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Ecotoxicological information

Long-term toxicity to fish

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Reference
Endpoint:
fish short-term toxicity test on embryo and sac-fry stages
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Justification for type of information:
For tin disulfide an algal study is available. This study demonstrated that the tin sulfide has no toxic effects at the limit of water solubility, i.e., at 0.67 µg/L. The other aquatic endpoints were covered using data from tin sulfide which has an almost identical water solubility, i.e., 0.6 µg/L. The algal study was used as bridging study since the WHO concluded in their report that alge are the most sensitive group. Furthermore, the WHO concluded that Sn II is more toxic than Sn IV. Hence, read across from tin sulfide (Sn II) to tin disulfide (Sn IV) was considered justified.
Reason / purpose:
read-across source
Vehicle:
no
Duration:
13 d
Dose descriptor:
EC50
Effect conc.:
> 33 µg/L
Nominal / measured:
meas. (TWA)
Conc. based on:
test mat.
Basis for effect:
mortality
Duration:
13 d
Dose descriptor:
NOEC
Effect conc.:
>= 33 µg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
test mat.
Basis for effect:
mortality
Remarks on result:
other: No mortality up to the highest concentration
Duration:
13 d
Dose descriptor:
EC50
Effect conc.:
> 33 µg/L
Nominal / measured:
meas. (TWA)
Conc. based on:
test mat.
Basis for effect:
number hatched
Duration:
13 d
Dose descriptor:
NOEC
Effect conc.:
>= 33 µg/L
Nominal / measured:
meas. (TWA)
Conc. based on:
test mat.
Basis for effect:
number hatched
Remarks on result:
other: No effect up to highest tested concentration
Duration:
13 d
Dose descriptor:
EC50
Effect conc.:
> 33 µg/L
Nominal / measured:
meas. (TWA)
Conc. based on:
test mat.
Basis for effect:
weight
Duration:
13 d
Dose descriptor:
LOEC
Effect conc.:
11 µg/L
Nominal / measured:
meas. (TWA)
Conc. based on:
test mat.
Basis for effect:
weight
Key result
Duration:
13 d
Dose descriptor:
NOEC
Effect conc.:
7 µg/L
Nominal / measured:
meas. (TWA)
Conc. based on:
test mat.
Basis for effect:
weight
Duration:
13 d
Dose descriptor:
LOEC
Effect conc.:
33 µg/L
Nominal / measured:
meas. (TWA)
Conc. based on:
test mat.
Basis for effect:
length
Duration:
13 d
Dose descriptor:
NOEC
Effect conc.:
18 µg/L
Nominal / measured:
meas. (TWA)
Conc. based on:
test mat.
Basis for effect:
length
Reported statistics and error estimates:
The ECx values based on survival, hatching, weight and length data were calculated by probit method. Lethal and sub-lethal effects are assessed and compared with control to determine LOEC and hence NOEC values. The LOEC (Lowest Observed Effect Concentration) is the lowest concentration of the test item used in the test at which a significant effect was observed when compared with the control. The NOEC (No Observed Effect Concentration) is the test concentration immediately below the LOEC. The LOEC and NOEC values were estimated based on statistical analysis.

In the highest test concentration 100% Vol/Vol one embryo was coagulated, tail detached from yolk and somites were observed for all survivors on day 1. On day 2 four embryos were found dead (coagulated) but for all survivors heart beat was recorded. On day 3 five were not hatched, among all hatched one with scoliosis of tail was reported. On day 4 one was still non‑hatched. On day 6 normal development, mobility, positive reaction to stimuli for most of survivors, but scoliosis of tail for one and yolk sac-edema for two larvae were observed. Further, mobility deteriorated with time, reactions became slower and zebrafish were weaker with progressing yolk absorption. Cumulative mortality increased with time and at test termination survivors were very weak with yolk absorbed, no scoliosis or edemas were observed among survivors.

In test concentration 50% Vol/Vol one embryo was coagulated, for all survivors tail detached from yolk and somites were observed on day 1. On day 2 heart beat was reported. On day 3 four non-hatched and among hatched one with scoliosis of tail were observed. On day 4 one was still non-hatched, but on day 5 all were hatched with normal mobility and reaction to stimuli. On day 6 apart from the one with scoliosis of tail, one was with yolk sac edema, but no other abnormalities in development were reported. Mobility of survivors deteriorated with time, reactions became slower and zebrafish were weaker with progressing yolk absorption. At test termination mortality increased to 11.7% and development of survivors was normal.

In test concentration 25% Vol/Vol coagulation of one embryo was reported on day 1. Four other embryos were coagulated on day 2. On day 3 only two embryos were non-hatched, among hatched two larvae with scoliosis of tail were observed. On day 4 one was still non-hatched. Mobility of survivors deteriorated with time, reactions became slower and zebrafish were weaker with progressing yolk absorption. At test termination mortality increased to 18.3% and development of all survivors was normal.

In test concentration 12.5% Vol/Vol three embryos on day 1 and three other embryos on day 2 were coagulated. On day 3 only one non-hatched embryo was observed but one larvae was found dead. Mortality did not change further during the test. Development of all survivors was normal, i.e. tail detachment and formation of somites on day 1, heart beat on day 2 and hatching started on day 3. Mobility and reaction to stimuli were weak at test termination.

In lowest test concentration 6.25% Vol/Vol two embryos were coagulated on day 2. No abnormalities in comparison with zebrafish in controls were observed. On day 3 two with scoliosis of tail were reported and three embryos were non-hatched, but on day 4 hatching was completed. Two larvae without any visible developmental abnormalities were found dead on day 8 and two other were found dead on day 9. Total number of survivors was fifty four what remained unchanged till the test termination.

In the control double filtered initial mortality was two embryos coagulated on day 1 and one embryo on day 2. Hatching started on day 3, ten zebrafish with delay of one day, and was completed on day 4. Normal development for all zebrafish was recorded. On day 8 one larvae was found dead. One zebrafish was found dead on each of days 11, 12 and 13. Therefore, total number of survivors was fifty two.

In the control with non filtrated conditioned water one embryo was coagulated on day 2, one non-hatched and two hatched larvae were dead on day 3. Hatching was completed on day 3. Mortality increased by one zebrafish on days 8 and 11. On day 12 three and on day 13 two zebrafish were found dead.

No other effects were recorded.

Overview of observed endpoints and calculated effect concentrations

 

Concentration of test item [% of filtrate from soluble fraction of 100 mg/L]

Control non-filtered

Control

6.25

12.5

25

50

100

time-weighted mean of concentrations of the test item [µg/L]

0

0

6

7

11

18

33

not hatched on day 3 [%]

1.8

17.5

5.2

1.9

3.6

6.8

9.1

fry mortality after 13 days [%]

18.3

13.3

10

18.3

18.3

11.7

13.3

reduction of fry fish dry weight per survivor after 13 days [%]

4.5

0.0

0.0

0.0

11.4

18.2

13.6

reduction of fry fish length after 13 days [%]

-1.0

0.0

-1.7

-0.7

-1.0

0.0

6.4

Hatchability endpoints (based on time-weighted means of concentrations of the test item)

EC10

>33µg/L

LOEC

>33µg/L

NOEC

≥33µg/L

Survival endpoints (based on time-weighted means of concentrations of the test item)

EC10

>33µg/L

LOEC

>33µg/L

NOEC

≥33µg/L

Weight endpoints (based on time-weighted means of concentrations of the test item)

EC50

>33µg/L

LOEC

11µg/L

NOEC

7µg/L

Length endpoints (based on time-weighted means of concentrations of the test item)

EC10

>33µg/L

LOEC

33µg/L

NOEC

18µg/L

The results are considered relevant for tin disulfide since both substances have the same metal moiety and have similar physico-chemical properties, e.g., they are almost insoluble in water. Further evidence is provided in the read across justification. 

 

Validity criteria fulfilled:
yes
Conclusions:
Effects were observed only at concentrations higher than the water solubility limit. Therefore, these effects are considered as not relevant.
Executive summary:

The 13–day chronic toxicity of tin sulfide to early life stage of Brachydanio rerio was studied under semi-static conditions. Testmedia: conditioned tap water. Totally 60 embryos were exposed to measured tin sulfide concentrations up to 33 µg/L. Highest concentration was prepared as a saturated fraction from a nominal 100 mg/L Tin sulfide in conditioned tap water. The test system was maintained at 23.9 to 25.8 ºC and a pH of 6.91 to 7.67.  The 13–day EC50 and NOEC value, based on mortality, was >33 µg a.i./L.  The sublethal effects included were hatching, weight and length of animals. The most sensitive end point was weight.

 

This toxicity study is classified as valid without restrictions and satisfies the guideline requirement for early life toxicity study with fish.

 

Results Synopsis

 

Test Organism Size: Brachydanio rerio embryos

Test Type: Semi-static

Test media: conditioned tap water

 

LOEC: 11 µg a.i./L

NOEC: 7 µg a.i./L

EC50: >33µg/L (maximum observed effect: 18%)

Endpoint(s) Effected:  weight

Conclusion: Effects were observed only at concentrations higher than the water solubility of tin sulfide (0.6 µg/L). Therefore, these effects are considered as not relevant.

The results are considered relevant for tin disulfide since both substances have the same metal moiety and have similar physico-chemical properties, e.g., they are almost insoluble in water. Further evidence is provided in the read across justification. 

Description of key information

The test was perfomed on the read-across substance tin sulfide but is considered relevant for tin disulfide as well. Up to the limit of water solubility, tin disulfide is not toxic to fish in a long-term study.

Key value for chemical safety assessment

EC10, LC10 or NOEC for freshwater fish:
7 µg/L

Additional information

The endpoint was covered by read across from tin sulfide.

The 13–day chronic toxicity of tin sulfide to early life stage of Brachydanio rerio was studied under semi-static conditionsaccording to OECD 212. Testmedia: conditioned tap water. Totally 60 embryos were exposed to measured tin sulfide concentrations up to 33 µg/L. Highest concentration was prepared as a saturated fraction from a nominal 100 mg/L Tin sulfide in conditioned tap water. The test system was maintained at 23.9 to 25.8 ºC and a pH of 6.91 to 7.67.  The 13–day EC50and NOEC value, based on mortality, was >33 µg a.i./L.  The sublethal effects included were hatching, weight and length of animals. The most sensitive end point was weight.

 

This toxicity study is considered as valid without restrictions and satisfies the guideline requirement for early life toxicity study with fish.

 

Results Synopsis

 

Test Organism Size:Brachydanio rerio embryos

Test Type: Semi-static

Test media: conditioned tap water

 

LOEC: 11 µg a.i./L

NOEC: 7 µg a.i./L

EC50: >33µg/L (maximum observed effect: 18%)

Endpoint(s) Effected:  weight

Conclusion: Effects from tin sulfide were only observed at concentrations higher than the water solubility of tin sulfide (0.6 µg/L). Therefore, these effects are considered as not relevant. Read across from tin sulfide to tin disulfide was considered as possible (see Read Across justification document attached to the dossier). Hence it can be concluded that there is no long-term toxicity to fish at the limit of water solubility of tin disulfide, i.e., at 0.67 µg/L.