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Environmental fate & pathways

Adsorption / desorption

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Description of key information

Adsorption to solid soil phase is not expected.

Key value for chemical safety assessment

Additional information

Supporting information is vaialable in an adsorption/desorption study with radiolabelled methyl methacrylate:

Adsorption of MMA to soil was investigated using 5 different types of soil: sandy loam (=aquatic sediment), loamy sand, two types of loam, clay loam. pH varied from 5.2 to 7.5. Concentrations of test material (methyl methacrylate carboxy 14C) were: 0.5, 0.89, 1.6, 2.8, 5, 8.9 µg/mL. Concentration and assurance of integrity of the test substance throughout the study were confirmed by HPLC analysis. The adsorption phase (24 hours at 23 °C) was followed by 3 desorption phases. Distribution of MMA between aqueous and solid phases was followed by monitoring 14C-levels.

On the basis of its vapour pressure and its low adsorption to soil adsorption constants (Koc) ranged from 8.7 to 72 with an average value of 34 it can be expected that MMA volatizes rapidly from soil. Once adsorbed, MMA was less readily desorbed from soil. Desorption constants ranged from 14.8 to 263 with an average value of 95.

While methyl methacrylate must be classed as being quite mobile under laboratory conditions, care must be taken in predicting and interpreting its actual behavior under field conditions. In an outdoor environment,

other factors such as soil microbial degradation may significantly alter the actual field results from what would be predicted based solely upon the laboratory adsorption / desorption study. Additionally, as no correlation

was noted between the soil organic content and individual Koc values, care must also be exercised in predicting a detailed leaching behavior of methyl methacrylate in other, non-studied soils, based solely

upon an average Koc value obtained in the current study.