some piercers, particularly in the United Kingdom and Europe. The anaesthesia may be topical or injected. Piercers and other non-medical personnel are not legally permitted to administer anaesthetics in the United States. Risks associated with body piercing Body piercing is an invasive procedure with risks. In a 2005 survey of 10,503 persons over the age of 16 in England, complications were reported in 31% of piercings, with professional help being necessary in 15.2%. 0.9% had complications serious enough to require hospitalization. Some risks of note include: Allergic reaction to the metal in the piercing jewellery, particularly nickel. This risk can be minimized by using high quality jewellery manufactured from titanium or niobium or similar inert metals. Metal piercing jewellery puts metal in contact with damaged skin, increasing the risk of developing a metal allergy; this is thought to be why such allergies are more common in women. Infection, bacterial or viral, particularly from Staphylococcus aureus, group A streptococcus and Pseudomonas spp. Reports at the 16th European Congress of Clinical Microbiology and Infectious Diseases in 2006 indicated that bacterial infections are seldom serious, but that ten to twenty percent of piercings result in local benign bacterial infection. The Mayo Clinic estimates 30%. Risk of infection is greatest among those with congenital heart disease, who have a much higher chance of developing life-threatening infective endocarditis, hemophiliacs and diabetics, as well as those taking corticosteroids. In 2006, a diabetic woman in Indiana lost a breast due to an infection from a nipple piercing. Viral infections may include hepatitis B, hepatitis C and, potentially, HIV, although as of 2009 there had been no documented cases of HIV caused by piercing. While rare, infection due to piercing of the tongue can be fatal. Higher prevalence of colonization of Candida albicans was reported in young individuals with tongue piercing, in comparison to non-tongue-pierced matched individuals. Excess scar tissue, including hypertrophic scar and keloid formation. While piercings can be removed, they may leave a hole, mark or scar. Physical trauma including tearing, friction or bumping of the piercing site, which may cause edema and delay healing. The risks can be minimized by wearing properly sized jewellery and not changing it unnecessarily, by not touching the piercing more than required for aftercare, and by being conscious of environmental factors (such as clothing) that may impact the piercing. Oral trauma, including recession of gingival tissue and dental fracture and