PFAS, more commonly known as “forever chemicals”, are a group of chemicals that have been used in manufacturing since the 1950s. They’re found in everything from waterproof clothing to electrical devices, and they take decades to degrade. There are thousands of different types, and now research has shown that some of them may cause cancer, prompting the government to recommend that the amount of certain chemicals allowed in our drinking water should be reduced. Matilda Boseley asks science reporter Donna Lu whether these chemicals are as scary as their name suggests and how much of a risk they pose to human health