<Tr> <Td> Full thickness (3rd - degree) </Td> <Td> Extends through entire dermis </Td> <Td> Stiff and white / brown . No blanching . </Td> <Td> Leathery </Td> <Td> Painless </Td> <Td> Prolonged (months) and incomplete </Td> <Td> Scarring, contractures, amputation (early excision recommended) </Td> <Td> </Td> </Tr> <Tr> <Td> 4th - degree </Td> <Td> Extends through entire skin, and into underlying fat, muscle and bone </Td> <Td> Black; charred with eschar </Td> <Td> Dry </Td> <Td> Painless </Td> <Td> Requires excision </Td> <Td> Amputation, significant functional impairment and in some cases, death . </Td> <Td> </Td> </Tr> <P> Burns are caused by a variety of external sources classified as thermal (heat - related), chemical, electrical, and radiation . In the United States, the most common causes of burns are: fire or flame (44%), scalds (33%), hot objects (9%), electricity (4%), and chemicals (3%). Most (69%) burn injuries occur at home or at work (9%), and most are accidental, with 2% due to assault by another, and 1--2% resulting from a suicide attempt . These sources can cause inhalation injury to the airway and / or lungs, occurring in about 6% . </P> <P> Burn injuries occur more commonly among the poor . Smoking and alcoholism are other risk factor . Fire - related burns are generally more common in colder climates . Specific risk factors in the developing world include cooking with open fires or on the floor as well as developmental disabilities in children and chronic diseases in adults . </P>

Where do 80 of all burn injuries occur
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