What exactly are micro plastics?
Microplastics are synthetic, high-molecular weight compounds that have been micronized into plastic particles smaller than 5 mm in size. Such materials have a low biodegradation rate and, thus, mostly remain in the environment and adversely affect the human body, the final consumer in the food chain. These tiny fragments of plastic fail to break down in our earthly environment. Scientists have estimated that adults ingest the equivalent of one credit card per week in micro plastics.
Worldwide, plastic use is growing year by year, with current figures showing plastic production exceeding 450 million tons in 2020.
How do we get exposed?
Routes of plastic particles entry into the human body. There are three key routes for micro- and nanoplastics entry into the human body: Inhalation, ingestion, and skin contact. Nanoplastics may interact with proteins, lipids, carbohydrates, nucleic acids, ions, and water in the human body, leading to the formation of coronated nanoplastic particles for absorption. The plastic particles can enter the human body through ingestion of contaminated food and water supplies, or inhalation of the airborne plastic particles that originate from synthetic textiles and polluted outdoor air. While the skin membrane is too fine for these plastic particles to pass through, nanoplastics may penetrate through a wound and weakened the skin barrier, directly or indirectly.
They are in the water we drink, the food we eat, the clothes we wear, and the air we breathe; particles are even in tea bags, seafood, meat, and bottled water. They’ve pervaded every ecosystem in the world, from coral reefs to Antarctic ice. Researchers discovered that plastic fragments were being spread by wind and water, contaminating everything from the depths of the oceans to the summit of Mount Everest.
And they’ve infiltrated the human body, lodging themselves in everything from brain tissue to reproductive organs.
How will micro plastics affect my health?
Research on the health impacts of micro plastics in humans is just beginning. The particles have been found in multiple organs and tissues, including the brain, testicles, heart, stomach, lymph nodes, and placenta. They’ve also been detected in urine, breastmilk, semen, and meconium, which is a newborn’s first stool.
Evidence is growing that this exposure could be harmful. Interestingly, more than 10,000 chemicals are used to make plastic; two-thirds have not been assessed for safety, while over 2,400 are considered potentially toxic.
Studies show that micro plastics make fish and birds more vulnerable to infections. Animal and cellular studies have linked micro plastics to biological changes including inflammation, an impaired immune system, deteriorated tissues, altered metabolic function, abnormal organ development, cell damage, and more.
A recent large-scale review of existing research by scholars at the University of California, San Francisco, concluded that exposure to micro plastics is suspected to harm reproductive, digestive, and respiratory health and suggested a link to colon and lung cancer.
First, the digestive systems are affected when micro plastics are ingested, and physical irritation to the gastrointestinal tract may eventually cause inflammation, resulting in various gastrointestinal symptoms. Microplastics may cause changes in the intestinal microbiome, resulting in an imbalance between beneficial and harmful bacteria, which can lead to various gastrointestinal symptoms, such as abdominal pain, bloating, and changes in bowel habits. In addition to their physical effects on the digestive system, micro plastics can cause chemical toxicity, which involves the absorption and accumulation of environmental toxins such as heavy metals and polycyclic aromatic hydrocarbons. These toxic substances can enter the body through the gastrointestinal tract when micro plastics are ingested orally, leading to various gastrointestinal symptoms including nausea, vomiting, and abdominal pain.
One complicating factor is the ubiquitous nature of glyphosate. This herbicide causes increased permeability of the gastrointestinal lining and the brain making its easier for all forms of pathogens, heavy metals, and chemicals to enter the body more easily.
Regarding the effects on the respiratory system, micro plastics may cause oxidative stress in the airways and lungs when inhaled, leading to respiratory symptoms such as coughing, sneezing, and shortness of breath due to inflammation and damage, as well as fatigue and dizziness due to a low blood oxygen concentration. A recent study showed that nano-sized plastics were associated with mitochondrial damage in human respiratory cells. Microplastics can act as carriers of other environmental toxins, such as polystyrene, and exposure to high concentrations of polystyrene are detrimental to human lung cells, increasing the risk of chronic obstructive pulmonary disease.
In addition, micro plastics interfere with the production, release, transport, metabolism, and elimination of hormones, which can cause endocrine disruption and lead to various endocrine disorders, including metabolic disorders, developmental disorders, and even reproductive disorders (i.e., infertility, miscarriage, and congenital malformations). Micro plastics can act as a medium for environmental toxic substances such as bisphenol A (synthetic estrogen), which are absorbed into the body and cause various diseases of the endocrine system and reproductive system. In a recent study, micro plastics were also found in the placentas of six pregnant women by Raman microspectroscopy. The potential negative effects of micro plastics on the human immune system warrant further research. Accumulated exposure to micro plastics induced chronic inflammation and homeostasis changes in animal experiments, and a study on human lung cells showed that micro plastics can activate innate immunity by regulating the expression of genes and proteins involved in the immune response.
One of the first papers to directly examine the risks of micro plastics exposure in humans, published in The New England Journal of Medicine in March 2024, studied patients undergoing surgery to remove plaque from their arteries. More than two years after the procedure, those who had micro plastics in their plaque had a higher risk of heart attack, stroke, and death than those who didn’t.
Bisphenol A (BPA), an industrial chemical that is widely used to make polycarbonate (PC) plastics and epoxy resin as lining layer of food and beverage containers. Studies reported that the leaching of BPA from food containers into the food and drinks can cause a series of diseases, including obesity and cardiovascular diseases. BPA also acts as a hormonal disruptor, imitating or blocking the production, action, and function of hormones in the human body. BPA also known to affect brain development in the womb, causing damage to the developing fetus. Polyvinyl chloride (PVC) polymers and plastisol generally contain phthalate esters as plasticizers, in order to increase their durability and flexibility. Human exposure to phthalate esters has been shown to associate with abnormal sexual development and changes in the levels of sex hormones. Additionally, studies have demonstrated that some phthalate esters such as butyl benzyl phthalate (BBP) and di-2-ethylhexyl phthalate (DEHP) can increase tumor incidence in humans, representing potential carcinogens.
The toxicity of BPA causes changes in liver function and insulin resistance, damage of a developing fetus and modification of the reproductive system and neurological functions. BPA acts as an agonist for estrogen receptors and inhibits thyroid hormone-mediated transcription by acting as an antagonist, and alters pancreatic beta cell function. There is an increased likelihood of developing obesity and cardiovascular diseases, and several other reproductive and developmental issues have been noted when humans are exposed to BPA at concentrations of 0.2–20 ng/mL.
Besides the chemical toxicity issue there is also the physical damage that micro plastics particles can create passing through organs and tissues.
How can I protect myself?
All of us need to stop using plastic as much as we can to protect our health, especially single-use plastics. avoiding nonstick and plastic cookware, wearing clothes made of natural fibers, and seeking out plastic-free toiletries and cosmetics.
When possible only buy products, peanut butter and beverages in glass jars. When ordering out, ask restaurants to put food in a glass container that you bring along. Avoid plastic wrap and only buy metal or wooden toys for babies and small children.
Heat more than likely increases leaching; it isn’t recommended to hand-wash plastic items and not use plastic containers to reheat food in the microwave. Wear and tear may also increase exposure to particles; do not reuse degraded plastic items.
