4,4'-isopropylidenediphenyl dicyanate

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

February - June 2016

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

EU Method C.3 (Algal Inhibition test)

Deviations:

no

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Freshwater Alga and Cyanobacteria, Growth Inhibition Test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Test Substance Name: LZ 514
- Source: Lonza Ltd, Visp/Switzerland
- Lot/batch No. of test material: 5011
- Expiration date of the lot/batch: 2nd December 2017
- Manufacture date: 3rd December 2015

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage conditions: Controlled room temperature (15-25 ºC, below 70 RH%), protected from light and humidity.
- Stability under test conditions: stable
- Safety precautions: Routine safety precautions (lab coat, gloves, safety glasses, face mask) for unknown materials were applied to assure personnel health and safety.

Analytical monitoring:

yes

Details on sampling:

at start and end of each renewal

Vehicle:

no

Details on test solutions:

Because the Test Item is poorly soluble in water, a test solution was prepared using a saturated solution method according to the Guidance Document on Aquatic Toxicity Testing of Difficult Substances and Mixtures, OECD No. 23. A saturated Test Item solution (nominal loading rate of 100 mg/L) was prepared by
dispersing/dissolving the amount of Test Item into the test medium (OECD Medium) one day before the start of the test. This solution was shaken for about 24 hours at approximately 30°C and then was equilibrated for about 2 hours at approximately 20°C. The non-dissolved test material was removed by filtration through a fine (0.22 μm) filter to give the 100 % saturated solution. The test solutions were prepared by appropriate diluting of this stock solution and these solutions were distributed into the appropriate test flasks.

Test organisms (species):

Raphidocelis subcapitata (previous names: Pseudokirchneriella subcapitata, Selenastrum capricornutum)

Details on test organisms:

TEST ORGANISM
- Common name: Pseudokirchneriella subcapitata (formerly known as Selenastrum capricornutum)
- Strain: 61.81 SAG (identical strains: CCAP 278/4; UTEX 1648; ATCC 22662)
- Source (laboratory, culture collection): SAG: Collection of Algal Cultures, Inst. Plant Physiology, and University of Göttingen, GERMANY.
- Culturing: Cultured under standardised conditions (see OECD 201) in the Ecotoxicological Laboratory of CiToxLAB Hungary Ltd.
- Breeding conditions: Stock cultures are small algal colonies that are inoculated onto agar regularly. These are transferred to fresh agar medium at least once every two months and are maintained under standardised conditions according to the test guidelines. The pre-culture is intended to give a quantity of algae
suitable for the inoculation of test cultures. The preculture was prepared with the OECD algal growth medium, incubated under the same conditions as the test
and used when still growing exponentially, normally after an incubation period of about three days. When the algal cultures contain deformed or abnormal cells, they were discarded.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Post exposure observation period:

none

Hardness:

reconstituted algal growth medium (OECD medium, according to OECD 201); total hardness of ca. 24 mg/L (as CaCO3)

Test temperature:

The temperature was 23.1°C measured in the flask and were in the range of 23.0 and 23.4 °C measured within the climate chamber.

pH:

The range of the pH was 7.60 – 8.92 during the experiment.

Salinity:

freshwater used

Nominal and measured concentrations:

The following nominal concentrations were tested: 6.25, 12.5, 25.0, 50.0 and 100 % saturated solutions. Test concentrations were analytically determined at the start of the experiment and 24-hour intervals thereafter in order to better define loss of the test substance during the exposure period. The corresponding measured geometric mean and calculated Test Item concentrations were 0.0001, 0.00029, 0.00089, 0.00272 and 0.00832 mg/L.

Details on test conditions:

Light Intensity: The algal culture flasks were continuously illuminated. The light intensity at the position occupied by algal culture flasks during the test was about 8145 lux (equivalent to ~110 μE/m2/s), which was ensured with fluorescent lamps (with a spectral range of 400-700 nm).

Reference substance (positive control):

no

Key result

Duration:

72 h

Dose descriptor:

EC50

Remarks:

expressed as ErC50

Effect conc.:

0.003 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

EC50

Remarks:

expressed as EyC50

Effect conc.:

0.002 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

other: yield

Key result

Duration:

72 h

Dose descriptor:

EC50

Remarks:

expressed as EbC50

Effect conc.:

0.002 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

biomass

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

0 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

other: for growth rate, yield and biomass

Key result

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

0.001 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

other: for growth rate, yield and biomass

Results with reference substance (positive control):

no reference substance tested

Reported statistics and error estimates:

The ErC50, EbC50 and EyC50 values of the Test Item and their confidence limits were calculated using Probit analysis by TOXSTAT software.

Validity criteria fulfilled:

yes

Conclusions:

Under the conditions of this Algal growth inhibition test, the calculated and observed endpoints for the effect of the test item were:
- 72h EC50 values: ErC50 0.0033 mg/L (growth rate / measured); EyC50 0.0017 mg/L (yield / measured); EbC50 0.0019 mg/L (growth rate / measured)
- 72h No-Observed Effect Concentration (NOEC): 0.00029 mg/L (growth rate, yield and biomass / measured)

Executive summary:

The effect of the test item was assessed on algal growth using the unicellular green alga Pseudokirchneriella subcapitata, over an exposure period of 72 hours. The following nominal concentrations were tested: 6.25, 12.5, 25.0, 50.0 and 100 % saturated solutions. Test concentrations were analytically determined at the start of the experiment and 24-hour intervals thereafter in order to better define loss of the test substance during the exposure period. The corresponding measured geometric mean and calculated Test Item concentrations were 0.0001, 0.00029, 0.00089, 0.00272 and 0.00832 mg/L. The biological results are based on the measured and calculated concentrations.

The substance was found to be very toxic to Green algae. With respect to the inhibitory effect of the test item, the 0-72 h average specific growth rates, yield and areas were significantly different from that of the control group at the concentrations of 0.0089 (calculated), 0.00272 mg/L (measured) and at 0.00832 mg/L (measured). The overall NOEC was determined as 0.00029 mg/L (calculated), the overall LOEC was determined as 0.00089 mg/L (calculated).

Description of key information

The effect of the test item was assessed on algal growth using the unicellular green alga Pseudokirchneriella subcapitata, over an exposure period of 72 hours. The following nominal concentrations were tested: 6.25, 12.5, 25.0, 50.0 and 100 % saturated solutions. Test concentrations were analytically determined at the start of the experiment and 24-hour intervals thereafter in order to better define loss of the test substance during the exposure period. The corresponding measured geometric mean and calculated Test Item concentrations were 0.0001, 0.00029, 0.00089, 0.00272 and 0.00832 mg/L. The biological results are based on the measured and calculated concentrations.

The substance was found to be very toxic to Green algae. With respect to the inhibitory effect of the test item, the 0-72 h average specific growth rates, yield and areas were significantly different from that of the control group at the concentrations of 0.0089 (calculated), 0.00272 mg/L (measured) and at 0.00832 mg/L (measured). The overall NOEC was determined as 0.00029 mg/L (calculated), the overall LOEC was determined as 0.00089 mg/L (calculated).

Key value for chemical safety assessment

EC50 for freshwater algae:

0.002 mg/L

EC10 or NOEC for freshwater algae:

0 mg/L

Additional information

Source: GLP-report