Effects of tert-butyl acetate on maternal toxicity and embryo-fetal development in Sprague-Dawley rats

Final Report of the Cosmetic Ingredient Review Expert Panel on the Safety Assessment of Methyl Acetate

Alkyl acetates, as well as acetic acid and acetate salts, are widely used cosmetic ingredients, with a wide range of functions as fragrances, solvents, or skin-conditioning agents, depending on the specific ingredient. Available data on alkyl acetates, and acetic acid and the alcohol to which they could be metabolized, were considered adequate to support the safety of the entire group in the present practices of use and concentration in cosmetics.

Maternal exposure to multi-wall carbon nanotubes does not induce embryo-fetal developmental toxicity in rats

BACKGROUND

Although the potential risk of carbon nanotubes (CNTs) to humans has recently increased due to expanding production and widespread use, the potential adverse effects of CNTs on embryo-fetal development have not yet been determined.

METHODS

This study investigated the potential effects of multi-wall CNTs (MWCNTs) on pregnant dams and embryo-fetal development in rats. MWCNTs were administered to pregnant rats by gavage at 0, 40, 200, and 1,000 mg/kg/day. All dams were subjected to Cesarean section on day 20 of gestation, and the fetuses were examined for any morphological abnormalities.

RESULTS

All animals survived to the end of the study. A decrease in thymus weight was observed in the high dose group in a dose-dependent manner. However, maternal body weight, food consumption, and oxidant-antioxidant balance in the liver were not affected by treatment with MWCNTs. No treatment-related differences in gestation index, fetal deaths, fetal and placental weights, or sex ratio were observed between the groups. Morphological examinations of the fetuses demonstrated no significant difference in incidences of abnormalities between the groups.

CONCLUSIONS

The results show that repeated oral doses of MWCNTs during pregnancy induces minimal maternal toxicity and no embryo-fetal toxicity at 1,000 mg/kg/day in rats. The no-observed-adverse-effect level of MWCNTs is considered to be 200 mg/kg/day for dams and 1,000 mg/kg/day for embryo-fetal development. In this study, the dosing formulation was not analyzed to determine the degree of reaggregation (or not), nor were blood levels of CNT's measured in the dosed animals to verify or characterize absorption.

LC50 Determination of tert-Butyl Acetate using a Nose Only Inhalation Exposure in Rats

tert-Butyl acetate (TBAc) is an organic solvent, which is commonly used in architectural coatings and industrial solvents. It has recently been exempted from the definition of a volatile organic compound (VOC) by the Air Resources Board (ARB) . Since the use of TBAc as a substitute for other VOCs has increased, thus its potential risk in humans has also increased. However, its inhalation toxicity data in the literature are very limited. Hence, inhalation exposure to TBAc was carried out to investigate its toxic effects in this study. Adult male rats were exposed to TBAc for 4 h for 1 day by using a nose-only inhalation exposure chamber (low dose, 2370 mg/m(3) (500 ppm) ; high dose, 9482 mg/m(3) (2000 ppm) ) . Shamtreated control rats were exposed to clean air in the inhalation chamber for the same period. The animals were killed at 2, 7, and 15 days after exposure. At each time point, body weight measurement, bronchoalveolar lavage fluid (BALF) analysis, histopathological examination, and biochemical assay were performed. No treatment-related abnormal effects were observed in any group according to time course. Based on those findings, the median lethal concentration (LC50) of TBAc was over 9482 mg/m(3) in this study. According to the MSDS, the 4 h LC50 for TBAc for rats is over 2230 mg/m(3). We suggested that this value is changed and these findings may be applied in the risk assessment of TBAc which could be beneficial in a sub-acute study.

Vascular and morphogenetic abnormalities associated with exposure of cigarette smoke condensate during chicken and murine embryogenesis

OBJECTIVE

Embryonic movements (EM) and angiogenesis pathways are evolutionarily conserved mechanisms which are essential for proper embryonic development. Deviations in these processes by exposure to cigarette smoke condensate (CSC) may cause vascular and morphogenetic disorders.

METHODS

Using chicken and mouse embryos, we have demonstrated the in vivo effects of CSC on EM, vascular development, and organogenesis.

RESULTS

Examination of the CSC exposed chicken embryos revealed a significant reduction in EM, stunted growth, deviated pattern of blood vessels, hemorrhages, and localized necrosis. Likewise, mouse embryos that were exposed to CSC at E8.5 and E9.5 died between E11.5 and E12.5, respectively. These mouse embryos showed defects in morphogenesis and remodeling of the embryonic vasculature, while littermate controls showed normal development.

CONCLUSIONS

Cigarette smoking during pregnancy is fatal for growing embryos. CSC may induce the remodeling of embryonic vasculature, leading to various pathologies.

Effects of Concrete and Wood Building Environments on Pregnant Dams and Embryo-Fetal Development in Rats

We have recently reported that the continuous exposure of rats to a concrete building environment under cool temperatures had adverse effects on general health parameters and embryo-fetal development. This study examined to compare the potential effects of concrete and wood building environments on pregnant dams and embryo-fetal development in rats. Groups of 10 mated females were exposed to polycarbonate (control), concrete, or wood cages from gestational days (GD) 0 to 20 under cool temperatures (11.9∼12.3°C). All the females underwent a caesarean section on GD 20, and their fetuses were examined for any morphological abnormalities. The temperatures in the cages were similar in all groups but the relative humidity in the concrete and wood groups were higher than in the control group. The concentration of volatile organic compounds in the wood group was higher than in the control group. In the concrete group, maternal effects manifested as an increase in the incidence of clinical signs, a lower body weight, and a decrease in the thymus and ovary weights. Developmental effects included increased post-implantation loss and decreased litter size. Infrared thermal analysis showed that the skin temperature of the rats in the concrete group was lower than that in the control group. In contrast, there were no exposure-related adverse effects on the maternal and developmental parameters in the wood group. Overall, the exposure of pregnant rats to a concrete building environment under cool temperatures has adverse effects on the clinical signs, body weight, skin temperature, organ weight, and embryo-fetal development. On the other hand, exposure to a wood building environment does not have any adverse effects in rats.