Zerovalent iron-sand filtration can reduce the concentration of multiple antimicrobials in conventionally treated reclaimed water.

Irrigation with reclaimed water is increasing in areas that lack access to, and infrastructure for, high-level treatment and distribution. Antimicrobial residues are known to persist in conventionally treated reclaimed water, necessitating the investigation of reuse site-based mitigation options to further reduce these contaminants. We examined the effectiveness of a 50:50 volume/volume, particle matched, micro-scale zerovalent iron (ZVI)-sand filter in reducing concentrations of mixtures of antimicrobials present in pH-unadjusted conventionally treated reclaimed water. Twelve antimicrobials (azithromycin, ciprofloxacin, erythromycin, linezolid, oxacillin, oxolinic acid, penicillin G, pipemidic acid, sulfamethoxazole, triclocarban, tetracycline and vancomycin) were quantified using high performance-liquid chromatography-tandem mass spectrometry in reclaimed water, and ZVI-sand filtered reclaimed water, in a two-month long greenhouse-based experiment. Data were analyzed using a non-parametric rank-based approach. ZVI-sand filtration significantly reduced concentrations of azithromycin, ciprofloxacin, oxolinic acid, penicillin G, sulfamethoxazole, linezolid, pipemidic acid and vancomycin. Azithromycin, the antimicrobial with the highest median concentration (320 ng/L), was reduced to below the limit of detection after ZVI-sand filtration. Inorganic element (antimony, beryllium, cadmium, chromium, iron, lead, selenium and thallium) and water quality (free and total chlorine, nitrates, nitrites, pH and total dissolved solids) analyses showed that ZVI-sand filtered reclaimed water quality (nitrate, salinity, and inorganic elements) met the recommended guidelines for agricultural irrigation with reclaimed water. Based on our initial results, ZVI-sand filtration may be a promising basis for a point-of-use filtration system for reclaimed water irrigation on small-scale farms.

Pharmaceuticals, herbicides, and disinfectants in agricultural water sources.

Agricultural water withdrawals account for the largest proportion of global freshwater use. Increasing municipal water demands and droughts are straining agricultural water supplies. Therefore, alternative solutions to agricultural water crises are urgently needed, including the use of nontraditional water sources such as advanced treated wastewater or reclaimed water, brackish water, return flows, and effluent from produce processing facilities. However, it is critical to ensure that such usage does not compromise soil, crop, and public health. Here, we characterized five different nontraditional water types (n = 357 samples) for the presence of pharmaceuticals, herbicides, and disinfectants using ultra-high-pressure liquid chromatography tandem mass spectrometry based method (UPLC-MS/MS). We then evaluated whether the levels of these contaminants were influenced by season. The highest level of herbicides (atrazine) was detected in untreated pond water (median concentration 135.9 ng/L). Reclaimed water had the highest levels of antibiotics and stimulants including azithromycin (215 ng/L), sulfamethoxazole (232.1 ng/L), and caffeine (89.4 ng/L). Produce processing plant water also tended to have high levels of atrazine (102.7 ng/L) and ciprofloxacin (80.1 ng/L). In addition, we observed seasonal variability across water types, with the highest atrazine concentrations observed during summer months, while the highest median azithromycin concentrations were observed in reclaimed water during the winter season. Further studies are needed to evaluate if economically feasible on-farm water treatment technologies can effectively remove such contaminants from nontraditional irrigation water sources.

Household air pollution and lung cancer risk among never-smokers in Nepal.

More than half of the global population relies on biomass fuels (wood, charcoal, crop residue, dung) for cooking and/or heating purposes. Household air pollution (HAP) resulting from the use of these solid fuels is of particular concern, given the overall prevalence as well as the intensity of exposure and the range of potential adverse health outcomes. Long term exposure to HAP is a major public health concern, particularly among women and children in low and middle income countries. In this study, we investigated the association between exposure to HAP resulting from combustion of biomass and lung cancer risk among Nepalese population. Using a hospital-based case-control study (2009-2012), we recruited 606 lung cancer cases and 606 healthy controls matched on age (±5 years), gender, and geographical residence. We used unconditional logistic regression to compute odds ratios (ORs) and 95% Confidence Intervals (95% CI) for lung cancer risk associated with HAP exposures, adjusting for potential confounders (tobacco use, TB status, SES, age, gender, ethnicity, and exposure to second hand smoke. In our overall analysis, we observed increased risk of lung cancer among those who were exposed to HAPs (OR: 1.77, 95% CI: 1.00-3.14). A more detailed analysis stratified by smoking status showed considerably higher risk of lung cancer associated with increasing duration of exposure to HAP from biomass combustion, with evidence of a borderline exposure-response relationship (Ptrend=0.05) that was more pronounced among never-smokers (Ptrend=0.01). Our results suggest that chronic exposure to HAP resulting from biomass combustion is associated with increased lung cancer risk, particularly among never-smokers in Nepal.

Oral microbiome dysbiosis among cigarette smokers and smokeless tobacco users compared to non-users.

Tobacco use significantly influences the oral microbiome. However, less is known about how different tobacco products specifically impact the oral microbiome over time. To address this knowledge gap, we characterized the oral microbiome of cigarette users, smokeless tobacco users, and non-users over 4 months (four time points). Buccal swab and saliva samples (n = 611) were collected from 85 participants. DNA was extracted from all samples and sequencing was carried out on an Illumina MiSeq, targeting the V3-V4 region of the 16S rRNA gene. Cigarette and smokeless tobacco users had more diverse oral bacterial communities, including a higher relative abundance of Firmicutes and a lower relative abundance of Proteobacteria, when compared to non-users. Non-users had a higher relative abundance of Actinomyces, Granulicatella, Haemophilus, Neisseria, Oribacterium, Prevotella, Pseudomonas, Rothia, and Veillonella in buccal swab samples, compared to tobacco users. While the most abundant bacterial genera were relatively constant over time, some species demonstrated significant shifts in relative abundance between the first and last time points. In addition, some opportunistic pathogens were detected among tobacco users including Neisseria subflava, Bulleidia moorei and Porphyromonas endodontalis. Overall, our results provide a more holistic understanding of the structure of oral bacterial communities in tobacco users compared to non-users.

Antibiotic Concentrations Decrease during Wastewater Treatment but Persist at Low Levels in Reclaimed Water.

Reclaimed water has emerged as a potential irrigation solution to freshwater shortages. However, limited data exist on the persistence of antibiotics in reclaimed water used for irrigation. Therefore, we examined the fate of nine commonly-used antibiotics (ampicillin, azithromycin, ciprofloxacin, linezolid, oxacillin, oxolinic acid, penicillin G, pipemidic acid, and tetracycline) in differentially treated wastewater and reclaimed water from two U.S. regions. We collected 72 samples from two Mid-Atlantic and two Midwest treatment plants, as well as one Mid-Atlantic spray irrigation site. Antibiotic concentrations were measured using liquid-chromatography- tandem mass spectrometry. Data were analyzed using Mann-Whitney-Wilcoxon tests and Kruskal Wallis tests. Overall, antibiotic concentrations in effluent samples were lower than that of influent samples. Mid-Atlantic plants had similar influent but lower effluent antibiotic concentrations compared to Midwest plants. Azithromycin was detected at the highest concentrations (of all antibiotics) in influent and effluent samples from both regions. For most antibiotics, transport from the treatment plant to the irrigation site resulted in no changes in antibiotic concentrations, and UV treatment at the irrigation site had no effect on antibiotic concentrations in reclaimed water. Our findings show that low-level antibiotic concentrations persist in reclaimed water used for irrigation; however, the public health implications are unclear at this time.

Ethnic Variation in Consumption of Traditional Tobacco Products and Lung Cancer Risk in Nepal.

Lung cancer is the leading contributor to cancer deaths in the developing world. Within countries, significant variability exists in the prevalence of lung cancer risk, yet limited information is available whether some of the observed variability is associated with differences in the consumption pattern of local tobacco products with differing potency. We recruited 606 lung cancer cases and 606 controls from the B.P. Koirala Memorial Cancer Hospital in Nepal from 2009-2012. We estimated odds ratios (ORs) and 95% confidence intervals (CI) for lung cancer risk associated with different tobacco products, using unconditional logistic regression. Unfiltered cigarettes tended to be the most frequently used products across ethnic subgroup with about 53.7% of Brahmins, 60.1% of Chettris, and 52.3% of Rai/Limbu/Magar/others. In contrast, about 39.9% of Madishe/Tharu smokers reported using bidi compared with only 27.7% who smoked unfiltered cigarettes. Among those who only smoked one type of product, choor/kankat smokers had the highest lung cancer risk (OR 10.2; 95% CI 6.2-16.6), followed by bidi smokers (OR 5.6; 95% CI 3.6-8.7), unfiltered cigarettes (OR 4.9; 95% CI 3.4-7.2), and filtered cigarettes (OR 3.4; 95% CI 2.2-5.3). A clear dose-response relationship was observed between increased frequency of smoking and lung cancer risk across all ethnic subgroups. These results highlight the important role of traditional tobacco products on lung cancer risk in the low income countries.