What is a very flammable substance used in children's clothing?

A very flammable substance historically used in children's clothing is cotton, especially when untreated or not treated with flame retardants. While cotton itself is not inherently dangerous, its flammability can pose risks if not properly treated. Modern safety regulations often require children's clothing to be made from materials that meet specific flame-resistant standards to enhance safety. Consequently, many manufacturers now use synthetic fibers or treatments to reduce flammability.