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Toxicity to aquatic algae and cyanobacteria

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Based on read across the toxicity of (benzoato-O,O')hydroxy(octadecanoato-O,O')aluminium to algal growth is predicted to showed no effects at a water accommodated fraction nominal loading rate of 100 mg/L. Therefore, the 72 hour ErL50 is determined to be > 100 mg/L (WAF) and the 72 hour NOErLR is 100 mg/L (WAF).

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As no data was available for the toxicity to aquatic algae and cyanobacteria of (benzoato-O,O')hydroxy(octadecanoato-O,O')aluminium, the endpoint was read across from aluminum, benzoate C16-18-fatty acids complexes.The toxicity of the read across substance to algal growth was determined in a proprietary, GLP-compliant, static, freshwater test (Harlan 2013) following OECD guideline 201. As no effects were observed in the preliminary range finding test, the definitive toxicity to algal growth study was conducted as a limit test at a nominal loading rate of 100 mg/L alongside a blank control. Algae (Pseudokirchneriella subcapitata) were exposed to water accommodated fraction (WAF) of aluminum, benzoate C16-18-fatty acids for 72 hours in standard ecotoxicity media adjusted to a hardness of approximately 150 mg/L CaCO3. Observations of algal biomass were made at 24, 48 and 72 hours and the test solutions analysed for aluminium content and total organic carbon at test initiation and termination. As no inhibition to algal growth was observed, the 72 hour ErL50 is determined to be > 100 mg/L (WAF) and the 72 hour NOErLR is 100 mg/L (WAF).

Aluminum, benzoate C16-18-fatty acids complexes (CAS No. 94166-87-7, EC No. 303-385-6) is considered suitable for read across to (benzoato-O,O')hydroxy(octadecanoato-O,O')aluminium as it is structurally similar being an approximate 2:1 mixture of (benzoato-O,O')hydroxy(octadecanoato-O,O')aluminium and (benzoato-O,O')hydroxy(hexadecanoato-O,O')aluminium. The only significant difference therefore, being the presence of about 30% of the aluminium complex containing the saturated C16-fatty acid, hexadecanoate in place of the saturated C18-fatty acid, octadecanoate. This small difference in composition is expected to have no adverse influence on the toxicity to algae and cyanobacteria.