4-chloro-o-cresol

Long-term toxicity to aquatic invertebrates

Administrative data

Endpoint:

long-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Study period:

27th May 1997- 3rd June 1997

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: The study is GLP compliant and is to OECD Guidelines.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1997

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

other: OECD 202, Part II adopted 4 April 1984

Deviations:

yes

Remarks:

The daphnia were individually separated.

Test guideline 2

Qualifier:

according to guideline

Guideline:

other: EPA, Hazard Evaluation Division Standard Evaluation Procedure 540/9-86-141

Principles of method if other than guideline:

The daphnia were individually separated in accordance with Brixham Environmental Laboratory Standard Operating Procedure BA271, version 2.

GLP compliance:

yes (incl. QA statement)

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

Sampling and analysis

Analytical monitoring:

yes

Details on sampling:

On four renewal occasions of the samples, the new test solutions were analysed to determine the concentration of the 4-chloro-o-cresol. Samples from the corresponding 'old' test solutions were analysed on the following renewal day.

Test solutions

Vehicle:

no

Test organisms

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: Daphnia Magna
- Source: Continuous cultures held at Brixham Laboratory
- Age of parental stock (mean and range, SD): 12 +/- 1 days old
- Feeding during test
- Food type: Cultured algae (Chlorella vulgaris), strain CCAP 211/12 and a commercially available microencapsulated diet "Frippak Booster".
- Amount: Each test vessel recieved 3.0 x10(7) algal cells and 57 micrograms of Frippak (as suspension)
- Frequency: Per day

Study design

Test type:

semi-static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

21 d

Test conditions

Hardness:

The total hardness of the dilution water control (measured as CaCO3) was within the range 216.3 - 242.3mg/L throughout the duration of the test. The 0.56mg/L PCOC solution was measured on day 14 - 16 and was determined to have a total hardness as CaCO3 of 223.7 - 226.3 mg/L.

Test temperature:

The temperature of the test solutions was within the range 19.6 - 20.7 °C throughout the duration of the test.

pH:

The pH of the test solutions was within the range pH7.50 - 8.12 throughout the duration of the test. This includes readings on both new and old test solutions.

Dissolved oxygen:

The dissolved oxygen concentrations of the solutions ranged from 8.2 - 9.2 mg/L for the old solutions. The new solutions were within the range 9.2 - 9.4 mg/L.

Nominal and measured concentrations:

The nominal value and the measured values are summarised below. The concentrations were measured on the fresh solutions and the old solutions.
All results are quoted as mg/L.

Nominal Value New Old
Dilution water control <0.016 <0.016
0.032 0.031 0.024
0.056 0.057 0.043
0.10 0.10 0.081
0.18 0.19 0.15
0.32 0.34 0.28
0.56 0.58 0.51

Details on test conditions:

TEST SYSTEM
- Test vessel: Borosilicate glass beakers with loose fitting lids
- fill volume: 80mls providing a depth of 47mm
- Aeration: No
- Renewal rate of test solution (frequency/flow rate): test solutions were renewed three times per week - Tuesday, Thursday, Saturday
- No. of organisms per vessel: 1
- No. of vessels per concentration (replicates):10
- No. of vessels per control (replicates): 10

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Reconstituted water medium Elendt M4 Medium
- Dissolved non purgeable organic carbon (DNPOC): 1.1 -1.73mg/L
- Metals: Cadmium, Copper, Cobalt, Nickel <= 1micrograms/L
Iron 2-19 micrograms/L
Lead <1 -2 micrograms/L
Manganese 12-27 micrograms/L
Zinc 1-2 micrograms/L

- Alkalinity: 39.6 -43.0 mg/L as CaCO3
- Conductivity: 623 - 629 microsiemens/cm at 25°C

OTHER TEST CONDITIONS
- Adjustment of pH: no adjustment made to pH
- Photoperiod: 16 hours light : 8 hours dark with a 20 minute dawn and dusk transition period.
- Light intensity: Average intensity of 671 Lux

Results and discussion

Effect concentrations

Effect concentrations 1

Duration:

1 d

Dose descriptor:

LC50

Effect conc.:

> 0.56 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

other: Reproduction, growth and mortality were all considered as basis for effects

Effect concentrations 2

Duration:

21 d

Dose descriptor:

LC50

Effect conc.:

> 0.56 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

other: Reproduction, growth and mortality were all considered as basis for effects

Details on results:

The LC50 was calculated on days 1,2,4,7,14 and 21, in all cases the LC50 was >0.56 mg/L.
The details on the results are summarised below.

- Mortality of parent animals: There were no mortalities in the dilution water control or in the nominal concentrations of 0.032, 0.056, 0.18 or 0.56mg/L PCOC after 21 days. A single mortality was observed in both the 0.1 and 0.32mg/L PCOC nominal concentrations after 12 and 14 days respectively. Both deaths were considered to be random as no other deaths were observed in these or in the higher 0.56mg/L nominal concentration.

- No. of offspring produced per day per female: In the dilution water control and nominal test concentrations up to and including 0.32mg/L all Po daphnia had released their first offspring on day 8 or 9, and had completed 4 or 5 broods by the end of the study, with the exception of those that were identified as male.

- Body length and weight of parent animals: Based on a statistical procedure, Wilcoxon's Rank Sum Test, the length of the daphnia was not significantly reduced in any of the treatments when compared to the control.

Results with reference substance (positive control):

No positive control used.

Reported statistics and error estimates:

The growth data was not normally distributed therefore a non parametric statistical procedure, Wilcoxon's Rank Sum Test was used.
The reproduction data was normally distributed, therefore a parametric statistical procedure , Bonerroni's T-test was used.

Any other information on results incl. tables

Note - The Po daphnia in treatment 0.032 rep3, 0.056 rep 9, 0.18 rep 7 and 0.56 rep 8 were identified as males and were not included in the analysis.

Applicant's summary and conclusion

Conclusions:

Based on the results from the study the LC50 was shown to be >0.56mg/L. The overall No Observed Effect Concentration was shown to be >=0.56mg/L.

Executive summary:

The effects of PCOC on the reproduction of Daphnia magna over a 21 day period was studied in a Chronic Toxicity test performed to OECD Guideline 202 Part II. The PCOC sample tested was a 50:50%w/w combination of PCOC technical grade supplied by A H Marks and Co Limited and Nufarm UK Limited. The test medium was Elednt M4 medium.

Nominal concentrations of 0.032, 0.056, 0.1, 0.018, 0.32 and 0.56mg/L PCOC were used with a dilution water control. Ten replicates were performed at each concentration, each replicate containing a single daphnia. The test systems were held at 20 +/-1°C under 16 hours of light per day. The test solutions were renewed three times a week throughout the duration of the test.

The LC₅₀values were calculated at various time intervals during the test period.

The mortalities and reproduction data were used to calculate the LC₅₀, the length of the daphnia was recorded at the end of the test.

There were no mortalities in the dilution water control or in the nominal concentrations of 0.032, 0.056, 0.18 or 0.56mg/L PCOC after 21 days. A single mortality was observed in both the 0.1 and 0.32mg/L PCOC nominal concentrations after 12 and 14 days respectively. Both deaths were considered to be random as no other deaths were observed in these or in the higher 0.56mg/L nominal concentration. In the dilution water control and nominal test concentrations up to and including 0.32mg/L all Po daphnia had released their first offspring on day 8 or 9, and had completed 4 or 5 broods by the end of the study, with the exception of those that were identified as male. Based on a statistical procedure, Wilcoxon's Rank Sum Test, the length of the daphnia was not significantly reduced in any of the treatments when compared to the control.

Based on the results from the study the LC50 was shown to be >0.56mg/L. The overall No Observed Effect Concentration (NOEC) was shown to be >=0.56mg/L.