Although its risks have long been known, synthetic forms of henna paste that contain harmful chemicals continue to be used for body art by women, senior health officials said in the capital on Wednesday. Warning that these synthetic pastes, especially black henna, have suspected carcinogenic effects, they urged women to apply only natural henna free from harmful additives. \"We have found that dry, raw henna tends to be the safest, especially as hazardous chemicals cannot be added to it easily,\" Khalifa Al Rumaithi, acting director of public health at the Municipality of Abu Dhabi City, told Gulf News. \"Women should therefore purchase the raw henna powders and supervise the preparation of the paste, even when applying henna at a beauty parlour. They should also only purchase from trusted manufacturers who list all the ingredients on the container,\" he added. Henna, a paste made from grinding dry leaves of the Lawsonia inermis or mignonette tree, has long been used for temporary tattoos and body art, and its use is particularly prominent during festivals and celebrations. In the capital, henna is sold both as a raw powder as well as a paste contained in tubes across supermarkets and beauty parlours.