SGIM Forum

Plasticemia: Microplastic Accumulation in the Human Body and its Health Implications 

04-26-2023 08:49

Sign of the Times

Plasticemia: Microplastic Accumulation in the Human Body and its Health Implications 

Dr. Jacobs (jacobsz@ohsu.edu) is an assistant professor in the division of hospital medicine at the Oregon Health & Science University (OHSU), program director for the OHSU Health Hillsboro Medical Center Transitional Year Residency, and assistant program director for global health for the Internal Medicine Residency at OHSU. 

Habituation is a powerful cognitive response. As you read this, think about the sensation of your shirt against your skin. The outline of your nose in the center of your vision. The taste of your saliva. Now that I mention them, it’s as if they pop suddenly back into existence. In the same way, plastics have become such a pervasive part of the human experience that so often they go entirely unnoticed. How many times do you think you came into contact with a plastic object today? To name a few: the cup that held your morning coffee and the straw you drank it with. Your desk chair, mouse, and keyboard. The cellphone in your pocket and the watch on your wrist. Your bottled water. These are self-evident, but plastics are also found in places you may not even realize, like chewing gum, aluminum cans, sunscreen, and the clothes you wear. Plastic remnants have been found almost everywhere imaginable on Earth, from its highest mountains to deepest ocean trenches, inside its remotest icecaps, and even in the air we breathe. In the last several years, tiny plastic particles have even been identified in the most unwelcome of places: accumulating within the human body.1

Largescale production of plastic began following the Second World War and sharply increased over time. Worldwide, more than 400 million metric tons of plastic are now produced annually; by 2050, this is estimated to reach a staggering 1.1 billion metric tons per year.2 Between 1950 and 2017, approximately 9.2 billion metric tons of plastic were made, the vast majority of which still remains to this day as waste in the natural environment, threatening global ecosystems. Microplastics (typically defined as plastic particles ranging between 1 and 5,000 micrometers in size) and nanoplastics (less than 1 micrometer in size) are formed when larger plastic objects degrade from regular use, or gradually break down in the environment. They are also manufactured at this size—so called microbeads—for consumer purposes.2,3 Micro- and nanoplastic particles are particularly concerning in that they exist on a scale where cellular uptake can occur.1

Microplastics were first detected in the environment nearly four decades ago, but only identified in human tissue for the first time in 2019.1 They primarily enter our bodies via ingestion of food, water, and other beverages; inhalation; and, to a lesser extent, direct skin contact with personal care products, cosmetics, and soil.1-3 According to a recently published literature review,1 over the last 4 years, microplastics have been detected in a variety of human bodily fluids (feces, saliva, sputum), circulating in the bloodstream, and in various human tissue samples, including the colon, lung, liver, lymphatics, and spleen. They have also been found in meconium, breastmilk, and placenta, suggesting humans are exposed to microplastics as early as in utero and immediately after birth.

Despite their ubiquity, the human health implications of cumulative microplastic exposure remain poorly understood. There is growing evidence suggesting the potential for harm, with several possible mechanisms by which this could occur:

  1. via direct effect from the foreign microplastic particles themselves (via local irritation, inflammation, cytotoxicity, oxidative stress, carcinogenesis, etc.)
  2. from the chemical additives used in the manufacturing of the plastic, which are associated with a number of adverse health outcomes like diabetes, reproductive issues, and altered neurodevelopment2,3
  3. due to the tendency of microplastics to adsorb and transport organic pollutants from their environment, which can then exert further toxic effect when released into the human body.1-3

Research has demonstrated a number of direct health impacts in mice/rats as well as human-derived cells, including toxicity to the intestinal tract, central nervous system, heart, and reproductive and immune systems; impaired pulmonary function; disruption of the metabolic system; and an increased risk of certain types of cancers.1 Importantly, communities of color, indigenous populations, and low-income families will bear the greatest weight of these health impacts as they are disproportionately affected by plastic waste and production and are at the greatest risk of microplastic accumulation.2-4 More high-quality research, including prospective, population-level studies are needed to fully understand the scope of the problem and risk of adverse outcomes. Comprehensive monitoring of microplastics in the environment is also needed, including the atmosphere, food and water supplies, and soil.

Meanwhile, action must be taken to curb the exponential growth of plastic waste. Corporations frequently tout recycling and other “green” initiatives as the answer, but this is woefully inadequate: since the 1950s, less than 10% of all plastics have been recycled or reused.2-4 Instead, the solution must involve a reversal of the meteoric rise in plastic production. This will require federal legislation to strengthen policies around production and disposal, as well as to reduce reliance on single-use plastics. New regulations should simultaneously support environmental justice by reattributing the burden of plastic waste from those currently shouldering it—the most vulnerable communities—to those ultimately responsible: the corporations producing it. Some examples of relevant legislation under consideration are highlighted in the table.

From a health perspective, public awareness campaigns are needed to engage and educate local communities, as many remain uninformed of the potential risks. This should include messaging around minimizing personal exposure to microplastics, such as avoiding heating and microwaving of plastic storage items to reduce leaching of microplastic fragments and harmful chemicals; avoiding takeaway beverage cups, polyester fleece fabrics, and any products containing microbeads; and reducing bottled water consumption, among other recommendations.3 Chemical-free plastics or, better yet, non-plastic substitutes like glass should be used for food storage whenever possible, though these costly alternatives will need to be subsidized for low-income families. Healthcare professionals can play a role through legislative advocacy, community education, and patient counseling on reducing microplastic exposure when discussing nutrition and preventive health. The table summarizes ways to minimize individual exposure, reduce plastic waste, and join the fight for change.

Plastics have undeniable benefits—they are durable, lightweight, and versatile. From electronics to healthcare technology, they have revolutionized our lives in countless ways. But as Judith Enck, president of the non-profit group Beyond Plastics, recently wrote in her testimony to the U.S. Senate, “we’re not seeing trees festooned with IV tubing, [or] car bumpers […] in our rivers and streams.”4 Plastic-based technologies with meaningful impacts on health and quality of life represent a negligible fraction of those being produced and discarded, and, in most cases, are utilized for years, not minutes.

Recently, a major step was taken toward curbing the plastic pollution crisis: in March 2022, at the fifth session of the United Nations Environment Assembly (UNEA-5.2), representatives from 175 countries ratified a historic resolution to end plastic waste and to develop an international, legally binding agreement for doing so by 2024.5 Negotiations are still underway, so work is needed to hold our leaders accountable. In addition to all of the health implications described above—which we are only beginning to understand—the substantial negative impact of plastic waste on the environment and its contribution to climate change are well established.2-4 Reducing plastic production and disposal is critical not only for the health of ourselves and of our children but also for the survival of our planet.

The word plastic is derived from the Latin plasticus and the Greek plastikos, meaning “able to be shaped or molded.” The future of our health and planet is still plastic—the end of this story has not yet been written and we can still impact the outcome. We are at the precipice of understanding these newly identified interlopers in our bodies and their impacts on our health, both known and hypothetical. Do not be fooled by habituation: The problem, like the outline of your nose, is right before your eyes. Now is the time to act.

References

  1. Liu M, Lui J, Xiong F, et al. Research advances of microplastics and potential health risks of microplastics on terrestrial higher mammals: A bibliometric analysis and literature review. Environ Geochem Health. 2023 Jan 4;1-36. doi:10.1007/s10653-022-01458-8. Online ahead of print.
  2. UN Environment Programme. Drowning in plastics—Marine litter and plastic waste vital graphics. https://wedocs.unep.org/xmlui/bitstream/handle/20.500.11822/36964/VITGRAPH.pdf. Published 2021. Accessed April 15, 2023.
  3. Benoit G. Plastics and microplastics: A threat to the environment and health. Environ Hum Health. https://www.ehhi.org/MicroplasticsBookfinal.pdf. Published December 2021. Accessed April 15, 2023.
  4. Testimony of Judith Enck, President of Beyond Plastics. U.S. Senate Committee on Environment & Public Works. https://www.epw.senate.gov/public/_cache/files/7/2/7256ca6c-6254-477e-859e-adea3a07d9c6/EAAD9CA5D2817DB2D2FE9913EF035973.12-15-2022-enck-testimony.pdf. Published December 15, 2022. Accessed April 15, 2023.
  5. United Nations Environment Assembly. 5/14. End Plastic Pollution: Towards an International Legally Binding Instrument - Resolution adopted by the United Nations Environment Assembly on 2 March 2022 [UNEP/EA.5/Res.14]. https://wedocs.unep.org/bitstream/handle/20.500.11822/39812/OEWG_PP_1_INF_1_UNEA%20resolution.pdf. Published March 7, 2022. Accessed April 15, 2023.


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