Hair care is a hygienic treatment and is supervised by the Local Environment and Public Health Committee in the municipality. According to the Swedish Environmental Code, hairdressers as all practitioners are required to take measurements to protect the environment and public health. In hygienic treatments hazards may arise from inadequate hygiene practice which spread infection. Hazards may also arise from the use of hair care products such as permanent wave solutions, bleaches and hair dyes. Some hair dye components are known to cause contact allergy, mostly in hair dressers who are exposed professionally but also in some cases in consumers. Bleaches increase the risk of occupational asthma in hairdressers. Some studies have shown an increased risk of cancer in hairdressers and possibly also in consumers. The use of cosmetic and hygienic products also affects the environment. Some components, e.g. surfactants, are hazardous to aquatic organisms, even though the contribution from hair care products is relatively small. Some hairdressers perform ear piercing. All activities that penetrate the skin involve a risk of infection. There is also a risk of developing a nickel allergy if the earrings are not nickel free. In Sweden, due to recently changed legislation, hairdressers no longer need to notify the Local Environment and Public Health Committee before starting a practice. The changes also mean that the rules about documentation of the measurements practitioners need to take to protect public health are less clear. The changes have made the supervision of hairdressers harder for the Local Environment and Public Health Committee.