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Ecotoxicological information

Toxicity to microorganisms

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Link to relevant study record(s)

Description of key information

Applying a conservative approach, the lowest test concentration applied in a ready biodegradability for a constituent belonging to the C7-C10 hydrocarbon group that resulted in a ready biodegradation pass and/or no toxicity to the inoculum has been used. Terpinolene was shown to be readily biodegradable in a test performed at 10 mg/L. Thus this concentration has been used to represent the NOEC for this group.

Key value for chemical safety assessment

EC10 or NOEC for microorganisms:
10 mg/L

Additional information

Absence of microbial toxicity can often be inferred from biodegradation studies. If a compound degrades well in a ready biodegradability test, or does not inhibit the degradation of a positive control at a certain concentration, this concentration can be used as a NOEC value. For the C7-C10 hydrocarbon assessment entity, biodegradation data is available for four constituents (see the biodegradation endpoint for details). Inhibition controls were included in the studies performed on para cymene and lime dienes ( 1-methyl-1,3-cyclohexadiene and isomers), which indicated no toxicity to the inoculum at 100mg/L. Terpinene alpha was found not to inhibit the intrinsic respiration of the inoculum at a test concentration of 30 mg/L while Terpinolene was found to be readily biodegradable in a sealed CO2 test performed at 10mg/L. Applying, a conservative approach the latter has been selected as the NOEC for this assessment entity and the details of the study included as an endpoint record.