Registration Dossier

Ecotoxicological information

Toxicity to microorganisms

Currently viewing:

Administrative data

Link to relevant study record(s)

Reference
Endpoint:
activated sludge respiration inhibition testing
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study without detailed documentation
Qualifier:
according to
Deviations:
not specified
Principles of method if other than guideline:
A defined amount of activated sludge is synthetic nutrient solution were assayed breathing rate. This respiration rate is compared with those measured in assays with different concentrations of test substance. The sensitivity of the activated sludge used is checked with 3,5-dichlorophenol as a reference substance.
GLP compliance:
yes
Specific details on test material used for the study:
- Batch no.: H 1431725
- Trade name: Vulkacit NZ
Analytical monitoring:
no
Test organisms (species):
activated sludge
Details on inoculum:
6 g/L TS
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
3 h
Nominal and measured concentrations:
concentrations: 100, 1000, and 10000 mg/L (nominal)
Reference substance (positive control):
yes
Remarks:
(3,5-Dichlorphenol)
Duration:
3 h
Dose descriptor:
EC50
Effect conc.:
> 10 000 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Remarks:
respiration rate
Details on results:
Only 7.7% respiration inhibition was observed at the test concentration of 10000mg/L.
Validity criteria fulfilled:
yes
Conclusions:
Toxicity of TBBS to activated sludge was determined at an EC50 of >10000 mg/L with a inhibition rate of 7.7 % after 3 hours exposure. The toxicity was observed to be greater than the limit of water solubility of TBBS.
Executive summary:

Toxicity of TBBS to activated sludge was determined according to the ISO 8192 -1986/E an EC50 of >10000 mg/L with a inhibition rate of 7.7 % after 3 hours exposure.

The toxicity was observed to be greater than the limit of water solubility of TBBS.

Due to fast hydrolysis of TBBS the observed effect is most probably a combined effect from both, TBBS and MBT. Thus, the value determined on TBBS was chosen as key study.

Description of key information

Toxicity of TBBS to activated sludge was determined at an EC50 of >10000 mg/L with a inhibition rate of 7.7 % after 3 hours exposure. The toxicity was observed to be greater than the limit of water solubility of TBBS. 

Key value for chemical safety assessment

EC50 for microorganisms:
10 000 mg/L

Additional information

Should read ">10 000 mg/L"

Due to fast hydrolysis of TBBS the observed effect is most probably a combined effect from both, TBBS and MBT. Thus, the value determined on TBBS was chosen as key study. The received value was far above the water solubility, but describes a realistic scenario for the sewage treatment plant.