It has been found in Arctic sea ice, one of the most remote and inhospitable places on the planet; at the bottom of the world’s deepest ocean trench, at thirty-six thousand feet below sea level. It’s present in the water that comes out of your tap. It litters beaches around the world. The Great Pacific Garbage Patch, a collection of floating debris that stretches across an area roughly the size of France between California and Hawaii, is thought to contain some 1.8 trillion plastic shards. It’s in the “cleanest” air above Mount Everest. It’s inside the fish we eat, as well as in fruit and vegetables. It’s even in the rain.  

As author, Matt Simon, writes in A Poison Like No Other: How Microplastics Corrupted Our Planet and Our Bodies: “We’ve contaminated every corner of Earth.”

Dealing with discarded plastic is bad enough, but it’s when it starts to break down that the real trouble begins. The very thing that makes plastic so useful and ubiquitous – its toughness – means it never really goes away. It just gets smaller and smaller: eventually small enough to enter our bodies.

Indeed, microplastics — tiny fragments of plastic measuring less than five millimeters – have been found embedded in human placentas, our blood, our hearts, our livers, and babies’ poop. 

The detrimental effects of plastic and microplastics on ecosystems and the environment are relatively well-documented. For marine life, plastic has turned the ocean into an outright minefield, whether it’s getting caught in nets or eating the stuff thinking it’s food. On land too, it’s killing Sri Lanka’s elephants, racoons, hyenas, zebras, tigers, camels, cattle, and more. 

In 2020, a first-of-its-kind study explored how microplastics can affect soil fauna. It showed that microplastic pollution has led to the decrease of species that live below the surface, such as mites, larvae and other animals. The decline of these species leads to less fertile soil and land. 

What has remained more elusive, however, is the impact of plastic on human health.

For the past 70-odd years, we've been using plastic like there's no tomorrow (literally). It’s only in recent years that the world is belatedly waking up to the many health risks of plastics: from elevated miscarriage rates to early puberty.

You might be wondering, if plastics are so poisonous, why is the world not up in arms about their continued ubiquity? 

Professor Sarah Dunlop, Head of Plastics & Human Health at Minderoo Foundation, suggests it’s because the world simply doesn’t know: “They think plastic is simple and safe. It's not. It's complex and toxic.”

For a long time, the idea that tobacco caused health issues was relegated to conspiracy theorists intent on destroying everyone’s fun, smokey time. In truth, cigarette companies had scientific evidence by the 1950s their product was deadly, but Philip Morris didn’t admit that publicly until over 40 years later. 

There are at least 4,200 chemicals present in plastics that are considered to be highly hazardous and linked to human health, such as cancers. Scarier still is what we don’t know yet. There are over 16,000 chemicals used in plastics of which at least 11,000 have not been assessed for human health. 

As plastics are subject to wear and tear, chemicals can leak out as it goes through a manufacturing process. A few years ago, a team of American scientists subjected disposable shopping bags to several days of simulated sunlight, to mimic the conditions that they’d encounter “out in the wild.” They found that a single bag from CVS leached more than 13,000 compounds; a bag from Walmart leached more than 15,000. Steve Allen, a researcher at Canada’s Ocean Frontier Institute cuts to the chase: “If you’ve got an IQ above room temperature, you have to understand that this is not a good material to have in the environment.”

Microplastics, meanwhile, don’t just leach nasty chemicals; they attract them. Persistent Bioaccumulative and Toxic substances (PBTs) are a hodgepodge of harmful compounds. Like microplastics, which are often referred to in the scientific literature as MPs, PBTs are everywhere these days. When PBTs encounter MPs, they stick to them. “In effect, plastics are like magnets for PBTs” is how the Environmental Protection Agency has put it. Consuming microplastics is thus a good way to swallow old poisons.

Here are just a few examples of how plastic is poisoning us.

1. Miscarriages and stillbirths. 

It was over a decade ago that a group of researchers from the Washington State University revealed that Bisphenol A (BPA), a chemical commonly used in the manufacturing of plastic, was harmful to women’s reproductive systems. 

The study found that the chemical interferes with the hormones that are responsible for reproduction — an interference that can lead to miscarriage and could even lead to the birth of stillborn babies. 

Following the study’s findings, the US Food and Drug Administration (FDA) ended its authorization of the use of BPA in baby bottles and infant formula packaging. Yet despite its classification as a hazardous chemical, it’s still used in food packaging plastic, including plastic boxes, protective coatings for cans, and food processing equipment. 

In the US, a coalition of environmental and public health groups is petitioning the FDA to tighten limits for bisphenol A and its substitutes in plastics that contact food while the European Commission has only just started thinking about phasing out the use of the controversial chemical in food contact materials.

However, the petrochemical industry, supported by the FDA, maintains that current BPA regulations are adequate, and that the likelihood of BPA causing health issues is minimal. We wonder why.

2. Neurodevelopmental disorders in children. 

Approximately one in six children in the US has a neurodevelopmental disorder, about 17% of all children. Prevalence rates of these disorders, including ADHD, autism spectrum disorder, cognitive impairment (IQ loss), dyslexia, reduced academic performance, behavioral changes, and reductions in brain volume appear to be increasing. 

A study in 2023 added to the growing science uncovering potential connections between common plastic chemicals and neurodevelopmental disorders.

“There is an extensive body of evidence for a relationship between neurodevelopmental disorders and environmental pollutants such as plasticizers,” note the researchers.

“It’s not legal to deliberately expose humans to toxic chemicals, yet we do — every day. Even babies can’t escape. They come pre-polluted with health impacts for the rest of their lives,” said Professor Dunlop.

3. Reproductive and genital defects.

As shown in the 2023 report from the Minderoo-Monaco Commission on Plastics and Human Health, there is evidence that BPA causes changes in the genitals of newborn baby girls (and clitoral distance) and newborn baby boys. 

Indeed, as early as 2008, links had also been found between phthalates and reproductive and genital defects.

4. Allergies. 

Approximately 300 million people worldwide currently have asthma, and its prevalence increases by 50% every decade.

In 2017, a group of German scientists demonstrated that phthalates can considerably increase the risk of allergies among infants and children including asthma and eczema.

We’ll let you connect the dots. 

5. Early puberty in girls. 

Phthalates have been linked to early puberty in girls. 

A landmark study published by researchers from Puerto Rico found “a possible association between plasticizers with known estrogenic and antiandrogenic activity and the cause of premature breast development in a human female population.”

Another study published in 2009 also found a link between early breast development and phthalate exposure among girls in Taiwan.

While these studies did not find causation, they certainly raise a whole lot of questions about the role phthalates play in early puberty among young girls.

6. Low sperm count. 

In 2022, a team of international researchers published a global review which revealed that sperm concentrations in semen have been freefalling for the last 50 years.

Sperm is on the decline. But why?

The same year, a study led by Andreas Kortenkamp, a professor of human toxicology at Brunel University offered a first-of-its-kind evaluation of the impact of chemicals found in everyday plastics on sperm concentration and count.

Kortenkamps’ work found that chemicals such as phthalates were “drivers of deteriorating semen quality.”

7. Aggression and hyperactivity. 

When mothers were exposed to BPA while pregnant, studies have shown that their toddlers were more hyperactive and more aggressive. 

How can I help?

The evidence is clear; plastics are harming our health. That's why we need a robust Global Plastics Treaty.

This treaty was put forward by Peru and Rwanda, with support from 27 countries and more than 750 civil society groups. It aims is to address the entire lifecycle of plastic, from the extraction of the fossil fuels used to make it, to its use, and finally its disposal.

From April 23 to 29, government representatives from 173 countries are set to gather in Ottawa, Canada, for the fourth session of the Intergovernmental Negotiating Committee (INC-4) to negotiate this legally binding treaty. Take action with Global Citizen now and share why you think we need a robust Global Plastics Treaty.

“Companies continue to vouch for their plastic use because they say it's such a cheap material. Plastic is not cheap,” says Valliant. “Ask those living among the plastic production facilities in Louisiana's Cancer Alley or Port Arthur in Texas if they think plastic is cheap … Plastic is only cheap for the manufacturers; individuals, especially those in environmental justice communities, are paying a high price.”