Researchers at the University of Bayreuth have discovered that the plasticizers DEHP and DINP have negative effects on the normal brain function of vertebrates. These plasticizers are used, for example, in PVC, paints, and cosmetics.
Phthalates are important additives in a wide variety of plastic products and are among the most commonly used plasticizers. However, these plasticizers usually leach out of the products over time and enter the environment and, via food, clothing, and dust, the human body. The plasticizer DEHP has been shown to have serious effects on development and reproduction , which is why it has already been replaced in many applications by the alternative DINP, which was previously considered safer. Recently, it has been shown that DEHP can also impair the blood-brain barrier , which protects the brains of vertebrates from pathogens or toxins in the blood. This could also pose a risk to adults. In this context, an assessment of the potential effects of DEHP, as well as its alternatives, on the adult brain is also crucial for evaluating 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 plasticizer for one month. They then examined the effects of DEHP and DINP on the brain using the Mauthner neuron—the largest nerve cell in the fish brain stem. The Mauthner neuron is accessible for such measurements and receives input from a variety of sensory systems, making it ideal for this study.
"The way humans come into contact with plasticizers is, of course, different from the way in which the fish studied swam in water to which plasticizers had been added. Nevertheless, the results of our study are alarming and, with some caution, can also be extrapolated to humans. Basic brain functions, such as how nerve cells process and transmit information, as well as the transmission of information from one nerve cell to another, are no different in fish than in humans. And this is where we find effects of plasticizer exposure," says Dr. Peter Machnik.
Measurements on the fish's Mauthner neuron revealed that both DEHP and DINP reduced the conduction velocity of the nerve cell by 20%. A reduction in conduction velocity would also have a negative effect on other nerve cells and normal brain function. Furthermore, the researchers were able to identify various negative effects on the connections between nerve cells – the synapses – and thus on the transmission of excitation from one nerve cell to another. The researchers also found evidence that both plasticizers impair the fish's visual perception.
"Our study shows a previously neglected high sensitivity of various important brain functions to phthalates. This is a fact that must be taken into account in future risk assessments of these substances," said Machnik.
original publication
Exposure to phthalate plasticizer compromises normal brain function in an adult vertebrate. Benedikt Maric, Stefan Schuster, Peter Machnik. Ecotoxicology and Environmental Safety (2024)
DOI: https://doi.org/10.1016/j.ecoenv.2024.117187
The article was published at www.medlabportal.de
