Chloroethane

Endpoint summary

Additional information

Toxicity tests on soil dwelling invertebrates are not available for the test substance. Chloroethane is a gaseous substance and thus will mainly distribute to the air if released to the environment. There is no intended direct release of the substance to soil during its lifecycle. Due to its gaseous nature, chloroethane is characterised by a high vapour pressure of 134200 Pa at 20 °C (62330 Pa at 0 °C). The substance may dissolve in water, as indicated by a water solubility of 5.74 g/L at 20 °C. However, a rapid volatilization from water or moist soil is expected based on a very high calculated Henry's Law constant: 1124.70 Pa m³/mol. If the substance is released to wastewater, a rapid volatilisation from sewage treatment plant during the primary treatment is expected based on very high volatility and low adsorption potential. A release to the soil compartment via the application of sewage sludge is not anticipated based on the log Pow (1.34) and the correlated very low Koc value (17.41 L/kg). While a transfer of the substance from the air compartment to the soil compartment via wet deposition (dissolved in rain) needs to be considered due to its relevant solubility, based on the very high Henry's law constant already during the passage from cloud to soil surface most of the substance will volatilize again due to the high surface to volume ratio of rain drops. Further relevant volatilization must be expected already at the soil upper surface layer. Accordingly, any ecotoxicologically relevant concentrations in the soil compartment can readily be excluded.

Based on the Chemical Safety Assessment according to Annex I of Regulation (EC) No 1907/2006 there is no need to conduct further studies with soil macroorganisms. The PNEC_soil was derived by the equilibrium partitioning method from the aquatic PNEC, and the environmental exposure and risk assessment for chloroethane indicates no risk for the terrestrial compartment (all RCR< 1; please refer to Chapter 9 and 10 of the Chemical Safety Report for detailed information).
According to ECHA guidance document R.7c, a derivation of PNEC_soil from the aquatic PNEC via the equilibrium partitioning method (EPM) is possible for chloroethane: the substance is not adsorbing and - due to its high volatility - of low persistence in soil (50% disappearance time (DT50) << 180 days). Further, it is not very toxic to aquatic organisms (lowest E(L)C_50: 58 mg/L). Consequently, it is categorized into "Soil Hazard Category 1" and qualifies for the assessment of hazards to soil exclusively by EPM.

In conclusion, there is no need to conduct any terrestrial toxicity testing.

A relevant supporting study investigating the effect of chloroethane to terrestrial plants due to exposure via the gas phase is available. The study was performed according to OECD 208 (Terrestrial Plant Test: Seedling Emergence and Seedling Growth Test) modified for atmospheric exposure. The effect of chloroethane on the emergence and growth of the plant species Avena sativa and Lepidium sativum were investigated. The plants were exposed to the gas at concentrations of 10 and 100 ppmv in a closed chamber. Nominal test concentrations were analytically verified and confirmed. The test was terminated after 17 days. Avena sativa was not affected by the substance, whereas the growth of Lepidium sativum was reduced by 20% at the highest concentration of 100 ppmv (statistically significant; LOEC).

By conversion of ppmv to mg/m^3 via molecular weight, atmospheric pressure and the temperature measured during the test, the following key values were derived:

NOEC (17 d; growth; Lepidium sativum) = 26.4 mg/m^3
LOEC (17 d; growth; Lepidium sativum) = 264.1 mg/m^3

The NOEC is used to derive a PNEC_air for chloroethane.