Incorrect Listing of Methyl Methacrylate (CAS Number: 80-62-6) as an "asthmagen" by
the Association of Occupational and Environmental Clinics (AOEC)

The Methacylate Producers Association has become aware of the inappropriate inclusion of Methyl Methacrylate (MMA, CAS Number: 80-62-6) as an "asthmagen" on the website of the Association of Occupational and Environmental Clinics (AOEC).

The term "asthmagen" is generally used to describe substances that are causally related to the development of asthma-like symptoms in individuals. The inference that MMA is causally related to the development of asthma is not supported by the available medical and other scientific literature.

MMA is a high production volume chemical that is an irritant to the skin, eyes and respiratory system and may cause sensitization in contact with the skin. It has an extensive database of published and unpublished toxicological studies that have been the subject of three in depth, independent reviews by international governmental agencies. These reviews have concluded that there is no convincing evidence that MMA causes asthma in humans.

Although some of these published studies appear to implicate MMA as a respiratory sensitizer/asthmagen, a thorough review of these publications does not support this conclusion.

In January 2001, the OECD (Organization for Economic Co-operation and Development) completed its Screening Inventory Dataset (SIDS) Initial Assessment Report (SIAR) for MMA concluding that "There is no convincing evidence that methyl methacrylate is a respiratory sensitizer in humans" http://portalserver.unepchemicals.ch/Publications/Screening%20Infornation%20Data%20Set.htm. The review panel consisted of medical, toxicological and regulatory experts from the Governmental Agencies of the member OECD countries (Australia, Austria, Belgium, Canada, Czech republic, Denmark, Finland, France, Germany, Greece, Hungary, Ireland, Italy, Japan, Korea, Norway, Poland, Portugal, Slovak Republic, Spain, Sweden, Switzerland, The Netherlands, UK, USA) as well as from the European Commission, UNEP, and WHO.

Soon therefore, in April 2001, the European Union finalized its Risk Assessment for MMA. This six-year risk assessment reviewed published and unpublished (company confidential) studies/reports on MMA, concluding that "no convincing evidence was found that MMA acts as a respiratory sensitiser in humans" in Chapter (section) 4.1.2.5. http://ecb.jrc.it/esis/esis.php?PGM=ora&DEPUIS=autre. The review panel consisted of the leading medical and toxicological experts of the Competent Authorities in the European Union as well as the World Health Organisation. The report was also reviewed and approved by an independent panel of International Peer Scientists/Professors/clinicians comprising the Scientific Committee for Toxicity, Ecotoxicity and the Environment (CSTEE). The review specifically addressed asthma and concludes: "The literature reports isolated cases of asthma in the context of MMA exposure. Substance-specific bronchoconstriction or delayed asthmatic responses respectively were confirmed only in very few cases. Asthmatic reactions seem to be restricted to exposure levels which primarily result in respiratory tract irritation.

More recently, in 2002, Health Canada (HC) actually reversed an earlier decision (1996) to classify MMA as a respiratory sensitizer (which required all products containing MMA, or MMA residues (polymers etc.); to be labelled "Contains a respiratory sensitizer"). This decision was based upon the conclusion that, "on balance, there is insufficient evidence at this time to regard MMA as a respiratory sensitizer". Accordingly HC has removed MMA from their list of known respiratory sensitizers. The ruling for MMA can be seen on the Health Canada (WHIMIS) website at http://www.hc-sc.gc.ca/ehp/ehd/psb/whmis/substance_specific_issues1.pdf.

In sum, these three international agencies, after thorough scientific reviews concluded that MMA should not be regarded as an asthma causing chemical or "asthmagen" was based upon the fact that:

(a) Despite MMA's widespread use it had been implicated in only a small number of clinical case histories reported in the literature and,

(b) that there was (1) inadequate evidence of an allergic mechanism, and (2) the case reports relied upon by AOEC were more consistent with individuals that had developed asthma for some other reason and this condition had been aggravated by their occupation exposure to an irritant vapour (MMA).