Registration Dossier

Environmental fate & pathways

Endpoint summary

Administrative data

Description of key information

Additional information

Stability:

- Phototransformation in air: Half-life for reaction with photochemically-produced hydroxyl radicals: estimated to be 56.5 hours

- Hydrolysis in water: half life - less than 5 minutes.

Degradation:

- Ready biodegradability in water: readily biodegradable

- Degradation in water and sediment: Half life of hexahydrophthalic acid in water estimated to be 208 hours; Half life in sediment estimated to be 1870 hours.

- Degradation in soil: Half life in soil estimated to be 416 hours

Bioaccumulation:

- The potential for bioaccumulation of hexahydrophthalic acid (degradation product) is low. Estimated BCF 3.16 L/kg ww. This estimation is supported by experimental data on cyclohexanedicarboxylic acid which determined BCF values of < 2.0.

Transport and distribution:

- The adsorption coefficient (Koc) of hexahydrophthalic acid (HHPAc) was estimated, from KOCWIN using the LogKow (logD) method, to have a log10Koc value of -1.863 (equivalent Koc= 0.0137).

According to the McCall classification scheme of soil mobility potential, the substance would be regarded as very highly mobile (0 < Koc < 50) on soil.

The adsorption coefficient (Koc) of hexahydrophthalic anhydride (HHPA) was determined, using the HPLC method in accordance with OECD/EU test guidelines, to have a log10Kocvalue of 2.3 (equivalent Koc= 190). According to the McCall classification scheme of soil mobility potential, the substance would be regarded as having medium mobility in soil.

- The Henry's Law constants of hexahydrophthalic acid (HHPAc), as hydrolysis product of cyclohexane-1,2-dicarboxylic anhydride (HHPA), was considered for the environmental assessment.

The value of 2.71E-4 Pa m³/mol shows that HHPAc is essentially non volatile from surface water.

- Distribution in environmental compartments has been calculated using a Fugacity model according to Mackay, Level III, under the following emission scenario: 1000 kg/h into each of air and soil compartments.The soil (96.4%) was found to be the major target compartment.

However, the substance is known to be unstable, rapidly hydrolysing to the corresponding di-carboxylic acid in aqueous media and this process is expected to occur in the environment should release occur. As a result the calculated distribution may not be a reasonable estimate.

Similar modelling of the degradation product of the hexahydrophthalic acid, under the following emission scenario: 1000 kg/h into each of air, water and soil compartments, leads to an estimated distribution in the various environmental compartments in which again the soil (65.2%) was found the major target compartment.