Let’s begin with an important fact: No matter what you’ve heard, you are not eating the equivalent of a credit card’s worth of microplastics every week.
You can read more about the confusion around this assertion in the article here.
However, the claim has sparked concerns, particularly after multiple studies reported microplastics accumulating in various environments—ranging from the highest mountains to the deepest ocean trenches, and even in isolated polar regions. Microplastics have also been detected in human tissues, including the heart, liver, kidneys, breast milk, and bloodstream.
Given their prevalence and potential health implications, it’s understandable to be worried, but is it truly warranted?

The ubiquity of microplastics can be traced back to the remarkable properties of plastics. The invention of Bakelite in the early 20th century marked a shift in how materials were produced—created from synthetic compounds rather than sourced from nature.
As plastic became more affordable and widespread, its applications flourished, impacting food packaging, electronics, medical devices, and more. Unfortunately, this durability also leads to a significant environmental issue; microplastics have been released into ecosystems for over a century, persisting for long periods. Consequently, these particles have made their way into the tissues and bloodstreams of various species, including us.
These microplastics are often present in everyday items we consume, such as salt, beer, and drinking water, as detailed here.

Yes, microplastics could likely be within you, but there’s no need to panic just yet. Assessing the health implications of pollutants involves several factors.
Firstly, consider the size of the microplastics, which varies significantly. Secondly, what concentration is required to elicit effects? Lastly, we must examine whether the effects are indeed harmful. Much of the current research is animal-based, which raises questions about its applicability to humans.

Microplastics and Credit Cards

In recent years, alarming headlines have often cited vague information about microplastic sizes or relied on inflated studies that use unrealistically high doses, not reflective of typical human consumption.
For example, widely circulated claims suggested that the average person ingests around 5 grams of microplastics a week—the amount in a credit card. This assertion stems from a 2019 study that employed questionable methodologies and can easily be debunked.

According to a more accurate assessment, most individuals consume only around 0.0041 milligrams per week—less than a grain of salt. This slower rate suggests that it would take over 1.2 million weeks, or 23,000 years, to consume the equivalent of one credit card’s worth of plastic.
If you were immortal, perhaps you could worry about it.

Research indicates that the average person accumulates about 12.2 milligrams of microplastics in their lifetime, but only around 41 nanograms might actually be absorbed by the body based on a study by the same researcher.

New concerns have also emerged surrounding the methodologies used to investigate microplastics within bodily tissues. Some studies employ vaporization techniques that analyze smoke for microplastics, potentially leading to false positives due to similar chemical structures released from fat.

Effects of Microplastics on Human Health

While we know that microplastics are present in our bodies, their effects remain unclear. Some studies indicate that microplastics may lead to behavioral changes and inflammation in animal models; however, these studies often utilize unrealistically high doses—1 gram per day for rodents, for example.
Other studies in pigs showed that a weekly dose of 1 gram affected gene expression and induced oxidative stress in the pancreas, yet this dosage vastly exceeds typical human exposure.
Reports from the World Health Organization have cautioned that most animal studies utilize concentrations of microplastics well above what humans typically encounter. Moreover, microplastics are processed differently in human bodies compared to rodents, complicating data interpretation.

Preliminary human studies have detected microplastics accumulating in plaques and have correlated the presence of these plastics with higher instances of heart attacks and strokes. However, correlation does not entail causation—it’s critical to avoid jumping to conclusions.

Investigating the impact of microplastics on human health is multifaceted. While these small particles carry chemicals capable of disrupting bodily processes, it is essential to recognize that not all these chemicals are absorbed immediately. Studies have demonstrated that the amount of chemicals leaching from microplastics is minimal under average conditions, as addressed in this report. Additionally, the body can excrete certain chemicals, negating long-term accumulation risks.

Concerns also revolve around the potential introduction of other hazardous substances linked to microplastics. Moreover, they may disrupt immune functions or even cause cell damage and inflammation. However, comparative assessments regarding the risks of microplastics versus other pollutants—such as air quality or dietary excesses—remain uncertain.

While it’s natural to fear the health risks posed by microplastics, we need definitive evidence to gauge their danger accurately. This discussion taps into our anxiety surrounding pollution. Just because we don’t consume a credit card’s worth of plastic each week doesn’t mean that the issue isn’t serious. However, the field of microplastic research is still nascent, and comprehensive data on their effects in humans is lacking.
Until further research emerges, I’ll focus my concerns elsewhere.