This study investigated the potential adverse effects of zinc oxide nanoparticles ([ZnO SM20(+) NPs] zinc oxide nanoparticles, positively charged, 20 nm) on pregnant dams and embryo–fetal development after maternal exposure over the period of gestational days 5–19 with Sprague-Dawley rats. ZnO SM20(+) NPs were administered to pregnant rats by gavage at 0, 100, 200, and 400 mg/kg/day. All dams were subjected to a cesarean section on gestational day 20, and all of the fetuses were examined for external, visceral, and skeletal alterations. Toxicity in the dams manifested as significantly decreased body weight after administration of 400 mg/kg/day NPs; reduced food consumption after administration of 200 and 400 mg/kg/day NPs; and decreased liver weight and increased adrenal glands weight after administration of 400 mg/kg/day NPs. However, no treatment-related difference in: number of corpora lutea; number of implantation sites; implantation rate (%); resorption; dead fetuses; litter size; fetal deaths and placental weights; and sex ratio were observed between the groups. On the other hand, significant decreases between treatment groups and controls were seen for fetal weights after administration of 400 mg/kg/day NPs. Morphological examinations of the fetuses demonstrated significant differences in incidences of abnormalities in the group administered 400mg/kg/day. Meanwhile, no significant difference was found in the Zn content of fetal tissue between the control and high-dose groups. These results showed that oral doses for the study with 15-days repeated of ZnO SM20(+) NPs were maternotoxic in the 200 mg/kg/day group, and embryotoxic in the 400 mg/kg/day group.

Silica is a very common material that can be found in both crystalline and amorphous forms. Well-known toxicities of the lung can occur after exposure to the crystalline form of silica. However, the toxicities of the amorphous form of silica have not been thoroughly studied. The majority of in vivo studies of amorphous silica nanoparticles (NPs) were performed using an inhalation exposure method. Since silica NPs can be commonly administered through the skin, a study of dermal silica toxicity was necessary to determine any harmful effects from dermal exposures. The present study focused on the results of systemic toxicity after applying 20 nm colloidal silica NPs on rat skin for 90 days, in accordance with the Organization for Economic Cooperation and Development test guideline 411 with a good laboratory practice system. Unlike the inhalation route or gastrointestinal route, the contact of silica NPs through skin did not result in any toxicity or any change in internal organs up to a dose of 2,000 mg/kg in rats.

No abstract

This study was undertaken to investigate the potential toxicity and establish the no observed adverse effect level (NOAEL) and target organ(s) of negatively charged colloidal silica particles of different sizes, ie, SiO 2 EN20(−) (20 nm) or SiO 2 EN100(−) 2(100 nm), administered by gavage in Sprague-Dawley rats. After verification of the physicochemical properties of the SiO 2 particles to be tested, a preliminary dose range-finding study and 90-day repeated dose study were conducted according to the Organisation for Economic Cooperation and Development test guideline. Based on the results of the 14-day dose range-finding study, a high dose was determined to be 2,000 mg/kg, and middle and low doses were set at 1,000 and 500 mg/kg, respectively. In the 90-day toxicity study, there were no animal deaths in relation to administration of SiO 2 particles of either size. In addition, no treatment-related clinical changes or histopathological findings were observed in any of the experimental groups. Moreover, no difference in toxic effects from chronic exposure to SiO 2 EN20(−) (20 nm) or SiO 2 EN100(−) (100 nm) was observed. The results of this study indicate that the NOAEL for SiO 2 EN20(−) and SiO 2 EN100(−) would most likely be 2,000 mg/kg, and no target organ was identified in rats of either sex.

This study investigated the potential adverse effects of zinc oxide nanoparticles (ZnO SM20[−] NPs; negatively charged, 20 nm) on pregnant dams and embryo–fetal development after maternal exposure over the period of gestational days 5–19 with Sprague Dawley rats. ZnO SM20(−) NPs were administered to pregnant rats by gavage at 0 mg/kg/day, 100 mg/kg/day, 200 mg/kg/day, and 400 mg/kg/day. All dams were subjected to caesarean section on gestational day 20, and all the fetuses were examined for external, visceral, and skeletal alterations. Toxicity in the dams manifested as significantly decreased body weight at 400 mg/kg/day and decreased liver weight, and increased adrenal glands weight at 200 mg/kg/day and 400 mg/kg/day. However, no treatment-related difference in the number of corpora lutea, the number of implantation sites, the implantation rate (%), resorption, dead fetuses, litter size, fetal deaths, fetal and placental weights, and sex ratio were observed between the groups. Morphological examinations of the fetuses demonstrated no significant difference in the incidences of abnormalities between the groups. No significant difference was found in the Zn content of fetal tissue between the control and high-dose groups. These results showed that a 15-day repeated oral dose of ZnO SM20(−) was minimally maternotoxic at dose of 200 mg/kg/day and 400 mg/kg/day.