Plasticizers disrupt normal brain function in vertebrates, research shows

Researchers from the University of Bayreuth have discovered that the plasticizers DEHP and DINP have negative effects on normal brain function in vertebrates. These plasticizers are used in products such as PVC, paints and cosmetics. The researchers reported their findings in the news Ecotoxicology and environmental safety.

Phthalates are important additives in a variety of plastic products and are among the most commonly used plasticizers. However, plasticizers often leach from these products over time, enter the environment and enter the human body through food, clothing and dust.

It has been proven that DEHP in particular has serious consequences for development and reproduction. Therefore, in many cases it has been replaced by DINP, which is considered a safer alternative.

However, recent studies have shown that DEHP can also damage the blood-brain barrier, which protects the brains of vertebrates from pathogens or toxins in the blood. This can also pose a risk to adults. Therefore, evaluating the potential impact of DEHP, as well as its alternatives, on the adult brain is critical when assessing the safety of plastic products.

For their research, Benedikt Maric, Prof. Dr. Stefan Schuster and Dr. Peter Machnik from the Department of Animal Physiology at the University of Bayreuth exposed goldfish to an environmentally relevant concentration of plasticizers for a month. They then examined the effects of DEHP and DINP on the brain by examining the Mauthner neuron – the largest nerve cell in the fish hindbrain.

The Mauthner neuron is accessible for such measurements and receives input from various sensory systems, making it a suitable model for research.

‘The way in which humans come into contact with plasticizers is obviously different from that of the fish we studied, which swam in water to which plasticizers had been added. Nevertheless, the results of our study are alarming and, with some caution, could also be applied to humans. Basic brain functions, such as how nerve cells process and transmit information, as well as the transfer of information from one nerve cell to another, are similar in both fish and human exposure to plasticizers,” says Dr. Peter Machnik.

Measurements on the fish’s Mauthner neurons showed that both DEHP and DINP reduced the nerve cell’s conduction speed by 20%.

A reduction in conduction velocity can negatively affect other nerve cells and impair normal brain function. In addition, the researchers observed several negative effects on the connections between nerve cells – the synapses – and therefore on the transmission of signals from one nerve cell to another. They also found evidence that both plasticizers affected the fish’s visual perception.

“Our study reveals a previously overlooked sensitivity of several important brain functions to phthalates. This is a factor that should be taken into account in future risk assessments of these substances,” says Machnik.