Human Consumption of Microplastics by Kieran D. Cox et al. 2019

Human Consumption of Microplastics by Kieran D. Cox et al. 2019

Human consumption of microplastics is a growing concern, as highlighted in the 2019 study by Kieran D. Cox and colleagues. The research evaluates the prevalence of microplastics in commonly consumed foods and beverages, focusing on the American diet. It estimates that individuals may ingest between 39,000 to 52,000 microplastic particles annually, with inhalation potentially increasing this number significantly. The study also examines how different sources of drinking water, such as bottled versus tap, affect microplastic consumption. This comprehensive analysis is crucial for understanding the implications of microplastics on human health and dietary habits.

Key Points

  • Estimates annual microplastic consumption in Americans ranges from 39,000 to 52,000 particles.
  • Examines the impact of bottled versus tap water on microplastic ingestion.
  • Analyzes 402 data points from 26 studies on microplastics in food and beverages.
  • Highlights the potential health risks associated with microplastic ingestion and inhalation.
  • newtopiccyclegrowin
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Human Consumption of Microplastics
Kieran D. Cox,*
,†,‡
Garth A. Covernton,
†
Hailey L. Davies,
†
John F. Dower,
†
Francis Juanes,
†
and Sarah E. Dudas
†,‡,§
†
Department of Biology, University of Victoria, Victoria, British Columbia V8P 5C2 Canada
‡
Hakai Institute, Calvert Island, British Columbia V0P 1H0 Canada
§
Fisheries and Oceans Canada, Pacific Biological Station, Nanaimo, British Columbia V9T 6N7 Canada
*
S
Supporting Information
ABSTRACT: Microplastics are ubiquitous across ecosystems, yet the exposure risk to
humans is unresolved. Focusing on the American diet, we evaluated the number of
microplastic particles in commonly consumed foods in relation to their recommended
daily intake. The potential for microplastic inhalation and how the source of drinking
water may affect microplastic consumption were also explored. Our analysis used 402
data points from 26 studies, which represents over 3600 processed samples. Evaluating
approximately 15% of Americans’ caloric intake, we estimate that annual microplastics
consumption ranges from 39000 to 52000 particles depending on age and sex. These
estimates increase to 74000 and 121000 when inhalation is considered. Additionally,
individuals who meet their recommended water intake through only bottled sources
may be ingesting an additional 90000 microplastics annually, compared to 4000
microplastics for those who consume only tap water. These estimates are subject to
large amounts of variation; however, given methodological and data limitations, these
values are likely underestimates.
■
INTRODUCTION
Microplastics are pervasive throughout marine and terrestrial
ecosystems.
1−3
Current projections indicate that if unimpeded,
12 billion metric tons of plastic waste will be in landfills or the
natural environment by 2050, compared to the 4.9 billion
metric tons (60% of all plastics ever produced) found in 2015.
4
A growing body of evidence suggests that microplastics are
being integrated into widely consumed food items via animals
ingesting microplastics in the environment,
5
contamination
during production,
6
and/or contamination by plastic pack-
aging.
7
Microplastic particles (MPs) less than 130 μmin
diameter have the potential to translocate into human tissues,
trigger a localized immune response, and release constituent
monomers, toxic chemicals added during plastic production,
and pollutants absorbed from the environment, including
heavy metals and persistent organic pollutants like PCBs and
DDT.
8
Despite increasing evidence that microplastics con-
taminate a large variety of food and beverages, in addition to
outdoor and indoor environments,
9
and the possibility of
deleterious effects on human health following ingestion and/or
inhalation,
10
an investigation into the cumulative human
exposure to MPs has not occurred.
Here, we created a microplastics database, based on a
thorough review of the literature, and used this in combination
with U.S. dietary data to generate human exposure estimates.
To do so, we analyzed the peer-reviewed literature to
determi ne the concent ration of microplastics present in
commonly consumed items in combination with the
recommended or reported consumption of these items by
the American public as stated by the United States Department
of Agriculture (U.S.D.A.), U.S. Department of Health and
Human Services, World Health Organization (WHO), and the
National Academies of Science, Engineering, and Medicine
(Table S1, S2, and S3). Commonly consumed items included
various sources of seafood, sugars, salts, honey, alcohol, as well
as tap and bottled water. Other food groups (e.g., meat, grains,
and vegetables) are not included in this analysis due to a lack
of data on their microplastic content. The potential
consumption of MPs through inhalation was evaluated using
repo rted microplastic concent rations in air and the US
Environmental Protection Agency’s (EPA) reported respira-
tion rates. Furthermore, we explored how the consumption of
only bottled water may impact microplastic consumption
relative to the consumption of only tap water and the current
average American consumption of bottled water. We also
determined how MP consumption might vary according to age
and sex.
■
MATERIALS AND METHODS
Data Collection. A literature review was conducted to
identify studies that determined the concentration of micro-
plastic particles (MPs) within food and beverages consumed
by Americans. Studies addressing the concentration of airborne
Received: March 11, 2019
Revised: May 9, 2019
Accepted: May 13, 2019
Published: June 5, 2019
Article
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© 2019 American Chemical Society 7068 DOI: 10.1021/acs.est.9b01517
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MPs were also identified. For studies to be considered, they
had to investigate items commonly consumed by humans and
report MP concentration as exact values (total count in a single
sample) or as a mean. One of the studies considering airborne
plastics
11
did not provide a mean so the median values were
extracted with the caveat that these are likely lower than means
given the distribution of the data. In this instance, the study
measured all particulates in the air of two apartments, an office,
and outside of an office building and determined that only 33%
of these particles were synthetic, petroleum-based polymers, so
the median number reported was adjusted to 33% of the total.
To ensure consistency, median values were also extracted from
the second study addressing airborne plastics. For all studies,
the type of MPs (e.g., fiber, bead) found was also noted, as well
as the type of chemical method (if any) used to verify whether
particles were plastic. Twenty-six studies were identified by this
process, specifically investigating the following consumption
groups: fish, shellfish, added sugars, salts, alcohol, water, and
air (Table S1). Only studies assessing items that are commonly
consumed by people were considered (e.g., whole fish, fish
tissue, table salts, tap water, refined and raw sugars, etc.). All
data were obtained from tables and text where possible; if
necessary, the software GraphClick was used to retrieve data
from figures.
12
A total of 402 data points, which represents
over 3600 processed samples, were collected from the 26
studies where each data point represents the concentration of
microplastics within a specific item presented within a study,
commonly composed of multiple replicates (Table S1).
Recommended dietary intakes for Americans were deter-
mined using the Dietary Guidelines for Americans 2015−2020,
eighth edition report, by the U.S. Department of Health and
Human Services.
13
Average consumption was separated by sex
and age: male adults, female adults, male children, and female
children. Adults were considered to be 19 years of age or older.
When consumption values were presented as ranges across an
age group, as was the case with seafood, the mean of the range
was used. During this process, we estimated caloric intake
assuming a moderately active lifestyle (as this seemed to be the
most widely applicable choice), which recommended calorie
intakes of 1965, 2733, 1694, and 2133 for male children and
adults, and female children and adults, respectively. Although it
was noted that the difference between sedentary/moderate and
moderate/active could be up to 400 calories per day depending
on age, this decision only directly affected the recommended
added sugar intake, which is 10% of consumed calories. To
account for the amount of honey consumed by the American
population, the per capita consump tion of honey was
subtracted from sugar consumption. The Department of
Agriculture’s National Agricultural Statistics Service Annual
Honey Report estimates Americans consume 1.61 pounds of
honey per year or 2.00 g per day. The amount of sugar
remaining was then assumed to be made up of the other forms
of sugar considered (e.g., refined).
To determine microplastics consumed via drinking water,
separate calculations were made for 100% tap water, 100%
bottled water, and a composite estimate of average current tap
and bottled water consumption. For the composite estimate,
the average per capita daily consumption of 0.436 L of bottled
water was used, with the remaining recommended water
consumption being made up by tap water; this was determined
to be roughly 17% bottled water and 83% tap water, based on
the amount of bottled water consumed per capita in the U.S.
relative to the recommended water consumption.
14
Thus, in
this instance, water was considered a combination of bottled
and tapped sources based on the average per capita water
consumption and The National Academy’s recommended
consumption of water for the age group and sex considered.
15
As the only available data on microplastics in alcohol were
concentrations within beer, the reported amount of per capita
alcohol consumption by adult men and women was evaluated
in terms of beer.
16−18
As the World Health Organization
(2014) reports male and female per capita consumption of
13.6 and 4.9 L of alcohol, it was assumed this consumption was
comprised entirely of beer. As the report lists beer as the most
commonly consumed alcohol for both sexes, by a large margin,
this is a reasonable assumption.
17
Mean respiration rates for different age groups and sexes
were obtained from the U.S. Environmental Protection Agency
exposure factors handbook 2011, with values ranging from
3.4−19.3 m
3
/day.
19
The age groups in this report were
combined and a veraged into the previously mentioned
categories of male children and adults, and female children
and adults; however, in this instance, adults were considered to
be 22 years of age or older due to the preformed groupings.
Data Analysis. The literature review resulted in MP
concentrations within commonly consumed items that could
be separated into the following categories: air, alcohol, bottled
water, honey, seafood, salt,sugar,andtapwater.MP
concentrations were converted, where necessary, to particles
per gram, liter, or cubic meters, depending on whether the
study focused on foods, liquids or air, respectively. At the study
level, a mean concentration was determined from all the items
within a single category (e.g., all the fish and bivalve values in
the seafood category). As a result, in studies that evaluated the
MP concentration within multiple items (e.g., bottled and tap
water), each case was treated independently and the average
for each item was determined. As the MP concentration across
items was never pooled during the analysis, treating these cases
as independent did not compromise our results.
The average intake of MPs associated with the daily
consumption of each item was determined. The mean MP
concentration for each study was determined within the
various items (Table S1). Subsequently, the mean and
associated standard deviation for each of the items was derived
from the study means. Tap water and sugar were comprised of
single studies. In these instances, the mean and standard
deviation were determined within each study (as compared to
across studies) using the five and 14 MP concentration values
presented within the sugar and tap water studies, respectively.
The number of MPs consumed for each age group and sex was
then determined by multiplying each of the microplastic
concentrations by the respective daily consumption value of
each item (Table S1, S2, and S3).
The annual consumption of MP was determined. The mean
MP concentration for each study was determined within the
various items as outlined above (Table S1). In a similar fashion
to the previously discussed mean and associated standard
deviation calculations, the mean and variance for each of the
items were derived from the study means. Again, tap water and
sugar were comprised of single studies. The mean and variance
for these items were determined within each study (as
compared to across studies). The number of microplastics
consumed annually by each age group and sex was determined
by multiplying each of the microplastic concentrations by the
respective annual consumption value of each item. To
determine the average standard deviation for the annual
Environmental Science & Technology Article
DOI: 10.1021/acs.est.9b01517
Environ. Sci. Technol. 2019, 53, 7068−7074
7069
consumption of MPs, the variances associated with each
consumed item were averaged. The square root of the averaged
variances was subsequently determined, which represents the
averaged standard deviation and is an indication of the range of
microplastics consumed when considering multiple sources
and their associated variances.
Figure 1. Total microplastic particle (MP) intake for female and male, children and adults from (A) annual consumption of commonly consumed
items and (B) annual inhalation via respiration. Points and error bars represent the summation (total) and average standard deviation of all
microplastics consumed.
Table 1. Daily and Annual Consumption and Inhalation of Microplastic Particles for Female and Male, Children and Adults
a
Daily Annual Total
Consumed Inhaled Consumed Inhaled Daily Annually
Male Children 113 110 41106 ± 7124 40225 ± 44730 223 81331
Male Adults 142 170 51814 ± 8172 61928 ± 68865 312 121664
Female Children 106 97 38722 ± 6977 35338 ± 39296 203 74060
Female Adults 126 132 46013 ± 7755 48270 ± 53676 258 98305
a
Points and error bars represent the summation (total) and average standard deviation of all microplastics consumed.
Figure 2. Mean and standard deviation of microplastic concentration within each source of ingested microplastic particles (MPs) including salt,
alcohol (beer), seafood (fish, shellfish and crustaceans), added sugars (sugar and honey), water (bottled and tap), and air in (A) male adults, (B)
female adults, (C) male children, and (D) female children.
Environmental Science & Technology Article
DOI: 10.1021/acs.est.9b01517
Environ. Sci. Technol. 2019, 53, 7068−7074
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FAQs of Human Consumption of Microplastics by Kieran D. Cox et al. 2019

What are microplastics and how do they enter the human diet?
Microplastics are small plastic particles less than 5mm in size that can originate from larger plastic debris breaking down in the environment. They enter the human diet primarily through the consumption of contaminated food and beverages, such as seafood, sugars, and bottled water. Animals ingest microplastics from their habitats, which can then accumulate in the food chain, leading to human exposure. Additionally, microplastics can be introduced during food processing and packaging, highlighting the pervasive nature of plastic pollution.
What are the health implications of consuming microplastics?
The health implications of consuming microplastics are still being studied, but there are concerns regarding their potential to cause harm. Microplastics can carry toxic chemicals and pollutants, which may be released into the human body upon ingestion. They can also trigger immune responses and may lead to inflammation or other adverse health effects. Understanding the long-term consequences of microplastic consumption is critical, as research is still in its early stages.
How does the study estimate microplastic consumption from food and beverages?
The study estimates microplastic consumption by analyzing the concentration of microplastics in various food items and beverages, including seafood, sugars, and water. It combines this data with dietary intake recommendations from U.S. health authorities to calculate the average annual consumption for different demographic groups. The researchers used a comprehensive database compiled from 26 studies, which included over 3,600 samples, to ensure accurate estimates of microplastic exposure.
What factors contribute to variations in microplastic consumption among individuals?
Variations in microplastic consumption among individuals can be attributed to several factors, including dietary habits, age, and sex. For instance, individuals who consume more seafood or bottled water are likely to ingest higher levels of microplastics. Additionally, lifestyle choices, such as the frequency of eating out or the type of food packaging used, can influence exposure levels. The study also highlights how inhalation of microplastics can further increase overall consumption estimates.
What recommendations does the study provide regarding microplastic exposure?
The study suggests that reducing the consumption of bottled water may significantly lower microplastic exposure, as bottled water has been found to contain higher concentrations of microplastics compared to tap water. It emphasizes the need for further research into the contamination of various food groups, especially those that are commonly consumed but have not been extensively studied. Overall, the findings call for increased awareness of plastic pollution and its potential impact on human health.

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