Positive and negative ions by air purifier have no effects on reproductive function or postnatal growth and development in rats

Air purifiers, which release positive and negative ions generated by electric discharge, are widely used in a variety of places. In this study, male and female SD rats [Crl:CD(SD)] were exposed by whole-body inhalation (6 hr/day) to ionized air containing positive and negative ions for at least 10 weeks before mating and throughout the mating, gestation, and lactation periods over two generations, and the effects on the reproductive function of parental animals and development of offspring were assessed. The concentrations of the ionized air were set at 0 and 7,000,000 ions/cm3 (280- to 1,000-fold higher than normally used in humans) and each group consisted of 24 F0 rats/sex/group and 20 to 23 F1 rats/sex/group. The ionized air had no general toxicological effects on parental animals in the observation for clinical signs, body weight and food consumption measurement, or pathological examination. As for the effects on the reproductive function, there were no exposure-related changes in mating ability, fertility, pregnancy, parturition, or nursing behavior, nor were there any changes in the estrous cycle or sperm parameters in either generation, nor in the ovarian follicle counts (only F1 females). Moreover, there were no effects on litter size, viability, growth, or development of F1 and F2 offspring, including sexual maturation. Therefore, it was suggested that the ionized air has no reproductive or developmental toxicity in rats.