Isooctadecan-1-ol

Long-term toxicity to aquatic invertebrates

Description of key information

No measured data are available for the long-term toxicity to invertebrates of the registration substance. The assessment of effects is based on available data for its constituents. The available evidence indicates that only the tetradecan-1-ol constituent has long-term effects in invertebrates. No further testing is necessary.

Additional information

A 21-d NOEC of 0.98 mg/L has been determined for the effects of octadecan-1-ol on reproduction rate and mortality of D. magna. The result is much higher than the limit of solubility of the test substance and should be treated with caution; the test substance did not appear to be toxic at the limit of solubility.

For tetradecan-1-ol, a reliable 21 d NOECrepro value of 1.6 µg/L has been identified for the effect of the test substance on the cumulative number of offspring of D. magna using an adapted semi-static test regime to minimise losses of the substance in test media between renewals.

For hexadecan-1-ol, no measured data are available for this endpoint. Therefore this endpoint has been calculated based on a validated reliable QSAR method to determine a NOEL value of >0.01 mg/L, i.e. non-toxic at the limit of solubility.

A 21-d NOEC(reproduction) value of 20.6 µg a.i./L has been determined for the effects of octadecanol, branched (single branch at the 2-position) on the number of reproductive young produced per day (D. magna). While this test is largely reliable, the interpretation is made very difficult by a number of uncertainties. The stock was prepared at a concentration which would have significantly exceeded the limit of solubility of the substance, and use of a proportional diluter without adequate equilibration time could have delivered undissolved material to test vessels, even at the nominal concentration levels that would have been below the limit of solubilty. The use of a flow-through test system with such a rapidly degradable substance may mean that microbial growth contributed to effects seen. It is not possible to be certain whether the analytical measurements made were of dissolved or undissolved test substance. The NOEC determined is significantly out of line compared to the clear trend of NOECs seen for alcohols with carbon number up to C14 (Schäfers et al., 2009). For all of these reasons, the study is disregarded in the present assessment.

For the purpose of risk characterisation, PNECs have been set for each constituent (by carbon number) individually. Branching is considered not to be significant.

For the purpose of hazard assessment, the contribution of each constituent to the toxicity of the registration substance has been considered. The substance contains C14 (linear only, 1% w/w), also linear and branched C16 (8.5% w/w in total), C18 (>80%) and C20. C14 has long-term effects in invertebrates.

 

Using the NOEC (rather than EC10) based on mean measured concs in fresh and old media, and setting the constituents C16 C18 and C20 as non-toxic at the limit of solubility: A NOELR of 0.17 mg/l whole substance is estimated using this method.