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Long-term toxicity to fish

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Reference
Endpoint:
fish early-life stage toxicity
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2016
Reliability:
1 (reliable without restriction)
Qualifier:
according to
Guideline:
OECD Guideline 210 (Fish, Early-Life Stage Toxicity Test)
Version / remarks:
In view of low water solubility, a limit test at saturation has been done. If effects were to be observed, in a second tier a full concentration/effect test would have been done
Deviations:
no
GLP compliance:
yes (incl. certificate)
Analytical monitoring:
yes
Details on sampling:
Solutions were sampled through SPE cartridges slowly for approximately 45 minutes. After elution, the cartridges were dried using a vacuum pump. The test item was eluted from the SPE cartridges with dichloromethane.
Vehicle:
yes
Remarks:
acetone
Details on test solutions:
limit test at spiked levels of 1.3 ug/L, corresponding to a level of five times the water solubility, renewal every 2nd day
Test organisms (species):
Pimephales promelas
Details on test organisms:
in house culture
Test type:
semi-static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
32 d
Hardness:
According to ISO medium: appoximately 180 mg/L as CaCO3 (196-214)
Test temperature:
25+/-1.5°C (25.3-26.4)
pH:
7.2-8.3
Dissolved oxygen:
>60% saturation (6.0-9.6 mg/L)
Salinity:
na
Conductivity:
na
Nominal and measured concentrations:
nominal: 1.3 µg/L
Measured concentrations in freshly prepared solutions ranged between 1.0 and 1.7 µg/L. As expected, based on a water solubility of 0.26 µg/L, measured concentrations decreased slightly during the renewal periods. However, at the end of each renewal period analyses showed that the concentration actually in solution was still above the water solubility limit. The average measured exposure concentration over the entire study period was calculated to be 0.84 µg/L, which was slightly above the water solubility.
Details on test conditions:
Test type Semi-static
Frequency of renewal Every second day
Test duration 33 days
Introduction egg Before cleavage of the blastodisc commenced (approximately 2-4 hours after fertilisation).
Test vessels Embryonic phase: 50 mL Petri-dishes.
Larval phase: stainless steel vessels (~1.7 L) and all-glass vessels (5 L)
Test medium Adjusted ISO medium with a hardness of 180 mg CaCO3 per litre and a pH of 7.7 ± 0.3.
Experimental design The experiment (nominal day 0) started with 80 fresh and healthy fertilised fathead minnow per test group. The fertilised eggs were randomly distributed and divided equally over four petri-dishes. Each petri-dish contained 20 eggs in 50 mL test medium and these dishes were incubated under gentle continuous shaking. On day 6 the hatched larvae were transferred to the stainless steel vessels and on day 16 to the larger glass vessels.
Light period 16 h photo-period daily, between 610 and 940 lux.
Feeding Embryonic phase: no feeding.
Newly hatched larvae: until day 18; Brine shrimp Nauplii 24-hours old.
Juvenile stage: day 19-33: Brine shrimp Nauplii 48-hours old.
Food was supplied ad libitum.
Euthanasia At the end of the test the surviving larvae were rapidly killed by exposing them to ca. 1.2% ethylene glycol monophenylether in water.
Reference substance (positive control):
no
Duration:
32 d
Dose descriptor:
NOEC
Basis for effect:
number hatched
Remarks on result:
not determinable
Duration:
32 d
Dose descriptor:
NOEC
Basis for effect:
larval development
Remarks on result:
not determinable
Details on results:
Embryonic survival, development and hatching:
The overall survival of embryos at the end of hatching was 96% and 100% in respectively the blank- and solvent-control. The overall survival in the limit concentration of 0.84 µg/L was 93%. There was no delay in the onset of hatching observed in this study. Statistical analyses showed no significant differences between the two controls and controls were therefore pooled. Statistical analyses however showed that hatching in the limit concentration was significantly affected in comparison to the pooled control, hence, the NOEC could not be determined. Instead, the EC10 could be used as an alternative measure for NOEC. The percentages of larvae not hatched were 1.9% in the pooled control versus 7.5% in the limit concentration. Hence, in this case the EC10 for effects on hatchability exceeded a concentration of 0.84 µg/L.

Larval survival and development
Post-hatch survival was 78 and 85% in the blank- and solvent-control, respectively. Hence, the validity criterion for post-hatch survival of at least 75% was met. Post-hatch survival in the limit concentration of 0.84 µg/L was slightly lower at 62%. Statistical analyses showed no significant differences between the two controls and controls were therefore pooled. Statistical analyses showed that survival in the limit concentration was not significantly different in comparison to the pooled control, despite the slightly lower survival in the limit concentration. Hence, the NOEC for post-hatch survival was 0.84 µg/L.
A number of clinical effects were observed in this study. The effects were of minor severity and observed in all test groups. They were therefore not related to the test item.

Effects on larval growth
Body lengths and body weights measured at the end of the test period. Statistical analyses showed no significant differences between the two controls and the controls were therefore pooled. Statistical analyses showed that both weight and length in the limit concentration were not significantly different in comparison to the pooled control. Hence, the NOEC for effects on growth (weight and length) equalled 0.84 µg/L.


Validity criteria fulfilled:
yes
Conclusions:
Limit test at concentration slightly above water solubility limit did not show biologically relevant effects. No NOEC/LOEC or EC10 can therefore be derived from the experiment.
Executive summary:

A long-term toxicity test on freshwater fish (fathead minnow) according to OECD 210 was carried out on polysulfide, tert-dodecyl the request of ECHA. As the substance is very poorly soluble (OECD 105: WSL=0.26 µg/L) a limit test has been carried out at a concentration slightly above saturation (on average 0.84 µg/L). No biologically significant effect has been observed on embryonic survival, development and hatching, on larval survival and development, and on larval growth. Therefore, no concentration/effect relationship could be established and no NOEC or EC10 can be derived and used for calculation of a PNECaqua.

Description of key information

A limit test according to OECD TG 210 (Fish Early Life Stage) has been carried out at a concentration (0.84 µg/L) slightly above WSL (0.26 µg/L). The results show not biologically significant effects on embryonic survival, development and hatching, on larval survival and development, and on larval growth.

No NOEC or EC10 can be derived and used for a PNECfreshwater (and marine water) calculation.

Key value for chemical safety assessment

Additional information