Registration Dossier

Ecotoxicological information

Endpoint summary

Administrative data

Description of key information

Additional information

As no complete data set is available for TAME, the missing endpoints will be filled using read-across from MTBE. Comparing all available experimental results on toxicity of ETBE, MTBE and TAME, it seems likely that the chronic toxicity of TAME is expected to be more similar to ETBE than to MTBE. However, there is no data for ETBE that can cover the endpoints for TAME. Therefore, the results from MTBE will be taken for read across and a safety factor of 10 will be applied on the effect parameters (see Appendix 1 for a more details justification of the analogue approach).

A general problem in testing the toxicity of TAME to aquatic organisms is the volatility of the substance. The vapour pressure shows TAME 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.

There are three guideline studies available for freshwater fish. The studies are either semi-static or flow-through. The most critical study is therefore chosen as the key study. The lowest observed effect concentration is a 96-h LC50 value of 580 mg/l in Onchorhynchus mykiss (Springborn Laboratories, Inc.., 1994a). As no data are available for marine fish, the data from MTBE are used for read-across. The lowest effect concentration in marine fish for MTBE is a 96 -h LC50 of 574 mg/l in inland silverside (Menidia beryllina) (BenKinney et al., 1994). Applying a safety factor of 10 to this value results in an effect concentration of 57.4 mg/l for TAME. Both values will be used in the assessment.

An OECD 212 study is available for TAME. This showed a NOEC of 64 mg/l for TAME, which will be used in the assessment.

There are several guideline studies available for freshwater invertebrates. The most critical study is therefore chosen as the key study. For freshwater invertebrates the lowest observed effect concentration is a 48-h EC50 value of 100 mg/l in Daphnia magna(Springborn Laboratories, Inc., 1994b). For marine invertebrates only one study was available; the study was conducted according to accepted guidelines and gave a 96-h LC50 of 14 mg/l in Americamysis bahia (Springborn Laboratories, Inc., 1994c). Both values will be used in the assessment.

One chronic test with marine invertebrates is available; the study is conducted according to accepted guidelines. The 28-d NOEC in Americamysis bahia is 3.39 mg/l (T.R. Wilbury Laboratories, Inc., 2004). No chronic studies with freshwater invertebrates are available. A guideline study is available for MTBE with Daphnia magna, the 21-d NOEC is 51 mg/l (Wildlife International Ltd., 1999). Applying a safety factor of 10 to this value results in an NOEC of 5.1 mg/l for TAME. These values are used in the assessment.

Several studies with algae are available; all are conducted according to accepted guidelines. One study was considered invalid as test concentrations could not be maintained and the cell concentration in the controls in all replicates was smaller after 72 hours than after 48 hours (Springborn Laboratories Inc., 1995). From the other studies the most critical study is chosen as the key study. The lowest 72-h ErC50 value is 780 mg/l and the 72-h NOEC is 77 mg/l in Pseudokirchneriella subcapitata (SafePharm Laboratories, 2003a). These values are used in the assessment.

One study with Pseudomonas putida is available for TAME, which is conducted according to ISO 10712, the 16 -h EC10 is 25 mg/l (SafePharm Laboratories, 2003c). This value will be used in the assessment.

No studies with sediment and terrestrial organisms are available, however as the log Kow is very low (1.55) direct and indirect exposure of these compartments is not expected as was demonstrated by the exposure assessment.

No data on bird toxicity is available, however a large mammalian dataset is available (see Section 5) and as the log Kow is very low (1.55) secondary poisoning is not expected.