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Ecotoxicological information

Long-term toxicity to fish

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Description of key information

Reliable weight of evidence from both surrogate substances and QSARs indicate that the chronic NOEC for ethoxypropanol in fish will be > 100 mg/L.

Key value for chemical safety assessment

EC10, LC10 or NOEC for freshwater fish:
100 mg/L

Additional information

In a reliable guideline (OECD 204) and GLP prolonged fish toxicity study (21 -day; flow-through), exposure of rainbow trout to dipropylene glycol monoethyl ether at concentrations up to 260 mg/L did not cause lethality or other adverse effets. Based on these findings the 21 -day LC0 for DPGEE is considered to be greater than 260 mg/L, and the 21 -day NOEC is considered to be >= 260 mg/L. These results for DPGEE are considered to be a useful surrogate for predicting the likely effects of the submission substance, ethoxypropanol (propylene glycol monoethyl ether). Such read across is supported by the P series category justification document appended to section 13 of this registration dossier. This would translate on a molar basis to a predicted NOEC for ethoxypropanol of >167mg/l. Whilst an OECD204 study is not considered suitable to meet the requirements of this end point, the extended nature of the test along with the additional end points of behaviour and growth means that is should be considered as reliable with restrictions to meet the requirements of the end point and that, taking animal welfare issues into account, a study to a more recent guideline is not warranted. However, as a conservative approach, this end point is formally waived using the adaptation criteria of column 2 of annex IX of the REACH regulation.

Model estimates for four surrogate materials, methoxy propoxy and butoxy propanol along with dipropylene glycol monoethyl ether show how the toxicity primarily increases with increasing length of the alkyl chain. There is a slight decrease in toxicity with increasing number of PO units in the molecule, but overall, dipropylene glycol ethyl ether appears to be a good surrogate for propylene glycol ethyl ether (ethoxypropanol) and the QSAR supports the use of data from dipropylene glycol monoethyl ether as a surrogate to meet the data requirements for this end point.

These overall data consistently support the conclusion that the chronic NOEC for ethoxypropanol in fish is likely to be > 100 mg/l and this is taken forward to risk characterisation.