Expensive shampoos used and sold at hair salons can cause allergic reactions and are also linked to cancer, a magazine has reported. A test of 26 shampoos sold at salons here showed that seven contained halogen organic compounds, which can cause skin allergies, the January edition of the German magazine Oeko-Test reported. Perfumes found in six of the shampoos could cause allergic reactions, it said. Diethylphthalate, which can affect the natural protection mechanisms of the skin, was detected in some of the products.