BRIDGETON, Mo. (KSDK) - Newly uncovered documents show radioactive waste may have contaminated areas outside the West Lake Landfill in Bridgeton.

Soil samples taken in 2005 by the Missouri Department of Natural resources found at least three places along St. Charles Rock Road with unusually high levels of Thorium 230, a radioactive isotope that has been linked to certain types of cancer.

Thorium 230 does occur naturally. A spokesman for the St. Louis Army Corps of Engineers tells NewsChannel 5 the isotope is usually found in north St. Louis County in average levels of 1.5 pCi/g. Three soil samples collected by the DNR found areas with 8.81 pCi/g, 5.41 pCi/g and 4.41 pCi/g respectively.

While the levels are considerably higher than what is naturally occurring, experts say they do not pose an immediate threat to human health.

The Army Corps of Enigneers' Formerly Utilized Sites Remedial Action Program is currently working to remediate other radioactive sites in the St. Louis area. A spokesman says Thorium 230 would have to be found in levels of 14 pCi/g or higher before FUSRAP would move in to clean up the area