The effects of methyl methacrylate vapor on gastric motor function

Inhalation study of polymethyl methacrylate following radiologist exposure during percutaneous vertebroplasty

OBJECTIVE

To assess the atmospheric concentrations of methyl methacrylate (MMA) vapors during percutaneous vertebroplasty for the interventional radiologist and the other operating room staff.

MATERIALS AND METHODS

During percutaneous vertebroplasty, a polymethyl methacrylate (PMMA) mixture (about 20 mL) was prepared with a mixing system in a normally ventilated room. Atmospheric concentrations of MMA vapors were measured by a gas absorbent badge for individual exposure (GABIE) passive sampler attached to the surgical gowns of the interventional radiologist and the other operating room staff over a period of 460 min. Active sampling was performed over 15 min with an individual pump placed near the breathing zone of the radiologist. MMA vapor concentrations were then measured using gas chromatography and activated charcoal tubes.

RESULTS

Mean MMA vapor concentrations measured by the GABIEs over the period of 460 min were 0.51 parts per million (ppm) for the radiologist and 0.22 ppm for the other operating room staff. The emission peaks measured by using charcoal tubes over 15 min were 3.7 ppm.

CONCLUSION

MMA vapor concentrations during percutaneous vertebroplasty were well below the recommended maximum exposure of 100 ppm over the course of an 8-h workday.

Update on the toxicity of inhaled methyl methacrylate vapor

The current threshold limit value (TLV) of 100 ppm for methyl methacrylate vapor was originally set because it was considered to be a value sufficiently low to preclude either systemic toxicological effects or discomfort from irritation in workers chronically exposed to the vapor. Shortly after this limit was proposed we became interested in evaluating the toxicological properties of methyl methacrylate vapor and, subsequently, of providing experimental data which would be useful in evaluating the adequacy of this TLV. The purpose of this article is to review some of the more relevant literature prior to 1976 which pertains to inhalation exposure and to summarize our more recent data which resulted from statistically designed studies employing acute and subchronic exposures to known concentrations of the vapor including the near-TLV value of 116 ppm.

GI motor inhibition associated with acute exposure to methyl methacrylate vapor

A mixture of monomeric methyl methacrylate vapor in air was delivered into the breathing air of chloralose-urethan anesthetized dogs. Fixed length exposures to 2000-ppm doses of the vapor resulted in a transient drop in arterial blood pressure and a marked inhibition of ongoing GI motor activities. Motor inhibition always continued for a variable time (approximately 10-15 min) subsequent to the cessation of methyl methacrylate vapor administration. This inhibitory response was not blocked by bilateral vagotomy, spinal transection, splanchnectomy, or the intravenous administration of tetraethylammonium chloride. Another series of experiments determined that the administration of blood from a dog receiving methyl methacrylate vapor produced GI motor inhibition in another dog not connected to the experimental gas mixture. Therefore, it is concluded that, aside from any reflex effects produced, methyl methacrylate vapor in sufficient concentration probably exerts a direct inhibitory effect upon GI smooth muscle that is mediated by the cardiopulmonary systems.