I was shuttling between patients, carrying my reusable water bottle from room to room to stay hydrated.

“You shouldn’t drink out of that plastic bottle while you’re pregnant,” a kind social worker – grandmother to five – warned me gently.

I smiled, reassured her: “I checked – it’s BPA-free.”

It was my first pregnancy, over 13 years ago. At the time, when it came to plastics and health, I knew that it was important to avoid BPA (bisphenol A), a hormone signaling disruptor – but that was pretty much it.

I thought of plastic as a pollution problem, not a health hazard.

But over the past several decades, researchers have uncovered not just the breadth of our plastic exposure but the alarming depths of its potential harm. These harms come not just from the massive explosion of the tiniest microplastic fragments in our environment but also from the chemical additives and contaminants that plastics carry.

Why is plastic a health concern now? 

Plastic production has increased 230-fold since the 1950s, and production is projected to triple by 2060. More than half the total plastic ever made has been produced since 2002. 

Much of that growth is being driven by fossil fuel companies. 

“They’re very deliberately redirecting their investment away from the production of gasoline into the production of plastics and petrochemicals,” says Philip Landrigan, pediatrician and director of the Program on Global Public Health and the Common Good and the Boston College Observatory. 

The plastic boom means that carbon dioxide emissions from plastic production are projected to expand by 34% between 2015 and 2030. It also means that no place on Earth is free of plastic pollution. 

Read: How plastics contribute to climate change

Microscopic plastic particles have been found in every corner of the environment, from the peaks of Mount Everest to the depths of the Mariana Trench. The human body is no exception. Scientists have detected plastic particles in nearly every part of the human body – essentially, anywhere they have looked. They’ve been found in our lungs, liver, kidneys, blood, breast milk, placenta, colon, spleen, brain, and even reproductive organs like the testicles and ovaries. Emerging evidence of their impacts – ranging from inflammation to oxidative stress – suggests that plastic exposures may be fueling the growing wave of chronic disease.

What is plastic?

Every plastic has two components. 

The first is a polymer – a long, spaghetti-like chain of repeating carbon molecules. More than 98% of this carbon backbone is made from the byproducts of oil, gas, and coal – the same fossil fuels that are warming the climate when we burn them. 

The second component is a brew of chemicals added to give plastics different properties like flexibility, stability, or color. Over 16,000 different types of chemical additives are used to design the broad array of plastic products. These additives can leach out into the environment over time. Some of these chemicals are toxic, and most are very poorly regulated.

“Fewer than 20% have ever been tested for toxicity,” Landrigan says.

The combination of the ramp-up of single-use plastics, which make up 35-40% of plastic production, and abysmal rates of recycling means that most of the plastic produced is fated to be created mainly to litter the planet – and our bodies. 

How microplastics and chemical additives enter our bodies

We eat them. We drink them. We breathe them in.

Even fetuses can be exposed through blood traveling across the placenta. 

That’s because plastic has a shedding problem. 

Over time, tiny pieces from the plastic that litters our environment – toys, bottles, bags, food packaging, polyester clothing – break off. These fragments continue to break down into smaller and smaller particles. When plastic is heated – in the sun, microwave, or dishwasher, for example – it sheds even more.

Microplastics are plastic fragments smaller than five millimeters in length –  the size of a pencil eraser –  while nanoplastics are smaller than one micrometer, invisible to the naked eye. 

These particles are pervasive in our homes – in indoor air, household dust, bottled water, tap water, meat, salt, fruits, vegetables, seafood, baby formula, and breast milk. 

The chemical additives used in plastics can also leach into our food and water, pass through our skin, and migrate out of shedding microplastics. The most well-known of the toxic plastic additives are bisphenol A (BPA), added to make plastics harder; phthalates, used to make them flexible; and PFAS (per- and polyfluoroalkyl substances), also known as “forever chemicals,” added to make plastics resistant to heat, oil, and stains.

What do microplastics do to the human body?

What happens to micro- and nanoplastics once they enter our bodies is not completely understood. A lot depends on the particle’s size, shape, and chemical makeup – for now, their long-term fate and the long-term risk to our health is an area of active scientific study.

Plastic particles that enter through our mouths generally move through our digestive system and are eliminated in stool. But the smallest pieces can collect in the lining of our gut or even migrate into our bloodstream. From there, these microscopic pieces can travel to organs like the liver, kidneys, and brain. Some of these plastic particles are eventually flushed out through urine or bile, but some collect in our organs.

When we inhale plastic fibers, larger pieces are caught in the lining of our nose or throat and can be cleared out when we exhale. But smaller pieces can reach deep into our lungs, where some can cross into the bloodstream.

But the question remains: Do these plastic particles harm our health?

We’re starting to piece together data from a variety of sources.

“Wherever we find plastics – in cell culture experiments, in vitro experiments, in animal studies – there’s always a problem,” says Dr. Sanjay Rajagopalan, a cardiologist and director of the Cardiovascular Research Institute at Case Western Reserve University. 

Studies suggest these particles, along with toxic materials added or stuck to them, trigger inflammation, cell death, and tissue damage. In lab and animal model findings, microplastics and the dangerous chemicals they carry have disrupted gut and lung barriers, interfered with hormone regulation, and harmed sperm and egg cells.

Rajagopalan points to a landmark study published in the New England Journal of Medicine that suggests real-world human health consequences. Researchers found microplastics in the clogged neck arteries of close to 60% of studied patients. After three years, people with microplastics had 4.5 times the rate of heart attack, stroke, and death compared to people without microplastics in their clogged arteries.

More research is not needed to act

The phrase “more research is needed” is a familiar refrain when it comes to understanding the impact of plastic, in particular microplastics, on health. However, a growing foundation of evidence, including a detailed review by the Minderoo-Monoco Commission on Plastics and Human Health, lays out the case that there is enough evidence of harm to take action. 

The commission’s report outlined converging lines of evidence showing that plastics cause disease, disability, and premature death across every stage of their life cycle – from fossil fuel extraction to manufacturing, use, and disposal.

Some of the strongest evidence of plastic-related diseases is linked to specific chemical additives.

BPA is one of the most well-known plastic chemicals and is part of a larger group of additives known as endocrine-disrupting chemicals, substances that can mimic or interfere with the body’s hormone signals. This group also includes phthalates, PFAS, and certain flame retardants, all commonly found in everyday products.

“There is a lot of data linking specific plastic-related chemicals like certain phthalates, flame retardants, and PFAS with neurodevelopmental harm, including IQ loss and ADHD symptoms,” says Elizabeth Ryznar, a psychiatrist who focuses on the neuropsychiatric risks of plastic. 

Phthalates may also play a role in more than 10% of heart-disease-related deaths across the world in people between the ages of 55-64. This is a key finding in a recently published article looking specifically at one particular type, di-2-ethylhexylphthalate (DEHP). Previous research has linked DEHP exposure to more inflammation in blood vessels, a response that can elevate the risk of heart attacks and strokes over time.

As for the health harms of micro- and nanoplastic particles themselves, the evidence is nascent but concerning. 

In a recent analysis of human and animal studies, researchers reviewed the evidence for health risks in three major body systems: digestive, reproductive, and respiratory. The strongest evidence linked microplastics to impaired sperm quality and weakened gut immunity. There was moderate evidence to suspect harm to female reproductive hormones, gut inflammation, and lung function. The research findings also supported a link to colon and lung cancer that needs further study. 

The precautionary principle and plastics

Given the growing evidence of harm, experts emphasize the importance of the precautionary principle: Although more research will always be needed to understand exactly how every organ system is affected, enough data exists to recognize that plastics are hazardous to our health. 

This is especially true for pregnant women, infants, and young children who may be among the most vulnerable. When dangerous exposures to any substance happen during critical windows of development, the damage can have lifelong repercussions. 

Microplastics have been identified in placentas and the first bowel movement that a baby has after birth, suggesting that plastics have made their way into the circulation and digestive tract of babies even before they are born. Early life exposures to microplastics and toxic chemical additives like BPA and phthalates may increase long-term risk for obesity, autism, and ADHD, changing the lifelong trajectory of a child and their family.

“The microplastics research is really early, but I’m a firm believer in the precautionary principle,” Ryznar says. “Our exposure is growing exponentially. We don’t want to wait 30 years for definitive proof – by then it’ll be too late and too many people will be harmed.”

As plastic production continues to boom, the environmental, climate, and health dangers loom large.

Though individuals can shift their behavior to minimize their personal risk and reduce demand for these hazardous products, it will take more than just personal choices to address the global health risks. 

There is good news. More than 100 countries have implemented some form of ban on single-use plastics. Most of these rules focus on plastic bags, but some countries have also banned other items like straws and cutlery. 

Landrigan also points to more coordinated action on the global stage.

“Over 100 countries are working to advance a Global Plastics Treaty that includes a cap on plastic production and transparency about chemicals. That’s where we need to go.” 

Some easy wins that you can achieve at home:

• Avoid microwaving food in plastic containers.
• Drink from glass or stainless steel instead of plastic bottles.
• Choose fresh or frozen foods over processed and packaged ones.
• Choose personal care products without microbeads, phthalates, or parabens.
• Ask your elected officials to take action.

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