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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:
1995
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
other: German standard method "DIN 38412, part 8 (Pseudomonas Zellvermehrungshemm-Test)"
Deviations:
no
GLP compliance:
yes
Analytical monitoring:
no
Vehicle:
no
Details on test solutions:
10 mL of nutrient solution were added to the 80 mL test substance solutions. Finally, 10 mL of the inoculum were added. Each test concentration and the control without test compound were set up in duplicate. Additionally, one test vessel without inoculum was used for each test concentration and the control in orderto analyse the substance-dependent turbidity (blank).
Test organisms (species):
Pseudomonas putida
Details on inoculum:
- The microorganisms for the pre-culture were taken from a stock up to seven days old, approx. 7 hours prior to the start of the incubation in the test
- They were kept in a pre-culture nutrient solution; 900 mL sterile distilled water were added; The pre-culture had a turbidity of 0.058 extinction units (equivalent to approximately TE/F 10) on the spectrophotometer
- This pre-culture was incubated for 7 hours at room temperature
- After the incubation period the turbidity of the pre-culture was measured with 0.430 extinction units, and the pre-culture was diluted to 0.214 extinction units (equivalent to approximately TE/F 50) with the pre-culture medium, ready to be used as inoculum
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
16 h
Hardness:
No data
Test temperature:
9.8 - 21.6°C
pH:
8.3
Dissolved oxygen:
No data
Salinity:
n.a.
Nominal and measured concentrations:
The dilutions used were the undiluted saturated solution and 1:10, 1:100, and 1:1000 dilutions thereof. The saturated solution had a concentration of 49.5 mg/L, measured by TOC analysis.
Details on test conditions:
- The test vessels were incubated on a shaker at room temperature (approx. 21°C)
- The test organisms were incubated with androstendione for 16 hours
- The test concentrations were prepared by using dilutions of a saturated solution
- The dilutions used were the undiluted saturated solution and 1:10, 1:100, and 1:1000 dilutions thereof
- All groups were set up in triplicate
- Growth was determined by analysing the turbidity of the solutions in a photometer at a wavelength of 436 nm, expressed as TE/F values (turbidity units in relation to a defined formazin solution)
Duration:
16 h
Dose descriptor:
EC10
Effect conc.:
>= 49.5 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
growth inhibition
Details on results:
Up to a saturated solution, there was no effect on growth of Pseudomona putida. Therefore, the EC10 was determined to be higher than a saturated solution (49.5 mg/L).

Validity criteria fulfilled:
yes
Conclusions:
Up to a saturated solution, there was no effect of Androstendion on growth of microorganism Pseudomona putida. Therefore, the 16 h-EC10 was determined to be higher than a saturated solution (49.5 mg/L).
Executive summary:

According to the German standard method "DIN 38412, part 8 (Pseudomonas Zellvermehrungshemm-Test)" the test organisms were incubated with Androstendion for 16 hours. The test concentrations were prepared by using dilutions of a saturated solution. The dilutions used were the undiluted saturated solution and 1:10, 1:100, and 1:1000 dilutions thereof. All groups were set up in triplicate. The saturated solution had a concentration of 49.5 mg/L, measured by TOC analysis. Growth was determined by analysing the turbidity of the solutions in a photometer, expressed as TE/F values (turbidity units in relation to a defined formazin solution).

Up to a saturated solution, there was no effect on growth of Pseudomona putida. Therefore, the EC10 was determined to be higher than a saturated solution (49.5 mg/L). This toxicity study is classified as acceptable and satisfies the guideline requirements for the toxicity study to microoragnisms.

Description of key information

Up to a saturated solution, there was no effect of Androstendion on growth of microorganism Pseudomona putida. Therefore, the 16 h-EC10 was determined to be higher than a saturated solution (49.5 mg/L).

Key value for chemical safety assessment

EC10 or NOEC for microorganisms:
49.5 mg/L

Additional information

"should read: EC10(16h) >= 49.5 mg/L"