New flame retardants developed
Flame retardants are invisible helpers in car seats, sealing foams, furniture and even in airplanes. However, their ingredients are not always harmless. Empa researchers have developed three novel flame retardants and tested them for toxicity - not all of them passed the test.
Researchers are striving to develop ever better and safer flame retardants. For example, the team led by Sabyasachi Gaan of the Empa-Advanced Fibers" department has synthesized three new agents that have the same or improved flame retardancy as previously available products.
Toxicological cross-check
But before a flame retardant can even be considered for mass production, it is essential to ensure its safety for humans. The fact that prior toxicological clarification is advantageous is shown by the example of the flame retardant TCCP, which was only classified as toxic to humans after its market launch and now has to be successively withdrawn from the market. The new flame retardants developed by the Empa team are derivatives of an existing agent and are called ETA-Dopo, EG-Dopo and EDA-Dopo. Experts from Empa's Particles-Biology Interactions department have subjected the substances to a toxicological cross-check.
Tests with different cells
Cordula Hirsch's team exposed both lung cells and macrophages (phagocytes) to the flame retardants. The Empa researcher was only able to determine no toxic reactions for one of the three substances. But the lungs are mainly affected by the effects of the flame retardants during production and processing in powder form. Later, the toxic substances enter the organism through the skin, where they can either cause skin damage or even neurotoxic effects.
Hirsch therefore passed the samples on to Stephanie Mathes from the Zurich University of Applied Sciences (ZHAW) in Wädenswil, who, together with her team, tested the new flame retardants for their skin compatibility. To do this, the researchers grew human skin and treated it with varying concentrations of the flame retardant. Stefan Schildknecht and his colleagues from the University of Constance were responsible for the neurological investigations. He investigated the direct effect of the substance on neuronal effects using tests with brain cells.
Conclusion
Conclusion of the researchers: Two of the three flame retardants failed the tests. Both resulted in damage to the test cells used and are therefore no longer considered for further development. However, the researchers also showed that the newly developed EDA-Dopo not only has a better flame retardant effect than previously available products, but also does not exhibit any toxic effects in the tests conducted. Thus, EDA-Dopo is a good candidate to take the next steps.
Text: Cornelia Zogg, Communication, Empa
