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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:
2000
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 203 (Fish, Acute Toxicity Test)
Version / remarks:
Adopted July 17th, 1992
Deviations:
yes
Remarks:
After 24 h of incubation, the temperature of the medium was lower than the range (21-25°C) proposed by the Guideline. This deviation is considered by the authors as having no influence on the integrity and validity of the study.
GLP compliance:
yes (incl. certificate)
Analytical monitoring:
yes
Details on sampling:
- Concentrations: TS in samples with nominal concentrations of 25, 50 and 100 mg/L; concentration were determined daily
Vehicle:
no
Test organisms (species):
Danio rerio (previous name: Brachydanio rerio)
Details on test organisms:
TEST ORGANISM
- Source: Tagis-Aquarium and Aquafarm Ryba (both Germany)
- Length at study initiation: approx. 3 cm
Test type:
semi-static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
96 h
Test temperature:
20.0 – 22.6°C
pH:
7.52 – 8.42
Dissolved oxygen:
7.6 – 8.2 mg/L
Nominal and measured concentrations:
Nominal concentrations:
Screening test: 1, 10, 100 mg/L + control
Main test: 6.25, 12.5, 25, 50, 100 mg/L + control
Details on test conditions:
TEST SYSTEM
- Type: open. However, the test was run semistatically due to probable volatility of the test substance.
- Renewal rate of test solution: Daily renewal
- No. of organisms per vessel: Screening test: 3 fish / 3 L solution; Main test: 7 fish / 3 L solution

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Tap water from municipal drinking water supply
- Intervals of water quality measurement: pH, oxygen content and temperature checked at the beginning and daily after 24 h.

OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod: light/dark cycle : 16 h / 8 h

EFFECT PARAMETERS MEASURED:
Daily examination for dead animals
Key result
Duration:
96 h
Dose descriptor:
LC50
Effect conc.:
71 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
mortality
Remarks on result:
other:
Remarks:
LC0 and LC100 were directly taken from the concentrations being tested. LC50 was calculated as the geometric mean between LC0 and LC100.
Duration:
96 h
Dose descriptor:
LC0
Effect conc.:
50 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
mortality
Duration:
96 h
Dose descriptor:
LC100
Effect conc.:
100 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
mortality
Details on results:
Effects other than mortality were not recorded.
No dead fish in the control vessels.

Results of determination ofthe test substance in the test medium:

Sampling time [h]

Nominal Conc. [mg/L]

Measured Conc. [mg/L]

to

100

121.05

to

50

63.46

to

25

30.91

to

control

<2

t24h

50

60.74

t24h

25

20.65

to’(24h)

100

88.60

to’(24h)

50

47.92

to’(24h)

25

23.86

t48h

100

84.99

t48h

50

62.33

t48h

25

19.58

t72h

100

119.15

t72h

50

40.02

t72h

25

31.30

to’’’(72h)

50

37.05

to’’’(72h)

25

31.26

t96h

50

58.09

t96h

25

18.10

The results in the table were not corrected for the recoveries obtained by the analytical methodhe mean recovery rate was 100%.

The authors stated that the test solutions showed no significant loss of the test substance. Therefore, nominal concentrations can be considered as the effective concentrations.

Applicant note: Some individually-measured concentrations deviate by more than 20% from the nominal. However, the mean values were within 20% of the nominal concentrations. A general trend towards loss of formaldehyde in 24 h old solutions, compared to freshly prepared media, cannot be observed. Therefore, the demands of the Guideline (stability ≥ 80% of nominal) can be regarded as fulfilled.

Results of main test:

Test substance
Concentration
(nominal)

[mg/L]

Mortality

Number

Percentage

24 h

48 h

72 h

96 h

24 h

48 h

72 h

96 h

Control

Not reported

0

0

0

0

100

14

86

100

100

50

0

0

0

0

25

0

0

0

0

12.5

0

0

0

0

6.25

0

0

0

0

Temp.[°C]1)

20.0-20.2

21.1

22.4-22.6

22.6

 

pH freshly prepared

7.61-7.86

7.52-7.86

7.76-7.91

-

 

pH after 24 h

8.23-8.40

8.28-8.42

8.27-8.40

8.12-8.38

 

Oxygen [mg/L]

7.6-8.1

7.7-8.1

7.7-8.2

7.6-8.1

 

1) After 24 h test temperature was lower than the range proposed by the Guideline (21-25°C). This deviation is not considered by the authors to have an influence on the integrity of the study.

Validity criteria fulfilled:
yes
Conclusions:
The LC50 was calculated as the geometric mean between LC0 and LC100 representing 71 mg/L of the test substance.
Executive summary:

The reaction products of ethylene glycol with paraformaldehyde were tested for acute toxicity towards Danio rerio according to OECD-Test Guideline 203. 7 fish were exposed in a semistatic system to 5 concentrations of the test substance between 6.25 and 100 mg/L and a control group. The test solutions were prepared in drinking water and renewed daily. Test duration was 96 hours and the test solutions were examined daily for dead fish. Oxygen concentrations, temperature and pH of the medium were measured in the same intervals. Analysis of the formaldehyde concentrations was performed daily by HPLC.

The test substance was found to be acutely harmful towards Danio rerio. All results refer to the nominal concentrations due to formaldehyde concentration being shown stable within the incubation period.

A clear concentration-response relationship can be established from the study results. Lethal effects were observed only at a concentration of 100 mg/L. The next concentration of the geometric series exhibited no toxicity (manifest as mortality). Therefore, the LC50 was calculated as the geometric mean between LC0 and LC100 representing 71 mg/L of the test substance.

The test substance EGForm hydrolyses rapidly and completely in the test medium, forming ethylene glycol and formaldehyde. Formaldehyde is expected to dominate the toxicity of EGForm in aqueous solutions. Dissolved formaldehyde is not expected to be volatile, and no losses due to adsorption are to be expected.

Analysis of the formaldehyde concentrations during the test proved that no significant losses occurred with respect to the mean measured values. Individual results, however, are deviating by more than 20% of the nominal concentration. A general trend towards loss of formaldehyde in 24 h old solutions, compared to freshly prepared media, cannot be observed. Therefore, the effective concentrations can be considered to be equal to the nominal concentrations.

Description of key information

In a study on the acute toxicity of the test substance towards fish the LC50 was determined to be 71 mg/L employing the zebrafish (Danio rerio) as the test organism.

The acute 96 h LC50 value of ethylene glycol to P. promelas was determined to 72860 mg/L.

Key value for chemical safety assessment

LC50 for freshwater fish:
71 mg/L

Additional information