Microplastics are plastic particles ranging from 0.1 to 5,000 micrometers, and nanoplastics are particles ranging from 1 to 100 nanometers, i.e., 0.001–0.1 micrometers. (For comparison, human hair is approximately 70 to 100 micrometers in diameter.) Some are intentionally produced, but most form when plastics break down in the environment or during use.
Traditionally, when evaluating health risk, pronouncements would not be made about global health crises until sufficient data were available regarding exposure, the amount of a substance released in the environment that reaches the human body, and the subsequent health effects – studied in humans or animals evaluating a specific adverse health effect (e.g., cancer, congenital disabilities).
Today, in the age of social media platforms such as TikTok, pronouncements are made before there is any credible data to back them up. Hysteria rapidly ensues.
Exposure
On October 15, the European Food Safety Authority(EFSA) published a blockbuster report, largely ignored by the press, that undercut the exposure to microplastics.
The EFSA is an agency of the European Union that provides scientific advice to risk managers on food safety issues. In their publication, they reviewed and extracted data from 122 articles on microplastic release from bottles/screw caps, food containers, cups, teabags, plastic bags, films, and other items.
What they found was startling: most of the studies gave inaccurate results based on shortcomings in sample preparation, test conditions, and reliability of the analytical methods, concluding that,
“Despite the uncertainties, the actual release is much lower than the results presented in many publications. In view of this, there is no sufficient basis at this stage to estimate microplastic release from food-contact materials during their use.”
According to them, there are two main reasons for the inaccurate results:
- Faulty analytical methods that could not accurately identify microplastics and nanoplastics. Most testing methods rely on identifying “spectra” that yield similar signals for plastic and non-plastic particles, leading to misidentification of particles. This is particularly a problem with microplastics, since they are commonly mixed with non-plastic particles, such as additives and pigments found in food-contact material.
- Background contamination from improper laboratory practices can allow materials or chemicals in the laboratory’s air, equipment, or other sources to contaminate the food contact material being tested, resulting in faulty results.
The EFSA was particularly critical of studies on tea bags, which reported the release of millions or billions of microplastics per plastic tea bag. The German Federal Institute for Risk Assessment concluded that the high particle counts were due to non-plastic particles and that the reported counts were 2 or 3 magnitudes too high. EFSA concluded that the “high numbers of microplastic release from tea bags now come into question as a result of increased understanding the field.”
EFSA also refuted the often-repeated assertion that, because there is a problem with plastic pollution in oceans (primarily water bottles), there is also a problem with microplastics. Microplastics cannot simply “migrate” from plastic material found in water bottles and cups. They are incorporated into the plastic matrix and will not diffuse out of the matrix. The only areas where there is potential for the release of microplastics from food contact materials are through mechanical stress, such as abrasion or friction, as with repeated opening and closing of screw-cap bottles or Ziploc bags. These scenarios are not very realistic – most of us don’t spend our day doing 100 bottle cap opens and closes, as was done in one study.
Health effects
To assess health effects, there must be credible studies showing adverse effects at concentrations relevant to humans.
Reproductive effects (infertility):
- Most studies focus on aquatic species (mainly fish), which are of limited relevance to humans. According to a recent study, “studies on mammalian reproduction are scarce, but a wealth of data from aquatic species indicate reproductive effects of microplastics.”
- Limited studies in rats and mice indicate possible effects on sperm count and quality, as well as on the ovaries, after exposure to high levels of microplastics.
With no studies in humans and most studies in fish, no meaningful conclusions can be made.
Respiratory disease:
Respiratory disease is the area with the most evidence of an association with microplastics.
- Microplastics can penetrate deep into the lungs, raising concerns about the development of respiratory diseases. As ACSH has reported, researchers are currently using a model of particle flow to understand the deposition of microplastics from the mouth to the lungs, but are far from understanding the actual impact of microplastics on respiratory health.
- Human studies are not available, and studies in rats and mice have reported chronic inflammation and lung injury from exposure to high levels of microplastics.
Human studies and more modeling are needed to confirm the results.
Lung and colon cancer:
- There are misleading claims that microplastics may be associated with lung and colon cancer. However, there is no evidence in human or animal studies.
- A review of studies on microplastics and human health concluded that “microplastics are suspected” to harm human reproduction and digestive and respiratory systems, with a suggested link to colon and lung cancer.” This suggested link was not based on any data.
There is no evidence of an association between microplastics and lung and colon cancer.
Cardiovascular effects:
- A 2024 study in the New England Journal of Medicine studied patients having surgery to remove plaque from their arteries. More than two years after the surgery, those who had microplastics in their plaque had a higher risk of heart attack, stroke, and death than those who didn’t. As stated in an ACSH article, “the clinical relevance of these findings are unknown.”
With only one human study available, there is insufficient data to draw conclusions.
Digestive effects:
- Several studies have shown that microplastics accumulate in the gut of fish and mice and affect the biodiversity of the intestinal microbiota.
- A recent study reported that stool samples exposed to microplastics had a lower pH (more acidic) than cultures not exposed. The authors claimed that changes in fecal pH are related to several gastrointestinal diseases, including colorectal cancer.
These are very preliminary studies, and more data is necessary to draw any meaningful conclusions.
Today, we live in a society that thrives on hysteria. Microplastics are the latest example of a “crisis” that benefits environmental groups and lawyers seeking their next big payday. This is not to say that plastic pollution is not a problem; an estimated 75 to 199 million tons of plastic are currently in the oceans, and that number is expected to rise. However, there needs to be many more robust studies on exposure and health before we declare microplastics to be the next international public health crisis.
