Registration Dossier

Administrative data

Hazard for aquatic organisms

Freshwater

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

Marine water

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

STP

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

Sediment (freshwater)

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

Sediment (marine water)

Hazard assessment conclusion:
PNEC sediment (marine water)
PNEC value:
0.007 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:
0.002 mg/kg soil dw
Extrapolation method:
equilibrium partitioning method

Hazard for predators

Secondary poisoning

Hazard assessment conclusion:
insufficient hazard data available (further information necessary)

Additional information

The hydrolysis half-life of triethoxy(3-thiocyanatopropyl)silane is 23 h at pH 7 and 25°C; the substance will therefore undergo moderately rapid hydrolysis in contact with water to form (3-thiocyanatopropyl)silanetriol and ethanol.

REACH guidance (ECHA 2010A, 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 itself”. TGD guidance, (EC 2003) and R.16 (2010A) also suggests 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 aquatic hazard assessment is based on the properties of the(3-thiocyanatopropyl)silanetriolhydrolysis product in accordance with REACH guidance. As described in Section 1, condensation reactions of the silanetriols are possible. However, the substance will also degrade in the sediment and soil compartments due to water and moisture being present, and given the residency time of the substance in the WWTP and the long-term exposure being more relevant for the hydrolysis product, these hazard assessment for these compartments is based on the hydrolysis product.

The other hydrolysis product, ethanol, is well characterised in the public domain and is considered to be not hazardous at the concentrations relevant to the study exposure concentrations.

Conclusion on classification

The environmental hazard data indicate that the lowest L/EC50 values obtained by testing with aquatic species are in the range 10-100 mg/l. Additionally, the substance and its silanetriol hydrolysis product are not readily biodegradable. The registered substance should therefore be classified as Chronic Category 3 according to Regulation (EC) No 1272/2008.