Polysulfides, di-tert-dodecyl

Short-term toxicity to fish

Link to relevant study record(s)

Reference

Endpoint:

short-term toxicity to fish

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

29 July to 2 August 2010

Reliability:

3 (not reliable)

Rationale for reliability incl. deficiencies:

significant methodological deficiencies

Qualifier:

according to guideline

Guideline:

OECD Guideline 203 (Fish, Acute Toxicity Test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

no

Details on sampling:

Observations were taken at 2, 24, 48, 72 and 96 hours for mortality and sublethal effects. Dead fish were removed daily.

Vehicle:

no

Details on test solutions:

990 uL of test item was added to 10000 mL of test water and carefully stirred in the dark for 24 hours. Solution was allowed to settle for 1 hour and the aqueous phase was carefully drawn off. The test solution was prepared just before test initiation.

Test organisms (species):

Danio rerio (previous name: Brachydanio rerio)

Details on test organisms:

Age: juvenile. Mean length: 2.2 cm +/- 0.18 cm. Mean body weight: 0.07 +/- 0.02 g. Source: Aquaristik-Studio Frohlich, 63165 Muhlheim, Germany. Sex: male and female. Feeding: three-times were week to daily until 24 hours prior to test initiation. Holding: held for at least seven days immediately prior to testing in water of test quality and there were no mortalities.

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

96 h

Hardness:

No data reported.

Test temperature:

21-22°C

pH:

7.7-8.0

Dissolved oxygen:

92 - 102% of air saturation. Test water not aerated.

Salinity:

No data reported

Nominal and measured concentrations:

Water accommodated fraction of 100 mg/L nominal concentration and a control were prepared and all results are given as loading rate as no analytical measurements were performed.

Details on test conditions:

Number of concentrations: 2 (100 mg/L nominal concentration, control). Number of replicates at each concentration: 1. Number of fish in each replicate: 7. Photoperiod: 16 hours light to 8 hours dark - 30 minutes transition. Light intensity: 510-890 lux. Fish were not fed during testing. A static closed vessel design was chosen in order to keep test concentrations as constant as possible and avoid cross contamination.

Reference substance (positive control):

no

Duration:

96 h

Dose descriptor:

LL50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

loading rate

Basis for effect:

mortality (fish)

Duration:

96 h

Dose descriptor:

LOEC

Effect conc.:

100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

loading rate

Basis for effect:

other: sublethal effects

Duration:

96 h

Dose descriptor:

NOEC

Effect conc.:

< 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

loading rate

Basis for effect:

other: sublethal effects

Duration:

96 h

Dose descriptor:

LC0

Effect conc.:

< 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

loading rate

Basis for effect:

other: sublethal effects

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

loading rate

Basis for effect:

other: sublethal effects

Details on results:

At test termination in the test vessel, 2 fish out of seven had died and 3 fish had sublethal effects (fins which were stacked together). Although there were signs of toxic effects at the test concentration, no further concentrations were tested.

Results with reference substance (positive control):

Fish in the control vessel showed no mortality or sublethal effects.

Reported statistics and error estimates:

The nominal concentration of 100 mg/L is the highest concentration which needs to be tested, as well as the threshold concentration. Further knowledge would not have been gained by carrying out a dose response test.

Validity criteria fulfilled:

yes

Conclusions:

The toxicity of polysulfide, di-tert-dodecyl to zebrafish (Danio rerio), based on the loading rate, gives a 96-hour LL50 of >100 mg/L, a NOEC of <100 mg/L and a LOEC of 100 mg/L.

Executive summary:

Hoffmann (2010) is a GLP-compliant, static closed vessel limit test following OECD guideline 203. No further dose-response test was performed despite the limit test showing toxic effects, as the concentration tested was the threshold concentration and the highest concentration at which substances need to be tested. No further information would have been gained about the toxicity of the test item from further dose-response testing.

The study has been considered initially as reliable with restriction and suitable for use for this endpoint.

Careful examination of the test design casts doubts on the reliability of the results. Indeed, during the preparation of the WAF at 100 mg/L (remark: it has been shown later on that the water solubility of t-dodecyl polysulfide is 0.26 µg/L at 20°C), further to 24h stirring, the mixture is allowed to settle for 1 hour. Given that the test substance relative density sets at 1.0028, this is likely insufficient to ensure that droplets are not present in the water column. Neither analysis nor light scattering has been applied in order to demonstrate that fish are exposed to realistic concentrations. This is why it is now considered that this study is not reliable due to this experimental deficiency.

Description of key information

According to Hoffmann (2010), the toxicity of polysulfide, di-tert-dodecyl to zebrafish (Danio rerio), based on the loading rate, gives a 96-hour LL50 of >100 mg/L, a NOEC of <100 mg/L and a LOEC of 100 mg/L

According to this study, the toxicity of polysulfide, di-tert-dodecyl to zebrafish (Danio rerio), based on the loading rate, gives a 96-hour LL50 of >100 mg/L, a NOEC of > 100 mg/L and a LOEC of 100mg/L.

This study is now considered as unreliable for the reason provided below and according to REACH regulation, considering the very low water solubility, a chronic fish toxicity test has been done instead.

Hoffmann (2010) is a GLP-compliant, static closed vessel limit test following OECD guideline 203. No further dose-response test was performed despite the limit test showing toxic effects, as the concentration tested was the threshold concentration and the highest concentration at which substances need to be tested. No further information would have been gained about the toxicity of the test item from further dose-response testing.

The study has been considered initially as reliable with restriction and suitable for use for this endpoint.

Careful examination of the test design casts doubts on the reliability of the results. Indeed, during the preparation of the WAF at 100 mg/L (remark: it has been shown later on that the water solubility of t-dodecyl polysulfide is 0.26 µg/L at 20°C), further to 24h stirring, the mixture is allowed to settle for 1 hour. Given that the test substance relative density sets at 1.0028, this is likely insufficient to ensure that droplets are not present in the water column. Neither analysis nor light scattering has been applied in order to demonstrate that fish are exposed to realistic concentrations. This is why it is now considered that this study is not reliable due to this experimental deficiency.

Additional information

Hoffmann (2010) is a GLP-compliant, static closed vessel limit test following OECD guideline 203. No further dose-response test was performed despite the limit test showing toxic effects, as the concentration tested was the threshold concentration and the highest concentration at which substances need to be tested. No further information would have been gained about the toxicity of the test item from further dose-response testing.

The study has been considered initially as reliable with restriction and suitable for use for this endpoint.

Careful examination of the test design casts doubts on the reliability of the results. Indeed, during the preparation of the WAF at 100 mg/L (remark: it has been shown recently that the water solubility of t-dodecyl polysulfide is 0.26 µg/L at 20°C), further to 24h stirring, the mixture is allowed to settle for 1 hour. Given that the test substance relative density sets at 1.0028, this is likely unsufficient to ensure that droplets are not present in the water column. Neither analysis nor light scattering has been applied in order to demonstrate that fish are exposed to realistic concentrations.

This is why it is now considered that this study is not reliable due to this experimental deficiency.

Given the very low water solubility, it has not been considered appropriate to redo an acute fish toxicity study but rather to carry out a chronic fish toxicity study, in accordance to column 2 of REACH regulation Annex VIII, section 9.1.3.: " The long-term aquatic toxicity study on fish (Annex IX, section 9.1.6) shall be considered if the substance is poorly water soluble."