The Science of the total environment
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Sci. Total Environ. · Apr 2020
UV dose effects on the revival characteristics of microorganisms in darkness after UV disinfection: Evidence from a pilot study.
Ultraviolet (UV) disinfection during water supply treatment aims to reduce the number of bacteria. Although UV disinfection is effective at inactivating most microorganisms, some microbe species may be entirely impervious. A pilot study was conducted to compare the quantity and community component of bacteria in surface water collected from filtration effluent before UV disinfection with different doses of UV, and those 1 and 2 days afterwards, in darkness. ⋯ Genera such as Exiguobacterium, Citrobacter, Acinetobacter, and Pseudomonas presented a selective advantage in terms of revival in darkness after UV disinfection, irrespective of the UV dose and storage time. The lowest rate of microbial revival (5% day-1) was noted at a UV dose of 266.10 mJ m-2 (with an average UV illumination time of 124.4 s and an average intensity of 86.61 W m-2). Our results suggest that higher UV intensity and lower illumination time are key factors in minimizing the revival of microorganisms in darkness.
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Sci. Total Environ. · Apr 2020
Early life tobacco exposure and children's telomere length: The HELIX project.
Telomere length and mitochondrial DNA content are considered biomarkers of cellular aging, oxidative stress, and inflammation, but there is almost no information on their association with tobacco smoke exposure in fetal and early life. The aim of this study was to assess whether prenatal and childhood tobacco exposure were associated with leukocyte telomere length (LTL) and mitochondrial DNA (mtDNA) content in children. As part of a multi-centre European birth cohort study HELIX (Human Early-Life Exposome) (n = 1396) we assessed maternal smoking status during pregnancy through questionnaires, and through urinary cotinine levels that were then used to classify women as not exposed to smoking (<10 µg/L), exposed to secondhand smoke (SHS) (10-50 µg/L) and active smokers (>50 µg/L). ⋯ Childhood SHS tobacco exposure was not associated with LTL in children. Global SHS exposure during childhood was associated with an increase of 3.51% (95% CI: 0.78, 6.27) in mtDNA content. Our findings suggest that tobacco smoke exposure during pregnancy, even at SHS levels, may accelerate telomere shortening in children and thus induce biological aging from an early age.
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Sci. Total Environ. · Apr 2020
Residential urban tree canopy is associated with decreased mortality during tuberculosis treatment in California.
Trees can sequester air pollutants, and air pollution is associated with poor tuberculosis outcomes. However, the health impacts of urban trees on tuberculosis patients are unknown. To elucidate the effects of urban tree canopy on mortality during tuberculosis treatment, we evaluated patients diagnosed with active tuberculosis in California from 2000 through 2012, obtaining patient data from the California tuberculosis registry. ⋯ Patients were followed for 23,280 person-years with 2370 deaths during tuberculosis treatment resulting in a crude mortality rate of 1018 deaths per 10,000 person-years. Increasing tree cover quintiles were associated with decreasing mortality risk during tuberculosis treatment in all buffers, and the magnitude of association decreased incrementally with increasing buffer radius: In the 50 m buffer, patients living in neighborhoods with the highest quintile tree cover experienced a 22% reduction in mortality (HR 0.78, 95%CI 0.68-0.90) compared to those living in lowest quintile tree cover; whereas for 100, 200, and 300 m buffers, a 21%, 13%, and 11% mortality risk reduction was evident. In conclusion, urban tree canopy was associated with decreased mortality during tuberculosis treatment even after adjusting for multiple demographic, socioeconomic, and clinical factors, suggesting that trees might play a role in improving tuberculosis outcomes.