Reaction mass of 2-ethylhexyl (6-isocyanatohexyl)-carbamate and bis(2-ethylhexyl) 1,6-hexan-1,6-diylbiscarbamate

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

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:

equivalent or similar to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Deviations:

no

GLP compliance:

yes

Analytical monitoring:

yes

Details on sampling:

- Sampling schedule: Control and test concentration at 0 and 72 hours

Vehicle:

no

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Details on test organisms:

TEST ORGANISM:
- Source : Strain of the test species obtained from 'The Collection of Algal Cultures' of the Institute of Plant Physiology at the University of Göttingen (Germany).
- Maintenance and Acclimatisation : Exponentially-growing stock cultures are maintained in the test facility under constant temperature conditions (23 +/- 2 °C) at a light intensity in the range 60 – 120 μE. x m-2 x s-1 (measured in the range 400 to 700 nm using a spherical quantum flux meter). The nutrient medium (according to BRINGMANN & KÜHN (1977) is renewed once a week. Cell density measurements are made using a microcell counter.
- Preparation of pre cultures : Pre cultures were set up three days before the start of a test. They were grown under identical exposure conditions as the stock cultures, except from the use of a different growth medium.
- Test cultures : The algal inocula for the test were taken from an exponentially growing pre culture and were mixed with the nutrient medium to make up to a final cell density of about 5000 cells per millilitre in the test medium.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Hardness:

1.3 °dH, corresponding to 22.5 mg/L CaCO3

Test temperature:

No data

pH:

pH range: 8.3/7.9 (at test start, after 72 h)

Dissolved oxygen:

No data

Salinity:

n.a.

Nominal and measured concentrations:

Nominal concentrations: 0.13, 0.25, 0.5 and 1 mg/L
Measured concentrations: 0.073, 0.132, 0.307 and 0.730 mg/L (HPLC mean value [mg/L] after 72 h)
Measured concentration of 1.0 mg/L without algal inoculum after 72 hours: 0.894 mg/L

Details on test conditions:

PRETREATMENT OF TEST ITEM:
- 1.4 mg of the test item were added into 1 L of dilution water 
- treated for 60 seconds at 8000 rpm with an ultra turrax, afterwards stirred for 24 h on a magnetic stirrer

TEST SYSTEM:
- test vessels: 300 mL Erlenmeyer flasks with cotton stoppers
- culturing apparatus: temperature 21 to 25 °C, continuous uniform illumination (spectral range 400 to 700 nm) 
- light intensity: 60 -120 µE x mE-2 x sE-1 or an equivalent range of  4000-8000 lx
- test cultures: final cell density 5000 cells/mL
- test concentration: 4 (0.13, 0.25, 0.50 1.0 mg/L) plus 1 control
- replicates: 3 (per concentration), 6 (per control)
- method of administration: stock solution
- test parameter: growth and growth rate
- chemical analysis: HPLC + MSD-detection

MONITORING DATA (concerning the highest test concentration):
- cell density measurements of growth (daily) 
- analysis: twice (at test start, after 72 h)

Key result

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

0.282 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: 0.235-0.321 mg/L

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

1.002 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: 0.905-1.145 mg/L

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

0.163 mg/L

Nominal / measured:

estimated

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

0.189 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

biomass

Remarks on result:

other: 0.081-0.267 mg/L

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

0.488 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

biomass

Remarks on result:

other: 0.382-0.646 mg/L

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

0.163 mg/L

Nominal / measured:

estimated

Conc. based on:

test mat.

Basis for effect:

biomass

Details on results:

Recovery rates ranged from 77.5-83.1 % of nominal values at 0 hours, and from 52.6-89.4 % of nominal values at 72 hours, respectively.

Validity criteria fulfilled:

yes

Remarks:

(- The factor of biomass parameter 80.8 >16; - The mean of the replicate coefficient of variation in the section-by-section growth 8.0 % <35 %; - The coefficient of variation of the mean specific growth rate replicates in the control 0.9 % <7 %.)

Conclusions:

An ErC50 of 1.002 mg/L was determined and a NOEC[r] of 0.163 mg/L was calculated after 72 hrs. Recovery rates ranged from 77.5 - 83.1 % of nominal values at 0 hours, and from 52.6 - 89.4 % of nominal values at 72 hours, respectively.

Executive summary:

The study was conducted in accordance with EEC Methods for Determination of Ecotoxicity Annex to Directive 92/69/EEC (O.J. No. L383A, 29.12.92) Part C, Method 3 'Algal inhibition test' which is in most parts equivalent to the OECD Guideline for Testing of Chemicals No. 201 'Alga, Growth Inhibition Test'. Exponentially growing algal cells of the planktonic freshwater algal species Desmodesmus subspicatus were exposed for a period of 72 hours to a range of concentrations, nominally 0.13, 0.25, 0.5 and 1.0 mg/L of the substance dissolved in water. Auxiliaries used to prepare the test media were an ultra turrax and a magnetic stirrer. The cell densities were measured at 24 hour intervals. Inhibition of the algal population was measured as reduction in growth (index b) and growth rate (index r), relative to control cultures grown under identical conditions. Growth and growth rates were used to calculate a No Observed Effect Concentration and a Lowest Observed Effect Concentration according to DUNNETT (1955, 1964). An ErC50 of 1.002 mg/L was determined and a NOEC[r] of 0.163 mg/L was calculated after 72 hrs. Recovery rates ranged from 77.5 - 83.1 % of nominal values at 0 hours, and from 52.6 - 89.4 % of nominal values at 72 hours, respectively.

This toxicity study is classified as acceptable and satisfies the guideline requirements for the Algae study.

Description of key information

An ErC50 of 1.002 mg/L was determined and a NOEC[r] of 0.163 mg/L was calculated after 72 hrs. Recovery rates ranged from 77.5 - 83.1 % of nominal values at 0 hour, and from 52.6 - 89.4 % of nominal values at 72 hours, respectively (Weyers, 2007).

Key value for chemical safety assessment

EC50 for freshwater algae:

1.002 mg/L

EC10 or NOEC for freshwater algae:

0.163 mg/L