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Toxicity to microorganisms

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Reference
Endpoint:
toxicity to microorganisms, other
Remarks:
cell multiplication inhibition test
Type of information:
experimental study
Adequacy of study:
key study
Study period:
22 August 1989
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
comparable to guideline study with acceptable restrictions
Qualifier:
according to guideline
Guideline:
DIN 38412-27 (Pseudomonas putida Zellvermehrungshemmtest)
Deviations:
not specified
GLP compliance:
no
Analytical monitoring:
no
Vehicle:
no
Details on test solutions:
Concentration of the stock solution: 1250 mg/L of the delivered aqueous solution corresponding to 371.3 mg/l of pure acetoacetamide
Stock solution: 1.25 g was mixed with 800 ml of highly purified water, stirred over a period of 1 hour at a temperature of 21'C. After this time
the pH was adjusted from 6.7 to 6.9 with NaOH in a 0.1 molar solution. The resulting clear solution of the test substance was filled up with de-ionized
water to a final volume of 1000 ml and used as stock solution.
1000 mg/L and 500 mg/L (only two concentrations tested) corresponding to 297 mg/L and 149 mg/L of pure acetoacetamide
Test organisms (species):
Pseudomonas putida
Details on inoculum:
Origin Strain: Pseudomonas putida MIGULA, DSM 50026, by Deutsche Sammlung Mikroorganismen, Mascheroder Weg 1b, D-38124 Braunschweig
State of acclimatization: not acclimatized to the test substance or the reference substance
lnoculum in the test vessels: diluted to a turbidity of 5 FAU (formazine attenuation units)
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
16.5 h
Test temperature:
21°C - 22°C
Details on test conditions:
To keep the bacteria in suspension, the test batches were conducted in an incubation rotary shaker with a diameter of the shaking circle of 5 cm. The shaking frequency was set to about 220 rpm.
The tested batches were incubated for a period of 16.5 hours. The temperature was controlled at 21°C - 22'C according to the DIN standard method cited. ln this item, there is difference to the ISO draft,
in which temperature of test batches is required to be at 25°C-30°C.
The composition of reaction medium corresponds to the DIN standard cited. The concentration of the growth substrate glucose was 2000 mg/L.
Reference substance (positive control):
no
Key result
Duration:
16.5 h
Dose descriptor:
EC50
Effect conc.:
> 297 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
test mat.
Basis for effect:
growth inhibition
Remarks on result:
other: calculated
Duration:
16.5 h
Dose descriptor:
EC10
Effect conc.:
> 297 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
test mat.
Basis for effect:
growth inhibition
Remarks on result:
other: calculated from 30% solution in water
Details on results:
Testing the growth inhibition of Pseudomonas putida was conducted according to the draft of November 1978 for the standard DIN 38412, part 8 (1991).
The test proceeded without disturbances. The turbidity of the inoculum in the blank controls increased to more than the 100-fold within the test period.
The sensitivity of the used bacteria strain was not controlled with a reference substance as it was described later as a standard procedure in DIN 38412,
part 8, and in the later published standard DIN EN ISO 10712:1996-02.
As no inhibition effect occurred with Acetoacetamide in the highest two concentrations to be tested, in this test only these two concentrations had been
implemented. Five duplicates were performed with the blank control and two duplicates with the test substance. All available data are reported in this document.
Validity criteria fulfilled:
yes
Conclusions:
The results of testing the toxicity of acetoactamid (approx. 30% solution) on the growth of bacteria Pseudomonas putida cell multiplication inhibition test revealed that the EC10 and EC50 values of acetoacetamid (approx. 30% solution in water are > 1000 mg/L.
The corresponding EC10 and EC50 values of the pure substance acetoacetamide are > 297 mg/L.
Executive summary:

Testing the growth inhibition of Pseudomonas putida was conducted according to the draft of November 1978 for the standard DIN 38412, part 8 (1991).

The results of testing the toxicity of acetoactamid (approx. 30% solution) on the growth of bacteria Pseudomonas putida cell multiplication inhibition test revealed that the EC10 and EC50 values

of acetoacetamid (approx. 30% solution in water are > 1000 mg/L.

The corresponding EC10 and EC50 values of the pure substance acetoacetamide are > 297 mg/L.

Description of key information

Testing the growth inhibition of Pseudomonas putida was conducted according to the draft of November 1978 for the standard DIN 38412, part 8 (1991).

The results of testing the toxicity of acetoactamid (approx. 30% solution) on the growth of bacteria Pseudomonas putida cell multiplication inhibition test revealed that the EC10 and EC50 values

of acetoacetamid (approx. 30% solution in water are > 1000 mg/L.

The corresponding EC10 and EC50 values of the pure substance acetoacetamide are > 297 mg/L.

Key value for chemical safety assessment

EC50 for microorganisms:
297 mg/L

Additional information