Benzeneacetyl chloride, 2,5-dimethyl-

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:

23 Aug - 07 Dec 2006

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Version / remarks:

2002

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

20.5 mg of the test item were dissolved in Acetonitrile and made up with Acetonitrile to the mark in a 100 mL volumetric flask to prepare a stock solution of 205 mg/L. Defined volumes of this stock solution were diluted with Milliporewater to obtain standard solutions in the range of 0.041 to 4.10 mg/L.
Although the overall method sensitivity may be better, the concentration of the lowest used calibration solution is employed as the limit of quantification.
These solutions were used to calibrate the HPLC-system.

Vehicle:

no

Details on test solutions:

To produce the only test concentration 125.6 mg of the test item were added to 1 litre of dilution water, treated for 1 hour in an ultrasonic bath and afterwards stirred for 24 h on a magnetic stirrer. Finally undissolved particles of the test item were removed by filtration using a folded filter of pore size 7-12 µm. The pH was adjusted to pH 8.0.

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Details on test organisms:

Common name: green algae
Source: Non-axenic strain of the test species obtained from "The Collection of Algal Cultures" of the Institute of Plant Physiology at the University of Gottingen (Germany).

Maintenance of stock cultures:
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 & KUHN (1977) is renewed once a week. Cell density measurements are made using a microcell counter.

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

72 h

Hardness:

The hardness of the dilution water used was 1.3 °dH (= 22.5 mg/L CaCO3).

Test temperature:

21-25 °C (+/- 2 °C)

pH:

8.0

Nominal and measured concentrations:

nominal: 100 mg/L
meassured: 97.6 - 101.6 mg/L (0 h), 98.1 - 102.2 mg/L (48 h)

Details on test conditions:

Exposure conditions
Test vessels: 300 mL Erlenmeyer flasks with cotton stoppers

Culturing apparatus:
Light chamber in which a temperature in the range 21 °C to 25 °C can be maintained at +/- 2 °C, and continuous uniform illumination is provided in the spectral range 400 to 700 nm.

Light intensity:
At the average of the test solutions, a light intensity in the range 60 to 120 µE x m-2 x s-1, or in equivalent range of 4000 to 8000 lx, is recommended to use.

Cell density measurements:
Cell densities are measured in a microcell counter or, alternatively, are determined by means of a microscopic counting chamber.

Experimental design:
1 test concentration plus 1 control
3 replicates per concentration, 6 replicates per control
initial cell density in the test cultures approximately 5000 cells per millilitre

Reference substance (positive control):

no

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Validity criteria for the measurement of the algae toxicity

Target condition according to guideline:	Actual condition according to the study:	Validity criteria met:
Exponentially growing test organisms are exposed to the test substance in batch cultures over a period of normally 72 hours.	Test organisms: Desmodesmos subspicatus Test period: 72 h	Yes
The biomass in the control cultures should have increased exponentially by a factor of at least 16 within the 72-hour test period.	Cell densitiy increased from 5000 cells/mL to 374444 cells/mL in the control.	Yes
For the final definitive test at least five concentrations, arranged in a geometric series with a factor not exceeding 3.2, should be selected. For test substances showing a flat concentration response curve a higher factor may be justified. The concentration series should preferably cover the range causing 5-75 % inhibition of algal growth rate.	Test was a limit test (conc. used was 100 mg/L).	Not applicable
The cultures should be maintained at a temperature in the range of 21 to 24 °C, controlled at ± 2°C.	Temperature was: 21 - 25 °C (+/- 2 °C)	Yes (a small deviation of 1 °C is acceptable)
The pH of the control medium should not increase by more than 1.5 units during the test.	Solvent control medium pH was 8.1 at the beginning of the test and 8.4 after 72 h.	Yes

 

Validity criteria fulfilled:

yes

Remarks:

See 'Any other information on results incl. tables'.

Conclusions:

At the only test concentration of 100 mg/L growth rate was inhibited by 1.1% compared to the control. Inhibition of biomass integral was 4.5%. All results are expressed in terms of nominal concentrations. Recovery rates ranged from 97.6 - 101.6% of nominal values at 0 hours, and from 98.1 - 102.2% of nominal values at 72 hours, respectively.

Executive summary:

A study was performed to assess adverse effects on the growth (= increase in cell density) and the growth rate (= rate of increase in cell density with time) of the planktonic freshwater algal species Desmodesmus subspicatus over several generations.

The study was conducted in accordance with EEC Methods for Determination of Ecotoxicity Annex to Directive 92/69/EEC (OJ. 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 were exposed for a period of 72 hours to a limit test concentration of nominally 100 mg/L dissolved in water. Auxiliaries used to prepare the test media were an ultrasonic bath, a magnetic stirrer and a folded filter.

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. The following values were determined:

Results	[mg/L]
ErC 50 (0-72 h)	> 100
EbC 50 (0-72 h)	> 100

At the only test concentration of 100 mg/L growth rate was inhibited by 1.1% compared to the control. Inhibition of biomass integral was 4.5%.

Recovery rates ranged from 97.6 - 101.6% of nominal values at 0 hours, and from 98.1 - 102.2% of nominal values at72 hours, respectively.

Description of key information

At the only test concentration of 100 mg/L growth rate was inhibited by 1.1% compared to the control. Inhibition of biomass integral was 4.5%. All results are expressed in terms of nominal concentrations. Recovery rates ranged from 97.6 - 101.6% of nominal values at 0 hours, and from 98.1 - 102.2% of nominal values at72 hours, respectively.

Key value for chemical safety assessment

EC50 for freshwater algae:

100 mg/L

Additional information

Should read > 100 mg/L.