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Toxicity to microorganisms

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toxicity to microorganisms, other
NOEC derived from a ready biodegradability test according to OECD TG 301C.
Type of information:
experimental study
Adequacy of study:
key study
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment
according to guideline
other: OECD Guideline 301C (Ready Biodegradability: Modified MITI Test (I))
Version / remarks:
From this study a NOEC may be derived as the substance is determined to be 'readily biodegradable'.
GLP compliance:
not specified
probably yes
Details on test solutions:
In the ready biodegradability study 100 mg/L test substance was inoculated with 30 mg/L activated sludge.
Test organisms (species):
activated sludge
Details on inoculum:
Although no specifics on used inoculum are reported, normally in Japanese studies a mixture of sewage, soil and natural water is used.
Test type:
Water media type:
Total exposure duration:
14 d
Nominal and measured concentrations:
- Nominal concentration: 100 mg/L
Key result
14 d
Dose descriptor:
Effect conc.:
100 mg/L
Nominal / measured:
Conc. based on:
test mat.
Basis for effect:
other: ready biodegradability
Details on results:
After 14 days inoculation of 100 mg of the substance with activated sludge, 80-90% biodegradation was observed and the substance assessed as readily biodegradable.

Description of key information

The NOEC is set at 100 mg/L based on the substance being ready biodegradability at this concentration in a screening study according to OECD TG 301C.

Key value for chemical safety assessment

Additional information

No activated sludge respiration inhibition test according to OECD TG 209 is available. However, in a biodegradation screening study according to OECD TG 301C, the substance was found to be readily biodegradable at a test substance concentration of 100 mg/L. According to REACH guidance R7.b, this concentration may be considered as a NOEC value for STP microorganisms.

The low toxicity is further supported by data available from a bacterial growth inhibition test according to DIN 38412. In this study Pseudomonas putida was exposed to nominal concentrations of 156.25, 312.5, 625, 1250, 2500, 5000, and 10000 mg/L mg/L for 17 hours under static conditions. The 17-h EC50 and EC10 values were determined at 468 mg/L and 337 mg/L, respectively.