Positive and negative ions by air purifier have no effects on embryo-fetal development in rats.

Air purifiers, which release positive and negative ions generated by an electric discharge into the air, have been widely used in common households. In this study, the developmental toxicity potential of the ionized air containing positive and negative ions was evaluated in SD rats [Crl:CD(SD)] following whole-body inhalation to obtain preliminary information for the definitive study. Two groups of 10 pregnant female rats were exposed to the ionized air at concentrations of 0 and 7,000,000 ions/cm(3) for 6 hr per day from Days 6 to 19 of gestation. All dams underwent a cesarean section on Day 20 of gestation and their fetuses were examined externally, viscerally, and skeletally for morphological changes. The ionized air had no effects on dams in terms of clinical signs, body weight, food consumption, gravid uterine weights, corrected body weight by gravid uterine weight, or necropsy findings. In addition, there were no effects on the maintenance of pregnancy, including abortion or premature delivery. No exposure-related changes were detected in the number of corpora lutea, implantations, dead embryos, or live fetuses, implantation loss, live fetal weights, sex ratio, or placental weight or features. Fetal examination revealed no external, visceral, or skeletal anomalies or variations caused by the ionized air, nor were there any changes in degree of ossification. Although this study did not fully adhere to the current guidelines because of a smaller number of animals per group, it was suggested that the ionized air has no maternal toxicity or embryo-fetal toxicity in rats.

Effects of preparation methods for multi-wall carbon nanotube (MWCNT) suspensions on MWCNT induced rat pulmonary toxicity.

Since there is a possibility of inhaling the fibers of multi-wall carbon nanotube (MWCNT) without any agglomeration, it is important that the pulmonary toxicity is evaluated by intratracheal instillation without agglomeration. MWCNT suspended in an artificial lung surfactant (ALS) with or without grinding in an agate mortar was instilled once intratracheally to rats to determine whether differences of the effects to pulmonary toxicity by different amounts of agglomerated MWCNT particle. The MWCNT suspension preparation method with grinding was effective at reducing agglomerates and in increasing uniform dispersion of the fibers. The ground MWCNT induced higher LDH levels and neutrophil ratios in the bronchoalveolar lavage fluid (BALF). There were no remarkable responses in rats in the non-ground MWCNT group, with the exception of inflammatory responses in the early phase. Some histopathological findings varied between rats given the ground MWCNT and non-ground MWCNT. A major difference was an MWCNT-laden macrophage infiltration site in the lung, which were in the alveolus in the ground MWCNT group, and in the interstitium in non-ground MWCNT group. Accordingly, the preparation method with grinding is considered to be effective at reducing agglomerates and ensuring uniform dispersion of the fibers. These findings lead us to conclude that the amount of agglomerates in the suspension is an important factor affecting the pulmonary toxicity of MWCNT.