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Ecotoxicological information

Toxicity to microorganisms

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Reference
Endpoint:
toxicity to microorganisms, other
Type of information:
experimental study
Remarks:
for representative component of the "monoterpene ether" constituent group
Adequacy of study:
key study
Study period:
2 June 1992 - 30 June 1992
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
comparable to guideline study
Reason / purpose:
reference to same study
Qualifier:
according to
Guideline:
other:
Principles of method if other than guideline:
Absence of microbial toxicity can be inferred from biodegradation studies. If a compound degrades well in a ready biodegradability test, this concentration can be used as a NOEC value. The ready biodegradability of D-limonene was assessed in a sealed CO2 ready biodegradability test at a test concentration of 10 mg/L (organic carbon). The level of biodegradation achieved after 28 days was 71.4% and the 10-day window was fulfilled. Thus D-Limonene was shown to be readily biodegradable.
GLP compliance:
yes
Specific details on test material used for the study:
D-Limonene, Purity 95%
Details on inoculum:
Secondary effluent from an unacclimatised activate sludge plant
Nominal and measured concentrations:
10 mg/L
Key result
Duration:
28 d
Dose descriptor:
NOEC
Effect conc.:
10 mg/L
Nominal / measured:
nominal
Remarks on result:
other: representative for unsaturated monoterpene hydrocarbon compoennts of the regiestered substance.
Details on results:
The ready biodegradability of D-limonene was assessed in a sealed CO2 ready biodegradability test at a test concentration of 10 mg/L (organic carbon). The level of biodegradation achieved after 28 days was 71.4% and the 10-day window was fulfilled. Thus D-Limonene is readily biodegradable and the absence of microbial toxicity inferred.
Conclusions:
The ready biodegradability of D-limonene was assessed in a sealed CO2 ready biodegradability test at a test concentration of 10 mg/L (organic carbon). The level of biodegradation achieved after 28 days was 71.4% and the 10-day window was fulfilled. Based on these results D-Limonene is considered readily biodegradable and the absence of toxicity to inoculum inferred. Thus the test concentration of 10 mg/L can be considered the NOEC for toxicity to STP micrrorganisms.

D-limonene has been used to represent the "unsaturated monoterpene hydrocarbons" assessment entity for the purposes of the environmental risk assessment of the registered multi-constituent substance. The rationale for using this substance is provided in the biodegradation endpoint.

Description of key information

For the "unsaturated monoterpene hydrocarbon" group, the representative substance Limonene was shown to readily biodegradable in a test performed at 10mg/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