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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
Study period:
1991-08-08 to 1995-08-10
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions
Remarks:
Analytical measurements only for three concentrations and two timepoints available.
Qualifier:
according to guideline
Guideline:
OECD Guideline 203 (Fish, Acute Toxicity Test)
GLP compliance:
yes (incl. QA statement)
Specific details on test material used for the study:
- ethyl S(-)lactate,
- Batch no.: EX 355.8,
- Purity: > 97 %
Analytical monitoring:
yes
Details on sampling:
At t = 24 h, samples of the freshly prepared test solution of 100,180 and 320 mg/L and the control medium were taken; at t = 48 h samples were taken from the same "spent" test solutions and the "spent" control medium. Samples of 50 mL were taken; samples were taken in 50 mL glass bottles and immediately transported under cool condition to the Analytical Department of the TNO Institute of Biotechnology arid Chemistry in Zeist.
Vehicle:
no
Test organisms (species):
Danio rerio (previous name: Brachydanio rerio)
Details on test organisms:
The organism used was the fresh-water fish species Brachydanio rerio from the commercial hatchery M.B. Ruysbroek B.V. (Noordvliet 159, Maassluis). The average total length and weight (± standard deviation) were 2.1 ± 0.17 cm and 0.07 ± 0.018 g respectively.
Test type:
semi-static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
96 h
Test temperature:
24.1–24.5 °C
pH:
7.7–8.1
Dissolved oxygen:
6.0 - 8.6 mg/L
Nominal and measured concentrations:
Nominal concentrations: 0, 100, 180, 320, 560, 1000 mg/L
Measured concentrations (for 100, 180 and 320 mg/L) after 24 h: 80, 154, 276 mg/L; after 48 h: 50, 120, 222 mg/L.
Average of nominal concentration at t = 24 h: 84%; at t = 48 h: 62 %
Details on test conditions:
TEST SYSTEM
- Test vessel: all-glass beakers
- Material, size, fill volume: glass, 2000 mL, 1500 mL
- Aeration: yes, medium was slightly aerated
- Renewal rate of test solution: replaced daily
- No. of organisms per vessel: 10
- No. of vessels per concentration (replicates): 1
- No. of vessels per control (replicates): 1

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water:
The dilution water used was a synthetic medium (DSWL) was prepared from ground water. This DSWL has proven to be suitable for the culture of Brachydanio rerio. This medium is prepared by addition of several salts to groundwater from a locality near Linschoten (the Netherlands). The groundwater contains several other trace elements (<< 1 mg/L). Media prepared from it have proved to be suitable for growing several species of water organisms. The equilibrium pH of the medium, after aeration, should be 8.3-8.5, but is usually slightly less, namely 8.0-8.2. The medium is prepared in large amounts (10,000 L) and the following components of the batch used for this test were checked by chemical analysis and found to be:
Na+ 1.26 mmol/L; K+ 0.23 mmol/L; Ca2+ 1.41 mmol/L; Mg2+ 0.78 mmol/L; Cl- 2.81 mmol/L; SO42- 0.71 mmol/L
The hardness, expressed as CaCO3, was 220 mg/L. The total organic carbon content was 2.0 mg/L.

OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod: 16 h light/8 h dark regime with transition periods of 30 minutes

EFFECT PARAMETERS MEASURED:
The dead animals were counted and removed after 24 h, 48 h, 72 h and 96 h. At the same times the condition (swimming behaviour, colour, respiratory function or any other observable morphological or visual behavioural criterion) of the survivors was visually compared with that of the control animals. At t = 2 h all test vessels were also checked for mortality and the dead animals counted and removed.

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 1.8
- Range finding study: yes (no details available)
Reference substance (positive control):
not required
Key result
Duration:
96 h
Dose descriptor:
LC50
Effect conc.:
320 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mortality (fish)
Remarks on result:
other: 95 % CI = 305–417 mg/L
Duration:
96 h
Dose descriptor:
NOEC
Effect conc.:
180 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mortality (fish)
Details on results:
- Observations on body length and weight: no
- Other biological observations: no
- Mortality of control: no
- Other adverse effects control: no
- Abnormal responses: no
- Any observations that might cause a difference between measured and nominal values: no
- Effect concentrations exceeding solubility of substance in test medium: no
Sublethal observations / clinical signs:

Table1: Measured concentrations of ethyl S(-) lactate.

Nominal concentration mg/L

Measured concentrations

t = 24 h

t = 48 h

mg/L

% of nominal

mg/L

% of nominal

0

<1

 

<1

 

100

80

80

50

50

180

154

86

120

67

320

276

86

222

69

Average % of nominal concentration

84

62

Average % of nominal during total test

73

 

Table 2: Number of surviving fishes at several concentrations of ethyl S(-) lactate and after several exposure times.

time (h)

Nominal concentration (mg/L)

0

100

180

320

560

1000

0

10

10

10

10

10

10

2

10

10

10

10

0

0

24

10

10

10

8

0

0

48

10

10

10

7

0

0

72

10

10

10

7

0

0

96

10

10

10

7

0

0

Table 3: Number of fishes and their condition at several concentrations of ethyl S(-) lactate and after several exposure times.

time (h)

Nominal concentration (mg/L)

0

100

180

320

560

1000

0

10a)

10a)

10a)

10a)

10a)

10a)

2

10

10

10

10

0

10d)

0

10d)

24

10a)

10b)

10b)

8

8b)

2d)

0

0

48

10a)

10b)

10b)

7

7b)

1d)

0

0

72

10a)

10b)

10b)

7b)

0

0

96

10a)

10b)

10b)

7b)

0

0

The following codes were used to denote condition:

a) Condition of all fisihes, visually assessed, normal (= good).

b) Condition of all fisihes, visualiy assessed, equal to that of the control fishes.

c) Number of slow swimming fishes.

d) Number of dead fishes.

Validity criteria fulfilled:
yes
Conclusions:
In a short-term toxicity test with Brachydanio rerio the LC50 value of 320 mg/L was measured.
Executive summary:

The acute toxicity of ethyl (S)-lactate to the fresh-water fish species Brachydanio rerio was determined as described in the OECD guideline no. 203 and according to the OECD principles of Good Laboratory Practice. The test was carried out as a semi-static test with daily replacement of the test solutions and with 10 fishes for each concentration. The exposure duration was 96 hours. The nominal concentrations tested were 100, 180, 320, 560 and 1000 mg/L. The test substance appeared to be completely dissolved at all concentrations tested (visually assessed). The actual concentrations of ethyl (S)-lactate in the freshly prepared test solutions were determined with gas chromatography (direct injection), they were between 80 and 86 % of the nominal concentrations (average 84 %). To test the stability of the test substance, the concentrations of ethyl (S)-lactate were also analysed for 3 concentrations at the end of the test and appeared to be between 50 and 69 % (average 62 %).

The results of the test were (in nominal concentrations): 96-h LC50 (mortality) = 320 mg/L; 96-h LC100 (mortality) = 560 mg/L; 96-h NOEC (mortality) = 180 mg/L

Description of key information

A short-term toxicity test with zebra fish (Danio rerio) resulted in a LC50 of 320 mg/L.

Key value for chemical safety assessment

Fresh water fish

Fresh water fish
Dose descriptor:
LC50
Effect concentration:
ca. 320 mg/L

Additional information

No adverse effects have been observed at the highest recommended concentration (100 mg/L). Accordingly, the substance is not hazardous in terms of the CLP Regulation.