Registration Dossier

Environmental fate & pathways

Endpoint summary

Administrative data

Description of key information

Additional information

The adsorption rate of n-BMA to soil was calculated based on average measured adsorption constants (Koc) for methacrylic acid (MAA), methyl methacrylate (MMA) and isobutyl methacrylate ( i-BMA). The calculated value of 2760 l/kg indicates a high adsorption potential of n-BMA to the solid soil phase. It should be recognised that when interpreting the measured data of the study with iBMA that they had assumed binding to soil since they could not detect iBMA in the aqueous desorption phase. However, they failed to use sterilised soil and therefore rapid biodegradation by soil microflora may have contributed to the disappearance of iBMA from the aqueous phase and the true Koc is likely to be lower than that assumed. On this basis the estimates made by Staples for EMA, nBMA and 2-EHMA may also be too high. Notwithstanding the reservations about the validity of some of the measured and calculated data, all substances are readily biodegradable. Furthermore, since for the most lipophilic (logP of 4.95) member of the category, 2-EHMA, with the greatest potential for adsorption to soil it has been established that there is a low potential for bioaccumulation in fish due to rapid metabolism there is no overall concern for any member of the category.

Based on the calculated Henry´s Law constant (34.4 Pa*m3/mol at 25°C) n-butyl methacrylate will evaporate moderately from the water surface. In addition, based on a Mackay Level 1 calculation the substance will mainly partition to air (ca. 96.2 %) in this equilibrium model. In the Mackay Level III model, which additionally takes into account transport and degradation processes, n-BMA, when released to air or water, will predominantly remain in the environmental compartment into which it was released (air: 96.6 %; water: 97.6 %).