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Ecotoxicological information

Short-term toxicity to fish

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Description of key information

The substance was not acutely toxic to fish when tested according to OECD 203.  The calculated 96-h EC50 is 19.8 mg/L; calculated from the geometric average concentrations of the EC0 (14.3 mg/L) and the EC100 (25.4 mg/L) assuming 37% loss over the course of the 96-hour fish assay at 22ºC.

Key value for chemical safety assessment

LC50 for freshwater fish:
19.8 mg/L

Additional information

Acute toxicity to Brachydanio rerio (new name: Danio rerio) was assessed according to OECD 203 by a study not following GLP procedures (Rufli, 1989). Fish were exposed under static conditions to the substance at a range of concentrations from 18, 32, 58, and 100 mg/L in freshwater. The test was performed with 10 fish per vessel and concentration. For each concentration, the percentage of mortality at 24, 48, 72, and 96 hours was recorded. The following OECD 203 validity criteria were met: mortality in the control did not exceed 10% at the end of the test; constant conditions (temperature and pH) were within specified deviations; and the dissolved oxygen concentration was at least 60% of the air saturation value throughout the test. The OECD 203 validity criterion, concerning evidence that the concentration of the substance was at least 80% of the nominal concentration throughout the test, was not met.

Štreit (2010) determined the water solubility to be 55.6 g/L, which is three orders of magnitude higher than the nominal 96-h LC50 in fish, clearly demonstrating that the test substance was soluble at the concentrations used in the study. However, evidence of hydrolysis was reported in the water solubility report, and a review of “Fig. No. 1:LC/MS analysis of Grilonit 1/10 water solution” in the Annexes revealed that the primary peak (Retention Time = 10.2 mins) fell from ~3.5 to ~2.2 over the course of the 4-day experiment (3 days at 30°C + 1 at 20°C). This amounts to 37% loss of the primary component over this 96-hour period, which is most probably due to ring-opening hydrolysis of the epoxy groups.

Assuming the same 37% loss over the course of the fish study (96-h at 22°C) and assuming that the actual concentrations were as follows:

Initial (= nominal) [mg/L]

10

18

32

58

100

Final (96-h) [mg/L]

6.3

11.3

20.1

36.5

62.9

Geometric average [mg/L]

7.9

14.3

25.4

46.0

79.3

 

The 96-h effect concentrations would be:

Duration

Endpoint

Effect conc.

(mg/L)

Nominal/Measured 

Conc. based on 

Basis for effect 

Remarks

96-h

LC50

19.8

Meas. (geom.. mean)

 

(Nominal value was 24 mg/L)

test mat.

mortality

Calculated from the geometric average concentrations, (half-way between 14.3 and 25.4 mg/L).

96-h

LC0

14.3

Meas. (geom.. mean)

 

(Nominal value was 18 mg/L)

test mat.

mortality

Assuming 37% loss over the course of the fish study (96-h at 22°C)

96-h

LC100

25.4

Meas. (geom.. mean)

 

(Nominal value was 32 mg/L)

test mat.

mortality

Assuming 37% loss over the course of the fish study (96-h at 22°C)

 

This estimate is conservative in that it assumes as much hydrolysis at 4-days at 22°C as was seen at 3-days at 30°C + 1-day at 20°C.