It's that time of year again, when children in countries that celebrate Christmas all over the world are dreaming of what awaits them in brightly wrapped packages — everything ranging from model cars to plastic building blocks, dolls and so much more. Yet the German Society for Endocrinology, a specialist society for researchers studying the effects of hormones, warns that many children's toys contain endocrine disruptors, which can have a negative impact on metabolic processes, growth, brain development and fertility. Endocrine disruptors (EDCs) are chemicals that, even in small quantities, can disrupt the way hormones function, and cause harmful effects. EDCs include plasticizers such as phthalates and bisphenols, which are found in a variety of food packaging. They also include brominated flame retardants, which make plastics less flammable, so-called forever chemicals (PFAS), as well as heavy metals such as cadmium and bromine. These substances can be found in all kinds of everyday household items such as cosmetic products, plastics, paints and textiles, but also in cheap children's toys, said Josef Köhrle of the Institute for Experimental Endocrinology at Berlin's Charite university hospital. He researches how different substances affect the body's hormone systems. "Children's skin and mucous membranes are not yet fully developed as barriers to harmful substances," said Köhrle during a press conference earlier this month. What's more, young children explore the world with their mouths. This typical behavior "can massively increase EDC exposure," the researcher warned.