Reaction mass of 3-Isocyanatolmethyl-3,5,5-trimethylcyclohexyl isocyanate (Isophorone diisocyanate) with 4-Methylpentan-2-one oxime.

Toxicity to microorganisms

Administrative data

Endpoint:

activated sludge respiration inhibition testing

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2010

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

comparable to guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2010

Report date:

2010

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

Deviations:

no

GLP compliance:

no

Remarks:

In accordance with ISO/IEC 17025

Test material

Test material information

Test material form:

liquid

Test solutions

Vehicle:

no

Test organisms

Test organisms (species):

activated sludge, domestic

Details on inoculum:

Not adapted and not pre-conditioned activated sludge from the aeration tank of the ARA Werdhölzli (CH-8048 Zürich), a municipal biological waste water treatment plant. 1.5 g/l dry matter in the final mixture.

Study design

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

Test conditions

Hardness:

36.6-37.5 (total hardness)

Test temperature:

22 ± 2 °C

pH:

7.2-7.4

Conductivity:

691-731 uS/cm (20ºC)

Nominal and measured concentrations:

The nominal concentrations of SPRPUZP were 125, 250, 500, 1000 and 2000 mg/l, respectively. These test concentrations were prepared by direct addition of the test substance.

No analysis of test concentrations was conducted. For the calculation of the EC10, EC20, EC50 and EC80 values the nominal content of the test substance in the test media was used (calculations based on assumption that test material consists of 100% a.i.).

Details on test conditions:

Test units: 1000 ml flasks containing a total volume of test suspension of 500 ml; aerated by shaking (150 r.p.m.)
Measuring apparatus: 300 ml flat bottom BOD flasks; polarographic oxygen electrode, connected to a potentio-metric recorder

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol

Results and discussion

Effect concentrations

Effect concentrations 1

Duration:

3 h

Dose descriptor:

EC10

Effect conc.:

193 mg/L

Nominal / measured:

estimated

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Effect concentrations 2

Duration:

3 h

Dose descriptor:

other: EC20

Effect conc.:

325 mg/L

Nominal / measured:

estimated

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Effect concentrations 3

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

1 572 mg/L

Nominal / measured:

estimated

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Effect concentrations 4

Duration:

3 h

Dose descriptor:

other: EC80

Effect conc.:

> 2 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

Not subject to classification and labelling.

Executive summary:

The inhibitory effect of SPRPUZP on the oxygen consumption of activated sludge microorganisms of a municipal sewage treatment plant was investigated under aerobic static conditions. The inhibitory effect may include the effect on respiration and nitrification. The exposure time of the test substance on the activated sludge was 3 h.
The nominal concentrations of SPRPUZP were 125, 250, 500, 1000 and 2000 mg/l, respectively. These test concentrations were prepared by corresponding dilution of stock solutions of the test substance.
No chemical analysis of test concentrations was conducted. For the calculation of the effective concentration leading to 10, 20, 50, and 80% respiration inhibition (EC10, EC20, EC50, EC80) the nominal content of the test substance was used, assuming the test compound to be stable in water over 3 h.
The following respiration inhibition of the activated sludge compared to the two blank controls was observed:
2000 mg/l (60%), 1000 mg/l (26%), 500 mg/l (46%). No significant toxic effects (<10% respiration inhibition) were observed at 250 and 125 mg/l.
Based on the inhibition data the EC10 value of SPRPUZP was calculated to be 193 mg/l, the EC20 value 325 mg/l and the EC50 value 1572 mg/l (95% confidence interval not assessable). The EC80 value was estimated to be >2000 mg/l.