1-chloro-1,1-difluoroethane

Endpoint summary

Additional information

Based on its physico-chemical properties, the air compartment is the preferred target one for 1-chloro -1,1- difluoroethane. The global atmospheric lifetime of 142b is 18.5 years corresponding to a 1/2 -lifetime of 12.8 years. The tropospheric lifetime due to removal by reaction with OH is 19.5 years. Atmospheric degradation products are essentially the aldehyde form of 142b which further degrades to form CF2(=O) which will hydrolyse in atmospheric water to form HF and CO2.

The ozone depletion potential (ODP) of 1-chloro -1,1-difluoroethane is the main concern of this substance. Due to its ODP value of 0.065, it is considered as an ozone depleting substance. The calculated Global Warming Potential of 1-chloro-1,1-difluoroethane is 1,800 for an integration horizon of 100 years. Its contribution to the Greenhouse effect is small i.e. 0.00108 W/m².

Indeed, the contribution to the greenhouse effect can be calculated by multiplying quantities emitted to the atmosphere of a substance by its global warming potential (GWP). The global warming potential is calculated by comparing the integrated radiative forcing on a period of 100 years due to 1 kg of a substance emitted to the atmosphere with a similar calculation done with CO2 which is the accepted reference. (IPCC 1990, 1995) The result is expressed in GWP/tonnes.

Contribution from atmospheric concentration in 1992: 0.00108 W/m2 has to be compared with 1.52 w/m²for CO₂ (value from IPCC 1995)

GWP (100) = 1800 (IPCC 1995) 

Production of 142b in 1996 = 38 Kt (AFEAS, 1996)

Contribution of 142b to global warming:

6.8 107 GWP.tonnes to be compared with 2.6 1010 GWP.tonnes for CO2 (IPCC 1995)

GWP values from IPCC 1995 are the accepted values for the Kyoto Protocol (Décision 2/CP.3 Methodological issues related to the Kyoto Protocol, FCCC/CP/1997/7/Add.1)

It is not expected to bioaccumulate (log Kow= 1.64 - 2.05). Overall, abiotic degradation of 1 -chloro-1,1 -difluoroethane occurs very slowly. The half life in air is estimated at 4860 days and in water a half life of 16,000 years is determined. 1 -Chloro-1,1-difluoroethane was not found to be ready biodegradable in a screening test (5% after 28 days). Simulation studies were not performed.

 

Any 1-chloro-1,1-difluoroethane which might be present in aqueous waste streams discharged directly into rivers and lakes would be expected to have a half-life of days or at the very most a few weeks. 1-chloro-1,1-difluoroethane present in surface or ground waters would have little tendency to partition onto solids as the log Kow is 1.6 - 2.05, indicating little potential for accumulation in soil.The sediment and soil simulation tests don't need to be conducted as the substance is a gas and has a low potential for adsorption (log Kow 2.05); it is expected that direct and indirect exposure of soil and sediment is therefore unlikely.