Tap water consumers differ from non-consumers in chlorine flavor acceptability but not sensitivity

Chlorine Water Taste Threshold and Acceptability among Indigenous and Non-Indigenous Populations in Rural Panama

Although gains in access to water services over the past two decades have been large, more than two billion people still lack access to safely managed drinking water. This study examines and compares free chlorine taste and acceptability thresholds of rural Indigenous Ngäbe and rural Latino Panamanians to study if taste aversion may be a limiting factor in chlorination of community systems in Panama using the three-alternative forced choice test methodology. This study is the first to establish a best-estimate taste threshold for a rural Indigenous group and the only study in Latin America to report best-estimate taste thresholds using those methods. Median taste thresholds were 0.87 mg/L Cl2 for Indigenous Ngäbe participants (n = 82) and 1.64 mg/L Cl2 for Latino participants (n = 64), higher than both the minimum concentration for biologically safe water (0.2 mg/L) and the recommended concentration range in Panama (0.3-0.8 mg/L). Median acceptability thresholds were established much higher than taste thresholds at 3.45 mg/L Cl2. The results show that the ability to accurately taste chlorine may not be the limiting factor for adoption of safe water initiatives in remote and Indigenous communities.

Do health concerns stemming from personality trait influence the choice of drinking water at home? An analysis of the survey results conducted in the Tokyo area under the COVID-19 pandemic

Many previous studies have already pointed out that health concerns influence people's choice of drinking water. The health concerns discussed in the preceding studies are those that are associated with the choice of a particular type of water. On the other hand, people also experience health concerns in their daily lives, unrelated to the choice of drinking water. These two need to be discussed separately, but preceding studies have failed to make a distinction. In this study, we refer to the former as 'health concerns attributable to water characteristics' and the latter as 'health concerns stemming from personality traits.' The purpose of this study is to explore the relationship, if any, between people's health concerns stemming from personality traits and their choice of drinking water. We use three types of health concerns that are stemming from personality traits (e.g. health maintenance, pesticide residues in food, and COVID-19 infection) to elucidate their influences on the choice of drinking water. Based on the results of the analysis, this study reveals that the influence of health concerns stemming from personality traits on the choice of drinking water differs depending on its typology.

Characterization of Metallic Off-Flavors in Drinking Water: Health, Consumption, and Sensory Perception

Characterization of taste- and flavor-producing metals, namely iron and copper, in drinking water is a multifaceted subject. Both metals are essential nutrients, can be toxic, and are known to produce unpleasant tastes and flavor sensations in drinking water. Ingestion of trace metal contaminants through drinking water is a probable source of human exposure. Biochemical mechanisms of metallic flavor perception have been previously described; however, less is known about how variations in salivary constituents might impact individuals' sensitivities to metallic flavors and beverage consumption behaviors. This research presents findings from in vitro experiments, using artificial human saliva, to better understand the role of salivary lipids and proteins on metallic flavor production as measured by biomarkers of metal-induced oxidative stress. The results indicate that metal-induced lipid oxidation, as measured by thiobarbituric acid reactive substances (TBARS), is dominated by salivary proteins, is slightly inhibited in the presence of salivary nitrite, and is detectable by the TBARS method at and above respective concentrations of 9 µM (0.5 mg/L) and 90 µM (5 mg/L), which are both above the aesthetic standards for iron (0.3 mg/L) and copper (1.0 mg/L) in drinking water. Preliminary study with human subjects indicated that reduction in metallic flavor sensitivity, as measured by the best estimate flavor threshold for ferrous iron among 33 healthy adults aged 19-84 years old (22 females), corresponded with reduced drinking water consumption and increased caloric beverage intake among older subjects (>60 years), as determined by a validated self-reported beverage intake questionnaire. These findings provide insights for further research to examine how salivary constituents can impact humans' sensory abilities in detecting metallic off-flavors in water, and how reduced metallic flavor sensitivity may influence beverage choices and drinking water consumption.

Removal of micropollutants in drinking water using UV-LED/chlorine advanced oxidation process followed by activated carbon adsorption

This study investigated the removal of three selected micropollutants (i.e., bisphenol A, diclofenac and caffeine) in drinking water using the UV-LED/chlorine advanced oxidation process (AOP) followed by activated carbon adsorption. The degradation of bisphenol A, diclofenac and caffeine was predominantly contributed by chlorination (>60%), direct UV photolysis (>80%) and radical oxidation (>90%), respectively, during the treatment by the UV-LED/chlorine AOP at three tested UV wavelengths (i.e., 265, 285 and 300 nm). The most effective UV wavelengths for the degradation of bisphenol A, diclofenac and caffeine were 265, 285 and 300 nm, respectively. The degradation of all the three micropollutants was enhanced with increasing pH from 6 to 8, though the reasons for the pH dependence were different. The residues of the micropollutants and their degradation (by)products were removed by post-adsorption using granular activated carbon (GAC). Interestingly and more importantly, the adsorption rates of the degradation (by)products were 2-3 times higher than the adsorption rates of the corresponding micropollutants, indicating the formation of more adsorbable (by)products after the AOP pre-treatment. The UV-LED/chlorine AOP followed by GAC adsorption provides a multi-barrier treatment system for enhancing micropollutant removal in potable water. The findings also suggest the merit of the sequential use of UV-LEDs followed by GAC in treating chlorine-containing potable water in small-scale water treatment systems (e.g., point-of-use or point-of-entry water purifiers).

Variations in sensitivity to chlorine in Ecuador and US consumers: implications for community water systems

Successful implementation of chlorination for disinfecting community water systems in developing countries faces obstacles, with rejection of chlorinous flavor as a significant factor. Determining consumers' abilities to accurately detect chlorine in treated water is important to identifying acceptable chlorination levels that are also effective for water disinfection. Chlorine detection sensitivity was tested in untrained Ecuadorian consumers with limited prior experience with chlorinated water and US consumers with extensive prior experience with chlorinated water. Water samples with free chlorine concentrations up to 3.0 mg/L were presented for flavor testing. Ecuadorian consumers showed higher sensitivity, being able to detect chlorination at 2.0 and 3.0 mg/L, while US consumers did not reliably detect chlorine presence for any concentration levels. Additionally, Ecuadorian consumers' rejection of water samples depended on chlorination, showing a statistically significant increase in rejections of samples with chlorine concentrations above 1.0 mg/L. On the other hand, although US consumers rejected more samples overall, their tendency to reject did not vary as a function of chlorination levels. This study demonstrated that limited experience with chlorination is a critical factor for accurate chlorine flavor detection in drinking water.

Barriers and Facilitators to Chlorine Tablet Distribution and Use in Emergencies: A Qualitative Assessment

Chlorine tablets are commonly distributed for household water treatment in emergencies. However, confirmed use after distribution ranges widely (from 7–87%), which raises concerns about chlorine tablet effectiveness, as measured by acceptance and appropriate use. To investigate chlorine tablet effectiveness, we conducted nine key informant interviews (KIIs) on tablet distribution in emergencies in general, five KIIs on chlorine taste and odor acceptance and rejection specifically, and a literature review on chlorine taste and odor concerns. We found: (1) chlorine tablets are regarded as one of the most effective water treatment methods and are often considered appropriate in emergency response, (2) dosing confusion and taste and odor rejection are perceived as the main problems limiting effectiveness, and (3) the primary solutions suggested for these problems were social and behavioral. We recommend that social and behavioral scientists are routinely integrated into chlorine tablet programming to improve user feedback and behavioral interventions for chlorine tablet promotion in emergencies. We also suggest that more research is conducted on chlorine taste and odor rejection in vulnerable populations, and that improved guidance is developed to facilitate intra-agency coordination and select, promote, and monitor tablets appropriate for each context.

Determinants of Caregivers' Use and Adoption of Household Water Chlorination: A Qualitative Study with Peri-Urban Communities in the Peruvian Amazon

The gap between the efficacy and the effectiveness of household water treatment in reducing diarrhea-related morbidity indicates the need for a better understanding of the determinants of long-term behavior change. To explore the barriers to drinking water chlorination in the Peruvian Amazon, where diarrhea is endemic among under-5 children, we conducted qualitative research with 23 caregivers from peri-urban communities of Iquitos, Peru. Our inquiry drew on the Transtheoretical Model of behavior change and the Integrated Behavioral Model for Water, Sanitation, and Hygiene to identify the most relevant contextual, psychosocial, and technological determinants of initial action and long-term adoption of chlorination. Our findings suggest that the decision to try out this practice resulted from the combined effect of knowledge of chlorination benefits and product availability and affordability. Progress from action to adoption was influenced by caretakers' understanding of dosage, the packaging of chlorine products, knowledge and skills for multipurpose laundry bleach, the taste of treated water, and reinforcement. This analysis suggests that a focus on these determinants and the household domain may help to improve the sustainability of future intervention efforts.

An environmental friendly procedure for photometric determination of hypochlorite in tap water employing a miniaturized multicommuted flow analysis setup

A photometric procedure for the determination of ClO(-) in tap water employing a miniaturized multicommuted flow analysis setup and an LED-based photometer is described. The analytical procedure was implemented using leucocrystal violet (LCV; 4,4',4''-methylidynetris (N,N-dimethylaniline), C(25)H(31)N(3)) as a chromogenic reagent. Solenoid micropumps employed for solutions propelling were assembled together with the photometer in order to compose a compact unit of small dimensions. After control variables optimization, the system was applied for the determination of ClO(-) in samples of tap water, and aiming accuracy assessment samples were also analyzed using an independent method. Applying the paired t-test between results obtained using both methods, no significant difference at the 95% confidence level was observed. Other useful features include low reagent consumption, 2.4 μg of LCV per determination, a linear response ranging from 0.02 up to 2.0 mg L(-1)  ClO(-), a relative standard deviation of 1.0% (n = 11) for samples containing 0.2 mg L(-1)  ClO(-), a detection limit of 6.0 μg L(-1)  ClO(-), a sampling throughput of 84 determinations per hour, and a waste generation of 432 μL per determination.