Microplastics harm human cells, but many questions remain

A new study from the University of York shows that ingesting high levels of microplastics is harmful to human cells. Study lead author Evangelos Danopoulos said that this is the first-time scientists have attempted to quantify the effects of microplastics on human cells using a statistical analysis of the available published studies.

“What we have found is that in toxicology tests, we are seeing reactions including cell death and allergic reactions as potential effects of ingesting or inhaling high levels of microplastics,” said Danopoulos.

The researchers compared levels of microplastic consumption affecting cell viability to levels of cell viability humans are exposed to by ingesting contaminated food. They did this by looking at three previous studies. 

The studies investigated the presence of microplastics in drinking water, seafood,  and table salt, revealing high levels of contamination. The scientists compared these levels of plastic contamination to the levels required to cause negative impacts on human cells in toxicology studies. 

“Our research shows that we are ingesting microplastics at the levels consistent with harmful effects on cells, which are in many cases the initiating event for health effects,” said Danopoulos. “However, the biggest uncertainty at the present time is how ingested microplastics are excreted from the body. This is a crucial point to understand the true level of risk.”

The research looked at five ways in which microplastics can cause cell damage: cell death; immune responses (and allergic reaction); how microplastics may harm cell membranes or cross into them; oxidative stress, which can lead to cell and tissue damage; and genotoxicity, or damage to genetic information. The first four of these seem to be affected by certain levels of microplastics. The researchers also found that not all microplastics pose the same threat. 

“Our analysis of the data showed that cell viability depends on the shape of the microplastics. Irregularly shaped microplastics, which are the majority found in the environment, are more hazardous than spherical,” explained Danopoulos.

“So far, most toxicology studies have been testing spherical microplastics. There needs to be a shift to testing irregularly shaped ones.”

The researchers said that little is known about what happens after microplastics enter the body, despite their research showing the impact of microplastics on cells. The study is published in the Journal of Hazardous Materials.

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By Zach Fitzner, Earth.com Staff Writer