Butane, 2-ethoxy-2-methyl-

Ecotoxicological Summary

Hazard for aquatic organisms

Freshwater

Hazard assessment conclusion:

PNEC aqua (freshwater)

PNEC value:

2.2 mg/L

Assessment factor:

10

Extrapolation method:

assessment factor

PNEC freshwater (intermittent releases):

1.43 mg/L

Marine water

Hazard assessment conclusion:

PNEC aqua (marine water)

PNEC value:

0.22 mg/L

Assessment factor:

100

Extrapolation method:

assessment factor

STP

Hazard assessment conclusion:

PNEC STP

PNEC value:

483 mg/L

Assessment factor:

1

Extrapolation method:

assessment factor

Sediment (freshwater)

Hazard assessment conclusion:

PNEC sediment (freshwater)

PNEC value:

204 mg/kg sediment dw

Extrapolation method:

equilibrium partitioning method

Sediment (marine water)

Hazard assessment conclusion:

PNEC sediment (marine water)

PNEC value:

20.4 mg/kg sediment dw

Extrapolation method:

equilibrium partitioning method

Hazard for terrestrial organisms

Soil

Hazard assessment conclusion:

PNEC soil

PNEC value:

39.5 mg/kg soil dw

Extrapolation method:

equilibrium partitioning method

Hazard for predators

Secondary poisoning

Hazard assessment conclusion:

PNEC oral

PNEC value:

6 670 g/kg food

Assessment factor:

300

Additional information

Substance-specific data are available to meet a majority of the standard REACH information requirements for TAEE, however read-across to MTBE is used for the assessment of long-term toxicity in fish. When read-across is used from TAEE to MTBE a safety factor of 2 will be taken into account.A general problem in testing the toxicity of TAEE to aquatic organisms is the volatility of the substance. The vapour pressure shows TAEE to be highly volatile and according to the Henry’s law constant the volatility from water is also very high. Volatilisation has been prevented as much as possible in the test designs and measured concentrations are essential when validating the tests.

A short-term toxicity test with TAEE is available for freshwater fish. The study is a semi-static GLP-compliant OECD 203 guideline study with the rainbow trout Oncorhynchus mykiss. The test concentrations were analytically verified but effect concentrations were based on nominal values. The 96-h LC50 is 240 mg/l (Harlan Laboratories, 2009f).

No long-term studies in fish are available for TAEE, an Early Life Stage test with eggs and larvae/fry of fathead minnow (Pimephales promelas) is available for MTBE (API, 1999). This result is used for read-across, the 31-d NOEC is 279 mg/l and a safety factor of 2 will be applied to this value. An effect concentration of 140 mg/l for TAEE will be used in the assessment.

One reliable study static GLP-compliant OECD 202 study with Daphnia magna is available for the short-term toxicity of TAEE to invertebrates (Brixham Environmental Laboratory, 2010a). The concentrations were analytically verified, the 48-h EC50 is 143.2 mg/l based on mean measured values.

For long-term toxicity test with invertebrates one study is available for TAEE. The study is a semi-static GLP-compliant OECD 211 study with Daphnia magna (Brixham Environmental Laboratory, 2010b). The concentrations were analytically verified, the 21-d NOEC is 22 mg/l.

A growth inhibition study with algae is available for TAEE. The study is a GLP-compliant OECD 201 study with Pseudokirchneriella subcapitata (Harlan Laboratories, 2009g). The concentrations were analytically verified, the 72-h ErC50 is 340 mg/l and 72-h NOEC for growth rate of 36 mg/l based on measured concentrations.

One respiration inhibition test with micro-organisms is available for TAEE. The study is A GLP-compliant ISO 10712 study with Pseudomonas putida (Harlan Laboratories Ltd, 2009h). The concentrations were analytically verified, the 16-h EC50 and EC10 are >483 mg/l based on measured concentrations.

Studies on sediment and terrestrial toxicity are not available for TAEE.

 No data on bird toxicity is available; however a large mammalian dataset is available which covers this endpoint.

 

Conclusion on classification

A limited set of ecotoxicity/environmental data is available for this substance, thus data from similar ethers are considered. Based on Directive 67/548/EEC, results of validated structure activity relationships and expert judgement may also be taken into account where appropriate with regard to classification and labelling of substances.

Based on all available data for daphnids, fish and algae, TAEE should not be classified as the lowest L(E) C50 value (48-h EC50 of 143.2 mg/l in Daphnia magna) is higher than 100 mg/l. Although it is not to be expected that TAEE is degradable in various compartments and the log Kow is ≥ 3.0, classification with R53 (may cause long-term adverse effects in the aquatic environment) is not necessary. The substance is not expected to bioaccumulative as the BCF is estimated to be 37.5 l/kg based on read-across with the structurally related aliphatic ether MTBE.

According to the EU Classification, Labelling and Packaging of Substances and Mixtures (CLP) Regulation (EC) No. 1272/2008 TAEE need not to be labelled for the same reasons as stated above.