Vinyl chloroacetate

Endpoint summary

Description of key information

A hydrolysis study was performed on vinyl chloroacetate (VCA) in accordance with the OECD Testing Guideline 111. At pH 4 the half-life of VCA was 3.92 hours, whereas at pH 7 the half-life of the substance was 1.22 hours. A trend was observed indicating that the half-life decreases when the pH increases. Chloroacetic acid (CAS 79-11-8 / EC 201-178-4) and acetaldehyde (CAS 75-07-0 / EC 200-836-8) were identified as the main degradation products of VCA.

 

Considering that VCA degrades rapidly in water, the aquatic toxicity of the substance is expected to be driven by its main degradation products. Therefore the aquatic toxicity of VCA was determined using available data on acetaldehyde and chloroacetic acid.

 

The short-term toxicity to the aquatic environment of VCA was investigated using reliable studies and literature data available on acetaldehyde and chloroacetic acid.

Acetaldehyde was identified as the most hazardous degradation products to freshwater fishes with a 96-hour LC50 of 30.8 mg/L obtained on Pimephales promelas. Based on the assumption that 1 mol of VCA will hydrolyse to give 1 mol of acetaldehyde and 1 mol of chloroacetic acid, we calculated the amount of VCA that needs to be hydrolysed in order to release 30.8 mg/L of acetaldehyde. This assumption was considered to represent a worst-case scenario. It was concluded that 84.084 mg/L of VCA needs to be hydrolysed in order to obtain 30.8 mg/L of acetaldehyde. Therefore the 96-hour LC50 of VCA for freshwater fishes was determined to be 80.084 mg/L.

Chloroacetic acid was identified as the most hazardous degradation products to freshwater invertebrates with a 48-hour EC50 of 77 mg/L obtained on Daphnia magna. Based on the assumption that 1 mol of VCA will hydrolyse to give 1 mol of acetaldehyde and 1 mol of chloroacetic acid, we calculated the amount of VCA that needs to be hydrolysed in order to release 77 mg/L of chloroacetic acid. This assumption was considered to represent a worst-case scenario. It was concluded that 98.56 mg/L of VCA needs to be hydrolysed in order to obtain 77 mg/L of chloroacetic acid. Therefore the 48-hour EC50 of VCA for freshwater invertebrates was determined to be 98.56 mg/L.

Chloroacetic acid was identified as the most hazardous degradation products to freshwater algae with a 48-hour EC50 of 0.028 mg/L obtained on Scenedesmus subspicatus. Based on the assumption that 1 mol of VCA will hydrolyse to give 1 mol of acetaldehyde and 1 mol of chloroacetic acid, we calculated the amount of VCA that needs to be hydrolysed in order to release 0.028 mg/L of chloroacetic acid. This assumption was considered to represent a worst-case scenario. It was concluded that 0.03584 mg/L of VCA needs to be hydrolysed in order to obtain 0.028 mg/L of chloroacetic acid. Therefore the 48-hour EC50 of VCA for freshwater algae was determined to be 0.03584 mg/L.

Considering that the 48-hour EC50 for algae is below 1 mg/L based on the hazardous properties of chloroacetic acid, VCA meets the criteria for classification as Aquatic Acute 1; H400 in accordance with Regulation (EC) N° 1272/2008. This Classification is consistent with the classification of chloroacetic acid as Aquatic Acute 1; H400.

A M-factor of 10 is proposed for the acute aquatic toxicity of the registered substance, based on the lowest 48-hour EC50 of VCA being comprised between 0.01 mg/L and 0.1 mg/L, in accordance with Regulation (EC) N° 1272/2008.

 

There is no available data on the chronic toxicity of VCA to the aquatic environment. As the substance is being registered under REACH in the 10-100 tonnage band there is no requirement for information on long-term studies to aquatic species. Therefore the Classification of the registered substance for chronic effects is based on the aquatic toxicity of the degradation products of VCA.

Considering that the 48-hour EC50 for algae is below 1 mg/L based on the hazardous properties of chloroacetic acid, and it cannot be proven that the substance is ‘rapidly biodegradable’, VCA meets the criteria for classification as Aquatic Chronic 1; H410 in accordance with Regulation (EC) N° 1272/2008. This Classification is consistent with the classification of chloroacetic acid as Aquatic Chronic 1; H410.

A M-factor of 1 is proposed for the chronic aquatic toxicity of the substance based on the expected ready biodegradability of the substance and the M-Factor attributed to chloroacetic acid for its chronic effects.