Chemicals in plastic consumer products may trigger obesity and weight gain, study finds

Chemicals from a third of plastic products investigated found to contribute to fat cell development

Dutch student Jerry de Vos shows his invention, a plastic scanner that identifies what type of plastic a product is made of, for which he was awarded the 2021 James Dyson award for Sustainability (ANP/AFP via Getty Images)

Chemicals found in plastic consumer products can affect human metabolism, contribute to the development of fat cells in the body and trigger obesity, according to a new study.

The research, published in the journal Environmental Science and Technology on Wednesday, found over 55,000 different chemical components in plastic consumer products and identified 629 substances of which 11 of them are known to be metabolism-disrupting chemicals (MDCs).

“Our experiments show that ordinary plastic products contain a mix of substances that can be a relevant and underestimated factor behind overweight and obesity,” Martin Wagner, a co-author of the study from the Norwegian University of Science and Technology (NTNU), said in a statement.

In the study, the researchers looked at 34 different daily-use plastic products such as yoghurt containers, drink bottles and kitchen sponges to see which chemicals they contained.

Obesity is a leading contributing factor linked to some of the most common causes of death in the world, such as cardiovascular disease and cancer, with nearly 650 million people across the globe living with the condition.

While previous research had already indicated that some plastics contained hormone-disrupting chemicals that could affect development and fertility, the new study found some chemicals in plastic can contribute to weight gain and obesity as well.

Chemicals from a third of the plastic products investigated in the study contributed to fat cell development in laboratory experiments, reprogramming precursor cells to become fat cells that proliferated more and accumulated more fat.

While some of the products assessed in the study contained known metabolism-disrupting substances, others did not.

However, researchers said these substances nevertheless induced the development of fat cells, suggesting that plastics may also contain currently unidentified chemicals that interfere with how our body stores fat.

“It’s very likely that it is not the usual suspects, such as Bisphenol A, causing these metabolic disturbances. This means that other plastic chemicals than the ones we already know could be contributing to overweight and obesity,” said Johannes Völker, the first author of the study who is affiliated with NTNU’s Department of Biology.

While the study did not reveal a clear cause-effect relationship between plastics and obesity, researchers said chemicals such as phthalates and bisphenols in daily use plastic consumer products, as well as others whose effects are yet unknown, may well be a factor.

Citing the limitations of the research, scientists said the sample set of plastics analysed in the study is “certainly not representative of all plastic chemicals humans are exposed to.”

By prioritising polymer types that are likely to contain MDCs such as Polyvinyl chloride and Polyurethane (PVC and PUR), they said further studies can help comprehensively characterise human exposure to plastic chemicals from all types of products.

“To the best of our knowledge, this is the first study investigating the adipogenic activity of chemicals extractable from plastic consumer products,” the researchers wrote in the study.

“Our study demonstrates that daily-use plastics contain potent mixtures of MDCs and can, therefore, be a relevant yet underestimated environmental factor contributing to obesity,” they added.