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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
Study period:
Dec 12, 2006 -Feb 26, 2007
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: For this endpoint control data data from a GLP compliant biodegradation study according to OECD TG 301F are available.
Qualifier:
according to
Guideline:
other: OECD TG 301F
Deviations:
no
GLP compliance:
yes (incl. certificate)
Analytical monitoring:
yes
Test organisms (species):
activated sludge, domestic
Details on inoculum:
- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure):activated sludge, micro organisms from a domestic waste water treatment plant- OriginMunicipal sewage treatment plant, Rossdorf, Germany-Conditioning:The activated sludge used for this study was washed by centrifugation and the supernatant liquid phase was decanted. The solid material was re-suspended in tap water and centrifuged again. This procedure was repeated twice. An aliquot of the final sludge suspension was weighed, dried and the ratio of wet sludge to its dry weight was determined. Based on this ratio, calculated aliquots of washed sludge suspension, corresponding to 1.5 g dry material per litre were mixed with test water.
Test type:
static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
28 d
Hardness:
250 g/L
Test temperature:
22°C
pH:
7.6
Dissolved oxygen:
saturated
Duration:
28 d
Dose descriptor:
NOEC
Effect conc.:
30 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: inhibition of degradation of reference material
Details on results:
Results of the Toxicity ControlIn the toxicity control containing both the test item and reference 27% biodegradation was noted within 14 days and 28% biodegradation was determined after 28 days of incubation. According to test guidelines the test item can be assumed to be not inhibitory on the activated sludge micro organisms because degradation was > 25 % within 14 days.
Validity criteria fulfilled:
yes
Conclusions:
From this degradation study a NOEC of 30 mg/L (nominal) can be derived for the activated sludge activity.
Executive summary:

Purpose

The test item was investigated for its ready biodegradability in a Manometric Respirometry Test over a period of 28 days. The biodegradation was followed by the oxygen uptake of the micro organisms during exposure. As a reference item sodium benzoate was tested simultaneously under the same conditions as the test item, and functioned as a procedure control.The GLP study was performed according to OECD TG 301F. The toxicity control of this study provides data to derive a NOEC for the activated sludge respiration inhibition.

Results

In the toxicity control containing both the test item and reference 27% biodegradation was noted within 14 days and 28% biodegradation was determined after 28 days of incubation. According to test guidelines the test item can be assumed to be not inhibitory on the activated sludge micro organisms because degradation was > 25 % within 14 days.

Conclusion

From this degradation study a NOEC of 30 mg/L (nominal) can be derived for the activated sludge activity.

Description of key information

For this endpoint data from a degradation study (Toxicity control) have been provided. The NOEC derived from this study amounts to 30 mg/L.

Key value for chemical safety assessment

EC10 or NOEC for microorganisms:
30 mg/L

Additional information