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Long-term toxicity to aquatic invertebrates

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Description of key information

No data on chronic toxicity to aquatic invertebrates is available for HiMO LAB.  Data from  C10-14 LAB (CAS no:68648-87-3) as structural analogue  was used to understand the chronic toxicity profile of substance to daphnia. The 21-day NOEC for daphnids was 0.0075 mg/L. As a consequence, due to the extremely low water solubility,  the chronic toxicity to aquatic invertebrates is above the water solubility (<0.1 mg/L).

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Additional information

Benzene, C16-24 alkyl derivatives are also known as High Molecular Weight Linear Alkylbenzenes (HiMo LAB).  The substance is a UVCB. Because of their high molecular weight, they are very similar in composition and properties to the heavy alkylate bottoms (HAB). Based on these structural and functional similarities, data on LAB (CAS no: 67774-74-7) being registered under REACH, LAB Alkylate Bottoms (CAS no: 85117-41-5) described in OECD SIDS dossier, and HAB (CAS no: 84961-70-6) being registered under REACH are suitable as supporting studies in case where specific data on the HiMo LAB is lacking. 

There is no chronic aquatic invertebra study available with HiMo LAB. The study from Benzene, C10-14-alkyl derivs. (LAB, CAS No: 68648-87-3) as structural analogue was used to cover this endpoint. Groups of 10 daphnids were exposed to concentrations of 1.9, 3.8, 7.5, 15 or 30 ug/L of C10-14 LAB for 21 days. Biological parameters included adult survival, total young produced and young produced per adult and were summarized on days 0, 4, 7, 14 and 21. Reproduction and growth was reduced at concentrations between 15 -30 ug/L. The 21-day NOEC for daphnids was 0.0075 mg/L. The 21-day LOEC was 0.015 mg/L. The 21-day EC50 for daphnids was 0.012 mg/L.

The EPISUITE QSAR modelling was used to predict the chronic toxicity profile of HiMo LAB. Modelled toxicity values for HiMo LAB (C20 and C24 alkyl derv.) confirmed that the aquatic chronic toxicity value exceeds (i) the predicted water solubility, indicating the substance is not soluble enough to measure the predicted effect and (ii) the log Kow cutoff value of 8.0 for chronic toxicity to daphnia.

According to data from analogue substances and QSAR modelling of HiMo LAB, the substance does not demonstrate chronic aquatic toxicity at water soluble concentrations.

 

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