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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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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:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Version / remarks:
2006
Deviations:
no
Qualifier:
according to
Guideline:
EU Method C.3 (Algal Inhibition test)
Version / remarks:
2009
Deviations:
no
GLP compliance:
yes
Specific details on test material used for the study:
Batch number : 0900250090
Date of receipt : 2017-02-06
Expiry date : 2018-01-20
Water solubility : 7.398 g/L at 20 °C
Analytical monitoring:
yes
Remarks:
HPLC analysis and UV/VIS-detection
Details on sampling:
Stability of test concentration/s during exposure : Examined by chemical analysis (HPLC) at 0, 24, 48 and 72 hours
Vehicle:
no
Details on test solutions:
Pre-treatment of test item and preparation of test item concentrations
A stock solution was prepared to give the desired series of test concentrations. 200.0 mg of the test item were added to 2 litres of dilution water, treated for 60 seconds at 8000 rpm with an ultra turrax and stirred for 24 h on a magnetic stirrer. Undissolved particles of the test item were removed by filtration using a folded filter with a pore size of 7 - 12 μm and an aseptic filter Sartobran sterile capsules with a pore size of 0.45 μm + 0.2 μm. The pH was measured to be 7.5.
To produce the different test item concentrations appropriate amounts of the stock solution were diluted with dilution water to a volume of 100 mL and 0.442 mL of the algal inoculum was added to each replicate resulting in a final cell density of 5000 cells/mL. For each test item concentration and the control 3 replicates were prepared. All flasks were sealed with cotton stoppers.
Test organisms (species):
Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)
Details on test organisms:
Strain No. 86.81 SAG
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 were maintained in the test facility under constant temperature conditions (21 - 24 °C with a maximum fluctuation of +/- 2 °C) at a light intensity in the range 60 to 120 μE x m-2 x s-1 (measured in the range 400 to 700 nm using a spherical quantum flux meter). The growth medium (according to BRINGMANN & KÜHN (1977) was renewed once a week. Cell density measurements were made using a microcell counter, Sysmex F300, Digitana.
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 growth medium (annex 1) to make up to a final cell density of about 5000 cells per millilitre in the test medium.
Test type:
not specified
Water media type:
other: sterilised deionised pure water
Limit test:
no
Total exposure duration:
72 h
Remarks on exposure duration:
Cell densities were recorded at 24 hour intervals. The 72 hour EC 10 and EC 50 were calculated by probit analysis.
Hardness:
1.3 °dH corresponding to 22.5 mg/L CaCO3
Test temperature:
21 - 24 °C
pH:
7.6 - 9.3
Nominal and measured concentrations:
Nominal concentrations: 0.1, 1.0, 10 and 100 mg/L
Test item concentration/s : 3.13, 6.25, 12.5, 25, 50 and 100 mg/L
Details on test conditions:
Exposure conditions
Test vessels : 300 mL Erlenmeyer flasks with cotton stoppers, test volume: 100 mL
Culturing apparatus : Shaking incubator in which a temperature in the range 21 °C to 24 °C was maintained at +/- 2 °C, and continuous uniform illumination was provided in the spectral range 400 to 700 nm. Temperature was measured and recorded daily.
Light intensity : A light intensity ranging from 60 to 120 μE x m-2 x s-1, or an equivalent range of 4000 to 8000 lux, was measured. The light intensity was checked before the start of the study.
Cell density
measurements : Cell densities were measured in a microcell counter (Sysmex F300, Digitana) by taking small aliquots from each test flask, which were not replaced.
Experimental design : 6 concentrations plus 1 control
3 replicates per concentration, 3 replicates per control Initial cell density in the test cultures appro-ximately 5000 cells per millilitre. Additionally highest test concentration without algae.
Test item
concentration/s : 3.13, 6.25, 12.5, 25, 50 and 100 mg/L
Method of
administration : stock solution
Duration of exposure : 72 hours
Criteria of effects : The criteria of adverse effects used in this study were the item-induced inhibition of yield [y] and growth rate [r] of the algal population.
Reference substance (positive control):
no
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
28 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: 95 % confidence limit: 26-30 mg/L
Duration:
72 h
Dose descriptor:
EC10
Effect conc.:
13 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: 95 % confidence limit: 11-15 mg/L
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
8.3 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
LOEC
Effect conc.:
18 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Details on results:
Reduction of growth rate (ErCx, NOEC [r]) is the preferred endpoint according to OECD 201 and for regulatory purposes in the EU.
Reported statistics and error estimates:
Resorcindiacetate
The correlation coefficient R2 was R2 = 0.99999
The recovery rate was 98.5 %, RSD 0.25 % (number of determinations: 8).

Resorcin
The correlation coefficient R2 was R2 = 0.99998
The recovery rate was 97.0 %, RSD 0.41 % (number of determinations: 8).

Remark: The test item degrades during the run of the test. Resorcindiacetate degrades to Resorcinmonoacetate and Resorcin.

Validity criteria fulfilled:
yes
Conclusions:
Resorcindiacetat shows an ErC50 value of 28 after 72 h.
Executive summary:

A study was performed to assess the adverse effects of Resorcindiacetat on the growth rate and the yield of the planktonic freshwater algal species Desmodesmus subspicatus over several generations.

The study was conducted in accordance with Commission Regulation (EC) No 761/2009 amending Regulation No 440/2008, Method C.3 ‘Freshwater Alga and Cyanobacteria, Growth inhibition test’ (2009) which is equivalent to OECD Guideline for Testing of Chemicals No. 201 (2006).

Exponentially growing algal cells were exposed for a period of 72 hours to a range of concentrations, nominally 3.13, 6.25, 12.5, 25, 50 and 100 mg/L of Resorcindiacetat dissolved in dilution water. Auxiliaries used to prepare the test media were an ultra turrax, a magnetic stirrer and a folded filter and an aseptic filter.

The cell densities were measured at 24 hour intervals. Inhibition of the algal population was measured as reduction in growth rate (index r), relative to control cultures grown under identical conditions. Growth rates were also used to calculate a No Observed Effect Concentration (NOEC) and a Lowest Observed Effect Concentration (LOEC) according to Welch-t test for Inhomogeneous Variances with Bonferroni-Holm Adjustment. The following values were determined:

ErC 50 (0-72 h): 28 mg/L

ErC 10 (0-72 h): 13 mg/L

NOEC [r] (tα 0.05): 8.3 mg/L

LOEC [r] (tα 0.05): 18 mg/L

The results are expressed in terms of geometric mean measured concentrations. Effective concentrations ranged from 101.5 % to 109.1 % of nominal values at 0 hours, from 61.5 % to 103.5 % of nominal values at 24 hours, from 51.1 % to 62.1 % of nominal values at 48 hours and from 49.7 % to 54.2 % of nominal values at 72 hours.

Description of key information

A study was performed to assess the adverse effects of Resorcindiacetat on the growth rate and the yield of the planktonic freshwater algal species Desmodesmus subspicatus over several generations.

The study was conducted in accordance with Commission Regulation (EC) No 761/2009 amending Regulation No 440/2008, Method C.3 ‘Freshwater Alga and Cyanobacteria, Growth inhibition test’ (2009) which is equivalent to OECD Guideline for Testing of Chemicals No. 201 (2006).

Exponentially growing algal cells were exposed for a period of 72 hours to a range of concentrations, nominally 3.13, 6.25, 12.5, 25, 50 and 100 mg/L of Resorcindiacetat dissolved in dilution water. Auxiliaries used to prepare the test media were an ultra turrax, a magnetic stirrer and a folded filter and an aseptic filter.

The cell densities were measured at 24 hour intervals. Inhibition of the algal population was measured as reduction in growth rate (index r), relative to control cultures grown under identical conditions. Growth rates were also used to calculate a No Observed Effect Concentration (NOEC) and a Lowest Observed Effect Concentration (LOEC) according to Welch-t test for Inhomogeneous Variances with Bonferroni-Holm Adjustment. The following values were determined:

ErC 50 (0-72 h): 28 mg/L

ErC 10 (0-72 h): 13 mg/L

NOEC [r] (tα 0.05): 8.3 mg/L

LOEC [r] (tα 0.05): 18 mg/L

The results are expressed in terms of geometric mean measured concentrations. Effective concentrations ranged from 101.5 % to 109.1 % of nominal values at 0 hours, from 61.5 % to 103.5 % of nominal values at 24 hours, from 51.1 % to 62.1 % of nominal values at 48 hours and from 49.7 % to 54.2 % of nominal values at 72 hours.

Key value for chemical safety assessment

EC50 for freshwater algae:
28 mg/L
EC10 or NOEC for freshwater algae:
8.3 mg/L

Additional information