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Environmental fate & pathways

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Description of key information

The test item MCPP-P 2-EHE hydrolyses relatively fast to the corresponding degradation products - acid (MCPP-P acid, CAS 16484-77-8) and alcohol (2 -ethylhexan-1-ol, CAS 104 -76-7). The alcohol is readily biodegradable substance with low potential for bioaccumulation (please refer to the ECHA Disseminated dossier of CAS 104-67-7). Therefore, the read-across was based on the other degradation product - MCPP-P acid, as it is considered that the acid is the degradation product that shows a relevant effect on the environment.

Based on the read-across approach to MCPP-P acid, the test substance MCPP-P 2-EHE is likely to be unstable and not persistent in natural water, to be readily biodegradable in water, have no effect to sediment due to the unlikliness of exposure, be slowly degradable in soils at low temperatures and show low potential for bioaccumulation in higher organisms.

Additional information

Hydrolysis:

MCPP-P 2-EHE is unstable under the conditions of hydrolysis and is not likely to be persistent in natural water.

Biodegradation in water:

For MCPP-P acid the 28-day degradation was 85 % and for the positive control (with reference substance benzoic acid, sodium salt) the biodegradation was 87 % after 14 days. In conclusion, MCPP-P acid is considered to be "Readily Biodegradable". MCPP-P 2-EHE hydrolyses to MCPP-P acid, the acid is used as a relevant point to assess the biodegradation of MCPP-P 2-EHE in water. Therefore, MCPP-P 2-EHE is considered to be readily biodegradable.

MCPP-P is readily degraded in the aerobic aquatic systems and is therefore unlikely to persist in the aquatic environment. Half-life in water of 24 hours and half-life in sediment/water system of 23 hours were determined.

Biodegradation in sediment:

The study on sediment screening does not need to be conducted becasue direct and indirect exposure of the sediment is unlikely.

Biodegradation in soil:

The rate of degradation of MCPP-P 2-EHE applied as a commercial formulation also containing ioxynil octanoate to sandy loam soil under aerobic conditions at 5 °C was studied over 56 days. The half-life of MCPP-P 2-EHE was calculated at 8.3 days. The major degradation product over the period of the study was MCPP-P acid.

Bioaccumulation:

MCPP-P 2-EHE hydrolyses rapidly in natural water. Therefore, the hydrolysis product MCPP-P acid was used for further assessment of MCPP-P 2-EHE with respect to its potential for bioaccumulation.

The bioaccumulation of the hydlosis product, MCPP-P acid, in fish species: Lepomis macrochirus, was experimentally determined to be BCF (edible fraction) = 1.2, BCF (non-edible fraction) = 5.5 and BCF (whole fish) = 3.0, respectively. Thus, MCPP-P 2-EHE has low potential for bioaccumulation as its hydrolysis products in higher organims.

Adsorption  

Determined in 3 sandy soils the Koc of MCPP-P acid was in the range of 135 - 167. The geometric mean of the Koc of 146 is used for further assessment. MCPP-P acid has a low sorption potential to soil and sediment, and a moderate migration potential to groundwater.