INTERACTIVE DEVELOPMENTAL TOXICITY OF RADIOFREQUENCY RADIATION AND 2-METHOXYETHANOL IN RATS

Concurrent exposures to chemical and physical agents occur in the work place; exposed workers include those involved with the microelectronic s industry, plastic sealers, and electrosurgical units. Previous anima l research indicates that hyperthermia induced by an elevation in ambi ent temperature can potentiate the toxicity and teratogenicity of some chemical agents. We previously demonstrated that combined exposure to radiofrequency (RF; 10 MHz) radiation, which also induces hyperthermi a and is teratogenic to exposed animals, and the industrial solvent, 2 -methoxyethanol (2ME), produces enhanced teratogenicity in rats. The p resent study replicates and extends the previous research investigatin g the enhanced teratogenicity of combined RF radiation and 2ME exposur es. The interactive dose-related teratogenicity of RF radiation (sham exposure or maintaining colonic temperatures at 42.O degrees C for 0, 10, 20, or 30 min) and 2ME (0, 75, 100, 125, or 150 mg/kg) was investi gated by administering various combinations of RF radiation and 2ME to groups of rats on gestation days 9 or 13; gestation-day 20 fetuses we re examined for external, skeletal, and visceral malformations. The re sults ore consistent with and extend our previous research findings. S ynergism was observed between RF rodiation and 2ME for some treatment combinations, but not for others. The study also clarified which gesta tional periods, RF radiation exposure durations, and 2ME doses would b e most informative in future interaction studies to determine the lowe st interactive effect level. Day 9 exposures generally evidenced littl e effect by 2ME, either by itself or in combination with RF radiation. In contrast, day 13 exposures resulted in highly significant effects from 2ME and RF radiation. The structures showing strong evidence of e ffects from both 2ME and RF radiation after exposure on gestation day 13 were the forepaw digits, forepaw phalanges, hindpaw digits, hindpaw phalanges, hind limbs, metacarpals, and metatarsals. Statistical anal yses did not show a global synergistic effect, but did show evidence f or a synergistic effect at intermediate levels of the dose ranges. Fut ure research will address potential interactions at lower doses. (C) 1 994 Wiley-Liss, Inc.