4. Use of metals

Lead mercuride was frequently applied to brighten the skin since the Wei and Jin dynasties (AD 220-420). The compound caused death of melanocytes, a type of skin cell responsible for pigmentation of the skin, hence brightening the skin color. However, extended use of large quantities of lead on skin causes lead poisoning. In light cases, skin becomes more coarse; in severe cases, it causes death.

Ancient Chinese people were not unaware of the toxicity of lead. Compendium of Materia Medicaclearly documents the harm of lead. But its speedy effect in whitening the skin still lured many young women in their pursuit of beauty over health.

Overdosing on lead in cosmetics remains a problem today. Even after thousands of years, human nature remains difficult to change.