BackgroundNeonicotinoids, which are novel pesticides, have entered into usage around the world because they are selectively toxic to arthropods and relatively non-toxic to vertebrates. It has been suggested that several neonicotinoids cause neurodevelopmental toxicity in mammals. The aim was to establish the relationship between oral intake and urinary excretion of neonicotinoids by humans to facilitate biological monitoring, and to estimate dietary neonicotinoid intakes by Japanese adults.Methodology/Principal FindingsDeuterium-labeled neonicotinoid (acetamiprid, clothianidin, dinotefuran, and imidacloprid) microdoses were orally ingested by nine healthy adults, and 24 h pooled urine samples were collected for 4 consecutive days after dosing. The excretion kinetics were modeled using one- and two-compartment models, then validated in a non-deuterium-labeled neonicotinoid microdose study involving 12 healthy adults. Increased urinary concentrations of labeled neonicotinoids were observed after dosing. Clothianidin was recovered unchanged within 3 days, and most dinotefuran was recovered unchanged within 1 day. Around 10% of the imidacloprid dose was excreted unchanged. Most of the acetamiprid was metabolized to desmethyl-acetamiprid. Spot urine samples from 373 Japanese adults were analyzed for neonicotinoids, and daily intakes were estimated. The estimated average daily intake of these neonicotinoids was 0.53–3.66 μg/day. The highest intake of any of the neonicotinoids in the study population was 64.5 μg/day for dinotefuran, and this was <1% of the acceptable daily intake.
This paper describes an analytical procedure for free estrogens and their conjugates in domestic wastewater. The procedure demonstrated in this study is innovative in terms of levels of detection and quantification of the following substances: estrone (E1); 17beta-estradiol (E2); 17alpha-ethynylestradiol (EE2); estriol (E3); estrone-3-sulfate (E1-S); beta-estradiol 3-sulfate (E2-S); estriol 3-sulfate (E3-S); estrone beta-D-glucuronide (E1-G); beta-estradiol 17-(beta-D)-glucuronide (E2-G); estriol 3-(beta-D)-glucuronide (E3-G); beta-estradiol 3-sulfate 17-glucuronide (E2-SandG); and estradiol 3,17-disulfate (E2-diS). The detection limits of this method ranged from 0.1 to 1.4 ng/l. The recovery efficiencies of the estrogens in the analysis from influent and effluent of the secondary settling tank in a wastewater treatment plant (WWTP) were higher than 94% for the free estrogens, but were less than 50% for the conjugated estrogens. The field study using this method was conducted at twenty WWTPs in Japan. The median concentrations of the estrogens ranged from ND to as high as >100 ng/l. In the influent and secondary effluent samples, the concentrations of E1, E2 and E3 were the same levels as those previously reported. We found that the conjugated estrogens exist at higher concentrations in the influent and the secondary effluent than in the other studies, and that the concentrations of the conjugated estrogens were higher than those of the free estrogens.
Residual pharmaceutical products in sewage and other water environments have recently become a serious social problem in advanced countries. Among these pharmaceutical products, antibiotics have attracted special attention due to their serious impact on the ecosystem and connections to the emergence of drug-resistant bacteria. Our research intended to develop a new method to analyse the three antibiotics estimated to be released out of the body in large amounts in Japan; levofloxacin (LVFX), clarithromycin (CAM) and azithromycin (AZM), and survey the state of pollution in the sewerage. The concentrations of the water-phase antibiotics LVFX, CAM and AZM were measured in each process of activated sludge process in six wastewater treatment plants. Liquid chromatography tandem mass spectrometry (LC/MS/MS) was used to analyse solutions of the antibiotics after pretreatment with a solid phase extraction. The limits of quantification and the average recoveries for these antibiotics in the influent were 1.2 to 29 ng/L and 46 to 93%, respectively. In the influent, LVFX, CAM and AZM were detected at concentrations of 552, 647 and 260 ng/L, respectively, while their removal efficiencies were 42, 43 and 49%, respectively. Although the CAM and AZM concentrations decreased as the treatment progressed, it was shown that the LVFX concentration increased in activated sludge reactors in some cases. Despite differences in octanol-water partition coefficients among LVFX, CAM and AZM, their removal efficiency showed no major difference. This indicates that this removal phenomenon cannot be explained by simple adsorption by the activated sludge.
Contamination of surface waters by pharmaceutical chemicals is an emerging environmental problem. This study evaluated the toxic effects of the antibacterial agents levofloxacin (LVFX) and clarithromycin (CAM), which are widely used in Japan, on aquatic organisms. Ecotoxicity tests using a bacterium, alga and crustacean were conducted. Microtox test using a marine fluorescent bacterium showed that LVFX and CAM have no acute toxicity to the bacterium. From the results of the Daphnia immobilisation test, LVFX and CAM did not show acute toxicity to the crustacean. Meanwhile, an algal growth inhibition test revealed that LVFX and CAM have high toxicity to the microalga. The phytotoxicity of CAM was about 100-fold higher than that of LVFX from a comparison of EC50 (median effective concentration) value. From the Daphnia reproduction test, LVFX and CAM also showed chronic toxicity to the crustacean. Concentrations of LVFX and CAM in the aquatic environment were compared with PNEC (predicted no effect concentration) to evaluate the ecological risk. As a result, the ecological risk of LVFX is considered to be low, but that of CAM is higher, suggesting that CAM discharged into an aquatic environment after therapeutic use may affect organisms in the aquatic environment.
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