Microplastics have become nearly impossible to avoid. They have been detected in oceans, drinking water and even the human body, but scientists are still uncovering how they affect human health.
Now, researchers at the Texas A&M College of Veterinary Medicine and Biomedical Sciences (VMBS) have uncovered evidence that one of the world's most common plastics may do more than pollute the environment. Their findings suggest that polyethylene may contribute to fatty liver disease and worsen the condition when combined with an unhealthy diet.
While scientists have previously studied other types of microplastics, polyethylene has received comparatively little attention despite accounting for roughly one-third of global plastic production. Because it is commonly used in food packaging, plastic wraps, food storage containers and beverage cup linings, researchers wanted to determine whether this widely used plastic could contribute to liver disease and, if so, how it produced those effects.
"No studies have really looked into polyethylene's effect on liver health, and it's the most widely produced plastic," said Dr. Adi Joshi , associate professor in VMBS' Department of Veterinary Physiology and Pharmacology . "What we now know is that these microplastics, especially polyethylene, affect our liver's natural defense and repair mechanisms."
Looking beyond a common microplastic
While previous studies have largely focused on other types of microplastics, researchers knew relatively little about how polyethylene affects liver health. Joshi's team set out to fill that knowledge gap by investigating whether exposure to the plastic could contribute to fatty liver disease, a condition where excess fat builds up in liver cells that affects about 25% of people globally, according to the American Liver Foundation.
The researchers found that polyethylene increased signs of fatty liver disease on its own and further exacerbated the condition when paired with a diet high in fat, fructose, and cholesterol. The findings suggest that environmental exposures and dietary habits may work together to accelerate liver damage.
"Those who have a more Western-style diet, including foods like burgers and sodas, may have a greater chance of progressing to fatty liver disease if they are also exposed to polyethylene," Joshi said.
The findings were particularly surprising because polyethylene has long been considered one of the more biologically inert microplastics. Rather than appearing harmless, the material showed the potential to influence liver health both on its own and in combination with dietary factors, prompting researchers to investigate how it was producing those effects.
Mapping damage cell by cell
To better understand how polyethylene affects the liver, the team collaborated with researchers at the University of Oklahoma to use spatial transcriptomics, an emerging technology that allows scientists to examine gene expression within an intact tissue while retaining the precise physical location of each cell.
Using this high-resolution approach, the researchers identified specific areas of liver damage and discovered that polyethylene activates PPAR-alpha — a protein already known to regulate fat production in the liver — as a key factor in liver's response to microplastic exposure. They also identified ANXA2, a gene involved in tissue repair, as another potential player in the disease process.
According to Joshi, identifying this pathway not only helps explain how polyethylene influences liver health but could also point researchers toward new therapeutic strategies.
Building on the discovery
Although this study provides important insight into how polyethylene affects liver health, it also opens several new avenues for research.
The research team next plans to investigate whether polyethylene contributes to later stages of liver disease, including fibrosis, while continuing to explore additional molecular pathways involved in the body's response to microplastic exposure. They also hope to determine whether manipulating the PPAR-alpha pathway can reduce polyethylene's harmful effects on the liver.
"This is the pioneering study showing that polyethylene can contribute to fatty liver disease and the use of spatial transcriptomics has determined exactly where the damage has happened within the liver," Joshi said. "The other microplastics might also be harmful to the liver, and we definitely need to look into other classes of microplastics."
As scientists continue to uncover the long-term health effects of microplastics, Joshi hopes the findings encourage both researchers and the public to think more carefully about how everyday environmental exposures may influence chronic disease.
By Camryn Haines, Texas A&M University College of Veterinary Medicine and Biomedical Sciences
