EPA’s "Study of the Risks Associated with Class I Underground Injection Wells" describes the:

• Current Class I UIC program
• History of Class I injection
• Studies of human health risks associated with Class I injection wells, which were conducted for past regulatory efforts and policy documentation

• Class I Underground Injection Control Program: Study of the Risks Associated with Class I Underground Injection Wells (PDF)(113 pp, 877 K, March 2001, 816-R-01-007)