To investigate if the interactive effects (enhanced teratogenicity) noted for radiofrequency irradiation and 2-methoxyethanol (see publication 3519, publication 3522, publication 2234, and publication 9062) are unique to these agents, or if another solvent would interact with radiofrequency irradiation or 2-methoxyethanol.
Because methanol is widely used as a solvent as well as fuel additive, and, at high levels, is teratogenic in animals, the authors selected methanol as a chemical to address generalizability.
Methanol was administered on gestation day 9 or 13 to groups of rats. Dams treated on day 9 were given methanol and exposed to radiofrequency irradiation sufficient to maintain colonic temperature at 41°C for 60 minutes. Those treated on day 13 were given methanol plus 2-methoxyethanol. Because the authors observed that methanol produced hypothermia, some groups were given the initial dose of methanol concurrently with the radiofrequency or 2-methoxyethanol, and others were given the first dose of methanol 1.5 hours prior to radiofrequency or 2-methoxyethanol. Dams were sacrificed on gestation day 20.
The data indicate that radiofrequency irradiation or methanol on day 9 increased the incidence of resorbed fetuses, but no interactive effects were revealed. The resorptions were highest in rats given the experimental treatments 1.5 hours apart. The higher dose of methanol also decreased fetal weights.
Administration of 2-methoxyethanol or methanol on day 13 increased the rate of malformations, and there was evidence of a positive interaction between 2-methoxyethanol and methanol. Fetal weights were decreased by 2-methoxyethanol and methanol alone, but no interaction was found.
These data point out that interactions in developmental toxicity, such as those of radiofrequency irradiation, 2-methoxyethanol, and methanol, are complex, and such interactions cannot be fully understood or predicted without more research. It is important that combined exposure effects be considered when developing both physical agent and chemical agent exposure guidelines.