Progressive Hair Dyes
Under the law, coal-tar hair dyes don’t need FDA approval, unlike color additives in general. But hair dyes from plant or mineral sources do. Lead acetate is a color additive that is approved for use in coloring hair. It is used in products that darken the hair gradually over time, with repeated applications. Unlike the limits on lead other color additives, lead is allowed at much higher levels in progressive hair dyes. But because of the dangers of lead exposure if these products are misused, lead acetate hair colorings must have a special warning on the label:
"Caution: Contains lead acetate. For external use only. Keep this product out of children's reach. Do not use on cut or abraded scalp. If skin irritation develops, discontinue use. Do not use to color mustaches, eyelashes, eyebrows, or hair on parts of the body other than the scalp. Do not get in eyes. Follow instructions carefully and wash hands thoroughly after use.