About: http://webisa.webdatacommons.org/35265513

Property	Value
http://www.w3.org/1999/02/22-rdf-syntax-ns#type	http://www.w3.org/ns/prov#Entity
http://www.w3.org/ns/prov#value	They can be produced from exposure to the sun, x-rays, tobacco smoke, car exhaust and other environmental pollutants.
http://www.w3.org/ns/prov#wasQuotedFrom	themetaarts.com