Disposition of bisphenol A in pregnant mice and fetuses after a single and repeated oral administration

The risk assessment of bisphenol A (BPA) on the development of offspring of humans is an important issue. There have been some reports on the fate of BPA in rodents, but information on the BPA level in fetal organs essential for the extrapolation to humans is inadequate. In the present study, we investigated the distribution pattern of ¹⁴C-BPA-derived radioactivity in fetal tissues following administration of 10?mg/kg ¹⁴C-BPA to the pregnant mice. The radioactivity was rapidly transferred through placenta and distributed to all fetal organs including reproductive organs and brains in a similar level. The concentration declined slowly compared with dams. Analysis of metabolites in fetuses showed that a fraction of BPA was unexpectedly large compared to the maternal blood. There was no clear effect of the fetal position in a uterus to influence the radioactivity concentration in whole fetuses. The dose dependence of pharmacokinetics should be recognized to extrapolate the pharmacokinetic result from animal experiments at high doses to humans at low doses. Similar experiments were conducted with an addition of two doses, 1 and 100?mg/kg, respectively. The pharmacokinetics seemed to be linear between 1 and 10?mg/kg, although at 100?mg/kg BPA was absorbed slowly and the radioactivity concentrations in fetuses were much higher than expected based on the linear dose dependence. Repeated doses were administered to pregnant mice since humans are exposed to BPA chronically. Radioactivity level in most of the fetal tissues on repeated administration was higher than single administration.     

Environmental geochemistry of technetium

Technetium-99 (⁹⁹Tc) is a radioactive isotope with a half-life of 2.13 × 10⁵ year. ⁹⁹Tc is a major radionuclide contaminant of concern for the world. Therefore, detailed understanding of ⁹⁹Tc environmental chemistry is important for protecting human and ecological health. Here, we review the aqueous geochemistry of ⁹⁹Tc, focusing on chemical properties and behavior of ⁹⁹Tc in the hydrosphere and pedosphere. We describe the general chemistry of Tc including coordination chemistry, isotope chemistry and solid-state chemistry. Then we present anthropogenic and indigenous sources of ⁹⁹Tc and their environmental distribution. We also discuss the radiotoxicity of ⁹⁹Tc and the use of ⁹⁹Tc for medical purpose. Tc biogeochemistry is described through sorption and desorption reactions at the mineral–water interface, thermodynamic of surface complexation, abiotic and biotic redox reaction of Tc(VII). Finally, we summarize the ⁹⁹Tc remediation technologies including cement waste forms, natural remediation, vitrification, nuclear waste transmutation.     

Residence time effects on phase transformation of nanosilver in reduced soils

Residence time effects on phase transformation of silver nanoparticles (AgNPs) (15–50 nm, with and without polyvinylpyrrolidone (PVP) coating) were investigated in reducing soils using experimental geochemistry and synchrotron-based x-ray techniques. After 30 days of anaerobic incubation, a substantial fraction of PVP-coated AgNPs (15 nm) were transformed into Ag₂S and or humic acid (HA) complexed Ag(I), whereas only the HA fraction was dominant in uncoated AgNPs (50 nm). Several investigations recently reported that sulfidation of AgNPs to Ag₂S was the predominant mechanism controlling the fate of AgNP in soil–water environments. However, this investigation showed each AgNP underwent particle-specific chemical transformations to different end compounds after 30 days. Considering the small contribution of Ag(I) dissolution from all AgNPs (less than 5 %), we concluded that changes in solid-state chemical speciation of sorbed AgNPs was promoted by particle-specific interactions of NPs in soil chemical constituents, suggesting a critical role of soil absorbents in predicting the fate of AgNPs in terrestrial environments.     

Variation in migratory history of Japanese eels,<Emphasis Type="Italic"> Anguilla japonica</Emphasis>, collected in coastal waters of the Amakusa Islands,Japan, inferred from otolith Sr/Ca ratios

In order to examine the variation in migratory history of the Japanese eel, Anguilla japonica, we measured otolith strontium (Sr) and calcium (Ca) concentrations by X-ray electron microprobe analysis in 5 yellow eels and 20 silver eels collected in the coastal waters of the Amakusa Islands during the spawning migration season. Three migratory types categorized as river eels, estuarine eels and sea eels were found. Estuarine eels were dominant (52%), sea eels were the second most abundant (28%), followed by river eels (20%). The low proportion of river eels from the spawning migration season suggested that the estuarine and sea eels that inhabit the nearby coastal areas might make a larger reproductive contribution to the next generation in this area, although similar analyses should be made over the wide-range geographic distribution of this species, to provide better estimates of the reproductive contributions by different migratory patterns of the population.     

Antiviral Activities of Hibiscus sabdariffa L. Tea Extract Against Human Influenza A Virus Rely Largely on Acidic pH but Partially on a Low-pH-Independent Mechanism

Food and Environmental Virology - Influenza A virus (IAV) infection is perennially one of the leading causes of death worldwide. Effective therapy and vaccination are needed to control viral...     

Could we remain simply applying discount rate to evaluate the life quality of our future generations?

When we try to estimate future environmental costs resulting from our current economic activities,we usually calculate the present value of the consequences for our future generations by utilizing a discount rate as a standard economic procedure.The popularity of this procedure is solely supported by its simplicity which assumes:(1)a perfect financial market over even 100 years,and(2)existence of a stable time preference between two consecutive periods for an individual consumer.An apparent deficiency of this approach is that the present value of life quality of future generations varies to a large extent along an arbitrarily chosen discount rate.As a matter of fact,the discount rate,which could reflect the time preference as2%or 5%,matters when we predict current strategies of environmental protection for future generations.Simply applying a discount rate to evaluate the quality of our future generation,without clarifying the actual production mechanism behind this,is almost to the same as ignoring the fact that all of the goods are produced through an actual production process and that environmental degradation reduces the efficiency of that process.The greatest concern for our future generations should not be given by an assumed discount rate,since the discount rate itself is determined by financial market conditions at certain points in time.     

Reproductive transfer of organochlorines in viviparous surfperch, Ditrema temmincki

To discuss the maternal-fetal transfer of persistent organic pollutants (POPs) in viviparous fish, the whole-body burdens of POPs were determined in gravid surfperches from Otsuchi Bay, Japan, and in their fetuses. The concentrations were 2.75-15.5 times higher in the maternal tissue. To compare the characteristics of the maternal-fetal transfer between species with different gestation systems, reports on the striped dolphin and long-finned pilot whales were studied. The transfer rates of POPs in surfperches were 0.6-6.0%, while in marine mammals they were 3.0-9.4%. The difference in transfer rates may derive from the difference in their reproductive systems. On the other hand, as in marine mammals, selective transfer of POPs was seen in surfperches. The transfer rates were higher in less hydrophobic compounds such as dieldrin, and lower in more hydrophobic compounds such as DDTs. A new transfer factor is also discussed which instantly indicates the difference in the concentrations between mother and fetus.     

Biological removal of selenate in saline wastewater by activated sludge under alternating anoxic/oxic conditions

Removal of selenate in saline wastewater by activated sludge was examined. Sequencing batch reactor was operated under alternating anoxic/oxic conditions. Above 97% removal of soluble selenium (Se) was achieved continuously. Major Se removal mechanism varied depending on the length of aeration period. Various Se-reducing bacteria likely contributed to coordinately to Se removal. Selenium (Se)-containing industrial wastewater is often coupled with notable salinity. However, limited studies have examined biological treatment of Se-containing wastewater under high salinity conditions. In this study, a sequencing batch reactor (SBR) inoculated with activated sludge was applied to treat selenate in synthetic saline wastewater (3% w/v NaCl) supplemented with lactate as the carbon source. Start-up of the SBR was performed with addition of 1–5 mM of selenate under oxygen-limiting conditions, which succeeded in removing more than 99% of the soluble Se. Then, the treatment of 1 mM Se with cycle duration of 3 days was carried out under alternating anoxic/oxic conditions by adding aeration period after oxygen-limiting period. Although the SBR maintained soluble Se removal of above 97%, considerable amount of solid Se remained in the effluent as suspended solids and total Se removal fluctuated between about 40 and 80%. Surprisingly, the mass balance calculation found a considerable decrease of Se accumulated in the SBR when the aeration period was prolonged to 7 h, indicating very efficient Se biovolatilization. Furthermore, microbial community analysis suggested that various Se-reducing bacteria coordinately contributed to the removal of Se in the SBR and main contributors varied depending on the operational conditions. This study will offer implications for practical biological treatment of selenium in saline wastewater.