Cyclohexane, 5-isocyanato-1-(isocyanatomethyl)-1,3,3-trimethyl-, homopolymer, acetone oxime-blocked

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Endpoint:

activated sludge respiration inhibition testing

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2012-02-01 to 2012-02-02

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

The test item was weighed out directly in an Erlenmeyer flask, filled up with 200 mL demineralised water and stirred overnight.

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

activated sludge of the municipal treatment plant of Hildesheim
The sludge was washed twice and adjusted with chlorine free tap water in order to achieve a dry sludge concentration of 3.0 g/L +/_ 10 %. The sludge was used within 24 h after sampling.
Dry sludge concentration: 2.76 g/L (corresponding to 1.38 g/L suspended solids in the test vessels)

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

3 h

Test temperature:

nominal 18 - 22 °C, actual measured 19 - 21 °C

pH:

The pH value of the activated sludge was determined prior to test start. The pH value of the synthetic waste water was determined prior to use and adjusted to 7.5 ± 0.5 was not necessary

Dissolved oxygen:

dissolved oxygen concentration above 60 - 70 % saturation

Nominal and measured concentrations:

1000 mg/L (nominal)

Reference substance (positive control):

yes

Remarks:

Copper (II) sulphate pentahydrate p.a.

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

> 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Duration:

3 h

Dose descriptor:

NOEC

Effect conc.:

> 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Results with reference substance (positive control):

The EC50-value for the reference item was 108 mg/L (Range of validity (EC50): 53 - 155 mg/L)

Reported statistics and error estimates:

The NOEC was determined by calculation of statistical significance of the inhibition of respiration in comparison to the control. One Way Analysis of Variance (ANOVA) was used for NOEC calculations. Before running the One Way Analysis of Variance a Normality test and an Equal Variance test were done first. P-values for both Normality and Equal Variance test were 0.05. The alpha-value (acceptable probability of incorrectly concluding that there is a difference) is 0.05.
The EC-value of the reference item was calculated by by linear regression using software GraphPad Prism5, GRAPHPAD SOFTWARE, INC. Calculation of the confidence intervals for the EC50-value was carried out using standard procedures.

Validity criteria fulfilled:

yes

Conclusions:

The NOEC of the test item VESTANAT B 1370 (solvent free) is 1000 mg/L.
VESTANAT B 1370 (solvent free) caused no inhibitory effects on activated sludge of a municipal sewage treatment plant at the limit concentration of 1000 mg/L.

Executive summary:

A Respiration Inhibition Test with activated sludge according to OECD Guideline No. 209 (2010) was carried out with the test item Vestanat B 1370 (solvent free; batch number: 11 -22 -18) from 2012-02-01 to 2012 -02 -02 at Dr. U. Noack Laboratorien.Test system was activated sludge of the municipal treatment plant of Hildesheim. The test was carried out under static conditions with the limit concentration 1000 mg/L. The respiration rates of the control, reference and test item replicates were measured after a contact time of three hours by means of oximeter immediately after transferring the solution to the measuring cell and the oxygen depletion was recorded for at least 3 minutes on a flat bed recorder.

The inhibitory effects of the test and reference item were determined in comparison to the control respiration rates. The inhibition of respiration for the test item replicates ranged from -9 to -7 %.

In order to check the activity of the test system and the test conditions a reference test was carried out with copper (II) sulphate pentahydrate as reference item and the reference toxicity was determined. The EC₅₀-value for the reference item was 108 mg/L.

Description of key information

A Respiration Inhibition Test with activated sludge according to OECD Guideline No. 209 (2010) was carried out with the test item Cyclohexane, 5-isocyanato-1-(isocyanatomethyl)-1,3,3-trimethyl-, homopolymer, acetone oxime-blocked. Test system was activated sludge of a municipal treatment plant. The test was carried out under static conditions with the limit concentration of 1000 mg/L. The respiration rates of the control, reference and test item replicates were measured after a contact time of three hours by means of oximeter immediately after transferring the solution to the measuring cell and the oxygen depletion was recorded for at least 3 minutes on a flat bed recorder.
The inhibitory effects of the test and reference item were determined in comparison to the control respiration rate. The inhibition of respiration for the test item replicates ranged from -9 to -7 %.
In order to check the activity of the test system and the test conditions a reference test was carried out with copper (II) sulphate pentahydrate as reference item and the reference toxicity was determined. The EC50-value for the reference item was 108 mg/L.

Key value for chemical safety assessment

EC10 or NOEC for microorganisms:

1 000 mg/L

Additional information

The NOEC of the test item Cyclohexane, 5-isocyanato-1-(isocyanatomethyl)-1,3,3-trimethyl-, homopolymer, acetone oxime-blocked is 1000 mg/L. The test substance caused no inhibitory effects on activated sludge of a municipal sewage treatment plant at the limit concentration of 1000 mg/L.