Titanium dioxide nanoparticles induce bacterial membrane rupture by reactive oxygen species generation

Nano-titania is widely used in the food industry due to its efficient antimicrobial activity. However, the mechanism of microbial toxicity of nano-titania is poorly known. Here, nano-TiO₂ has been fabricated by microwave-irradiation chemistry, a new method, and then tested for antimicrobial activity. Mutagenicity of nano-TiO₂ was evaluated using Salmonella typhimurium histidine-auxotrophic strains. The reactive oxygen generation test was performed using 2,7-dichlorofluorescein diacetate dye. To test membrane permeabilization, E. coli cultures were grown in nutrient broth at an optical density of 0.3–0.5 at 610 nm, harvested by centrifugation at 11,000g for 10 min, washed and resuspended in 0.5 % NaCl solution. We also analyzed superoxide formation and membrane integrity, and we used scanning electron microscopy. Results show that nano-TiO₂ has a minimum inhibitory concentration of 15 µg/mL, and a minimum bactericidal concentration of 20 µg/mL for E. coli. The bacterial inner wall was ruptured, and cytoplasmic content was released after 5 min of treatment in a dose-dependent manner. Notably, superoxide formation was not observed, which establishes the fact that reactive oxygen generation and alteration of membrane integrity, as well as permeability, is the major mechanism of antimicrobial activity of nano-TiO₂.     

High consumption of pesticides in agricultural fields leads to prevalence of cancer cases in rural pockets of eastern India: A case study

This study was performed to evaluate the carcinogenic health risk of pesticides used in agricultural field in rural pockets of eastern India. The analysis of pesticide residue in rice grain sample was performed by Gas Chromatography Mass Spectrometry (GC-MS). It was observed that for pesticide DDT, the HR values was ranging between 0.5 to 3.2 and for lindane HR was 0.4 to 1.1, respectively. The DDT and Lindane exhibited HR values >1 in some sampling sites which revealed the carcinogenic effects and HR <1 in some sampling sites which revealed non carcinogenic effects of same pesticide. These results revealed a clear indication of potential carcinogenic health risk to human health through consumption of contaminated rice in some areas of Bargarh district. DDT has a long half-life, so it persists in the environment for a longer period of time and induces carcinogenic risk to human health predominantly than other pesticide lindane. A case study on cancer prevalence in Bargarh district was also carried out to support the findings of quantitative analysis. The primary data collected from the cancer affected area by personal questionnaires method to the person concern and the secondary data collected from the Bargarh District Head Quarters Hospital's register. The cancer death reported by the from the year 2015 to 2021 was 320, 380, 293, 323, 278, 409, 346 in the year of 2015, 2016, 2017, 2018, 2019, 2020, 2021 respectively, with the total number of 2349 cases. From the questionnaire data, it was observed that the occurrence of male and female cancer cases was 51.75% and 48.25%, respectively. Therefore, it was concluded that there was no significant difference in gender wise cancer prevalence. The most affected age group was 51–60, that is, 26.92% followed by 41–50, that is, 23.42%. Therefore, it was concluded that the middle-aged adults (40–60) were more vulnerable to the cancer than young adults (3–40) and old adults (60–100). The most prevalent cancer was breast (22.72%) followed by stomach (14.33%).     

Metal speciation studies in the aquifer sediments of Semria Ojhapatti,Bhojpur District,Bihar

The pollution of aquifer sediments by heavy metals has assumed serious concern due to their toxicity and accumulative behavior. Changes in environmental conditions can strongly influence the behavior of both essential and toxic elements by altering the forms in which they occur and therefore quantification of the different forms of metal is more meaningful than total metal concentrations. In this study, fractionation of metal ions in aquifer sediments of Semria Ojhapatti area, Bhojpur district, Bihar has been studied to determine the ecotoxic potential of metal ions. The investigations suggest that iron, copper, and arsenic have a tendency to remain associated in the following order residual > reducible > acid-soluble > oxidizable; manganese and zinc have tendency to be associated as residual > acid-soluble > reducible > oxidizable. The risk assessment code reveals that manganese and zinc occur in significant concentration in acid-soluble fraction and therefore comes under the high risk category and can easily enter the food chain. Most of the iron, copper, and arsenic occur as immobile fraction (i.e. residual) followed by its presence in reducible fraction and would pose threat to the water quality due to changing redox conditions. The metal enrichment factor in the study area shows moderate to significant metal enrichment in the aquifer sediments which may pose a real threat in near future. The geo-accumulation index of metals also shows that the metals lie in the range of strongly contaminated (for iron at shallow depths) to moderately contaminated to uncontaminated values.     

Methane oxidation and abundance of methane oxidizers in tropical agricultural soil (vertisol) in response to CuO and ZnO nanoparticles contamination

There is worldwide concern over the increase use of nanoparticles (NPs) and their ecotoxicological effect. It is not known if the annual production of tons of industrial nanoparticles (NPs) has the potential to impact terrestrial microbial communities, which are so necessary for ecosystem functioning. Here, we have examined the consequences of adding the NPs particularly the metal oxide (CuO, ZnO) on CH₄ oxidation activity in vertisol and the abundance of heterotrophs, methane oxidizers, and ammonium oxidizers. Soil samples collected from the agricultural field located at Madhya Pradesh, India, were incubated with either CuO and ZnO NPs or ionic heavy metals (CuCl₂, ZnCl₂) separately at 0, 10, and 20 μg g^?1 soil. CH₄ oxidation activity in the soil samples was estimated at 60 and 100 % moisture holding capacity (MHC) in order to link soil moisture regime with impact of NPs. NPs amended to soil were highly toxic for the microbial-mediated CH₄ oxidation, compared with the ionic form. The trend of inhibition was Zn 20?>?Zn 10?>?Cu 20?>?Cu 10. NPs delayed the lag phase of CH₄ oxidation to a maximum of 4-fold and also decreased the apparent rate constant k up to 50 % over control. ANOVA and Pearson correlation analysis (α?=?0.01) revealed significant impact of NPs on the CH₄ oxidation activity and microbial abundance (p?<?0.0001, and high F statistics). Principal component analysis (PCA) revealed that PC1 (metal concentration) rendered 76.06 % of the total variance, while 18.17 % of variance accounted by second component (MHC). Biplot indicated negative impact of NPs on CH₄ oxidation and microbial abundance. Our result also confirmed that higher soil moisture regime alleviates toxicity of NPs and opens new avenues of research to manage ecotoxicity and environmental hazard of NPs.     

Environmental restoration of invaded ecosystems: How much versus how often?

This paper derives the optimal level of restorative efforts required to restore environments degraded by invasive species invasion. Specific attention is focused on a case when restoration faces the risk of failure through relapse of the restored environment caused by repeat invasions. The level of restored environment may also play a role in its future improvement or susceptibility to failure. The tradeoff between the optimal level of environmental quality and number of restorative efforts required to attain that given environmental quality is highlighted.     

The future of global warming: will it be emissions control or environmental damages?

This paper explores the role of risk perceptions in influencing public policy related to global warming. It solves for the optimal paths for emissions, abatement and investment in pollution-eliminating research by incorporating perceived risks into public decision making. It also compares the impact of differential risk perceptions on international collaboration on carbon abatement. Key findings are that the perception of risks related to environmental damages and technological breakthroughs plays an important role in determining the level of mitigation efforts. A high level of perceived risk of environmental damages discourages investment in pollution-eliminating research as there are few benefits from eliminating pollution after damages are realized. Other options that allow for sequestering carbon from the atmosphere may still remain viable. Another key finding is that when it comes to effort sharing between nations, differential mitigation efforts are primarily caused due to the differences in abatement technology, benefits from emissions and research capabilities. However, such differences could be accentuated or mitigated depending upon the differences in risk perception of developed and developing countries.     

Ecotoxicological risk assessment of pentachlorophenol,an emerging DBP to plants: evaluation of oxidative stress and antioxidant responses

Environmental Science and Pollution Research - Chlorophenols are not only noticed in an effluvium of industries but also can emerge from the water treatment plants for domestic supply which poses a...     

Applications of nanotechnology in agriculture and water quality management

Due to their small size and unique physico-chemical characteristics, nanomaterials have gained importance in the agri-food sector, notably in preservation and packaging. Future applications will focus on shelf life, food quality, safety, fortification and biosensors for contaminated or spoiled food, irrigating water and drinking water. Different types and shapes of nanomaterials are being used depending upon the needs and nature of the work in agriculture and water quality management. Here we review the application of nanotechnology in agriculture. The major points discussed are: (1) Nanomaterials for agriculture and water quality management. (2) Research interests such as nanoscale carriers, fabricated xylem vessels, nanolignocellulosic materials, clay nanotubes, photocatalysis, bioremediation of resistant pesticides, disinfectants, agricultural wastewater treatment, nanobarcode technology, quantum dots for staining bacteria and nanobiosensors. (3) Nanotechnological applications for agriculture, which includes nanolignodynamic metallic particles, photocatalysis, desalination, removal of heavy metals and wireless nanosensors.     

A quantitative risk assessment of waterborne infectious disease in the inundation area of a tropical monsoon region

Flooding and inundation are annual events that occur during the rainy season in Cambodia, and inundation has a strong relationship with human health. This study simulated the coliform bacteria distribution using a hydraulic model and estimated the impact of inundation on public health using a dose–response model. The model parameters were calibrated using field survey data from Cambodia and obtained good agreement with the coliform group count distribution. The results suggest that the impact of inundation on human health is most noticeable in residential areas. The annual average risk of infection during medium-sized flood events is 0.21. The risk due to groundwater use ranges from 0.12 to 0.17 in inundation areas and reaches as high as 0.23 outside the inundation areas. The risk attributed to groundwater use is therefore higher than that for surface water use (0.02–0.06), except in densely populated areas at the city center. There is a high risk for infection with waterborne disease in residential areas, and the annual average risk during small flood events is 0.94. An assessment of possible countermeasures to reduce the risk shows that the control of inundation may bring more risk to public health in Cambodia. Shallower inundation water (<0.3 m) leads to a higher risk of infection, but if the depth is greater than 2 m, the risk is low in residential areas. The simulated results explain the spatial distributions of infection risk,, which are vitally important for determining the highest priority places with relatively high risk and will be helpful for decision makers when considering the implementation of countermeasures.     

Climate-resilient strategies for sustainable management of water resources and agriculture

Environmental Science and Pollution Research - Warming of the earth is considered as the major adverse effect of climate change along with other abnormalities such as non-availability of water...