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Long-term toxicity to aquatic invertebrates

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Reference
Endpoint:
long-term toxicity to aquatic invertebrates
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2016
Reliability:
1 (reliable without restriction)
Qualifier:
according to
Guideline:
OECD Guideline 211 (Daphnia magna Reproduction Test)
Version / remarks:
limit test
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:
Test substance solutions were prepared in M7 medium
Nominal concentration of 1.3 µg/L was prepared by spiking 20µg/L of a stock solution of 65 mg/L (prepared in acetone) per liter of test solution. The final amount of acetone in solution was 20µg/L.
Solvent blanks were run in parallel during the experiment.
Test organisms (species):
Daphnia magna
Details on test organisms:
In-house laboratory culture with a known history.
Daphnids originated from a healthy stock, 2nd to 5th brood, showing no signs of stress such as mortality >20%, presence of males, ephippia or discoloured animals and there was no delay in the production of the first brood
Test type:
semi-static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
21 d
Hardness:
> 140 Mg/L as CaCO3 (161-214)
Test temperature:
18-22°C (18.8-19.8)
pH:
6.0 to 9.0, constant within 1.5 unit. (7.9-8.3)
Dissolved oxygen:
> 3 mg/L (4.7-9.4)
Salinity:
na
Conductivity:
na
Nominal and measured concentrations:
nominal 1.3 µg/L
measured: arithmetic mean (average) of geometric means of measurements in fresh and exhausted solutions along the experiment: 0.79 µg/L

Details on test conditions:
Test duration 21 days
Test type Semi-static
Frequency of renewal Every 48 hours
Test vessels Volume: 60 ml (6 x Ø 3.5 cm), all-glass covered with a Perspex plate.
Medium M7
Experimental design At the start of the experiment (nominal day 0) 20 neonate daphnids, less than one day old, per group were divided over twenty vessels each containing a minimum of 50 ml test medium.
Light 16 h photoperiod daily;
intensity at the start: 740-769 lux
intensity at the end: 737-760 lux
Feeding Twice daily an amount of 0.25 ml of a Chlorella sp. suspension . On weekend days an amount of 0.50 ml was added in one single feed. This daily ration corresponded to 0.2 mg C/Daphnia/day, which is the recommended value for daily feeding per daphnid in the reproduction test according to the OECD Guideline 211.
Reference substance (positive control):
no
Duration:
21 d
Dose descriptor:
NOEC
Basis for effect:
reproduction
Remarks on result:
not determinable
Duration:
21 d
Dose descriptor:
NOEC
Basis for effect:
growth
Remarks on result:
not determinable
Details on results:
On average, 171 and 183 offspring were produced per surviving daphnid in the blank-control and solvent-control, respectively. In the limit concentration the total number of offspring was 178.
Statistical analyses showed a significant difference between the two controls and therefore the reproduction of the limit concentration was compared to the solvent-control group.
Reproduction:
Statistical analysis showed that the reproduction of the daphnids in the limit concentration was not statistically significantly reduced.
Occasionally, a few immobilised offspring or aborted eggs were observed in the three test groups. The numbers were not considered significant and were not test item related.
Body length:
The group mean body lengths of the surviving daphnids per concentration measured at the end of the test and the relative reduction of body lengths were compared to the control. Statistical analyses showed a significant difference between the two controls and therefore the mean daphnid length of the limit concentration was compared to the solvent-control group. Statistical analysis showed that the mean length of the daphnids in the limit concentration was not statistically significantly reduced.

Effect parameters, as reported:

Parameter

Average measured concentration (µg/L)

NOEC for reproduction

0.79

EC10forreproduction

> 0.79

EC50for reproduction

> 0.79

NOEC for mortality

0.79

NOEC for growth

0.79

Validity criteria fulfilled:
yes
Conclusions:
Limit test at concentration slightly above water solubility limit (on average 0.79 µg/L vs 0.26) did not show biologically relevant effects. No NOEC/LOEC can therefore be derived from the experiment. No EC10 can be derived either.
Executive summary:

A long-term toxicity test on freshwater invertebrate (Daphnia magna) according to OECD 211 was carried out on polysulfide, di-tet-dodecyl, on 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 (nominal: 1.3 µg/L, average measured: 0.79 µg/L). No biologically significant effect has been observed. Therefore, no full concentration/effect could be measured and no NOEC or EC10 can be derived and used for calculation of a PNECaqua.

No long-term toxicity of polysulfide, di-tet-dodecyl to reproduction of daphnids has been observed.

Description of key information

A long-term toxicity test on freshwater invertebrate (Daphnia magna) according to OECD 211 was carried out on polysulfide, di-tet-dodecyl, on 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 (nominal: 1.3 µg/L, average measured: 0.79 µg/L). No biologically significant effect has been observed. Therefore, no full concentration/effect could be measured and no NOEC or EC10 can be derived and used for calculation of a PNECaqua.

No long-term toxicity of polysulfide, di-tet-dodecyl to reproduction of daphnids has been observed.

Key value for chemical safety assessment

Additional information