ABSTRACT
Background N-nitrosodimethylamine (NDMA), a new disinfection by-product in drinking water, has attracted extensive attention due to its high detection rate and concentration. Objective To investigate the concentration of NDMA in drinking water in Nanjing situated in the lower Yangtze River Basin of China, and to evaluate associated human health risk. Methods In dry period (January–March) and wet period (July–September) of 2021, raw water, finished water, and tap water from 16 centralized water treatment plants in Nanjing were collected to detect the concentration of NDMA in water samples by solid phase extraction and gas chromatography-triple quadrupole mass spectrometry with programmable temperature vaporizer-based large volume injection. The concentrations of NDMA in water samples of different water types, water periods, and disinfection methods were analyzed, and the daily exposure levels and carcinogenic risk values of NDMA in drinking water of different exposure routes and different exposed populations were calculated. Monte Carlo simulation was implemented with Crystal Ball 11 software to establish a health risk assessment model and conduct sensitivity analysis. Results A total of 61 drinking water samples were collected in Nanjing, and NDMA was positive in all the water samples, with concentrations ranging from 1.36 to 25.65 ng·L−1 and an overall average concentration of (8.00±4.06) ng·L−1. There were no statistically significant differences in the average concentrations of NDMA among raw water, finished water, and tap water samples (F=2.875, P=0.064), between wet season and dry season (t=−0.855, P=0.397), or among different disinfection methods by liquid chlorine, sodium hypochlorite, and chlorine dioxide (F=0.977, P=0.385). The results of health risk assessment showed that the average carcinogenic risk of NDMA and its P95 were 5.95×10−6 and 1.12×10−5 respectively for oral intake of drinking water, and the values for dermal contact were both lower than 1.00×10−6. The mean carcinogenic risks of exposure to drinking water NDMA in children, adolescents, and adults were 1.84×10−6, 8.27×10−7, and 3.28×10−6, respectively. The results of sensitivity analysis showed that the contributions of daily drinking water volume and NDMA concentration in drinking water to the calculated health risk were high, and the contribution of body weight was negative. Conclusion There is a potential carcinogenic risk of NDMA in the drinking water of Nanjing section of the lower Yangtze River Basin，but it is within the acceptable range.
ABSTRACT
The adverse health effects of fine particles in the air pollution has been confirmed, and health consequences induced by ultrafine particles (mass media aerodynamic diameter < 0.1 micrometer), which was also known as nanoparticles, was drawing an increasing attention by researchers. Firstly, this review discussed the sources and physicochemical characteristics of nanoparticles in the atmosphere in China. And then we focused on the biological effects and potential toxicity mechanisms of some common nanoparticles in the atmosphere on the major tissues and organs. Finally, the research focus of the nano particles in air pollutants was also presented.
Subject(s)
Humans , Air Pollutants , Biomedical Research , China , Nanoparticles , Particle SizeABSTRACT
BACKGROUND:Reports have demonstrated that cytotoxicity produced by ferric oxide (Fe2O3) nanoparticles is associated with cellular lipid peroxidation. Whether Fe2O3 nanoparticles have toxicity to macrophages, and what is the association of toxic mechanism and oxidization?OBJECTIVE: To observe the effects of different concentrations of Fe2O3 nanoparticles on the oxidative damage of macrophages.DESIGN: A controlled observation experiment.SETTING: School of Public Health, Southeast University.MATERIALS: RAW264.7 cells were peritoneal macrophages of mouse and purchased from Shanghai Institute of cells, Chinese Academy of Sciences. Fe2O3 nanoparticles (30 nm) suspension was provided by Department of Biomedical Engineering, Southeast University). Fe2O3 nanoparticle suspension was placed in 60 ℃ water for 10 hours,then in 37 ℃ water overnight. This procedure was repeated 3 times for germicidal treatment. Then, the suspension was packed into small bottles and stored at 4 ℃ for later use. DMEM high glucose culture fluid (Gibco Company,USA); trypsinase (Difco Company, USA, imported); new-bom calf serum(Sijiqing Company, Hangzhou); hydrogen dioxide (H2O2, Gibco Company); Kits for measuring hydrogen dioxide(H2O2), hydroxy radical (·OH), superoxide anion radical (O2·-), lactic acid dehydrogenase, ultramicro ATP enzyme and Coomassie brilliant blue protein levels (Jiancheng Biotechnique Co., Ltd.,Nanjing).METHODS: This experiment was carried out in the laboratory of Department of Labor and Environmental Health, School of Public Health, Dongnan University between March 2006 and July 2006. RAW264.7 cells (Abelson murine leukemia virus-induced tumor) were cultured in DMEM (Gibco Company) containing 100 g/L fetal bovineserum, 100 000 U/L penicillin and 100 mg/L streptomycin in the environment of 5% CO2. Cell growth was observed under an inverted radical in the cells: 1.5×108 L-1 macrophages were inoculated to 24-well plate, 1 mLa well. After the macrophages were cultured for 24 hours in incubation at 37 ℃ in a humidified atmosphere containing 5% CO2. 1.070 0, 0.5350 and 0.2675 g/L Fe2O3 nanoparticles (30 nm) suspension-intervened macrophages were set as Fe2O3 nanoparticle group, and normal saline group was set as control group. Following the intervention of nanoparticles, macrophages were disrupted with Determination of the activities of lactate dehydrogenase (LDH), Na+-K+-ATPase and Ca2+-Mg2+-ATPase: Macrophages in the Fe2O3 nanoparticle group and control group were treated as above. The activities of LDH in culture medium were determined according to the instruction of reagent kit (Nanjing Jiancheng Bioengineering Co., Ltd). And the activities of Na+-K+-ATPase and Ca+-Mg2+-ATPase were also determined according to the instruction of reagent kit (Nanjing Jiancheng Bioengineering Co., Ltd) at low temperature. MAIN OUTCOME MEASURES: ①Effects of different concentrations of Fe2O3 nanoparticles on the production of H2O2, ·OH and O2·- in RAW264.7 cells.②Effects of different concentrations of Fe2O3 nanoparticles on the activities of LDH ,Na+-K+-ATPase and Ca2+-Mg2+-ATPase in RAW264.7 cell culture fluid.RESULTS: ① Level of ·OH free radical in Fe2O3 nanoparticle 0.267 5, 0.535 0, 1.070 0 g/L groups was higher than that in control group, respectively [(0.605±0.066), (0.410±0.080), (0.764±0.051), (0.285±0.057)mkat/g, P ＜ 0.05]; Level of respectively [(9.935±1.159), (8.912±0.131), (13.479±0.752), (5.635±0.475)μkat/g,P ＜ 0.05]; Level of H2O2 in Fe2O3 nanoparticle 1.070 0 g/L group was higher than that in the control group [(14.695±2.815), (2.397±0.399) mmol/L, P ＜increased (P ＜ 0.05). Fe2O3 nanoparticles had effects on the activities of Na+,K+-ATPase and Ca2+,Mg2+-ATPase. With the increase of dose of Fe2O3 nanoparticles, the activities of Na+-K+-ATPase and Ca2+-Mg2+-ATPase were gradually decreased. There were significant differences as compared with control group (P ＜ 0.05)CONCLUSION:Increasing dose of Fe2O3 nanoparticles wouldcause more H2O2,·OH and O2·- free radicals in the cells, increase cell membrane permeability and inhibit the activities of LDH, Na+-K+-ATPase and Ca2+-Mg2+-ATPase.