Advertising exposure tracked bottled-water use in a 15,000-person survey recruited on social media

Divide 15,000 respondents by 81 countries and the average is about 185 people each ^[18]. Most respondents came from the United States and Canada ^[5], so the typical country on that list is represented by fewer than 185, probably many fewer. That is enough for the pooled associations the paper reports ^[1], and not enough to describe demand in a single lower-income country, where the researchers say bottled-water use may reflect limited access to safe drinking water ^[15].

Recruitment ran through social media, and the instrument was one 25-question form covering consumption, recycling, refillable bottle use, drinking water access, reasons for buying, advertising exposure, environmental and health awareness, and demographics ^[4]. Every variable comes from the same person on the same day. Sarah Sajedi, the lead author, said: "Interestingly, 75% of respondents believed that single-use water bottles contained nano- and microplastics, and 70% believed that there was a connection between these plastics and cancer" ^[7]. Those percentages describe people who volunteered to answer a questionnaire about water bottles. Sajedi's supervisor, Chunjiang An, an associate professor in Concordia's Department of Building, Civil and Environmental Engineering, co-authored the study ^[3].

The advertising result has the same shape. Respondents who reported seeing bottled-water advertisements more often also reported buying more single-use bottles, and the correlation was strongest among younger and more highly educated respondents ^[12]. One pass of the form dates both answers to the same day and leaves the order between them open ^[4]. Someone who buys a bottle most days passes more coolers, and more ad copy, than someone who fills a flask at home.

"The survey results show that awareness does not always change behavior," Sajedi said. "There is much more at play" ^[6]. The design supports that as a description of the sample: most respondents held the belief, and bought the bottles anyway ^[7]. The study did not run a campaign and did not measure anyone twice ^[4], so it cannot compare people who were told about microplastics with people who were not. The researchers' own recommendation keeps targeted public education about microplastics and sustainable water consumption in the package, alongside expanded refill infrastructure and greater scrutiny of bottled-water advertising ^[14].

phys.org reports more than 1 million plastic water bottles bought every minute, more than 1.3 billion a day and more than 500 billion a year ^[16]. A million a minute is 1.44 billion a day and about 526 billion a year ^[19]; the daily and annual figures are the per-minute rate rounded down ^[16].

On health, phys.org says the long-term implications are still unknown, with preliminary research showing nano- and microplastics accumulating in livers, kidneys and intestines ^[17]. The study's contribution is the behavioral half: what people buy once they already believe that ^[20]. Many respondents rated single-use bottled water as safer and of higher quality than other drinking water sources, and the researchers say that perception was an important factor in their purchasing ^[21].