PEER-REVIEWED ARTICLE Xiaodi Sun,1 Jooho Kim,2* Carl Behnke,1 Barbara Food Protection Trends, Vol 37, No. 6, p. 392–402 1 3 3 Copyright© 2017, International Association for Food Protection Almanza, Christine Greene, Jesse Miller and 6200 Aurora Ave., Suite 200W, Des Moines, IA 50322-2864 Bryan Schindler3 1The School of Hospitality and Tourism Management, Purdue University, 900 W. State St., West Lafayette, IN 47907, USA 2Hart School of Hospitality, Sport and Recreation Management, James Madison University, MSC 2305, Harrisonburg, VA 22807, USA 3NSF International, 789 North Dixboro Road, Ann Arbor, MI 48105, USA The Cleanliness of Reusable Water Bottles: How Contamination Levels are Affected by Bottle Usage and Cleaning Behaviors of Bottle Owners ABSTRACT INTRODUCTION Reusable water bottles are growing in popularity, but Demand for bottled water has consistently increased consumers regularly refill bottles without a corresponding in recent years, making bottled water the fastest growing effort at cleaning them. If the difficulties associated with segment of the non-alcoholic beverage market worldwide various bottle designs and materials are added in, it is (11). However, massive consumption of water in disposable clear that improperly cleaned water bottles may present bottles has been connected to increased pollution and a potential contamination risk and thus be a risk for landfill waste. The EPA(35) reported that each year foodborne illness. The purpose of this study was to measure Americans throw away about 28 billion bottles and jars; contamination levels of water bottles that are in use and to notably, only 26% of plastic bottles were recycled. The investigate bottle usage and cleaning behaviors by collecting environmental cost associated with bottled water has led to survey data from the bottle owners. Total organic materials a social push to adopt reusable water bottles. on the exterior surface and coliform and heterotrophic Reusable bottles are more environmentally friendly bacteria on the interior surface were enumerated, using and economical because consumers can repeatedly refill ATP bioluminescence and the agar plate count method, them. This ability to refill and reuse water bottles comes respectively. The HPC and coliform results revealed a with an implied mandate to clean the bottles on a regular marked microbial contamination level among reusable water basis. However, observation of consumer behaviors related bottles that are in use, and the ATP levels suggest that the to reusable water bottles suggests that users are regularly exterior bottle surfaces may serve as fomites that facilitate refilling bottles without making a corresponding effort the transmission of infectious organisms. The contamination at cleaning them. Moreover, the design of reusable water level can be affected by factors such as bottle material, bottles may pose a barrier to their cleanliness. Bottle refill frequency, beverage type, and cleaning behavior. options are numerous and range from portable plastic or Author for correspondence: Phone: +1 540.568.7668; E-mail: [email protected] 392 Food Protection Trends November/December November/December Food Protection Trends 393 collapsible bottles to multi-purpose containers that can water in the bottles. However, limited information has handle either hot or cold beverages. Some bottles come been published on the cleanliness of reusable water bottles with built-in carbon filters that are replaceable, but not and consumer behaviors related to reusable water bottles. cleanable, while others include straws and areas that are Therefore, the purpose of this study was two-fold: first, to difficult to clean properly. Some bottles have wide mouths measure contamination levels of water bottles that are in that make it easy to clean the interior, while others have use, and second, to understand how contamination levels an opening that is only an inch or so in diameter, making are affected by bottle usage and cleaning behaviors, by it challenging to clean the inside. Users may think that it is collecting survey data from the bottle owners. sufficient to simply put the bottle into the dishwasher for Three methods were used to assess water bottle cleaning, but not all reusable water bottles are dishwasher contamination. First was the use of adenosine triphosphate safe, and/or the diameter of the bottle mouth may not (ATP) bioluminescence on the exterior surface of water permit water and detergent to enter with sufficient force to bottles. ATP tests provide evidence on the level of general coat the interior surface. cleanliness (19) by measuring organic materials (41), with Improperly cleaned water bottles may present a results reported in terms of RLUs (relative light units). potential contamination risk and thus be considered a Results are obtained rapidly but are considered only a risk for foodborne illness, particularly to those at higher generalized assessment that cannot provide information risk such as immune compromised people, older adults, on the identity of organisms present in a sample (25). and young children. Microorganisms will normally grow Because of this, the second method quantified microbial in water and on surfaces in contact with water as biofilms contamination through a heterotrophic plate count (HPC) (3). The availability of nutrients and lack of residual from the bottles’ interior. “Heterotrophic bacteria” include disinfectant are some of the principal determinants of all bacteria that consume organic nutrients for growth. microbial growth in drinking water (3). According to These bacteria are universally present in all types of water, the FDA Food Code (16), water is considered a food. food, soil, vegetation, and air (2). The heterotrophic plate Reusable bottles are therefore food-contact surfaces count is a means of assessing the concentration of these requiring proper cleaning and sanitizing. Unfortunately, bacteria in foods and water (13). Enumeration of total consumers may not be aware of the potential hazards heterotrophic counts is commonly used as an indicator of related to water bottles; thus, there is a possibility for overall microbiological quality (12, 32, 40), and results are complacency with regard to cleaning behaviors. reported as colony forming units per milliliter (CFU/mL). It is recognized that water can be a source of disease Finally, coliform testing was used to assess more potentially outbreaks (27, 42). Despite worldwide efforts and the risky coliform bacterial contamination. Coliform organisms modern technology employed for production of safe have long been recognized as a suitable microbial indicator drinking water, transmission of waterborne diseases is still a of drinking-water quality, largely because they are easy to matter of major concern(9, 37). Some common foodborne detect and enumerate in water (9, 40). organisms associated with water include Campylobacter, E. coli O157:H7, Salmonella, and Vibrio cholerae, to name a few MATERIALS AND METHODS (7). These can lead to severe illnesses and death. Clearly, This study was piloted initially to ensure adequacy of the there are health implications associated with unclean water design, and a mixed methods approach was adopted in the consumption. full study. The bottle exteriors were assessed for organic Combined, the clues point to the possibility of a large contamination by ATP Bioluminescence testing. The bottle and growing problem. Reusable water bottles are growing in interiors were assessed for microbial contamination by use popularity, but consumers may not perceive the importance of Heterotrophic Plate Counts (HPC) and Coliform Plate of cleaning water bottles as other food-contact surfaces Counts. Lastly, the bottle owners were asked to complete must be cleaned, which can result in careless behaviors with a digital questionnaire intended to document routine regard to their cleaning. The difficulties associated with behaviors related to the use and cleaning of the reusable cleaning the bottles adequately, as well as the variability water bottles. Routine behaviors, bottle cleaning, and in designs and materials, make it easy to see the potential design of the bottles (documented during the surveys) were food safety hazard. Previous studies have conducted paired with the cleanliness assessment results through the microbiological evaluation of bottled water(18, 22, 33, 38), use of anonymous coding numbers. as well as cleaning protocols of infant feeding bottles(24, A total of 90 water bottles were collected from the 26). Oliphant, Ryan, & Chu (30) studied water quality in participants. As shown in Table 2, 65 (72.22%) were hard the personal water bottles of 75 elementary students and plastic bottles, 22 of which had a straw or nozzle. The third stated that the use of personal water bottles for students commonly used type of water bottle was a squeezable in elementary classrooms is not recommended because bottle (13.33%), followed by metal bottle (11.11%), and of the significant microbial contamination levels of the glass bottle (3.33%). Built-in carbon filters were also 392 Food Protection Trends November/December November/December Food Protection Trends 393 investigated; nine out of ninety (10%) bottles had a built-in HPC and coliform counts carbon filter. Membrane filtration and pour plating were used to enumerate heterotrophic bacteria and coliform bacteria Sample collection and surveying process from PBS-T samples, respectively. Samples were diluted The sample collection and surveying process was set