SILVER

Should we break our bottled water habit?

Examining microplastic exposure from water consumption in junior high students and teachers.
Joshua Chow
Grade 10

Hypothesis

Hypotheses

  1. I hypothesize that the amount of MPs consumed will be around 40 MP/day because according to the study, “What We Eat in America (WWEIA)1”, 17% of all water consumed is bottled and 83% is tap water. Therefore since the recommended daily intake (RDI) of water for most age groups and for both genders approx 2L, then:

2L * 0.17 = 340mL / 1000 = 0.34 L * 94.37 = 32.11 

2L * 0.83 = 1660mL / 1000 = 1.66 * 4.23 = 7.02 MP ; 32.11 + 7.02 = 39.13)

In other words, about 340 mL of the RDI for water consumption would be bottled water and the other 1660 mL would be tap water.

MP concentrations listed above were taken from the Cox et al. (2019) study.

  1. I hypothesize that adults will consume more MPs. Younger people don’t generally have an income and may not have as easy access to buy bottled water would drink more tap water instead. I also expect that males will consume more than females as this was shown in Mr. Cox’s study.
  2. I hypothesize that with an increased awareness of (micro)plastics and their effects may not change everyone's habits, there will be a substantial amount of people that DO change their habits.
  3. Since schools shut off all the water fountains because of COVID19, I hypothesize that more bottled water will be consumed, and MP exposure would increase.

Primary objectives

  1. To determine how much water on average participants are consuming per day and the source of the water (tap/bottle) in order to calculate microplastic consumption from water.

Secondary objective:

1. To compare my results with the Cox et al. (2019) study estimates of MP exposure from water

2. To determine if an increase in awareness (after a short in school presentation) of plastic/microplastic, reduces participants microplastic exposure by reducing bottled water consumption in favor of tap water.

3. To determine if bottled water consumption changed during the pandemic as schools closed water fountains (access to tap decreased).

 

________________________________

 

1Sebastian RS, Wilkinson Enns C, Goldman JD. Drinking Water Intake in the U.S.: What We Eat In America, NHANES 2005-2008.Food Surveys Research Group Dietary Data Brief No. 7. September 2011. http://ars.usda.gov/Services/docs.htm?docid=19476.

Research

Background

According to science journalist Susan Freinkel, over the last 70 years, the amount of plastic consumed annually worldwide has steadily risen from almost none in 1940 to about six hundred billion pounds in 20111. A 2018 National Geographic cover story described society as “drowning in plastic” and highlighted the fact that 18 billion pounds of plastic ends up in the oceans each year2. Microplastics (MP) are defined as plastic fragments less than 5mm in any dimension. Because of the growing demand for plastics, MPs are also found everywhere.  It is estimated that 1.5 million tonnes of primary MPs are released into water each year and, by 2050, it is estimated that there will be more MPs than fish in the ocean3. There are two main categories of microplastics: (a) primary MPs,  those that are manufactured to be that size and (b) secondary MPs, which are the products of degradation of larger plastic materials, by mechanical or photo-oxidative pathways. 

Over the past few years, several studies have reported the presence of MPs in treated tap and bottled water raising questions and concerns about the impact that MPs have on human health4. A report written by the WHO in 2019 summarized the research and evidence for potential human health risks of MPs from drinking water4. According to the WHO report, MPs can pose potential hazards in 3 ways: a physical hazard, a chemical hazard or microorganisms may attach onto MPs and colonize them which are known as biofilms4. Available evidence suggests that chemicals and microbial pathogens related to MPs pose the lowest concern for human health compared to its physical hazards4.  MPs are insoluble, therefore, it is unlikely that they would be absorbed in the digestive system. However, if the particle is small enough it could be absorbed. There are only limited animal studies of ingested MPs that suggest plastic particles smaller than 50 μm are absorbed into the digestive system4. These studies are said to be of questionable quality and therefore no firm conclusions on the risk of ingesting MPs have been reached. More research is needed to understand what happens to MPs after ingestion as well as how size, shape and chemical composition of MP affects its absorption.

Bottled water is one modifiable source of plastic pollution. According to Statista, a company specialised in market and consumer data, bottled water sales have risen by 8.25 billion dollars in 2006 and 14.4 billion in 20195

MPs in bottled water are secondary plastics as they are thought to arise from the bottling process and/or packaging (such as the bottle caps)4,6. In 2018, Mason SA et al. conducted a study to determine the quantity of MPs in bottled water from different bottled water sources from around the globe6. Their research showed that 93% (242 of 259) of bottles sampled showed contamination from MPs6. It was also observed that bottled water contained 1.9x more MPs than tap water (10.4 vs 5.45 particles/L)6.  However, even tap water contains MPs. Another study looking at the presence of man made particles in 159 different samples of globally sourced tap water found that of the samples tested, 81% contained MPs7.  Discarded bottles (Figure 1. - example below), along with other plastics, break down into microplastics which can end up in our water system and drinking water. 

Figure 1. A plastic bottle of water off a hiking trail in Radium, BC.

 

Recently, researchers from the University of Victoria evaluated MP exposure from water consumption8. They conducted a literature review to determine the average amount of MPs found in food and beverages, including water, then calculated an estimate of the amount of MPs that we ingest8. Cox et al. determined that the intake of MPs is about 20x higher if we drink bottled water opposed to tap water8 suggesting that MP consumption could be mitigating by reducing bottled water intake (Figure 2.).

Figure 2. Results from a Canadian study showing consumption of microplastics from bottled vs tap water by age and gender8

 

Although the ecological effects of MPs are not entirely known, understanding our exposure to MPs and its impacts is still important because plastic and MP pollution in water is on the rise. Reducing our bottled water intake could be a simple way to reduce our exposure to MPs.

_________________________________________________________________________________________________

 

1Susan Freinkel, A Plastic Love Story (New York: Houghton Mifflin Harcourt, 2011) 

2National Geographic, June 2018 Issue

3 Picó Y and Barceló D, MACS Omega 2019, 4, 4, 6709–6719 Publication Date:April 12, 2019 https://doi.org/10.1021/acsomega.9b00222

4 Microplastics in drinking-water. Geneva: World Health Organization; 2019. Licence: CC BY-NC-SA 3.0 IGO.

5https://www.statista.com/statistics/237832/volume-of-bottled-water-in-the-us/

6 Mason SA, Welch VG and Neratko J (2018) Synnthetic Polymer Contamination in Bottled Water. Front. Chem. 6:407. https://doi: 10.3389/fchem.2018.00407

7KosuthM, MasonSA, WattenbergEV(2018)Anthropogenic contaminationof tap water,beer,and sea salt. PLoSONE 13(4):e0194970.https://doi.org/10.1371/journal.pone.0194970

8 Kieran D. Cox, Garth A. Covernton, Hailey L. Davies, John F. Dower, Francis Juanes, and Sarah E. Dudas Environmental Science & Technology 2019 53 (12), 7068-7074 DOI: 10.1021/acs.est.9b01517 

 

Variables

Variables to test Primary Objective:

  • Manipulated: The people surveyed
  • Controlled: Timing of the survey, the timing of the presentation 
  • Responding: Amount of microplastics consumed from water

Variables to test Secondary Objective:

  • Manipulated: Timing of survey (2nd survey was conducted after a my presentation on MPs and their potential effects; 3rd survey was conducted 1 year later) 
  • Controlled: (1) Presentation - all participants will get the same presentation (2) Same participants 
  • Responding: Source of water consumed and microplastic exposure from water sources after the presentation to increase awareness.

Procedure

Methods:

A. Creating the Microplastic consumption survey (bottled and tap water)

  1. Background research on microplastics and how plastic water bottles contribute to microplastics in the environment.
  2. I designed a survey with 3 parts:
    1. Part 1 was to calculate the amount of tap and bottled water that participants consumed daily from different sources.
    2. Part 2 was to determine if there was a change in the source of water consumption among participants after listening to a presentation on plastics and microplastics.
    3. Part 3 was to determine if there was an increase in bottled water consumption/microplastic exposure 1 year after the inital survey (during pandemic).
  3. To develop the survey, I consulted Kieran Cox, PhD candidate from the University of Victoria, BC for his input. Kieran had published a paper on microplastic consumption from various sources including water.

B. Participants

I. Junior High Students 

  1. I gave out consent forms to the parents of junior high students at St Michael School at two school events (Dec. 5-11, 2019).
  2. I distributed the surveys in class between Feb 18-28th 2020 to the students who had signed consent forms.
  3. Consent forms and surveys were also handed out to any students who were interested in participating, but did not have a previously signed consent form. If students returned a completed consent form their surveys were included.
  4. Completed pre-presentation surveys were collected.
  5. I gave a short presentation (approx. 15 mins) on plastics and microplastics.
  6. A follow up post-presentation survey was sent by email to all of the participants for seven days.
  7. After one year, a repeat survey was emailed to all students to assess their water intake and water sources.

II. Teachers at St Michael School

  1. All teachers at St. Michael School K-9 were invited to participate in my project.
  2. Consent forms were handed out to teachers during both school events (see above). 
  3. Consent forms, for anyone who did not previously complete one, and surveys were also handed out to any teachers at a staff meeting (Feb. 6, 2020).
  4. Completed surveys were collected.
  5. I gave a short presentation (approx. 15 mins) on plastics and microplastics.
  6. A follow up post-presentation survey was sent by email to all of the participants for seven days.
  7. After one year, a repeat survey was emailed to all teachers to assess their water intake and water sources.

C. Collecting & Analyzing Data

  1. Raw data was entered from both the pre-presentation, post-presentation and the 12 month follow up surveys into an EXCEL spreadsheet.
  2. Demographic information was summarized.
  3. I calculated the amount of water consumed per person (tap vs bottled and total).
    1. For both the pre-presentation and the 12 month follow up surveys, participants were asked to recall their water intake and source from the  last 24 hours.
    2. For the post presentation survey, participants were asked to record their water consumption and source each day for seven days. The average amount of water per day (bottled vs tap) was then calculated.
  4. I calculated the average amount of water consumed per day by age and gender.
  5. To determine the amount of microplastics consumed, I multiplied the amount of water consumed by the concentration of microplastics (MPs/L) from each source (tap and bottled). The concentration of MPs was taken from the Cox study.
  6. Graphs were made to compare microplastic consumption according to the source of water by age and gender, pre/post-presentation and for the one year follow up.
  7. I compared my results to the results of the Cox study.

Observations

Table 1 - Survey participants

  # of consents # of participants
Pre-presentation  Post-presentation 12 months
Grade        
7 17 15 10 10
8 12 11 5 6
9 28 26 17 18
Adults/Teachers 26 24 22 15
TOTAL 83 76 54 49
Gender        
Male - adult 6 6 5 4
Male - child 21 20 11 9
Female - adult 20 18 17 11
Female - child 36 32 21 25
TOTAL 83 76 54 49

 

Table 2 - Average TOTAL water consumption (mL) from at all timepoints

Water Source
No. of participants Current Study
Bottled   Baseline Post-Presentation 12 mo. Follow-Up
male student 9 630.95 1000 111.11
male adult 4 0 200 125
female student 25 194.44 177.65 360
female adult 11 25 44.12 159.09
Tap   Baseline Post-Presentation 12 mo. Follow-Up
male student 9 5643.45 5086.54 2027.78
male adult 4 6041.67 6450 3000
female student 25 3795.14 4926.47 1530
female adult 11 4550 5661.76 2568.18
TOTAL   Baseline Post-Presentation 12 mo. Follow-Up
male student 9 6274.4 6086.54 2138.89
male adult 4 6041.67 6650 3125
female student 25 3989.58 5144.12 1890
female adult 11 4575 5705.88 2727.27

 

Table 3 - Comparison of microplastic consumption (MP/day) from bottled vs. tap water at all  timepoints

Water Source
No. of participants Current Study (mp/day) The Cox Study (mp/day)
Bottled   Baseline Post-Presentation 12-mo Follow-up  
male student 9 59.54 94.36 10.49 205
male adult 4 0 18.87 11.8 349
female student 25 18.35 11.1 22.65 174
female adult 11 2.36 4.16 15.01 255
Tap   Baseline Post-Presentation 12-mo Follow-up  
male student 9 23.87 21.52 8.58 9
male adult 4 25.56 27.28 12.69 16
female student 25 16.05 20.84 6.47 8
female adult 11 19.25 23.95 10.86 11
TOTAL   Baseline Post-Presentation 12-mo Follow-up TOTAL 
Tap +Bottled
male student 9 83.41 115.89 19.06 214
male adult 4 25.56 46.16 24.49 365
female student 25 34.4 31.94 40.45 182
female adult 11 24.01 28.11 25.88 266

 

*NOTE: If you are interesting in reviewing my raw data, please see attached files at the end.*

Analysis

Figure 1. This is graph shows the average amount of WATER consumed: both bottled (shown in blue) and tap (shown in orange) at BASELINE. Water consumption from STUDENTS are shown on the left; ADULTS on the right and each group is also broken down into males and females. At baseline, participants consumed between 4-6 L/day of water, the majority of which was tap water.

 

Figure 2.  This graph shows the average amount of microplastics consumed per day from both bottled water (shown in blue) and tap water (shown in orange) by age & gender and compares my findings with the results of the Cox study. In my study, the majority of microplastic exposure comes from BOTTLED water. Males consumed more MPs than females while STUDENTS consumed more than adults. Adult females drank the least BOTTLED water and had the lowest microplastic consumption. The highest MP exposure was among male students, who consumed the most BOTTLED water.  Overall the average MP consumed from water/day was LOWER in my study than in the Cox study.

 

Figure 3. This graph is shows the average total amount of water (from all sources) consumed prior to and after my in-school presentation to increase MP awareness. The amount of bottle water is shown in blue versus tap water shown in orange. The majority of participants did NOT change the source of their water consumption by much after my presentation.

 

Figure 4. This graph is shows the average MP consumption/day pre- and post-presentation by age & gender.  After my presentation to increase awareness of MP, very few participants changed the source of water consumed (Figure 3) and as a result, there was also little change in MP consumption.  Microplastic consumption remained highest among male students (115.89 MP/day) who continued to drink the most bottled water.

 

Figure 5. Approx. 12 months after the first 2 surveys, total water consumption decreased significantly for all groups. Males consumed more water than females. The majority of water consumed was still tap water, though there was an increase in bottled water consumption among females students (from 4.87% to 19.05%) and adults females (from 0.55% to 5.83%).

 

Figure 6. Even though all groups drank very little bottled water, the main source of MPs 1 year after my initial survey was still from bottled water. Male students previously consumed the most MPs, but at the 12 month time point, the greatest decrease in total MP consumption occurred among male students.

Conclusion

Below is a breakdown of my conclusions for each hypothesis listed:

HYPOTHESIS#1: I hypothesized that the amount of MPs consumed will be around 40 MP/day

Overall, the average amount of microplastics consumed per day (from all sources both bottled and tap water) was:

  • male students = 83.41 MPs/day (approx 209% higher than I hypothesized)
  • adult males = 25.56 MPs/day (approx 36% lower than I hypothesized)
  • female students = 34.40 MPs/day (approx 14% lower than I hypothesized)
  • adult females was = 24.01 MPs/day (approx 40% lower than I hypothesized)

HYPOTHESIS#2:

a) I hypothesize that adults will consume more MPs. Younger people don’t generally have an income and may not have as easy access to buy bottled water would drink more tap water instead.

b) I also expect that males will consume more than females as this was shown in Mr. Cox’s study.

  • After analyzing the results, the amount of MPs consumed by adults was generally lower than students. 
  • Males, compared to females, consumed more microplastics in both bottled and tap water.

HYPOTHESIS#3: I hypothesized that following my presentation, with an increased awareness of plastics and microplastics, there would be a substantial amount of people that changed their habits in terms of their source of water consumed.

  • After my presentation to increase awareness on microplastics, the MAJORITY of participants did not change the source of their water consumption much (< 10% change).  There could be several reasons why there was very little change:
  1. Habits are hard to change
  2. My presentation was short and only given once, therefore, it may not have convinced as many people.
  3. I only asked participants about their water consumption over a one-day period before my presentation whereas I surveyed participants about their water consumption over 7 days after the presentation. The results from the post-presentation survey may be a more accurate reflection of the participants' true water consumption and source.  Therefore, I may have underestimated the degree of change since the pre-presentation results are probably not as accurate.

HYPOTHESIS#4: Since schools shut off all the water fountains because of COVID19, I hypothesize that more bottled water will be consumed, and MP exposure would increase.

  • Water intake decreased in all groups at 12 months, the reasons of which are unclear.
  • The majority of water consumed among all participants was still tap water, though there was an increase in bottled water consumption among females (from 4.87% to 19.05% and 0.55% to 5.83%).

In summary, my project shows that surveys can be used to capture real world MP consumption from water among junior high students and teachers. Overall, the average amount of MPs consumed is less than estimates from the Cox et al. study (2019) as participants in my drank mainly tap water. At baseline, adults suprisingly consumed less MPs than students. As expected, males consumed more than females. Even with increased awareness of the possible effects of MPs, I was not able to influence the source of water intake among participants, to reduce MP exposure. This may be because choosing to drink bottle water is influenced by factors such as convenience or concern about tap water influence. Finally 12 months after my initial survey, bottled water consumption decreased significantly in male students and surprisingly there was a slight increase in both female students and adults. However due to the smaller sample size at the 12 month timepoint, water consumption and MP exposure estimates may not have been as accurate.

Application

Although the ecological effects of MPs are not entirely known, understanding our exposure to MPs and its impacts is still important because plastic and MP pollution in water is on the rise. My project shows that real world MP consumption from water among junior high students and teachers is already lower than those of the Cox et al. study (2019). Reducing our bottled water intake remains a simple way to further reduce our exposure to MPs. However, habits and attitudes can be hard change and behavioral changes take time.  I was not able to influence the source of water intake among participants - to reduce MP exposure - with my short, one-time in-school presentation on MP and plastic exposure. Perhaps a longer, more in-depth presentation and/or repeating the message about MPs and their possible effects on human health through different media souces could be more influential in altering students/teacher choice of water source.  Individuals' willingness to participate in surveys and information sessions suggests the public is keen to try to mitigate plastic pollution and exposure. 

 

Sources Of Error

There were 3 main limitations in my study.

1. Sample size

Although I surveyed 83 students and teachers at baseline, an even larger sample of participants may have more accurately captured the water consumption of students and adults in general. At the second and third timepoints, only 76 (93%) and 54 (65%) of participants responded which reduces the accuracy of the results. At 12 months, the sample size was especially small in certain groups (eg: adult males n = 4) making it hard to generalize my findings.

In addition, I was limited to surveying students and teachers from one school, therefore, my study did not include participants from different age ranges, socioeconomic groups and different geographic regions which might have influenced their water consumption and whether they drank tap vs bottled water.

2. Survey design issues

i) Due to time constraints, I used a one day point estimate for water consumption in both the first and 3rd surveys. Water consumption data would have been more accurate if I could have done a 7-day survey, as I did for the post-presentation survey, during all timepoints. Point estimates don’t take into account day to day fluctuations.

ii) My surveys relied on the participant's memory of how much water they consumed and from what source. If the students didn't correctly remember how much water they consumed or from what source, the water intake reported, and MP exposure calculated, may not be accurate. Asking participants to keep a water consumption diary would have been more accurate.

3. Analysis

i) The concentrations of MPs/L in bottled and tap water were taken from the Cox et al. study which were estimates from a literature review and not measured from bottled water and tap water. We know that there is variability in MP concentrations across different brands and bottles of water as well as from different sources of tap water.

Citations

References:

1Sebastian RS, Wilkinson Enns C, Goldman JD. Drinking Water Intake in the U.S.: What We Eat In America, NHANES 2005-2008.Food Surveys Research Group Dietary Data Brief No. 7. September 2011. http://ars.usda.gov/Services/docs.htm?docid=19476.

2Susan Freinkel, Plastic a Toxic Love Story (New York: Houghton Mifflin Harcourt, 2011) 

3National Geographic, June 2018 Issue

4 Picó Y and Barceló D, MACS Omega 2019, 4, 4, 6709–6719 Publication Date:April 12, 2019 https://doi.org/10.1021/acsomega.9b00222

5 Microplastics in drinking-water. Geneva: World Health Organization; 2019. Licence: CC BY-NC-SA 3.0 IGO.

6https://www.statista.com/statistics/237832/volume-of-bottled-water-in-the-us/

7 Mason SA, Welch VG and Neratko J (2018) Synnthetic Polymer Contamination in Bottled Water. Front. Chem. 6:407. https://doi: 10.3389/fchem.2018.00407

8KosuthM, MasonSA, WattenbergEV(2018)Anthropogenic contaminationof tap water,beer,and sea salt. PLoSONE 13(4):e0194970.https://doi.org/10.1371/journal.pone.0194970

9 Kieran D. Cox, Garth A. Covernton, Hailey L. Davies, John F. Dower, Francis Juanes, and Sarah E. Dudas Environmental Science & Technology 2019 53 (12), 7068-7074 DOI: 10.1021/acs.est.9b01517 

 

Photo credits:

Project header - https://www.rd.com/wp-content/uploads/2018/01/rd.com_-800x450.jpg

Acknowledgement

Special thanks to:

1. The judges, for your time.

2. The students and teachers who participated in my survey, without whom I could not have done this project.

3. Donors • Flames Foundation & Libre • for donating reusable water bottles for a draw among participants.

4. Kieran Cox, PhD candidate, Department of Biology, University of Victoria; Hakai Institute, Calvert Island, BC, who helped guide me through this project.