Tinsel first appeared in Nuremburg, Germany in 1610 and was made out of strands of silver. It became very popular, as it enhanced the flickering glow of candles on Christmas trees, but silver tends to tarnish and lose its shine very easily.
In the early 20th century, lead and aluminum tinsel was mass-marketed and by the 1950s was more popular than Christmas lights since it was less of a fire hazard. In 1971, though, the Food and Drug Administration determined that lead tinsel was dangerous to children. The agency didn’t ban it, but companies who made it gradually phased it out, and the tinsel we use today is usually made from polyvinyl chloride with a metallic coating.