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An experimental algae inhibition study was available for Butene homopolymer (CAS 9003-29-6). This study was a limit test and used a water accommodated fraction. No inhibition of growth was reported at the WAF of 19.2 mg/L. An study was also available for algae for the stream CAS 97280-83-6 which reported an ErC50 of >100mg/L and similarly for the same stream for Daphnia an EC50 of >100 mg/L was reported. An additional study on the toxicity to fish was available for tetrabutene (CAS 68514-35-2) which is not a member of Butylene oligomers but is a C16 olefin (CAS 68514-35-2) and so was considered suitable for read-across. This study did not record any mortality at WAF concentration of 1.55 mg/L, the highest concentration tested. These studies are based on the WAF and normally for UVCB streams of high complexity, such data must be treated with care. In this category, however, given the relatively high purity and consistency of the streams, the data may be used for PBT assessment.

Experimental data are not available for the predominantly C8 streams in this category.In the absence of measured data for this category member, QSAR estimates (ECOSAR, part of EPISuite V4.0) were used to predict toxicity. The 48 hour EC50 to aquatic invertebrates was calculated to be 0.92 mg/L and was the most sensitive species for a representative C8 structure. Classification would therefore be based on this calculated data and this would result in a classification of R50/53 (DSD) and Acute and Chronic Category 1 (CLP) as the lowest predicted EC50 is 0.92 mg/L for Daphnia and the predicted log Kow for this stream is >4.

The available data show no effects observed below the limit of solubility for C12 and C16 streams. As C12 streams are readily biodegradable, these do not meet the criteria for environmental classification. As C16 streams are considered to be poorly soluble substances for which no acute toxicity is recorded at levels up to the water solubility, which are not rapidly degradable and have a log Kow ≥ 4, these substance meet the criteria for chronic category 4 classification.

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