5-chloro-2-(4-chlorophenoxy)phenol;[DCPP]

Toxicity to aquatic algae and cyanobacteria

Administrative data

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1999-01-22 to 1999-03-18

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: GLP, OECD guideline study. The coefficient of analysis of the daily growth rate in the control replicates and the coeffient of analysis of the average specific growth rates in the control replicates were not reported.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1999

Report date:

1999

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Version / remarks:

1984

Deviations:

yes

Remarks:

The coefficient of analysis of the daily growth rate in the control replicates and the coeffient of analysis of the average specific growth rates in the control replicates were not reported.

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method C.3 (Algal Inhibition test)

Version / remarks:

1992

Deviations:

yes

Remarks:

The coefficient of analysis of the daily growth rate in the control replicates and the coeffient of analysis of the average specific growth rates in the control replicates were not reported.

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

-

EC Number:

429-290-0

EC Name:

-

Cas Number:

3380-30-1

Molecular formula:

C12 H8 Cl2 O2

IUPAC Name:

5-chloro-2-(4-chlorophenoxy)phenol

Details on test material:

- Name of test material (as cited in study report): FAT 80'220/A
- Physical state: solid powder
- Batch no.: GRU 98
- Expiration date: October 31, 2008
- Purity: >99%
- Stability in water: >1 year (estimated half-life at 25 °C; determined in RCC Project 712260)
- Solubility in water: 19.5 mg/L (determined in RCC Project 712012)
- pH in aqueous solution: 5-7 at a concentration of 0.01 g/L
- Storage conditions: at room temperature at about 20 °C, away from direct sunlight.

Sampling and analysis

Analytical monitoring:

yes

Details on sampling:

For the analytical measurements of the test item concentrations, one sample from the freshly prepared stock solution and duplicate samples from the freshly prepared test media of all test concentrations and from the control were taken just before the start of the test (without algae).
For the determination of the stability of the test item under the test conditions, and for the maintenance of the test item concentrations during the test period respectively, additional flasks with adequate volumes of the freshly prepared test media of all test concentrations and the control were incubated under the same conditions as in the actual test (but without algae). And were sampled in duplicate at the end of the test (after the 72 hours test period).
All samples were deep-frozen (at about -20 °C) immediately after sampling.
The concentrations of the test item were analyzed in the stock solution sample and in the duplicate test media samples from the test concentrations of nominal 10-46 µg/L from both sampling times (0 and 72 hours). From the control samples only one of the duplicate samples was analysed from each of both sampling times (0 and 72 hours). The samples from the test concentrations were below the determined 72-hour NOEC.

Test solutions

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
A stock solution of nominal 10 mg/L was prepared by dissolving 20 mg of the test item in 2000 mL test water by ultrasonic treatment (15 minutes) and intense stirring by a magnetic stirrer (72 hours at room temperature in the dark). Adequate volumes of this intensively mixed stock solution were added to test water to prepare the test media of the following nominal test concentrations: 46, 22, 10, 4.6 and 2.2 µg/L. Additionally, a control was tested in parallel (test water without addition of the test item).
No undissolved test item could be evidenced.

Test organisms

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Details on test organisms:

TEST ORGANISM
- Common name: Scenedesmus subspicatus CHODAT
- Strain: No. 86.81 SAG
- Source (laboratory, culture collection): "Sammlung von Algenkulturen, Pflanzenphysiologisches Institut der Universitat Gottingen", D-37073 Gottingen
- Method of cultivation: the algae had been grown under standardized conditions according to the test guidelines

ACCLIMATION
- Culturing media and conditions (same as test or not): same

Study design

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Test conditions

Hardness:

0.24 mmol/L (= 24 mg/L) as CaCO3

Test temperature:

23 °C

pH:

7.8 (start) and 8.2 to 8.8 (end)

Dissolved oxygen:

no data

Nominal and measured concentrations:

- nominal concentrations: 2.2, 4.6, 10, 22, 46 µg/L
- measured concentrations: not determined for the 2 lowest nominal concentrations, 9.47, 25.1, 45.1 µg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: 50 mL Erlenmeyer flasks
- Initial cells density: a biomass of 10,000 algal cells per mL test medium
- Control end cells density: a biomass of 10,000 algal cells per mL test medium
- No. of organisms per vessel: 15 mL per test vessel
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6

GROWTH MEDIUM
- Standard medium used: yes

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: synthetic water
- Metals: metals dissolved in test medium was according to the guideline
- Alkalinity: no data

OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod: fluorescent tubes
- Light intensity and quality: intensity of about 8147 Lux (mean value), range: 7820 to 8620 Lux

EFFECT PARAMETERS MEASURED
- Growth as biomass and as growth rate, at 24, 48 and 72 h

TEST CONCENTRATIONS
- Range finding study: yes
- Test concentrations: The test concentrations were based on the results of a range-finding test and the results of the pre-experiment to the solubility of the test item.

Reference substance (positive control):

no

Results and discussion

Effect concentrations

Effect concentrations 1

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

22 µg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: biomass and growth rate

Effect concentrations 2

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

10 µg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: biomass and growth rate

Effect concentrations 3

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

14 µg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Effect concentrations 4

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

23 µg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Effect concentrations 5

Duration:

72 h

Dose descriptor:

EC90

Effect conc.:

40 µg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Effect concentrations 6

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

20 µg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Effect concentrations 7

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

38 µg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Effect concentrations 8

Duration:

72 h

Dose descriptor:

EC90

Effect conc.:

73 µg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: this EC-value should be taken with caution, since the inhibition of growth rate was up to the highest test concentration lower than 90%

Details on results:

MEASURED CONCENTRATIONS
In the sample from the freshly prepared stock solution 104% of the nominal concentration was measured. In the test media the mean measured test item concentrations at the start of the test ranged from 112 to 124% of the nominal values. During the test period of 72 hours a slight decrease of the test item concentration in the test media was determined. At the end of the test 77 to 114% of the nominal values were found. The losses could be due to an adsorption of the test item onto glass surfaces, particularly in the low-level samples. However, the total mean measured test concentrations (calculated as the average over all measurements per test concentration) varied in the range of 95 to 119% of the nominal values. Therefore, all biological results are related to the nominal concentrations of the test item.
EFFECTS
The test item had a statistically significant inhibition effect on the growth rate of Scenedesmus subspicatus after the exposure period of 72 hours first at the test concentration of 22 µg/L, which was therefore set as LOEC (72 h). Thus, the NOEC (72 h) was 10 µg/L, since up to this test
concentration both the mean biomass and the mean growth rate of the algae were statistically not significantly lower than in the control. Referring to abnomalities, the shape of the algal cells growing up to 10 µg/L was obviously not affected.
CONTROL
In the control the cell density has increased from nominal N = 1 x 10 +E4 cells/mL at the start of the test (0 hours) to N = 95.6 x 10+E4 cells/mL (mean value) after 72 hours by a factor of approximately 96. Thus, the algal growth in the control meets the validity criteria (increase by a factor of at least 16), and growth in the control was exponential.
REMARK
At the start of the test, the pH values in the test media was 7.8, at the end of the test pH values were measured between 8.2 and 8.8.
No remarkable observations were made concerning the appearance of the test media. All test media were clear solutions throughout the test period.