Lead is one of mankind's oldest used metals. Lead and its compounds have been employed for thousands of yeas in many areas of life, from construction to gastronomy. It is not so long ago that sewage pipes were made from lead. If you have renovated an old house, you might have noticed leaded pipes as they were replaced. They are easy to recognise by their unusual weight. However, lead and most of its compounds are today considered to be highly toxic. Lead is a potent neurotoxin that over time accumulates in bone and soft tissues. Nonetheless, because of its low reactivity and solubility, lead poisoning usually only occurs in cases when the lead is dispersed and after long term exposure.

Lead acetate is one of the main active ingredients in progressive hair colorants such as Grecian formula, GreyBan and Youthair. It is valued due to its ability to change the colour of your white hair gradually and unnoticeably. Like lead, it is toxic, although it has been used for centuries as a wine sweetener. Since the beginning of the 1980s, lead has been withdrawn from many applications, such as gasoline, paints, pipes, etc., and in the last decade lead compounds such as lead acetate have become the target of growing attention. Lead acetate has been banned from hair dyes in several counties of the European Union and in Canada but there is no universal ban within the EU, let alone on a larger scale. However, lead-based hair dyes continue to be available in shops in most countries in the world.

In one recent study, conducted in the US, people using lead acetate-containing hair colorant were monitored but no absorption of lead into their blood stream was registered. Therefore, it was concluded that lead acetate-based hair dyes can remain in use but the concentration of lead acetate may not exceed 0.6%. Most of the currently available hair dyes contain a maximum of 0.4% of lead acetate. In spite of that, these lotions may not be applied on facial hair or cut scalp and if redness or inflammation appear their use must be discontinued. It is obvious that you should wash your hands after applying them.

As the toxicity of lead has become more apparent in recent years and it is even suspected of being carcinogenic, bismuth has become its increasingly important substitute. Following a ban on sales of lead-containing hair dyes in some countries, the products affected have been reformulated to include bismuth citrate. Bismuth, like lead, also happens to be a heavy metal but it is considered to be much less toxic and is not believed to be carcinogenic. Nevertheless, the same careful handling is required when applying bismuth-based hair colorants as with lead-based products.