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Open Access Publications from the University of California

Scholarly Works (7 results)

  • Article
  • Peer Reviewed
UC Berkeley Previously Published Works (2017)
Globally, approximately 2 billion people lack microbiologically safe drinking water. Boiling is the most prevalent household water treatment method, yet evidence of its health impact is limited. To conduct this systematic review, we searched four online databases with no limitations on language or publication date. Studies were eligible if health outcomes were measured for participants who reported consuming boiled and untreated water. We used reported and calculated odds ratios (ORs) and random-effects meta-analysis to estimate pathogen-specific and pooled effects by organism group and nonspecific diarrhea. Heterogeneity and publication bias were assessed using I2, meta-regression, and funnel plots; study quality was also assessed. Of the 1,998 records identified, 27 met inclusion criteria and reported extractable data. We found evidence of a significant protective effect of boiling for Vibrio cholerae infections (OR = 0.31, 95% confidence interval [CI] = 0.13-0.79, N = 4 studies), Blastocystis (OR = 0.35, 95% CI = 0.17-0.69, N = 3), protozoal infections overall (pooled OR = 0.61, 95% CI = 0.43-0.86, N = 11), viral infections overall (pooled OR = 0.83, 95% CI = 0.7-0.98, N = 4), and nonspecific diarrheal outcomes (OR = 0.58, 95% CI = 0.45-0.77, N = 7). We found no evidence of a protective effect for helminthic infections. Although our study was limited by the use of self-reported boiling and non-experimental designs, the evidence suggests that boiling provides measureable health benefits for pathogens whose transmission routes are primarily water based. Consequently, we believe a randomized controlled trial of boiling adherence and health outcomes is needed.
    • Thesis
    • Peer Reviewed
    UC Berkeley Electronic Theses and Dissertations (2016)

    Across the world, well over one billion people lack access to safe drinking water. There are a variety of low cost household drinking water treatment technologies available, but hitherto none have achieved widespread adoption. Globally, boiling is the most common treatment method.

    Over the last few decades, China has achieved historically unprecedented reductions in rural poverty and concomitant expansions of piped drinking water access. However, hundreds of millions of rural Chinese still lack reliable access to safe drinking water. Most households in rural China boil their drinking water, often using biomass or coal for fuel. Though boiling is microbiologically effective, once it cools boiled water is susceptible to recontamination, and the combustion of solid fuels for boiling creates hazardous air pollution.

    This research sought to evaluate the microbiological effectiveness of the household water treatment methods used in rural China, and to investigate the socioeconomic predictors associated with water treatment methods and preferences.

    To conduct this research, I collaborated with the National Center for Rural Water Supply Technical Guidance, an agency of the Chinese Center for Disease Control and Prevention, and their counterparts in Guangxi Province. In 2013 we collected survey and water quality data from 450 households across 15 villages. Household drinking water samples were analyzed for indicators of fecal contamination and physicochemical analyses were conducted for village drinking water sources. Data collection was repeated in a subset of villages over the 2013-2014 winter to address seasonality, and remote temperature sensors affixed to kettles and pots were used to corroborate household survey responses about boiling frequencies and durations.

    As far as I am aware, this was the first research study in China focused on household water treatment, and the first to quantify the advantages of boiling with electric kettles.

      Cover page: Household Drinking Water Treatment in Rural China: Microbiological Effectiveness and Socioeconomic Predictors
      • Article
      • Peer Reviewed
      UC Berkeley Previously Published Works (2023)
      Though safe drinking water for all is a global public health goal, disparities in access persist worldwide. We present a critical review of primary-data based environmental justice (EJ) studies on drinking water. We examine their findings in relation to the broader EJ and drinking water literatures. Using pre-specified protocols to screen 2423 records, we identified 33 studies for inclusion. We organized our results using the following questions: (1) what sampling and data collection methods are used; (2) how is (un)just access to water defined and measured; (3) what forms of environmental injustice are discussed; (4) how are affected communities resisting or coping; and (5) what, if any, mechanisms of redress are advocated? We find that while many studies analyze the causes and persistence of environmental injustices, most primary-data studies on drinking water are cross-sectional in design. Many such studies are motivated by health impacts but few measure drinking water exposures or associated health outcomes. We find that, while distinct types of injustice exist, multiple types are either co-produced or exacerbate one another. Recognitional injustice is emerging as an undergirding injustice upon which others (distributional or procedural) can take hold. Tensions remain regarding the role of the state; redress for inequitable water access is often presumed to be the state's responsibility, but many EJ scholars argue that the state itself perpetuates inequitable conditions. The accountability for redress under different forms of water governance remains an important area for future research. This article is categorized under: Human Water > Methods.
        Cover page: Environmental justice and drinking water: A critical review of primary data studiesCreative Commons 'BY-NC-ND' version 4.0 license
        • Article
        • Peer Reviewed
        UC Berkeley Previously Published Works (2017)
        Approximately two billion people drink unsafe water. Boiling is the most commonly used household water treatment (HWT) method globally and in China. HWT can make water safer, but sustained adoption is rare and bottled water consumption is growing. To successfully promote HWT, an understanding of associated socioeconomic factors is critical. We collected survey data and water samples from 450 rural households in Guangxi Province, China. Covariates were grouped into blocks to hierarchically construct modified Poisson models and estimate risk ratios (RR) associated with boiling methods, bottled water, and untreated water. Female-headed households were most likely to boil (RR = 1.36, p < 0.01), and among boilers those using electric kettles rather than pots had higher income proxies (e.g., per capita TV ownership RR = 1.42, p < 0.01). Higher-income households with younger, literate, and male heads were more likely to purchase (frequently contaminated) bottled water, or use electric kettles if they boiled. Our findings show that boiling is not an undifferentiated practice, but one with different methods of varying effectiveness, environmental impact, and adoption across socioeconomic strata. Our results can inform programs to promote safer and more efficient boiling using electric kettles, and suggest that if rural China's economy continues to grow then bottled water use will increase.
          Cover page: Predictors of Drinking Water Boiling and Bottled Water Consumption in Rural China: A Hierarchical Modeling Approach.
          • Article
          • Peer Reviewed
          Berkeley Research Impact Initiative (BRII) (2015)

          In rural China ~607 million people drink boiled water, yet little is known about prevailing household water treatment (HWT) methods or their effectiveness. Boiling, the most common HWT method globally, is microbiologically effective, but household air pollution (HAP) from burning solid fuels causes cardiovascular and respiratory disease, and black carbon emissions exacerbate climate change. Boiled water is also easily re-contaminated. Our study was designed to identify the HWT methods used in rural China and to evaluate their effectiveness.

          Methods: We used a geographically stratified cross-sectional design in rural Guangxi Province to collect survey data from 450 households in the summer of 2013. Household drinking water samples were collected and assayed for Thermotolerant Coliforms (TTC), and physicochemical analyses were conducted for village drinking water sources. In the winter of 2013–2104, we surveyed 120 additional households and used remote sensors to corroborate self-reported boiling data.

          Findings: Our HWT prevalence estimates were: 27.1% boiling with electric kettles, 20.3% boiling with pots, 34.4% purchasing bottled water, and 18.2% drinking untreated water (for these analyses we treated bottled water as a HWT method). Households using electric kettles had the lowest concentrations of TTC (73% lower than households drinking untreated water). Multilevel mixed-effects regression analyses showed that electric kettles were associated with the largest Log10TTC reduction (-0.60, p<0.001), followed by bottled water (-0.45, p<0.001) and pots (-0.44, p<0.01). Compared to households drinking untreated water, electric kettle users also had the lowest risk of having TTC detected in their drinking water (risk ratio, RR = 0.49, 0.34–0.70, p<0.001), followed by bottled water users (RR = 0.70, 0.53–0.93, p<0.05) and households boiling with pots (RR = 0.74, 0.54–1.02, p = 0.06).

          Conclusion: As far as we are aware, this is the first HWT-focused study in China, and the first to quantify the comparative advantage of boiling with electric kettles over pots. Our results suggest that electric kettles could be used to rapidly expand safe drinking water access and reduce HAP exposure in rural China.

            • Article
            • Peer Reviewed
            UC Berkeley Previously Published Works (2020)

            Background

            Inadequate access to safe drinking water remains a global health problem, particularly in rural areas. Boiling is the most commonly used form of point-of-use household water treatment (HWT) globally, although the use of bottled water in low- and middle-income countries (LMICs) is increasing rapidly.

            Objectives

            We assessed the regional and seasonal prevalence of HWT practices (including bottled water use) in low-income rural areas in two Chinese provinces, evaluated the microbiological safety of drinking water and associated health outcomes, and estimated the air pollution burden associated with the use of solid fuels for boiling.

            Methods

            We conducted cross-sectional surveys and collected drinking water samples from 1,033 rural households in Guangxi and Henan provinces. Temperature sensors affixed to pots and electric kettles were used to corroborate self-reported boiling frequencies and durations, which were used to model household air pollution (HAP) in terms of estimated particulate matter ≤2.5μm in aerodynamic diameter (PM2.5) concentrations.

            Results

            Based on summer data collection in both provinces, after controlling for covariates, boiling with electric kettles was associated with the largest log reduction in thermotolerant coliforms (TTCs) (-0.66 log10 TTC most probable number/100mL), followed by boiling with pots (-0.58), and bottled water use (-0.39); all were statistically significant (p<0.001). Boiling with electric kettles was associated with a reduced risk of TTC contamination [risk ratio (RR)=0.25, p<0.001] and reported diarrhea (RR=0.80, p=0.672). TTCs were detected in 51% (n=136) of bottled water samples. For households boiling with biomass, modeled PM2.5 concentrations averaged 79 μg/m3 (standard deviation=21).

            Discussion

            Our findings suggest that where boiling is already common and electricity access is widespread, the promotion of electricity-based boiling may represent a pragmatic stop-gap means of expanding safe water access until centralized, or decentralized, treated drinking water is available; displacing biomass use for water boiling could also reduce HAP concentrations and exposures. Our results also highlight the risks of increasing bottled water use in rural areas, and its potential to displace other sources of safe drinking water, which could in turn hamper efforts in China and other LMICs toward universal and affordable safe water access. https://doi.org/10.1289/EHP7124.
              Cover page: Boiled or Bottled: Regional and Seasonal Exposures to Drinking Water Contamination and Household Air Pollution in Rural China
              • Article
              • Peer Reviewed
              UC Berkeley Previously Published Works (2022)
              Bottled water is a rapidly growing yet relatively understudied source of drinking water globally. In addition to concerns about the safety of bottled water, the adverse environmental health and social impacts associated with bottled water production, distribution, consumption, and reliance are considerable. Our objective was to comprehensively review, analyze, and synthesize ∼20 years of publicly available data on bottled water quality and associated health outcomes in China. We conducted a systematic review and meta-analysis of publicly available studies of bottled water quality and associated health outcomes in China published between 1995 and early 2016 (in Chinese and English). We pre-specified and registered our study protocol, independently replicated key analyses, and followed standardized reporting guidelines. Our search identified 7059 potentially eligible records. Following screening, after full-text review of 476 publications, 216 (reporting results from 625 studies) met our eligibility criteria. Among many findings, 93.7% (SD = 10.1) of 24 585 samples tested for total coliforms (n = 241 studies), and 92.6% (SD = 12.7) of 7261 samples tested for nitrites (n = 85 studies), were in compliance with China's relevant bottled water standards. Of the studies reporting concentration data for lead (n = 8), arsenic (n = 5), cadmium (n = 3), and mercury (n = 3), median concentrations were within China's standards for all but one study of cadmium. Only nine publications reported health outcome data, eight of which were outbreak investigations. Overall, we observed evidence of stable or increasing trends in the proportions of samples in compliance over the ∼20 year period; after controlling for other variables via meta-regression, the association was significant for microbiological but not chemical outcomes (p = 0.017 and p = 0.115, respectively). Bottled water is typically marketed as being safe, yet in most countries it is less well-regulated than utility-supplied drinking water. Given the trend of increasing bottled water use in China and globally - and the associated environmental health impacts - we hope this work will help to inform policies and regulations for improving bottled water safety, while further highlighting the need for substantially expanding the provision of safe and affordable utility-supplied drinking water globally.
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