Hüls AG, 1991a; RBM, 1996a; Slovnaft VÚRUP, a. s., 2005a); the percentage of biodegradation observed in these studies ranged from 0 to 9.24 %. Therefore, MTBE is not considered readily biodegradable in the aquatic environment according to the standardised aerobic ready-biodegradation tests. As no test results from standard inherent test systems for aquatic biodegradation are available, non-standard tests were considered (Shell, 1981, Mo et al., 1997).
Certain adapted micro-organisms are capable of degrading MTBE (e. g. Kharoune et al., 2002). Thus, a well-adapted industrial sewage treatment plant (STP) is able to degrade the substance. High degradation rates have been observed in non-standard tests using special types of inoculum, pure cultures and mixed cultures (Shell, 1993; Salanitro et al., 1994; Steffan et al., 1997; Cano et al., 1999; Fortin & Deshusses, 1999; Fortin et al., 2001; Kharoune et al., 2001; 2002). These studies show that at least some microbial species are capable to degrade MTBE and to use it even as their sole carbon source.
The main responsible enzyme for the first steps of MTBE metabolism are P450 enzymes (e.g. Kharoune et al., 2002; Pruden et al., 2004), which are widely present in all living organisms and have even been found in viruses. Many P450 enzyme families and subfamilies have been reported in 905 bacterial species and 2570 fungal species (Nelson, 2009), which can explain why microbial populations are able to degrade MTBE. Furthermore the bacterial pathways of metabolism of MTBE are well known, as described in the degradation following pathway of MTBE in the EAWAG Biocatalysts/Biodegradation Database (EWAG, 2015).
While there is no doubt that bacteria and fungi are generally able to degrade MTBE, for biodegradation of MTBE, adaptation is needed and would usually be induced by simultaneous exposure to alkanes and MTBE. In biodegradation simulation studies according to EPA methodology, the half saturation concentration, at which the growth of the MTBE degrading microbial organism is 50% of the maximum, was found to be between 0.07 and 0.13 mg MTBE per litre (Cano et al., 1999).
It could be assumed that where there are continuous releases of MTBE to a STP, such as for large production and processing sites, sewage sludge will have become adapted to the substance and in these cases, the substance could be considered as readily biodegradable. For professional and consumer releases and releases on the regional scale, where adaptation may not occur, the non-standard test data available indicate that MTBE degradation might not fulfil the test criteria (of OECD 302), and a slower degradation categorisation as “inherently biodegradable, not fulfilling criteria” could be considered.
However, owing to the lack of ready biodegradation seen in the available standard screening tests, and as mandated by ECHA via a substance evaluation decision, a conservative approach to the available data means that the conclusion ‘under test conditions no biodegradation observed’ has been used for exposure assessment purposes.
References:
EAWAG (2015). Methyl tert-butyl ether Graphical Pathway. Available at http://eawag-bbd.ethz.ch/mtb/mtb_image_map.html (accessed May 2015)
Fortin, NY and Deshussses, MA (1999).Treatment of methyl tert-butyl ether vapors in biotrickling filters. 1. Reactor startup, steady-state performance, and culture characteristics. Environ Sci Technol 33, 2980-2986.
Fortin, NY, Morales, M, Nakagawa, Y, Focht, DD and Deshusses, MA (2001). Methyl tert-butyl ether (MTBE) degradation by a microbial consortium. Environ Microbiol 3(6), 407-416.
Nelson, DR (2009). The Cytochrome P450 Homepage. Hum Genom 4, 59-65.
Pruden, A and Suidan, M (2004). Effect of benzene, toluene, ethylbenzene, and p-xylene (BTEX) mixture on biodegradation of methyl tert-butyl ether (MTBE) and tert-butyl alcohol (TBA) by pure culture UC1. Biodegradation 15, 213–227.
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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