1,3-diphenyl-2-thiourea

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Endpoint:

toxicity to microorganisms, other

Type of information:

experimental study

Adequacy of study:

key study

Study period:

Experimental start: 07/04/11 - Experimental end: 05/05/11

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Reason / purpose for cross-reference:

reference to same study

Qualifier:

according to guideline

Guideline:

other: OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

no

Test organisms (species):

activated sludge, domestic

Details on inoculum:

The inoculum came from the activated sludge of the biological wastewater treatment plant from Abidos (France, 64). The effluent, obtained 2 days before seeding the flasks, was centrifuged at approximately 20 °C for 20 min at 4000 g; the base was re-suspended in dilution water in order to keep the concentration unchanged with respect to the sample. The inoculum was preconditioned (aeration) until the flasks were inoculated. The amount of dry material in the inoculum, determined by desiccation at 105 °C until a constant weight is obtained, was 6.84 g/L.

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

28 d

Test temperature:

22 ± 2°C

Nominal and measured concentrations:

Nominal concentration 100 mg/L

Details on test conditions:

This test was performed according to OECD 310F with the following conditions:

N,N’-Diphenyl Thiourea has a low solubility, then 25 mg are weighted and introduce directly into the flasks, corresponding to a theoretical O2 mass of 56 mg per flask (ThOD 2.243 mg O2/mg).
A parent solution of sodium benzoate in the dilution water to 2.5 mg/mL, was used in a proportion of 10 mL for 250 mL of dilution water, i.e. 25 mg, corresponding to a theoretical O2 mass of 41.65 mg per flask (ThOD 1.67 mg O2/mg).
In the inhibition monitoring flask, equivalent quantities of test and reference items are introduced. For this flask, the corresponding theoretical mass of O2 is 97.7 mg per flask.
The flasks were installed in the respirometer where the stirring system was started. After a waiting period of approximately 0.5 hour, which is necessary to reach the thermal equilibrium of the solutions at a temperature of 22 ± 2°C, the aerated inoculum, preconditioned if required, is added to all the flasks that are then plugged.

Reference substance (positive control):

no

Duration:

28 d

Dose descriptor:

NOEC

Effect conc.:

100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: inhibition of the biodegradation of the reference test item during a ready biodegradability test

Details on results:

N,N’-Diphenyl Thiourea did not inhibit the micro-organisms as shown by the toxicity control flask where biodegradation percentage is already 38 %, higher than 25 % after 14 days.

Validity criteria fulfilled:

not applicable

Conclusions:

The toxicity of 1,3-diphenyl-2-thiourea was assessed in a ready biodegradability study performed according to OECD 301F guideline. The data obtained from the toxicity control used in this study indicates that the substance is not toxic to micro-organisms at the 100 mg/L concentration (NOEC = 100 mg/L)

Executive summary:

The toxicity of 1,3-diphenyl-2-thiourea was assessed in a ready biodegradability study performed according to OECD 301F guideline. The data obtained from the toxicity control used in this study indicates that the substance is not toxic to micro-organisms at the 100 mg/L concentration (NOEC = 100 mg/L)

Description of key information

The toxicity was assessed in a ready biodegradability study performed according to OECD 301F guideline.
28d-NOEC = 100 mg/L

Key value for chemical safety assessment

EC10 or NOEC for microorganisms:

100 mg/L

Additional information

The toxicity of 1,3-diphenyl-2-thiourea was assessed in a ready biodegradability study performed according to OECD 301F guideline. The data obtained from the toxicity control used in this study indicates that the substance is not toxic to micro-organisms at the 100 mg/L concentration (NOEC = 100 mg/L)