Toxic chemicals from microplastics can be absorbed through skin

The study offers the first experimental evidence that chemicals present as additives in microplastics can leach into human sweat, and then be absorbed through the skin, into the bloodstream.

Many chemicals used as flame retardants and plasticisers have already been banned, due to evidence of adverse health effects including damage to the liver or nervous system, cancer, and risks to reproductive health. However, these chemicals are still present in the environment in older electronics, furniture, carpets, and building materials.

While the harm caused by microplastics is not fully understood, there is increasing concern over their role as conduits of human exposure to toxic chemicals.

The research team demonstrated in a study published last year, that chemicals were leached from microplastics into human sweat. The current study now shows that those chemicals can also be absorbed from sweat across the skin barrier into the body.

In their experiments, the team used innovative 3D human skin models as alternatives to laboratory animals and excised human tissues. The models were exposed over a 24-hour period to two common forms of microplastics containing polybrominated diphenyl ethers (PBDEs), a chemical group commonly used to flame retard plastics.

The results, published in Environment International, showed that as much as 8% of the chemical exposed could be taken up by the skin, with more hydrated — or ‘sweatier’ — skin absorbing higher levels of chemical. The study provides the first experimental evidence into how this process contributes to levels of toxic chemicals found in the body.

Dr Ovokeroye Abafe, now at Brunel University, carried out the research while at the University of Birmingham. He said: “Microplastics are everywhere in the environment and yet we still know relatively little about the health problems that they can cause. Our research shows that they play a role as ‘carriers’ of harmful chemicals, which can get into our bloodstream through the skin. These chemicals are persistent, so with continuous or regular exposure to them, there will be a gradual accumulation to the point where they start to cause harm.”

Dr Mohamed Abdallah, Associate Professor of Environmental Sciences at the University of Birmingham, and principal investigator for the project, said: “These findings provide important evidence for regulators and policymakers to improve legislation around microplastics and safeguard public health against harmful exposure.”

Professor Stuart Harrad, co-author of the paper, added “the study provides an important step forward in understanding the risks of exposure to microplastics on our health. Building on our results, more research is required to fully understand the different pathways of human exposure to microplastics and how to mitigate the risk from such exposure.”

In future research, the team plan to investigate other routes through which microplastics could be responsible for toxic chemicals entering the body, including inhalation and ingestion. The work is funded by a Marie Curie Research Fellowship, within the European Union’s Horizon 2020 Research and Innovation Programme.