Methacrylate Fate and Degradation

The basic methacrylates are not persistent in the environment. The two main degradation pathways are biodegradation and photodegradation.

In water they biodegrade fast – all substances are rapidly biodegraded by bacteria present in water and sewage treatment plants. Laboratory test data show ready biodegradation with complete mineralization. While the products are not intentionally released during manufacturing processes and use, trace amounts present in waste water streams would rapidly disappear by biological degradation and evaporation. Due to rapid degradation they do not enter the food chain.

In air they react with photo-chemically produced hydroxyl radicals and also with ozone. Half-lives for these reactions have been estimated with the EPI Suite™ program as provided by US EPA. The reaction half-lives for the atmospheric oxidation of the methacrylate esters by hydroxyl radicals range between 6.9 h (MAA), 7.0 h (MMA), 6.5 h (EMA), 5.7 h (n-/i-BMA) and 4.4 h  (2-EHMA) with a slight trend of shorter half-lives with increasing molecular weight. For the reaction with ozone an atmospheric half-life of approximately one day has been calculated for all esters.

The substances do not possess a significant ozone depletion potential and trace emissions will not contribute significantly to global warming.

References:

OECD, 2001, OECD SIDS/SIAP/SIAR Methacrylic acid, CAS no. 79-41-4

OECD, 2001, OECD SIDS/SIAP/SIAR Methyl Methacrylate, CAS no. 80-62-6

OECD, 2009, SIDS/SIAP/SIAR Category Short-chain Alkyl Methacrylates (Rem.: assessment referring to ethyl methacrylate, n- and iso-butyl methacrylate and 2-ethylhexyl methacrylate)

Staples CA, Farr C, Hunt EK, McLaughlin JE, Müllerschön H, Pemberton MA, 2009. Using Quantitative Structure–Activity Relationships to Support the Assessment of the Environmental Fate and Aquatic Toxicity of a Series of Methacrylic Acid Esters, Human and Ecological Risk Assessment, 15: 503–525