4,6-bis(octylthiomethyl)-o-cresol

Ecotoxicological Summary

Hazard for aquatic organisms

Freshwater

Hazard assessment conclusion:

PNEC aqua (freshwater)

PNEC value:

0.1 µg/L

Assessment factor:

1 000

Extrapolation method:

assessment factor

PNEC freshwater (intermittent releases):

0.001 mg/L

Marine water

Hazard assessment conclusion:

PNEC aqua (marine water)

PNEC value:

0.01 µg/L

Assessment factor:

10 000

Extrapolation method:

assessment factor

STP

Hazard assessment conclusion:

PNEC STP

PNEC value:

1 mg/L

Assessment factor:

100

Extrapolation method:

assessment factor

Sediment (freshwater)

Hazard assessment conclusion:

PNEC sediment (freshwater)

PNEC value:

8.27 mg/kg sediment dw

Extrapolation method:

sensitivity distribution

Sediment (marine water)

Hazard assessment conclusion:

PNEC sediment (marine water)

PNEC value:

0.827 mg/kg sediment dw

Extrapolation method:

sensitivity distribution

Hazard for terrestrial organisms

Soil

Hazard assessment conclusion:

PNEC soil

PNEC value:

0.172 µg/kg soil dw

Extrapolation method:

sensitivity distribution

Hazard for predators

Secondary poisoning

Hazard assessment conclusion:

PNEC oral

PNEC value:

1.67 mg/kg food

Assessment factor:

300

Additional information

The acute toxicity study in Fish produced no adverse results, with LC50 and NOEC values presented as limits at >100 mg/L. The study in Daphnia produced results which were attributed to be physical and not toxic (deposits of the substance within the bodies affecting mobility), with respective LC0 / LC100 values presented as limits at <0.5mg/L and >5.5mg/L. The substance is not considered to be environmentally dangerous on this basis.

The algae study conducted yielded the following results: 

72 h EC50 growth rate > 0.1 mg/L

72 h EC50 biomass > 0.1 mg/L

72 h NOEC 0.1 mg/L

72 h LOEC > 0.1 mg/L

 

It should be noted that the substance did not demonstrate any toxic effects at the limit of solubility in water. As such, the values presented for PNEC are as derived using guidance document “R10 - Characterisation of dose [concentration] - response for environment”. However, as no effects were noted at the limit of solubility, a more accurate PNEC can be construed to be the soluble limit; i.e. 0.1 mg/l. Review of the guidance indicates that in section R.10.2.2.2 (Q)SAR and grouping approaches, QSAR can be used to provide additional supporting evidence of toxicity. Within the guidance, Table R.10-20 : Overview of programs for prediction of aquatic toxicitytools such as ECOSAR (U.S. EPA 1994) can be used to perform assessment. An assessment of Thanox 1520 using this QSAR system indicated that no effects at saturation are predicted for these endpoints.

 

As the guidance for deriving the PNEC for does not provide assessment factors for substances with no effects at the limit of solubility, the assessment factors as proposed have been applied. 

The results given shows no toxic effect at saturation, the EC50 and LOEC values are higher than the solubility level of the test item in the test medium. No classification and labelling is applicable. 

The substance is therefore proposed to be “not classified” and appropriate comments are detailed within Section 2 of the registration dossier.

Conclusion on classification

The environmental studies conducted on the substance have all been ranked reliability 1 according to the Klimish et al system. This ranking was deemed appropriate because the studies were conducted to GLP and in compliance with agreed protocols. The majority of the information has been provided from a migrated NONS file referring to studies which are more than 12 years old, with the permission of ECHA. Sufficient dose ranges and numbers are detailed; hence it is appropriate for use based on reliability and animal welfare grounds.

The results triggered no classification under the Dangerous Substance Directive (67/548/EEC) and the CLP Regulation (EC No 1272/2008). No classification for acute environmental effects is therefore required.