Methyl methacrylate (MMA) is a “monomer” used as a raw material to make various “polymers”, which are plastics and resins used in many important applications. Persons who work in facilities that manufacture MMA or that manufacture polymers with MMA can be exposed to MMA.

Epidemiology studies are used to investigate the relationship between, for example, exposure to a chemical in the workplace and the occurrence of diseases, such as a specific type of cancer. A cancer mortality study compares the observed rate of cancer mortality in the group of individuals being studied with the rate of cancer mortality in the general population with the same age, sex distribution and, if possible, life-style habits, etc. Since there are many risk factors for developing cancer, including, age, genes, immunity, viruses and life styles (smoking, drinking, sunbathing and diet), the design, conduct and interpretation of epidemiology studies is complex.

To date six epidemiology studies have been conducted on occupational (worker) populations with exposure to MMA and reported in the open, scientific literature. Four studies were commissioned by industry on workers in the MMA-monomer production and/or PMMA sheet production industry (polymerized MMA). Two studies were made on orthopedic surgeons, some of which implant medical devices based upon MMA and PMMA (i.e., bone cements).

Collectively, no consistent elevations of specific cancer types were reported across the available studies. The production industry investigations found an increase in colorectal cancer in early studies, but this was not confirmed in follow-up or more extensive studies. In the studies on orthopedic surgeons, an increased cancer rate for esophagus and myeloproliferative cancers was reported in one study and increased breast cancer in another. Overall the epidemiology studies do not support a causal link between these cancers and MMA exposure. First, these cancer types were not elevated in the larger studies conducted by industry as would be expected if there was a causal relationship between MMA and cancer in humans. Second, independent review of these studies by a recognized epidemiologist, Dr. G. Swaen, identified limitations in the methodology used in the orthopedic surgeon studies that make a conclusion of a causal relationship between MMA exposure and cancer unreliable (Swaen, 2019).

With this recent opinion, Dr. Swaen confirmed the conclusion of Dr. J. Tomenson and coworkers in 2005. They concluded that the available human data are not in support of an increased cancer risk from occupational exposure to MMA, based on an exhaustive review of the then available epidemiologic literature. Dr. Swaen goes on to highlight that in his opinion the industry studies conducted in the United States and Great Britain were of sufficient size, statistical power and design, that they still represent the most comprehensive information available on the occurrence of cancer in humans exposed to high concentrations of MMA, and that they demonstrate that exposure to MMA, even at relatively high concentrations, is not associated with cancer risk.

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