According to his study, which is published in the December issue of the Journal of Environmental Health, lead levels in indoor/outdoor Christmas lights that they tested were all said to be above regulatory limits for equivalent areas of windowsills and floors set by the US Environmental Protection Agency and the Department of Housing and Urban Development (HUD). Unfortunately, there are no standards for lead content that exist as of yet for Christmas lights, according to the researchers.
Lead (about 2-5%) is said to be used in the polyvinyl chloride (PVC) jacketing of the Christmas light cords to make them resistant to heat, light, and moisture damage. The researchers said lead in the Christmas lights could be ingested from hand-to-mouth contact after handling the lights; and can also be released into the air during installation and removal. At present, they said that there is no way to know how much lead exists in jacketing or in various products without independent testing.