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Ecotoxicological information

Ecotoxicological Summary

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Hazard for aquatic organisms

Freshwater

Hazard assessment conclusion:
PNEC aqua (freshwater)
PNEC value:
0.005 mg/L
Assessment factor:
1 000
Extrapolation method:
assessment factor
PNEC freshwater (intermittent releases):
0.053 mg/L

Marine water

Hazard assessment conclusion:
PNEC aqua (marine water)
PNEC value:
0.001 mg/L
Assessment factor:
10 000
Extrapolation method:
assessment factor

STP

Hazard assessment conclusion:
PNEC STP
PNEC value:
2.6 mg/L
Assessment factor:
10
Extrapolation method:
assessment factor

Sediment (freshwater)

Hazard assessment conclusion:
PNEC sediment (freshwater)
PNEC value:
0.02 mg/kg sediment dw
Extrapolation method:
equilibrium partitioning method

Sediment (marine water)

Hazard assessment conclusion:
PNEC sediment (marine water)
PNEC value:
0.002 mg/kg sediment dw
Extrapolation method:
equilibrium partitioning method

Hazard for air

Air

Hazard assessment conclusion:
no hazard identified

Hazard for terrestrial organisms

Soil

Hazard assessment conclusion:
PNEC soil
PNEC value:
0.001 mg/kg soil dw
Extrapolation method:
equilibrium partitioning method

Hazard for predators

Secondary poisoning

Hazard assessment conclusion:
no potential for bioaccumulation

Additional information

The hydrolysis half-life of 3-(trimethoxysilyl)propane-1-thiol is 2.6 h at pH 7, 20-25°C. The registration substance will hydrolyse in contact with water and atmospheric moisture to 3-(trihydroxysilyl)propanethiol and methanol. REACH guidance (ECHA 2016b, R.16) states that “for substances where hydrolytic DT50 is less than 12 hours, environmental effects are likely to be attributed to the hydrolysis product rather than to the parent substance itself”. TGD and ECHA guidance, (EC 2003, ECHA 2016c, R7b) also suggest that when the hydrolysis half-life is less than 12 hours, the breakdown products, rather than the parent substance, should be evaluated for aquatic toxicity. Therefore, the environmental hazard assessment, including sediment and soil compartments due to water and moisture being present, is based on the properties of the silanol hydrolysis product, in accordance with REACH guidance. As described in Section 1.4 of the CSR, 1.8 of IUCLID, the silanol hydrolysis products may be susceptible to condensation reactions.

References:

ECHA 2016b: European Chemicals Agency. Guidance on information requirements and chemical safety assessment Chapter R.16: Environmental Exposure Assessment. Version: 3.0, February 2016 (Section A.16-3.2.2 part (A): Hydrolysis)

ECHA 2016c: European Chemicals Agency. Guidance on information requirements and chemical safety assessment Chapter R.7b: Endpoint specific guidance. Version: 3.0, February 2016 (Section R.7.9.5.2, subsection on Assessment of the potential persistence of metabolites)

Conclusion on classification

The substance has reliable short-term E(L)C50 values of 439 mg/l in fish, 6.7 mg/l in invertebrates and 931 mg/l in algae. It has reliable ErC10 92 mg/l in algae.

The substance hydrolyses rapidly in water and is not readily biodegradable.

These data are consistent with the following classification under Regulation (EC) No 1272/2008 (as amended) (CLP):

Acute toxicity: Not classified.

Chronic toxicity: Category Aquatic Chronic 2.