An environmental organization says an 11-month-old state Department of Environmental Protection report, which found little risk of radioactivity exposure from shale gas drilling and development, is incomplete, inaccurate and invalid, and should be redone. According to a 25-page review released last week by the Delaware Riverkeeper Network, the DEP study of technologically enhanced naturally occurring radioactive materials - TENORM - brought to the surface by the shale gas drilling industry did not accurately measure the radioactivity levels of water, sludge and rock cuttings at drill sites and landfills, and minimized the risk of exposure to the public, drilling industry workers and the environment.