Spatial variation and health risk assessment of fluoride in drinking water in the Chongqing urban areas, China.

Fluoride is an essential trace element for humans, and its deficiency or excess in the environment could lead to disease. To investigate the spatial distribution and health risk assessment of fluoride (F-) in drinking water, 302 tap water samples from Chongqing urban areas, China, were collected to analyze F- using an ion chromatograph. The results showed that (1) F- concentration in drinking water ranged from 0.100 to 0.503 mg/L, with an average of 0.238 ± 0.045 mg/L. (2) The spatial autocorrelation analysis showed that high-low clusters were mostly located in Dadukou District and Beibei District, while low-low clusters were mainly in southern Banan District. (3) The fluoride average daily doses of children, teens and adults were 0.030, 0.029 and 0.031 mg/(kg day). (4) Hazard quotients of excessive fluoride (HQe) of children, teens and adults were 0.51 ± 09, 0.49 ± 0.09 and 0.52 ± 0.10, respectively (inferior to 1.00), whereas hazard quotients of inadequate fluoride (HQi) of those groups were 1.21 ± 0.26, 1.23 ± 0.26 and 1.15 ± 0.25, respectively (superior to 1.00). Therefore, average daily fluoride intake of residents with drinking water was inadequate. This could pose dental caries and osteoporosis threats for residents from Chongqing urban areas.

Fluoride content and distribution pattern in groundwater of eastern Yunnan and western Guizhou, China.

For study, the fluoride (F) content and distribution pattern in groundwater of eastern Yunnan and western Guizhou fluorosis area in southwestern China, the F content of 93 water samples [groundwater (fissure water, cool spring, and hot springs), rivers water] and 60 rock samples were measured. The result shows the F content of the fissure water and cold spring water is 0.027-0.47 mg/L, and river water is 0.048-0.224 mg/L. The F content of hot spring water is 1.02-6.907 mg/L. The drinking water supplied for local resident is mainly from fissure water, cool spring, and river water. And the F content in all of them is much lower than the Chinese National Standard (1.0 mg/L), which is the safe intake of F in drinking water. The infected people in eastern Yunnan and western Guizhou fluorosis area have very little F intake from the drinking water. The hot spring water in fluorosis area of eastern Yunnan and western Guizhou, southwest China has high F content, which is not suitable for drinking.

Removal of cadmium and tetracycline by lignin hydrogels loaded with nano-FeS: Nanoparticle size control and content calculation.

Cadmium (Cd) and tetracycline (TC) cause serious environmental risks. Nanomaterials have been extensively applied for environmental remediation. The size and content of nanoparticles directly affect the removal of contaminants. However, size regulation and quantitative determination of nanoparticles cannot be easily realized. In this study, hydrogels with different polymerization degrees were prepared by adjusting the contents of acrylamide (AM) and sodium lignosulfonate polymeric monomers. Ferrous sulfide (FeS) nanoparticles of different sizes were synthesized in situ within the hydrogels. The nanoparticle size decreased from 600 to 200 nm with increasing hydrogel polymerization degree, and an incomplete crystalline state was observed at the highest polymerization degree. By combining energy dispersive spectroscopy (EDS) images with the maximum between-class variance (Otsu) method, the content of nanoparticles was calculated to be 7.81%, 15.05%, 22.62%, 27.10%, 21.97%, and 23.95%. The distribution state of FeS compounds was also obtained. A low polymerization degree resulted in high FeS dispersal, and a high polymerization degree affected the uniformity distribution based on irregular ion diffusion. The obtained nanocomposites with different polymerization degrees were applied to the removal of Cd and TC in water. The removal capacity for both contaminants revealed a trend of initially increasing and then decreasing. The initial increase was related to the increasing content and decreasing size of the FeS nanoparticles, while the following decrease was due to the decreasing content and incomplete crystallization of the FeS nanoparticles. Overall, changing the proportion of polymeric monomers is an effective way to regulate particle size, and the Otsu method combined with EDS mapping images is a feasible method for calculating the content of nanoparticles.

Nano-FeS incorporated into stable lignin hydrogel: A novel strategy for cadmium removal from soil.

Strategies for reducing cadmium (Cd) content in polluted farmland soils are currently limited. A type of composite with nanoparticles incorporated into a hydrogel have been developed to efficiently remove heavy metals from sewage, but their application in soils faces challenges, such as organic hydrogel degradation due to oxygen exposure and slow Cd2+ release from soil constituents. To overcome these challenges, a composite with superior stability for long-term application in soil is required. In this study, ferrous sulfide (FeS) nanoparticle@lignin hydrogel composites were developed. The lignin-based hydrogels inherited lignin's natural mechanical and environmental stability and the FeS nanoparticles efficiently adsorbed Cd2+ and enhanced Cd2+ desorption from soils by producing H+. The high sorption capacity (833.3 g kg-1) of the composite was attributed to four proposed mechanisms, including cadmium sulfide (CdS) precipitation via chemical reaction (84.06%), lignin complexation (13.19%), hydrogel swelling (0.61%), and nanoparticle sorption (2.15%). In addition, Fe2+ displaced from the composite was gradually oxidized to form solid iron oxide hydroxide, which increased Cd2+ sorption. The composite significantly reduced the total, surfactant-soluble, and fixed Cd in heavily and lightly polluted paddy soils by 22.4-49.6%, 13.5-68.6%, and 40.1-16.6%, respectively, in 7 days.

A Hydrogel-Based Hybrid Theranostic Contact Lens for Fungal Keratitis.

Fungal keratitis, a severe ocular disease, is one of the leading causes of ocular morbidity and blindness, yet it is often neglected, especially in developing countries. Therapeutic efficacy of traditional treatment such as eye drops is very limited due to poor bioavailability, whereas intraocular injection might cause serious side effects. Herein, we designed and fabricated a hybrid hydrogel-based contact lens which comprises quaternized chitosan (HTCC), silver nanoparticles, and graphene oxide (GO) with a combination of antibacterial and antifungal functions. The hydrogel is cross-linked through electrostatic interactions between GO and HTCC, resulting in strong mechanical properties. Voriconazole (Vor), an antifungal drug, can be loaded onto GO which retains the drug and promotes its sustained release from the hydrogel-based contact lenses. The contact lenses also exhibited good antimicrobial functions in view of glycidyltrimethylammonium chloride and silver nanoparticles. The results from in vitro and in vivo experiments demonstrate that contact lenses loaded with Vor have excellent efficacy in antifungal activity in vitro and could significantly enhance the therapeutic effects on a fungus-infected mouse model. The results indicate that this hydrogel contact lenses-based drug delivery system might be a promising therapeutic approach for a rapid and effective treatment of fungal keratitis.

The daily fluorine and arsenic intake for residents with different dietaries and fluorosis risk in coal-burning fluorosis area, Yunnan, Southwest China.

The daily fluorine (F)/arsenic (As) intake (DFI/DAsI) for residents at different ages with different dietaries and dietary changes was investigated to analyze the fluorosis risk in coal-burning fluorosis area in Yunnan, Southwest China. The DFI for residents with a dietary of roasted corn and roasted chili was 5.06, 9.60, and 14.38 mg for age groups 3-7, 8-15, and over 15 years, respectively. Over 90 % of DFI was from roasted foodstuffs. The DFI for residents of the same age group living on rice and roasted chili was 1.94, 3.50, and 4.95 mg, respectively, which were less than that for the former dietary type, and 65 % of DFI was from roasted chili. The main sources for their DFI are roasted foodstuffs. Both were higher than the dietaries with non-roasted foodstuffs and the recommended daily allowances (RDAs) for USA and China at different levels. The DAsI for all residents ranged from 25 to 135 µg, and at this level of DAsI, it would not influence human health. However, As pollution of roasted foodstuffs might have an important influence for the fluorosis. Residents are changing their staple food from roasted corn to rice, and especially, younger people are more focused on quality life. However, even if residents change their staple food, the habit of eating chili will not change, which also may cause them getting fluorosis. Developing economy, changing dietary types, and changing the habit of drying and keeping chili will help to reduce the fluorosis risk in coal-burning fluorosis area of Southwest China.

The pollution control of fluorine and arsenic in roasted corn in "coal-burning" fluorosis area Yunnan, China.

Pilot experiments were carried out to reduce the fluorine (F) and arsenic (As) pollution of roasted corn dried by open ovens in "coal-burning" fluorosis area Yunnan, China. The results indicated that the average emission amount of F and As in briquettes in experimental group were 29.20mg/kg and 0.76 mg/kg in Xiaolongdong, and 46.8 mg/kg and 0.54 mg/kg in Mangbu respectively. The results also indicated that the fixing rate of F and As in briquettes in experimental group was more than 4 times and 1.2 times of that in control group respectively. The average concentration of F and As in roasted corn in experimental group were 3.86 mg/kg and 13.23 µg/kg in Xiaolongdong, and 4.77 mg/kg and 122.96 µg/kg in Mangbu respectively, which reduced by more than 65% and 75% respectively compared with that in control group. Adding local natural calcium-based materials in briquettes can reduce the emission of F and As and their pollution on roasted corn largely, and thus will reduce the risk of fluorosis for residents greatly in "coal-burning" fluorosis area of southwestern China.