Plasticisers impair normal brain function in vertebrates
Researchers at the University of Bayreuth have discovered that the plasticisers DEHP and DINP have negative effects on normal brain function in vertebrates. These plasticisers are used in products such as PVC, paints, and cosmetics. The researchers reported their findings in the journal Ecotoxicology and Environmental Safety.
Phthalates are important additives in a variety of plastic products and are among the most commonly used plasticisers. However, plasticisers often leach from these products over time, entering the environment and making their way into the human body via food, clothing, and dust. DEHP, in particular, has been proven to have severe impacts on development and reproduction, which is why it has been replaced in many instances by DINP, which is considered to be a safer alternative. Recent studies, however, have 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 pose a risk to adults as well. Therefore, evaluating the potential impacts of DEHP, as well as its alternatives, on the adult brain is critical in 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 plasticisers for one month. They then investigated the effects of DEHP and DINP on the brain by examining the Mauthner neuron – the largest nerve cell in the hindbrain of fish. The Mauthner neuron is accessible for such measurements and receives input from a variety of sensory systems, making it a suitable model for investigation.
“The way humans come into contact with plasticisers is, of course, different from that of the fish we studied, which swam in water to which plasticisers had been added. Nevertheless, the results of our study are alarming and, with some caution, can also be applied 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, is comparable in both fish and humans. This is where we observe the effects of plasticiser exposure,” says Dr Peter Machnik.
Measurements taken from the Mauthner neurons of the fish showed that both DEHP and DINP reduced the conduction speed of the nerve cell by 20%. A reduction in conduction speed could negatively affect other nerve cells and impair normal brain function. In addition, the researchers observed various negative impacts on the connections between nerve cells – the synapses – and thus on the transmission of signals from one nerve cell to another. They also found evidence that both plasticisers impair the visual perception of the fish.
“Our study reveals a previously overlooked sensitivity of various important brain functions to phthalates. This is a factor that must be taken into account in future risk assessments of these substances,” says Machnik.
The study was funded by a Reinhart Koselleck Project of the German Research Foundation (DFG) (Schu1470/8).
Wissenschaftlicher Ansprechpartner:
Dr. Peter Machnik
Department for Animal Physiology
University of Bayreuth
Phone: +49 (0)921 / 55-2473
Mail: peter.machnik@uni-bayreuth.de
Originalpublikation:
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
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