Tanning processes largely differ in which chemicals are used in the tanning liquor. Bronzers are a temporary sunless tanning or bronzing option. DHA is primarily used as an ingredient in sunless tanning products. Oak bark is also rich in tannin, and is used by tanners for tanning leather. It is also used in specialist medical care lamps for skin tanning and disinfection. Levels in blood are higher in frequent uses of tanning salons. The ultraviolet radiation from tanning beds increases the risk of melanoma. Sunburns associated with indoor tanning can be severe. This is the physiological purpose of sun tanning. Barker has had several mild bouts with skin cancer, a result of his frequent tanning. Health Canada recommends against the use of tanning equipment. Tannins are an important ingredient in the process of tanning leather. However, there are risks to using tanning beds. Textile, leather tanning and food processing plants are plentiful. Private ownership of tanning beds is permitted.