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Short-term toxicity to fish

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Reference
Endpoint:
short-term toxicity to fish
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
Guideline:
OECD Guideline 203 (Fish, Acute Toxicity Test)
GLP compliance:
yes
Details on test solutions:
The limit test concentration was prepared by direct addition of the test substance into the 10-L test chambers. Test substance was weighed onto weigh paper, which was rinsed with Haskell well water (HWW) and then placed into tank to soak. Periodically, tweezers were used to pick up the weight paper and rinse with HWW until all of the test substance was rinsed into the tank. The test solutions were stirred for approximately 63 minutes. The limit test concentration was very cloudy with no visible precipitate present and bubbles on the surface.
Test organisms (species):
Oncorhynchus mykiss (previous name: Salmo gairdneri)
Details on test organisms:
TEST ORGANISM
- Age at study initiation: juvenile
- Feeding during test: No

ACCLIMATION PERIOD: 2 days
Test type:
static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
96 h
Hardness:
100-140 mg/L
Test temperature:
11.9 - 12.1 °C
pH:
7.9 to 8.3
Dissolved oxygen:
6.4 to 10.9 mg/L
Nominal and measured concentrations:
A nominal limit test concentration of 100 mg/L
Details on test conditions:
The nominal limit test concentration of 100 mg/L of test substance was chosen for the definitive limit test based on the results of a preliminary range-finding study.

Test chambers were stainless steel aquaria [30 (length) x 30 (width) x 30 (height) cm] which held approximately 10 L of test solution (26-L maximum volume; 11.5-cm test solution depth). One dilution water control test chamber and 1 limit test concentration chamber with 7 fish in each chamber were used for testing (total of 7 fish in the control and 7 fish in the limit test concentration). Each chamber was covered with a glass plate to prevent fish from escaping. Random numbers were used to assign the position of test chambers in the waterbath.

Rainbow trout used in this study were not fed approximately 71.5 hours prior to nor during the test, and were assigned to the test chambers using random numbers. Mortality and behavioural observations were made at test start, every 24 hours thereafter, and at test end. Criteria for death were the absence of opercular movement and lack of reaction to gentle prodding.

A recirculating waterbath was used to maintain mean temperature in the test chambers during the 96-hour test at approximately 12.0ºC with a range of 11.9 to 12.1ºC. In addition, a continuously-recording thermometer was used to check temperature variations in the waterbath. A photoperiod of 16 hours light (approximately 338-362 Lux) and 8 hours darkness was employed, which included 30 minutes of transitional light (121-154 Lux) preceding and following the 16-hour light interval. Test solutions were not aerated during the test and were disposed of in an appropriate manner at test end.
Duration:
96 h
Dose descriptor:
LC50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Basis for effect:
mortality (fish)
Details on results:
At test conclusion, fish from the dilution water control ranged from 2.6 to 3.1 cm in standard length (mean 3.0 cm) and 0.180 to 0.327 g in wet weight, blotted dry (mean 0.261 g). Standard length of the longest fish was not more than twice the length of the shortest fish in the control. Loading in the water control was 0.183 g/L at test conclusion. No mortality or sublethal effects were seen in the dilution water or in the 100 mg/L nominal test substance limit test concentration at the end of 96 hours.
Sublethal observations / clinical signs:

Table 1: Mortality and Sublethal Effects of Rainbow Trout in Unaerated Static Acute, 96 -Hour Limit Test

Nominal Concentration (mg/L)

Number Dead /Number at Study Start

24 Hours

48 Hours

72 Hours

96 Hours

Dilution Water Control

0/7

0/7

0/7

0/7

100

0/7

0/7

0/7

0/7

 

 

 

Validity criteria fulfilled:
yes
Conclusions:
96-h LC50 > 100 mg/L
Executive summary:

The acute toxicity of the test substance to unfed fingerling rainbow trout, Oncorhynchus mykiss, was determined in an unaerated, static, acute, 96-hour limit test. The study was conducted with a 100 mg/L nominal concentration of the test substance and a dilution water control at a mean temperature of 12.0 ºC (range of 11.9-12.1 ºC). A dilution water control test chamber and a limit test concentration chamber with 7 fish in each chamber were used for testing (total of 7 fish in the control and in the limit test concentration). Fish in the dilution water control ranged from 2.6 to 3.1 cm in standard length (mean 3.0 cm), and 0.180 to 0.327 g in wet weight, blotted dry (mean 0.261 g) at test end. Control loading at test end was 0.183 g/L. No mortality or sublethal effects were seen at the 100 mg/L nominal limit test concentration of the test substance or in the control at the end of the 96-hour limit test. The 96-hour LC50, based on the nominal limit test concentration of the test substance and mortality, was greater than 100 mg/L.

Description of key information

96-hour LC50>100 mg/L.

Key value for chemical safety assessment

Fresh water fish

Fresh water fish
Effect concentration:
100 mg/L

Additional information