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Toxicity to aquatic algae and cyanobacteria

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No standard toxicity test data were found for unrefined / acid-treated oils. However, the potential effects of unrefined / acid treated oils can be predicted from aquatic toxicity data from studies of distillate aromatic extracts. This is valid for the following reasons: Unrefined / acid treated oils contain aromatic hydrocarbons, the quantities of which are substantially reduced through more severe refining steps. These aromatic compounds extracted from unrefined / acid treated oils are the primary constituents in distillate aromatic extracts, which are produced as by products in the refining of lubricant base oils. Therefore, aquatic toxicity data from studies of distillate aromatic extracts will provide a basis for a ‘worst case’ hazard assessment for the aromatic fraction contained in unrefined /acid treated oils.

In a read-across key 72 -hour alga (Pseudokirchneriella subcapitata formerly Selenastrum capricornutum) toxicity test (OECD 201; KS =1), the freshwater alga was exposed to the WAF of a light paraffinic distillate solvent (CAS # 64742 -05-8) at nominal concentrations of 0.1, 1, 10, 100, and 1000 mg/L. The 72-hour EL50 was calculated to be 18.8 mg/L and the NOEL was 0.1 mg/L based on the slope of the growth rate (ExxonMobil, 2010b).

Supporting data estimated from the PETROTOX computer model show no toxicity of unrefined / acid treated oil to aquatic algae at or below its maximum attainable water solubility (Redman et al., 2010b). These data support the applied read across.