An Invisible Threat: Microplastics’ Impact On Our Health
At A Greener Future, we spend our days walking the shorelines of Lake Ontario, picking up the pieces of a bigger problem: plastic pollution. From water bottles and cigarette butts to small fragments of plastic, our mission is to remove as much of this waste as possible from our environment before it breaks down even further. But what happens when it already has? What happens when plastic becomes so small that it turns into something we can’t just pick up?
Microplastics are tiny fragments of plastic less than five millimeters long. Some microplastics are created intentionally, such as plastic pellets, referred to as nurdles, which are used in plastic manufacturing. However, they can also form when larger plastic items degrade over time from exposure to the sun, water, and friction. Once they're in the environment, they don’t go away - they just get smaller. Plastics that are less than 1 micrometre are called nanoplastics and aren’t visible to the naked eye. And as the plastics get smaller, they make their way into everything: the water we drink, the food we eat, the air we breathe. We’ve known for some time that fish and seabirds are consuming these plastics, but recent studies are beginning to reveal that humans are too - and the effects might be more serious than we ever imagined.
When we eat, we may be swallowing plastic. Seafood is a common source since many marine animals ingest microplastics directly. But it’s not just fish. Studies have found microplastics in salt, bottled water, and even fruits and vegetables. Once inside the body, these tiny particles can irritate the lining of the digestive tract, much like sandpaper rubbing against soft tissue. This physical irritation can lead to inflammation, and over time, chronic inflammation in the gut, which has been linked to discomfort, bloating, and even more serious gastrointestinal disorders.
Exposure assessments to microplastics through various individual sources
nr Not reported, na Not applicable
aNot stained by the Rose Bengal dye
From: Microplastics in food: scoping review on health effects, occurrence, and human exposure
Microplastics may also disrupt the delicate balance of bacteria in the gut microbiome, which plays a crucial role in digestion, immune function, nutrient absorption, and mental health. On top of that, microplastics can act like tiny vessels, carrying toxic chemicals such as heavy metals and pollutants into the body. These toxins may be absorbed into the bloodstream from the intestines, quietly spreading through the body.
Microplastics don’t just enter through food. We also breathe them in. Indoor air, especially in homes with synthetic fabrics and plastic-based furnishings, can release microplastic dust. Outdoors, road dust and industrial emissions contribute to airborne plastic exposure. Once inhaled, microplastics can travel deep into the lungs, where they may trigger oxidative stress—a harmful imbalance between free radicals and antioxidants. This kind of stress can damage lung tissue and impair breathing. In more serious cases, particles may reach the alveoli, the tiny air sacs where oxygen enters the blood. Animal studies suggest that this can lead to inflammation and even disrupt mitochondrial function in lung cells, potentially leaving people feeling fatigued or short of breath without knowing why.
These particles are also catching the attention of immunologists. When the immune system encounters microplastics, it may respond as if facing a threat, even if there's nothing it can eliminate. This ongoing low-level immune activation can lead to chronic inflammation, and over time, such a constant state of alert can weaken the body’s ability to respond to actual infections. Some research even suggests that microplastics may alter how immune cells function and express genes, possibly contributing to allergic reactions or autoimmune disorders. Essentially, the body is fighting an invisible enemy it doesn’t fully recognize—and it’s wearing itself out in the process.
A container filled with nurdles (microplastics).
Perhaps most startling are recent findings showing that microplastics may be able to cross into the brain. A new study published this year found shard-like plastic particles embedded in human brain tissue, particularly in the frontal cortex—an area tied to decision-making and memory. While it's too early to say whether these plastics caused neurological harm, the presence of these particles—especially in higher quantities in individuals with dementia—raises urgent questions. Lab research on mice has already shown that microplastics can pass the blood-brain barrier, trigger inflammation in brain tissue, activate immune cells like microglia, and lead to behavioural changes. The fact that this research is no longer just theoretical or limited to animals signals a critical need for more investigation—and more caution.
Microplastics also act as delivery vehicles for chemicals that disrupt hormones. Compounds like BPA and phthalates, often found in plastics, are known endocrine disruptors. They can mimic or block the body’s natural hormones, potentially throwing off systems that regulate metabolism, growth, mood, and fertility. Microplastics carrying these chemicals into the body may affect thyroid function, interfere with reproductive health, and disrupt normal development. Animal studies have linked exposure to reduced fertility, developmental delays, and pregnancy loss.
And it doesn't stop there. Microplastics have been found in human placentas, breast milk, and even infant formula, suggesting that exposure starts early, before birth, in some cases. The developmental period is one of the most sensitive times in a person’s life. According to Developmental Origins of Health and Disease (DOHaD), exposures during this window can shape the risk of chronic diseases later on. This means that microplastics encountered in utero or early infancy could play a role in long-term health outcomes like obesity, diabetes, and cardiovascular disease.
Rochelle Byrne and a group of volunteers nurdle hunting at the beach.
At A Greener Future, we are often asked why we do what we do. Why spend hours combing the shoreline for litter or counting every piece of garbage we collect? It’s because of facts like these. The plastics we see on the ground today are the microplastics that end up in our bodies tomorrow. Our cleanups are not just about making a beach prettier; it’s about breaking the chain of pollution before it becomes invisible, ingested, and deeply embedded in our lives.
We still have a lot to learn about microplastics and health. Much of what we know comes from lab experiments and animal studies, not yet from long-term human trials. But the signs are clear enough: this isn’t a problem we can afford to ignore. It's not about panic—it's about preparation. The better we understand the risks, the more we can do to protect ourselves, our communities, and future generations.
So what can you do?
Our actions, big and small, ripple outward, and together, we help build a cleaner, healthier, and greener future for all. Volunteer at a cleanup, especially a Nurdle Hunt, where we focus on removing these tiny microplastic pieces along our shorelines. Rethink your plastic use. Stay curious, and stay informed.
