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Toxicity to microorganisms

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Reference
Endpoint:
toxicity to microorganisms
Type of information:
experimental study
Adequacy of study:
key study
Study period:
4 September - 28 September 1989
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Non GLP, guideline not stated, available as unpublished report.
Qualifier:
no guideline followed
Principles of method if other than guideline:
The inhibitory effect of polysulfide di-tert-dodecyl was tested by comparing cell growth of Pseudomonas putida strain in the test substance against controls. The test substance is insoluble in water and three possibilities for testing were considered: by adding direct product due in mid-cultivation; by dispersing the product in water using an ultrasonic probe; by dissolving the product in a third solvent (Dimethylformamide) miscible with water. The biomass produced was determined by turbidimetric measure after an incubation period of 16 ± 1 hour at 21 ± 1°C.
GLP compliance:
no
Specific details on test material used for the study:
Details on properties of test surrogate or analogue material (migrated information):
No data reported
Analytical monitoring:
yes
Details on sampling:
The cell density (biomass Product-) was determined after an incubation period of 16 ± 1 hours.
Vehicle:
no
Details on test solutions:
Since polysulfide di-tert-dodecyl was insoluble in water, 3 methods of introduction of polysulfide di-tert-dodecyl were used:
1- polysulfide di-tert-dodecyl was introduced directly in 100 mL of test medium by fractions from 10 mg to 1000mg. Flasks were placed under agitation during 16 hours at 21°C.
2- Formation of initial emulsion 5g/L of deionised water; by ultra sounds. Different dilutions of this emulsion were prepared until 1000mg/L. Flasks were placed under agitation during 16 hours at 21°C.
3- Dissolution of polysulfide di-tert-dodecyl in DMF(diméthylformamide) forming an initial solution at 5g/L. In the different dilutions of this initial solution, the limit of DMF must be < 0.2% , above this limit the DMF have an inhibitory effect > 10% to bacteria. Flasks were placed under agitation during 16 hours at 21°C.
Test organisms (species):
Pseudomonas putida
Details on inoculum:
A preculture was seeded by a bacterial suspension on levied miliu agar (under the age of 7 days) and incubated for 7 hours to obtain an exponential growth phase. The bacterial suspension with a turbidity of 30 to 60 NTU thus obtained served as inoculum for seeding the test medium.
Test type:
not specified
Water media type:
freshwater
Total exposure duration:
16 h
Remarks on exposure duration:
Sterile water was used
Post exposure observation period:
No data reported
Hardness:
No data reported
Test temperature:
21˚C
pH:
7.2 + 0.2
Dissolved oxygen:
No data reported
Salinity:
No data reported
Nominal and measured concentrations:
0; 10; 13; 17; 22; 29 and 37 mg/L.
Details on test conditions:
Orbital shaker flasks (100 rpm) incubated in the dark, thermostated at 21 ± 1°C, for 16 ± 1 hours. Inoculum was obtained from a preculture in logarithmic phase of coissance, having reached a turbidity of 30 to 50 NTU. Concentration 'test: maximum dose tested polysulfide di-tert-dodecyl: 10g/L (10,000 mg/L). Measurement of bacterial biomass: by turbidimetry expressed in NTU (nephelometric turbidity units). Controls used but unclear whether replicates used.
Reference substance (positive control):
yes
Remarks:
3, 5 dichlorophenol
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
10 mg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
not specified
Basis for effect:
growth inhibition
Remarks on result:
other: Solvent added
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
10 g/L
Nominal / measured:
meas. (not specified)
Conc. based on:
not specified
Basis for effect:
growth inhibition
Remarks on result:
other: Ultrasonic method
Details on results:
Direct addition to the middle culture: In general, turbidity was of same order or higher than those in the controls. The product tended to form oily globules in the bottom of the flask and adsorbed on the wall when in turmoil. It has not been possible to determine an inhibitory effect up to a dose of 10 g/L for which it was found that bacterial growth was superior to that of controls.
Ultrasonic dispersion: The turbidity of the emulsion obtained at the limit of testing reads more or less as random. Emulsion diluted in the test medium and put into agitation for 16 hours seems to have been stable (formation of oily droplets, adsorption on the wall), and yet an inhibitory effect was not observed under a concentration of 1000 mg/L.
Dissolution in dimethylformamide: The solution was added into the middle of culture. The test was limited by turbidity characteristic of the product and the contribution of the solvent, with the maximum concentration tested being 10 m/L. A significant inhibitory effect was not observed.
Results with reference substance (positive control):
No data reported
Reported statistics and error estimates:
No data reported
Validity criteria fulfilled:
not applicable
Conclusions:
The toxicity of polysulfide di-tert-nonyl to micro-organisms has been read across from polysulfide di-tert-dodecyl. The study attempts to test an insoluble substance in different types of solutions. No effect concentrations ranged 10mg/L (solvent added) - 10000 mg/L (ultrasonic method); direct addition of polysulfide in the GST middle culture did not determine an inhibitory effect up to a dose of 10 g/L but found that bacterial growth was superior to that of controls.
Executive summary:

The toxicity of polysulfide di-tert-nonyl to micro-organisms has been read across from polysulfide di-tert-dodecyl. Hervouet (1989) is 16 hour, freshwater study on Pseudomonas putida following the method ISO/TC 147/SC 5 WG 1(N111). Due to the low solubility of the substance, several solutions were prepared, leading to a range of No Effect Concentrations from 10mg/L to 10 g/L. The study is considered suitable for use for this endpoint.

Description of key information

The toxicity of polysulfide di-tert-nonyl to micro-organisms has been read across from polysulfide di-tert-dodecyl. The study attempts to test an insoluble substance in different types of solutions.  No effect concentrations ranged from 10mg/L (solvent added) to 10000 mg/L (ultrasonic method); direct addition of polysulfide in the GST middle culture did not determine an inhibitory effect up to a dose of 10 g/L but found that bacterial growth was superior to that of controls.

Key value for chemical safety assessment

EC10 or NOEC for microorganisms:
10 g/L

Additional information

The toxicity of polysulfide di-tert-nonyl to micro-organisms has been read across from polysulfide di-tert-dodecyl. Hervouet (1989) is 16 hour, freshwater study on Pseudomonas putida following the method ISO/TC 147/SC 5 WG 1(N111). Due to the low solubility of the substance several solutions were prepared, leading to a range of No Effect Concentrations from 10mg/L to 10 g/L. The study is considered suitable for use for this endpoint.