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Ecotoxicological information

Toxicity to microorganisms

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Reference
Endpoint:
toxicity to microorganisms
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
test procedure in accordance with national standard methods with acceptable restrictions
Reason / purpose:
reference to same study
Principles of method if other than guideline:
Chemical oxygen demand (COD) was assessed by standard methods. The bio-chemical oxygen demand (BOD) was analysed using a Sapromat BOD measuring unit. Biological degradation-inhibition test was performed using the Offhaus method.
GLP compliance:
no
Analytical monitoring:
no
Test organisms (species):
activated sludge
Test type:
not specified
Water media type:
freshwater
Total exposure duration:
5 d
Key result
Duration:
5 d
Dose descriptor:
EC10
Effect conc.:
< 200 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration

The BOD5 test showed good biological degradation.

The inhibition study showed negligible (but not decreasing) inhibition of 5.4%.

Hence, under the conditions of this test, the 5d-EC10 is > 200 mg/L.

Based on the observed respiration activity and negligible inhibition, toxicity to microorganisms is not expected to occur.

Conclusions:
5d-EC10 > 200 mg/L
Executive summary:

In this study the chemical oxygen demand (COD) was assessed by standard methods. The bio-chemical oxygen demand (BOD) was analysed using a Sapromat BOD measuring unit on a test solution containing ca. 200 mg/L of L-histidine. A biological degradation-inhibition test was performed using the Offhaus method. It is not a GLP study and no OECD guideline was followed.

The BOD5 was determined to be 517 mg O2/g, showing good biological degradation.

The inhibition study showed a negligible (but not decreasing) toxic inhibition of 5.4%.

Hence, the EC10 > 200 mg/L.

Based on the observed respiration activity and negligible inhibition, toxicity to microorganisms is not expected to occur.

Description of key information

In a biodegradation test using a Sapromat apparatus, the BOD5 of L-histidine was determined to be 517 mg O2/g after 5 days, which indicates 50% degradation after 5 days. The tested concentration was ca. 200 mg/L.

The inhibition study included in this biodegradation test showed negligible toxic inhibition of 5.4%. Based on the observed respiration activity and negligible inhibition, toxicity to microorganisms is not expected to occur.

Key value for chemical safety assessment

Additional information

In the key study the chemical oxygen demand (COD) was assessed by standard methods. The bio-chemical oxygen demand (BOD) was analysed using a Sapromat BOD measuring unit. Biological degradation-inhibition test was performed using the Offhaus method. It is not a GLP study and no OECD guideline was followed.

BOD5 was determined to be 517 mg O2/g, showing good biological degradation.

The inhibition study showed negligible degradation of 5.4%, however not decreasing.

Based on the observed respiration activity, the degradation should take place undisturbed, even at higher concentrations and especially after certain adaptation.