Microplastics and nanoplastics are increasingly prevalent in our environment and food system, raising concerns about their impact on human health.
A new review of the scientific literature explores the potential for these tiny plastic particles to negatively affect brain health.
Key facts:
- Microplastics are 0.1-5mm in size, nanoplastics are smaller than 0.1mm. They come from the breakdown of larger plastics and microbeads in consumer products.
- Limited studies show micro- and nanoplastics can cross into the circulatory system and accumulate in organs, including the brain.
- Exposure is linked to oxidative stress, inflammation, inhibited neurotransmitter function, and behavioral changes in marine species. Effects in mammals are less studied.
- More research is urgently needed on realistic long-term exposures in humans and lab animals. But early evidence suggests a potential risk to brain development and function.
Source: Part Fibre Toxicol.
A World Awash in Plastic Debris
Plastic production has skyrocketed to over 300 million tons per year worldwide.
But our inability to properly dispose of these synthetic polymers means plastic waste has become ubiquitous across the planet.
Of particular concern are microplastics, breakdown fragments under 5mm in size, and nanoplastics, microscopic particles smaller than 0.1mm.
These tiny plastic bits make their way into our oceans, lakes, food, and drinking water through the breakdown of larger plastic products and microbeads added to consumer goods like cosmetics.
Over 5 trillion pieces of plastic are estimated to be floating in Earth’s oceans alone.
Can Plastic Particles Infiltrate the Brain?
Given the global spread of micro- and nanoplastics, exposure is essentially unavoidable for humans and wildlife.
But what happens when these particles enter the body?
Can they cross biological barriers and accumulate in organs like the brain?
Unfortunately, research on plastic particle toxicity has lagged behind their proliferation in the environment.
However, early studies suggest reason for concern.
When fish and rodents are exposed to high doses, a small number of particles can cross the intestinal barrier and blood-brain barrier.
In fish, fluorescence imaging revealed the presence of plastic nanoparticles in brain tissue.
And mice orally dosed with polystyrene microplastics showed accumulation in the gut, liver, and kidneys.
The implications for low-level chronic exposures in humans remain uncertain.
But the fact that some plastic particles can infiltrate critical physiological barriers highlights a potential for harm.
Linking Plastic Exposure to Brain Health Risks
A limited but growing number of studies have investigated the health effects of micro- and nanoplastics in the nervous system.
Experiments expose different marine species and cell cultures to plastic particles and analyze impacts on markers of brain function and behavior.
While variations exist across species and plastic types, overall trends are emerging.
Exposure promotes oxidative stress, neuroinflammation, inhibited neurotransmitter enzymes, and altered swimming/feeding behaviors.
Mammals are less studied, but changes in energy metabolism, neurotransmitters, and acetylcholinesterase inhibition have been observed in mouse liver.
The cumulative results suggest micro- and nanoplastics disrupt key neurological processes tied to brain development, cognition, motor function, and mood.
However, the dose and duration of exposures exceed realistic human scenarios.
Much more research is urgently needed to clarify if — and at what levels — plastic particles may pose a neurotoxic risk.
Microplastics, Nanoplastics, Brain Damage Potential?
Currently, too many unknowns exist to determine the neurological risk posed by ordinary micro- and nanoplastics exposure.
Major research gaps include:
- Limited data on real-world exposure levels in humans
- Unclear to what extent tiny plastic particles cross into the human nervous system
- Minimal studies on impacts in mammals compared to aquatic species
- Effects of chronic low doses versus short-term high doses
- Role of plastic size, shape, surface charge, and polymer type
- Interactions with environmental chemicals sorbed onto plastic
These uncertainties make it challenging to translate early experimental findings to human health outcomes.
The doses causing neuronal changes in cell cultures or marine life generally exceed exposure levels from food and water sources.
But considering the rising environmental prevalence of micro- and nanoplastics, even a potential low risk applied to everyone becomes concerning from a public health perspective.
Protecting Our Brains Against Plastic Pollution
While risks remain uncertain, early evidence links micro- and nanoplastics to neurological harm.
To protect our brains and bodies, a wise precautionary approach involves curbing plastic waste and reducing exposure.
Strategies include phasing out single-use plastics, developing safer alternatives to microbeads in consumer goods, improving water filtration, and ingesting less seafood known to contain microplastics.
Such proactive measures offer benefits beyond neurotoxicity by reducing plastic pollution damaging ecosystems worldwide.
Additionally, plastic particles should be rigorously studied at doses and exposure times reflective of real-world scenarios.
Developing a stronger grasp of neurological risks will provide insights on appropriate regulation to limit health impacts.
Our understanding remains limited, but the possibility that ubiquitous plastic debris may harm the brain suggests a pressing need for scientific attention and pollution prevention.
References
- Study: The plastic brain: neurotoxicity of micro- and nanoplastics
- Authors: Minne Prust et al. (2020)
