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Ecotoxicological information

Toxicity to microorganisms

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Reference
Endpoint:
activated sludge respiration inhibition testing
Type of information:
experimental study
Adequacy of study:
key study
Study period:
Not specified
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
Short-term toxicity screening test conducted to evaluate the toxicity of organotins to activated sludge and the impact of sludge age on the toxicity of these compounds. Study is well documented and meets generally accepted scientific standards. No analytical confirmation of exposure concentrations. Inhibition of respiration rate was chosen as a short-term screening test for the evaluation of toxicity.
Qualifier:
no guideline followed
Principles of method if other than guideline:
Method: other: American Public Health Association, 1989, Standard Methods for Examination of Water and Wastewater, 17th ed.
GLP compliance:
not specified
Analytical monitoring:
yes
Vehicle:
no
Test organisms (species):
activated sludge
Details on inoculum:
See below
Test type:
static
Water media type:
freshwater
Limit test:
no
Details on test conditions:
Composition of synthetic wastewater:

Glucose: 787.5 mg/L
(NH4)3PO4: 111.8 mg/L
K2HPO4: 1750 mg/L
KH2PO4: 250 mg/L
Reference substance (positive control):
yes
Key result
Dose descriptor:
IC50
Effect conc.:
134.5 mg/L
Remarks on result:
other: reported as Ki in study
Reported statistics and error estimates:
Ki = inhibition coefficient (concentration of inhibitor giving half of the maximum inhibition) (mg/L)
Validity criteria fulfilled:
not applicable
Conclusions:
The inhibition concentration of the test material was 134.5 mg/L.
Executive summary:

The test material is unlikely to inhibit microorganisms in the activated sludge process because the concentrations giving 50% of the maximum inhibition respiration rate are higher than those often detected in activated sludge treatment plants. The toxicity ofthe test material is reduced as exposure time increases. The inhibition concentration of the test material was 134.5 mg/L.

Description of key information

The inhibition concentration of the test material was 134.5 mg/L.

Key value for chemical safety assessment

EC50 for microorganisms:
134.5 mg/L

Additional information

The test material is unlikely to inhibit microorganisms in the activated sludge process because the concentrations giving 50% of the maximum inhibition respiration rate are higher than those often detected in activated sludge treatment plants. The toxicity ofthe test material is reduced as exposure time increases. The inhibition concentration of the test material was 134.5 mg/L.