their are chemicals in holi colours:
Green colour is obtained from copper sulphate -which may cause allergies in eye or even temporary blindness.
Purple is obtained from chromium iodide - which may cause bronchial asthma or other forms of allergy.
Silver is obtained from aluminum bromide - a known carcinogenic.
Black is obtained from lead oxide - may cause renal failures or learning disability.
Red is obtained from mercury sulphite - may cause skin cancer or Minamata disease (mental retardation, paralysis, impaired vision...)
Shiny Colours are a result of powdered glass being added to the colours.