Methyl Methacrylate Vapor Research Articles

Chronic biological effects of methyl methacrylate vapor: III. Histopathology, blood chemistries, and hepatic and ciliary function in the rat

Inhalation experiments were conducted by exposing rats, mice, and frogs to methyl methacrylate (MMA) monomer vapor in air. Rats were exposed for periods of up to 6 months to near threshold limit value (TLV) concentrations and for a shorter period to approximately ten times the TLV. Blood chemistries were unremarkable. Histopathological findings were essentially nil except for microscopic indications of damage to the tracheal mucosa, supported by scanning electron microscopy (SEM) observations that the cilia and microvilli characteristic of these epithelial cells were absent. A reduction in oropharyngeal transport efficiency was shown when frogs were exposed to 400 ppm of MMA vapor. The sodium pentobarbital detoxification function of mouse liver may be altered consequent to exposures to 160 hr to both 100 and 400 ppm of MMA vapor. It is concluded that, at the TLV, cellular responses may be manifested regardless of whether gross systemic effects are seen.

Chronic biological effects of methyl methacrylate vapor: II. Body and tissue weights, blood chemistries, and gross metabolic performance in the rat

Chronic exposures of mature male Sprague-Dawley rats to near threshold-limit value (TLV) concentrations of methyl methacrylate (MMA) monomer vapor were conducted in order to assess the effects of such exposures on gross metabolic performance. There was no significant effect on food or water intake or water excretion. Average fecal excretion during the exposure portion of the week tended to be higher in the exposed than in sham-exposed rats. These differences were absent for average values obtained on weekends. Final mean body, adrenal, epididymal fat pad, and popliteal fat pad weights were not significantly different.

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.

Methylmethacrylate

To determine possible deleterious effects of methylmethacrylate vapor on mouse gestation, pregnant mice were exposed to average vapor concentrations of 1330 parts per million for two hours twice daily during Day 6 through Day 15 of pregnancy. A slight increase in the average weight of the fetuses of the exposed mothers were demonstrated but no other evidence of fetal toxicity or teratologic effects was found. During three total hip replacements, the concentration of methylmethacrylate in operating-room air never rose above 280 parts per million.

ESR studies of the radiation‐induced multiple graft polymerization

AbstractThe radiation‐induced multiple‐graft polymerization was studied by an ESR method. When methyl methacrylate vapor was introduced onto preirradiated polyethylene already grafted with styrene, the second step of grafting of methyl methacrylate occurred mainly in the polyethylene portion. The kinetic treatment proved that the termination rate constant kt of methyl methacrylate decreased with the amount of styrene grafted in advance. On the other hand, when styrene vapor was introduced onto polyethylene grafted with methyl methacrylate, only radicals of poly(methyl methacrylate) decreased. In this case, the second step of grafting of styrene occurred in the poly‐(methyl methacrylate) portion which covered the whole surface of the polyethylene powder. When monomer vapors were alternately introduced onto preirradiated polyethylene powder, the second step of grafting occurred at the growing chain end of the first monomer.

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 (~10–15min) 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.

Chronic biological effects of methyl methacrylate vapor: I. Body and tissue weights, blood chemistries, and intestinal transit in the rat

The effects upon body and tissue weights, various blood parameters, and intestinal transit time associated with chronic exposures of rats to monomeric methyl methacrylate (MMA) vapor concentrations are summarized in this report. The most remarkable and readily apparent phenomenon was the obvious lack of body fat in the group which had been exposed for 3 months to an MMA vapor concentration of 116 ppm in air. It was determined that rats which have received a daily 8-hour exposure to 116 ppm of MMA vapor for 6 months have significantly lower adiposity, as measured by the popliteal fat pad, than those of a similar group which have received sham exposures. It was also determined that protracted exposures to MMA vapor in this concentration were associated with a significant decrease in intestinal transit performance.

Laminar flame spread over PMMA surfaces

A study is made of the mechanisms by which laminar flames spread over flat surfaces of polymethylmethacrylate, in directions ranging from downward to horizontal. Measurements of spread rates, temperature fields and velocity fields are reported. Techniques employed include thermocouple probing, photography, interferometry, radiometer measurements, sampling followed by gas chromatography, and particle-track photography. A simplified theoretical model of the spread process is developed, involving forward heat conduction through the solid as the major mode of the energy transfer and thermal runaway of a gas-phase ignition reaction of methylmethacrylate vapor in a boundary layer just upstream from the point of flame attachment. The extent to which this physical model applies to other materials will depend on the thermal and chemical-kinetic properties of those materials.

The effects of methyl methacrylate vapor on gastric motor function

Results of preliminary in vivo experiments suggest that inhalation of methyl methacrylate vapor inhibits gastric motor activity in rats and humans. Exposure of rats to less than LD50 doses of methyl methacrylate vapor is shown to produce significant effects on the motor activities of the stomach. A preliminary observation indicates that exposure of a human to these vapors also results in a prompt decrease in gastric motor activity. Results of preliminary in vivo experiments suggest that inhalation of methyl methacrylate vapor inhibits gastric motor activity in rats and humans. Exposure of rats to less than LD50 doses of methyl methacrylate vapor is shown to produce significant effects on the motor activities of the stomach. A preliminary observation indicates that exposure of a human to these vapors also results in a prompt decrease in gastric motor activity.