4-chlorophenol

Short-term toxicity to fish

Administrative data

Endpoint:

short-term toxicity to fish

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

1984

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Acceptable publication with several data sets (based on-GLP studies), including the result for the test substance .

Data source

Reference

Reference Type:

publication

Title:

Measurement of median lethal dose as a rapid indication of contaminant toxicity to fish

Author:

Hodson PV., Dixon DG, Kaiser KLE

Year:

1984

Bibliographic source:

Environmental Toxicology and Chemistry, 3:243–254.

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 203 (Fish, Acute Toxicity Test)

Version / remarks:

Version: originally adapted in 1981

Deviations:

yes

Remarks:

single mortality data are not presented.

GLP compliance:

no

Test material

Test material information

Constituent 1

Reference substance name:

4-chlorophenol

EC Number:

203-402-6

EC Name:

4-chlorophenol

Cas Number:

106-48-9

Molecular formula:

C6H5ClO

IUPAC Name:

4-chlorophenol

Sampling and analysis

Analytical monitoring:

yes

Test solutions

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: Hamilton syringe pump to create the 100% concentration of the test substance
- Eluate: Mount-Brungs diluter to achive dilutions of the test substance

Test organisms

Test organisms (species):

Oncorhynchus mykiss (previous name: Salmo gairdneri)

Details on test organisms:

TEST ORGANISM
- Common name: Rainbow trout
- Strain: Oncorhynchus mykiss
- Source: Trout Farm. R.R. #1 (Otterville, ON, Canada)
- Length at study initiation (range): 4.6 - 6.4 cm
- Weight at study initiation (range): 1.2 - 3.8 g
- Method of breeding: The fish were not all from the same hatch.

ACCLIMATION
- Acclimation period: At least 1 week prior to use
- Acclimation conditions (same as test): 15 °C on a 16 h light / 8 h dark photoperiod
- Type and amount of food: Trout pellets (Ewos, Rundle Feed MilIs, Palmerston, ON, Canada), ratio recommended for their weight and acclimation temperature
- Feeding frequency: daily, except on weekends

Study design

Test type:

flow-through

Water media type:

freshwater

Total exposure duration:

96 h

Post exposure observation period:

Not reported.

Test conditions

Hardness:

averaged 86 mg/L as CaCO3

Test temperature:

14.4 - 16.5 °C (mean)

pH:

7.60 - 8.19 (mean)

Dissolved oxygen:

5.6 - 9.4 mg/L (mean)

Salinity:

Not applicable.

Nominal and measured concentrations:

0 (control), 100, 180, 320, 560, 1000 mg/L (nominal concentrations); concentrations were measured during the test

Details on test conditions:

TEST SYSTEM
- Test vessel: Bioassay tank
- Type: open
- Material, size, headspace, fill volume: 14 L
- Aeration: none
- Renewal rate of test solution (frequency/flow rate): Flow per tank varied between tests from 21 to 111 mL/min (depending on the chemical)
- No. of organisms per vessel: 10
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 3
- The size of test fish was chosen such that the flow rate was always greater than 2 L per gram of fish per day.

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: municipal supply drawn from Lake Ontario
- Chlorine: Less than 10 µg Cl/L by charcoal filtration and sunsequent addtion of 1 mg/L sodium sulfite
- Alkalinity: Not reported.
- Ca/mg ratio: Not reported.
- Conductivity: 340 µmhos/cm²

Reference substance (positive control):

not required

Results and discussion

Effect concentrations

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

14.8 µmol/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Remarks:

measured concentrations

Basis for effect:

mortality (fish)

Remarks on result:

other: LC50 (96 h) = 1.9 mg/L

Details on results:

Reported LC50 value was based on the means of measured concentrations

Reported statistics and error estimates:

The LC50 values were calculated from records of percent mortality using computerized probit analysis validated by analyzing data sets from Finney. When the number of partial mortalities was too low for probit analysis, the slopes of the probit lines were quite high. Hence, a graphical method for estimating LC50 values was an accurate alternative.
The means of triplicate LC50 value were compared by stepwise multiple regression analysis. In addition, LC50 values were ranked and compared by chi-square tests (x²). The probability level for all statistical tests for Type I error was p >= 0.05.

Any other information on results incl. tables

Sublethal observations / clinical signs:

Furthermore, a new method was developed to rapidly measure the toxicity of contaminants to fish over 96 h. The method is the measurement of median lethal doses by intraperitoneal injection (IP-LD50). The test substance was dissolved in 5% ethanol in saline or in cod-liver oil and injected at a rate of 1.0 mL per 100 g of fish.

The results of parallel bioassays to measure toxicity by oral intubation (OI-LD50) or aqueous exposure (LC50) were closely linked to IP-LD50 values.The coefficient of determination (r²) for a linear regression between IP-LD50 and OI-LD50 values was 0.99. In contrast, the r² between IP-LD50 and LC50 values was lower (0.44) and the regression curvilinear. However, r² improved to 0.82 when LD50 values were divided by the logarithm of the octanol-water partition coefficient (log P).Therefore, some of the differences in toxicity between chemicals may be due to interactions between their lipid (or water) solubilities and their rate of uptake by fish.

The IP-LD50 values of five chemicals varied with the carrier used; toxicity was lower for the oil carrier compared to injections with 5% ethanol in saline. The magnitude of the difference varied with the chemical tested, so that the two measures of toxicity did not appear to be related. However, the relationships again improved when the IP-LD50 (oil) was divided by log P.

The measurement of IP-LD50 values was faster, simpler and less expensive than traditional LC50 bioassays. The use of IP-LD50 values to screen chemicals for their relative toxicity to fish will save time and money without any real loss in the relevance of conclusions.

Applicant's summary and conclusion

Executive summary:

In a short-term study with the test substance, 0 (control), 100, 180, 320, 560, 1000 mg/L (nominal concentrations) were exposed to Oncorhynchus mykiss. The LC50 was deemed as 1.9 mg/L in this non-GLP study on the basis of OECD203 (Hodson, 1984).