4-chloro-o-cresol

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:

08/05/1989 - 12/05/1989

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: The study was performed to guidelines however no GLP compliance statement was included with the report although is believed that it complies with the 'principles of GLP'.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1989

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

other: DIN38412 L9

GLP compliance:

not specified

Remarks:

Believed to be in accordance with the principles of GLP.

Test material

Test material information

Constituent 1

Reference substance name:

4-chloro-o-cresol

EC Number:

216-381-3

EC Name:

4-chloro-o-cresol

Cas Number:

1570-64-5

Molecular formula:

C7H7ClO

IUPAC Name:

4-chloro-2-methylphenol

Test organisms

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Details on test organisms:

TEST ORGANISM
- Strain: Chodat
- Source (laboratory, culture collection): Gottingen Algal Collection SAG 86.81

Study design

Test type:

not specified

Water media type:

not specified

Total exposure duration:

96 h

Test conditions

Nominal and measured concentrations:

The test solutions were prepared at the following concentrations:
1.0, 2.5, 5.0, 10.0 25.0 and 50.0 mg/L

Details on test conditions:

TEST SYSTEM
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4

OTHER TEST CONDITIONS
- Adjustment of pH: initial and end point measurements in all test batches
-Temperature: incubation of test and control batches at 21 -25°C , temperature must remain within 2 degrees for the duration of the test.


EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: fluorimeter

Reference substance (positive control):

yes

Remarks:

Potassium Dichromate

Results and discussion

Effect concentrations

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

ca. 14.81 mg/L

Nominal / measured:

not specified

Conc. based on:

other: Not specified but assumed to be nominal.

Basis for effect:

other: Cell density, growth rate and Inhibition of biomass.

Details on results:

The results were measured using a pulse fluorimeter. The mean results for the 4 replicates at each concentration after 72 hours are summarised below .
Cell Density
0h 24h 48h 72h 96h
Concentration
mg/L (N/ml x 103) (N/ml x 103) (N/ml x 103) (N/ml x 103) (N/ml x 103)
Control 12 29 67 206 564
1.0 13 29 57 158 434
2.5 13 29 57 160 424
5.0 13 29 58 157 438
10.0 13 30 56 128 330
25.0 13 24 35 58 136
50.0 13 17 21 26 23

Evaluation after 72 hours
Concentration
mg/L Growth Rate Inhibition of biomass [%] Rate-Related Inhibition [%]
Control 0.95 - -
1.0 0.83 19.7 12.1
2.5 0.84 19.3 11.7
5.0 0.83 19.1 12.4
10.0 0.76 26.5 19.6
25.0 0.50 61.7 47.4
50.0 0.23 83.3 75.6

EC 10: 1.856 mg/L EbC 10: 0.971 mg/L
EC 50: 26.904 mg/L EbC 50: 14.809 mg/L


Evaluation after 96hours
Concentration
mg/L Growth Rate Inhibition of biomass [%] Rate-Related Inhibition [%]
Control 0.95 - -
1.0 0.88 23.3 8.9
2.5 0.87 23.5 9.5
5.0 0.88 23.2 8.6
10.0 0.81 38.3 16.0
25.0 0.59 73.6 39.0
50.0 0.14 92.5 85.2

EC 10: 2.670 mg/L EbC 10: 0.890 mg/L
EC 50: 25.766 mg/L EbC 50: 8.247 mg/L


The EC50 after 72 hours was calculated to be 14.81 mg/L

Applicant's summary and conclusion

Conclusions:

The EC50 calculated from the study was 14.81 mg/L .

Executive summary:

A guideline study was performed to determine the effect of PCOC on algal cell multiplication.

The test was performed using the test system Scenedesmus subspicatus Chodat, at PCOC concentrations of 1.0, 2.5, 5.0, 10.0, 25.0 and 50.0 mg/L. The cell densities were measured every 24 hours using a fluorimeter..

The test solutions and control were incubated at 21 -25°C with a 2 degree maximum variation over the duration of the test.

The cell density, growth rate and inhibition of biomass were used to calculate the EC 50 value.

The EC50 (72 hours) was 14.81 mg/L PCOC.