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Study region: The upper, forested reaches of the Ota River, 24.4 km northwest of the Fukushima Daiichi nuclear power plant, was studied. Study focus: There is concern about the effects of dissolved radiocesium (137Cs) released from forest litter on long-term contamination of aquatic ecosystems caused by the Fukushima nuclear accident. Therefore, hydrology and water quality measurements were performed under base flow and storm flow conditions in a high-dose-rate forest watershed in Fukushima Prefecture, to investigate the involvement of litter in 137Cs release. New hydrological insights for the region: Under base flow conditions, the dissolved 137Cs activity concentration significantly positively correlated with the dissolved organic carbon and potassium ion concentrations (the main components leached from litter) over the entire study period. Differences in the annual variations in the 137Cs activity concentrations and potassium ion concentrations indicated that litter indirectly increased 137Cs concentrations in river water by releasing potassium ions that caused 137Cs to desorb from river sediment and riparian soil. In each large runoff event, the dissolved 137Cs activity concentration was higher at the time of maximum runoff than at the start of the event. The relationships between the dissolved 137Cs, dissolved organic carbon, and potassium ion concentrations strongly suggested that 137Cs leached from litter in runoff was directly responsible for the increase in the 137Cs activity concentration in river water.

Following the Fukushima Daiichi Nuclear Power Plant accident in 2011, most of the released 137Cs remained in the litter and surface soil of the adjacent forest floor. However, 137Cs absorption by large soil invertebrates near this site has not been estimated. The aim of this study was to understand the role of soil macroinvertebrates in 137Cs uptake from forest litter into forest ecosystems. Breeding experiments were conducted using scarab beetle larvae (Protaetia orientalis). Dissection experiments revealed that 85% of the total 137Cs was concentrated in the digestive tract of larvae, while a low proportion was absorbed into the skin and muscle tissues. The 137Cs absorption rate, indicating the transfer of 137Cs from consumed litter to larval tissue, was low (0.39%). 137Cs concentrations decreased to one-fourth from larva to imago, possibly due to excretion from the digestive tract and during eclosion. In the elimination experiment, biological half-lives were 0.26–0.64 and 0.11–0.47 days and 3.35–48.30 and 4.01–17.70 days for the digestive tract and muscle/skin tissues in the fast and slow components, respectively, corresponding to 137Cs discharge from the gastrointestinal tract and physiological clearance. In the sequential extraction experiment, litter digestion by flower chafer larvae significantly reduced the bioavailable fraction of 137Cs including water-soluble, exchangeable, oxidized, and organic forms, from 23.2% in litter to 17.7% in feces. Residual 137Cs was not reduced by digestion, probably because it was fixed in soil clay. Our study on breeding experiments of the Scarabaeidae beetle confirmed the low bioavailability of 137Cs in the litter in Fukushima. However, litter feeders may play an important role in transferring 137Cs to higher trophic levels in the forest ecosystem by extracting the bioavailable fraction of the vast stock of 137Cs on the forest floor. [ABSTRACT FROM AUTHOR]

We report the first case of drug‐induced interstitial lung disease attributed to lemborexant. A 66‐year‐old man reported to our hospital with the acute onset of cough and breathlessness with ground‐glass opacity on radiological examination. Symptoms were identified after taking lemborexant for 2 consecutive days. The patient had undergone lemborexant treatment 2 years prior and had exhibited no symptoms at that time. The drug‐induced lymphocyte stimulation test for lemborexant was positive. He showed rapid improvement upon treatment with steroid. With the rise in prescriptions of lemborexant for insomnia, lemborexant should be considered as a possible cause of drug‐induced interstitial lung disease. [ABSTRACT FROM AUTHOR]

After the Tokyo Electric Power Company Fukushima Daiichi Nuclear Power Plant accident in Japan, freshwater ecosystems near the site remained contaminated by radiocesium (RCs). Clarifying RCs concentrations in aquatic insects is crucial because fishes consume these insects that transfer RCs into freshwater ecosystems. As aquatic insects are usually measured for radioactivity in bulk samples of several tens of insects, variation in RCs concentration among individuals is not captured. In this study, we investigated the variability in 137Cs activity concentration in individual aquatic insects in detritivorous caddisfly (Stenopsyche marmorata) and carnivorous dobsonfly (Protohermes grandis) larvae from the Ota River, Fukushima. Caddisfly larvae showed sporadically higher radioactivity in 4 of the 46 caddisfly larvae, whereas no such outliers were observed in 45 dobsonfly larvae. Autoradiography and scanning electron microscopy analyses confirmed that these caddisfly larvae samples contained radiocesium-bearing microparticles (CsMPs), which are insoluble Cs-bearing silicate glass particles. CsMPs were also found in potential food sources of caddisfly larvae, such as periphyton and drifting particulate organic matter, indicating that larvae may ingest CsMPs along with food particles of similar size. Although CsMP distribution and uptake by organisms in freshwater ecosystems is relatively unknown, our study demonstrates that CsMPs can be taken up by aquatic insects. [ABSTRACT FROM AUTHOR]