Plastic is in our clothes, cars, mobile phones, water bottles and food containers. But recent research adds to growing concerns about the impact of tiny plastic fragments on our health.

A study from the United States has, for the first time, found microplastics in human brains. The study, which has yet to be independently verified by other scientists, has been described in the media as scary, shocking and alarming.

But what exactly are microplastics? What do they mean for our health? Should we be concerned?

What are microplastics? Can you see them?

We often consider plastic items to be indestructible. But plastic breaks down into smaller particles. Definitions vary but generally microplastics are smaller than five millimetres.

This makes some too small to be seen with the naked eye. So, many of the images the media uses to illustrate articles about microplastics are misleading, as some show much larger, clearly visible pieces.

Microplastics have been reported in many sources of drinking water and everyday food items. This means we are constantly exposed to them in our diet.

Such widespread, chronic (long-term) exposure makes this a serious concern for human health. While research investigating the potential risk microplastics pose to our health is limited, it is growing.

How about this latest study?

The study looked at concentrations of microplastics in 51 samples from men and women set aside from routine autopsies in Albuquerque, New Mexico. Samples were from the liver, kidney and brain.

These tiny particles are difficult to study due to their size, even with a high-powered microscope. So rather than trying to see them, researchers are beginning to use complex instruments that identify the chemical composition of microplastics in a sample. This is the technique used in this study.

The researchers were surprised to find up to 30 times more microplastics in brain samples than in the liver and kidney.

They hypothesised this could be due to high blood flow to the brain (carrying plastic particles with it). Alternatively, the liver and kidneys might be better suited to dealing with external toxins and particles. We also know the brain does not undergo the same amount of cellular renewal as other organs in the body, which could make the plastics linger here.

The researchers also found the amount of plastics in brain samples increased by about 50% between 2016 and 2024. This may reflect the rise in environmental plastic pollution and increased human exposure.

The microplastics found in this study were mostly composed of polyethylene. This is the most commonly produced plastic in the world and is used for many everyday products, such as bottle caps and plastic bags.

This is the first time microplastics have been found in human brains, which is important. However, this study is a “pre-print”, so other independent microplastics researchers haven’t yet reviewed or validated the study.

How do microplastics end up in the brain?

Microplastics typically enter the body through contaminated food and water. This can disrupt the gut microbiome (the community of microbes in your gut) and cause inflammation. This leads to effects in the whole body via the immune system and the complex, two-way communication system between the gut and the brain. This so-called gut-brain axis is implicated in many aspects of health and disease.

We can also breathe in airborne microplastics. Once these particles are in the gut or lungs, they can move into the bloodstream and then travel around the body into various organs.

Studies have found microplastics in human faeces, joints, livers, reproductive organs, blood, vessels and hearts.

Microplastics also migrate to the brains of wild fish. In mouse studies, ingested microplastics are absorbed from the gut into the blood and can enter the brain, becoming lodged in other organs along the way.

To get into brain tissue, microplastics must cross the blood-brain-barrier, an intricate layer of cells that is supposed to keep things in the blood from entering the brain.

Although concerning, this is not surprising, as microplastics must cross similar cell barriers to enter the urine, testes and placenta, where they have already been found in humans.

Is this a health concern?

We don’t yet know the effects of microplastics in the human brain. Some laboratory experiments suggest microplastics increase brain inflammation and cell damage, alter gene expression and change brain structure.

Aside from the effects of the microplastic particles themselves, microplastics might also pose risks if they carry environmental toxins or bacteria into and around the body.

Various plastic chemicals could also leach out of the microplastics into the body. These include the famous hormone-disrupting chemicals known as BPAs.

But microplastics and their effects are difficult to study. In addition to their small size, there are so many different types of plastics in the environment. More than 13,000 different chemicals have been identified in plastic products, with more being developed every year.

Microplastics are also weathered by the environment and digestive processes, and this is hard to reproduce in the lab.

A goal of our research is to understand how these factors change the way microplastics behave in the body. We plan to investigate if improving the integrity of the gut barrier through diet or probiotics can prevent the uptake of microplastics from the gut into the bloodstream. This may effectively stop the particles from circulating around the body and lodging into organs.

How do I minimise my exposure?

Microplastics are widespread in the environment, and it’s difficult to avoid exposure. We are just beginning to understand how microplastics can affect our health.

Until we have more scientific evidence, the best thing we can do is reduce our exposure to plastics where we can and produce less plastic waste, so less ends up in the environment.

An easy place to start is to avoid foods and drinks packaged in single-use plastic or reheated in plastic containers. We can also minimise exposure to synthetic fibres in our home and clothing.

Sarah Hellewell, Senior Research Fellow, The Perron Institute for Neurological and Translational Science, and Research Fellow, Faculty of Health Sciences, Curtin University; Anastazja Gorecki, Teaching & Research Scholar, School of Health Sciences, University of Notre Dame Australia, and Charlotte Sofield, PhD Candidate, studying microplastics and gut/brain health, University of Notre Dame Australia

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Articles about badly behaved people and how to spot them are common. You don’t have to Google or scroll too much to find headlines such as 7 signs your boss is a psychopath or How to avoid the sociopath next door.

You’ll often see the terms psychopath and sociopath used somewhat interchangeably. That applies to perhaps the most famous badly behaved fictional character of all – Hannibal Lecter, the cannibal serial killer from The Silence of the Lambs.

In the book on which the movie is based, Lecter is described as a “pure sociopath”. But in the movie, he’s described as a “pure psychopath”. Psychiatrists have diagnosed him with something else entirely.

So what’s the difference between a psychopath and a sociopath? As we’ll see, these terms have been used at different times in history, and relate to some overlapping concepts.

What’s a psychopath?

Psychopathy has been mentioned in the psychiatric literature since the 1800s. But the latest edition of the Diagnostic Statistical Manual of Mental Disorders (known colloquially as the DSM) doesn’t list it as a recognised clinical disorder.

Since the 1950s, labels have changed and terms such as “sociopathic personality disturbance” have been replaced with antisocial personality disorder, which is what we have today.

Someone with antisocial personality disorder has a persistent disregard for the rights of others. This includes breaking the law, repeated lying, impulsive behaviour, getting into fights, disregarding safety, irresponsible behaviours, and indifference to the consequences of their actions.

To add to the confusion, the section in the DSM on antisocial personality disorder mentions psychopathy (and sociopathy) traits. In other words, according to the DSM the traits are part of antisocial personality disorder but are not mental disorders themselves.

US psychiatrist Hervey Cleckley provided the first formal description of psychopathy traits in his 1941 book The Mask of Sanity. He based his description on his clinical observations of nine male patients in a psychiatric hospital. He identified several key characteristics, including superficial charm, unreliability and a lack of remorse or shame.

Canadian psychologist Professor Robert Hare refined these characteristics by emphasising interpersonal, emotional and lifestyle characteristics, in addition to the antisocial behaviours listed in the DSM.

When we draw together all these strands of evidence, we can say a psychopath manipulates others, shows superficial charm, is grandiose and is persistently deceptive. Emotional traits include a lack of emotion and empathy, indifference to the suffering of others, and not accepting responsibility for how their behaviour impacts others.

Finally, a psychopath is easily bored, sponges off others, lacks goals, and is persistently irresponsible in their actions.

So how about a sociopath?

The term sociopath first appeared in the 1930s, and was attributed to US psychologist George Partridge. He emphasised the societal consequences of behaviour that habitually violates the rights of others.

Academics and clinicians often used the terms sociopath and psychopath interchangeably. But some preferred the term sociopath because they said the public sometimes confused the word psychopath with psychosis.

“Sociopathic personality disturbance” was the term used in the first edition of the DSM in 1952. This aligned with the prevailing views at the time that antisocial behaviours were largely the product of the social environment, and that behaviours were only judged as deviant if they broke social, legal, and/or cultural rules.

Some of these early descriptions of sociopathy are more aligned with what we now call antisocial personality disorder. Others relate to emotional characteristics similar to Cleckley’s 1941 definition of a psychopath.

In short, different people had different ideas about sociopathy and, even today, sociopathy is less-well defined than psychopathy. So there is no single definition of sociopathy we can give you, even today. But in general, its antisocial behaviours can be similar to ones we see with psychopathy.

Over the decades, the term sociopathy fell out of favour. From the late 60s, psychiatrists used the term antisocial personality disorder instead.

Born or made?

Both “sociopathy” (what we now call antisocial personality disorder) and psychopathy have been associated with a wide range of developmental, biological and psychological causes.

For example, people with psychopathic traits have certain brain differences especially in regions associated with emotions, inhibition of behaviour and problem solving. They also appear to have differences associated with their nervous system, including a reduced heart rate.

However, sociopathy and its antisocial behaviours are a product of someone’s social environment, and tends to run in families. These behaviours has been associated with physical abuse and parental conflict.

What are the consequences?

Despite their fictional portrayals – such as Hannibal Lecter in Silence of the Lambs or Villanelle in the TV series Killing Eve – not all people with psychopathy or sociopathy traits are serial killers or are physically violent.

But psychopathy predicts a wide range of harmful behaviours. In the criminal justice system, psychopathy is strongly linked with re-offending, particularly of a violent nature.

In the general population, psychopathy is associated with drug dependence, homelessness, and other personality disorders. Some research even showed psychopathy predicted failure to follow COVID restrictions.

But sociopathy is less established as a key risk factor in identifying people at heightened risk of harm to others. And sociopathy is not a reliable indicator of future antisocial behaviour.

In a nutshell

Neither psychopathy nor sociopathy are classed as mental disorders in formal psychiatric diagnostic manuals. They are both personality traits that relate to antisocial behaviours and are associated with certain interpersonal, emotional and lifestyle characteristics.

Psychopathy is thought to have genetic, biological and psychological bases that places someone at greater risk of violating other people’s rights. But sociopathy is less clearly defined and its antisocial behaviours are the product of someone’s social environment.

Of the two, psychopathy has the greatest use in identifying someone who is most likely to cause damage to others.

Bruce Watt, Associate Professor in Psychology, Bond University and Katarina Fritzon, Associate Professor of Psychology, Bond University

This article is republished from The Conversation under a Creative Commons license. Read the original article.