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Long-term toxicity to fish

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Description of key information

OECD 234 – Fish Sexual Development Test (FSDT; see Section 6.1.8. for the Study Summary). The OECD 234 Endpoint Summary is provided in this section because this method is sufficient for fulfilling the long-term toxicity to fish data requirement, so the key value for the chemical safety assessment from this study is utilised for this endpoint. Further, no Endpoint Summary functionality is available in Section 6.1.8 Endocrine Disruptor Testing in Aquatic Invertebrates – in vivo , hence all relevant discussion related to Section 6.1.8 is also included below.


The test was performed on the read-across source substance: 3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctanol (6:2 FTOH, which is a metabolite/transformation product of 6:2 FTA)



  • A statistically significant effect was observed on hatching success at nominal concentrations of 0.96 mg/L and above.

  • Statistically significant effects were observed on survival and growth (male and female length and weight) at the highest nominal test concentration of 3.0 mg/L.

  • Sex ratio was not affected by the test substance at the concentrations employed with no statistically significant differences observed between the test concentrations and solvent control for either genetic or phenotypic sex ratio.

  • Whilst no statistically significant increase or decrease in VTG concentration in female fish was observed, statistically significant effects were observed for male secondary sex characteristics and male VTG concentration. A significant decrease in the number of anal fin papillae was observed at the 3.0 mg/L test concentration whilst a significant increase in VTG concentration was observed at the 0.30 mg/L test concentration and above.


The overall NOEC covering all endpoints tested was considered to be 0.096 mg/L based on nominal test concentrations (0.0137 mg/L based on geometric mean measured concentrations). A summary of the individual endpoints assessed are given in Table 1 below:


Table 1.  NOEC and LOEC values for all endpoints examined
















































































Response



Nominal concentration
(mg/L)



Geometric Mean Measured Concentration (mg/L)



NOEC



LOEC



NOEC



LOEC



Hatching success



0.30



0.96



0.0231



0.0537



Final survival



0.96



3.0



0.0537



0.0953



Female growth (lengths and weights)



0.96



3.0



0.0537



0.0953



Male growth (lengths and weights)



0.96



3.0



0.0537



0.0953



Genetic sex ratio (% males)



≥3.0



>3.0



≥0.0953



>0.0953



Phenotypic sex ratio (% males)



≥3.0



>3.0



≥0.0953



>0.0953



VTG concentration (female)



≥3.0



>3.0



≥0.0953



>0.0953



VTG concentration (male)



0.096



0.30



0.0137



0.0231



Secondary sex characteristics



0.96



3.0



0.0537



0.0953


Key value for chemical safety assessment

Fresh water fish

Fresh water fish
Dose descriptor:
NOEC
Effect concentration:
0.014 mg/L

Additional information

Endocrine disruptor testing in aquatic vertebrates - in vivo - Endpoint Summary - IUCLID Section 6.1.8 - OECD 234 (Fish Sexual Development Test; FSDT) Summary


A test in accordance with OECD 234 (2011), a FSDT, has been performed in order to assess the endocrine-disrupting potential of the test item (read-across source substance: 3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctanol), in particular the potential for an estrogenic mode of action was investigated.


The test was initiated by adding fertilised Oryzias latipes eggs to test vessels (120 eggs per concentration; < 12 h old), which were exposed to a range of concentrations of the test substance dissolved in water under semi-static test conditions (with daily renewal of the test media). Due to difficulties encountered with maintaining concentrations with a flow-through system, based on the results of media preparation trials, a solvent spike (acetone) using semi-static (daily) renewal was used as the dosing type for this study. The test was continued until fish were sexually differentiated at 112 days post-hatch (dph) (total duration: 122 days).


The definitive test was conducted at nominal test concentrations of 0.030, 0.096, 0.30, 0.96 and 3.0 mg/L. Control and solvent control groups were also included. Four replicate vessels were used for the controls and each test concentration.


At the end of the exposure, the adult fish were assessed for growth (weight and length), secondary sex characteristics (anal fin papillae count), genetic sex (by PCR method) and vitellogenin (VTG; by ELISA method). In addition, gonad histology was performed to determine the phenotypic sex of the fish. Hatching success and final survival were also examined.


Chemical analysis was conducted weekly throughout the test on freshly prepared media and the corresponding 24 h old media. Despite all measures taken, nominal concentrations were generally not achieved and were not maintained over the 24 h semi-static exposure periods. This was due to the highly volatile nature of the test substance and the requirement to aerate the vessels to maintain fish health. Given the variability in measured concentrations throughout the test, the results have been calculated based on both nominal and mean measured concentrations. The geometric mean measured concentrations were calculated to be 0.00933, 0.0137, 0.0231, 0.0537 and 0.0953 mg/L.


The results of individual endpoints are described in Table 1 in the free text box ‘Description of key information’ above. The overall NOEC covering all endpoints tested was considered to be 0.096 mg/L based on nominal test concentrations, or 0.0137 mg/L based on geometric mean measured concentrations.