Officials in North Carolina Gov. Pat McCrory's administration are telling a string of misleading half-truths about the safety of well water near Duke Energy coal ash pits containing a cancer-causing chemical and are responsible for any resulting fear and confusion, a state toxicologist said after being attacked by state officials.

Toxicologist Ken Rudo comments came in a statement issued through his attorney a day after North Carolina's state public health director Dr. Randall Williams and Department of Environmental Quality Assistant Secretary Tom Reeder on Tuesday blamed Rudo for sowing fear about dangerous chemicals near Duke Energy sites with "questionable and inconsistent scientific conclusions."

The high-ranking state environmental and health officials targeted Rudo individually as the creator of a too-severe standard for the presence of hexavalent chromium in groundwater. The standard — a one chance in a million that people drinking contaminated water could develop cancer over a lifetime — was set by the state agencies before warning letters were issued last year to about 330 neighbors of Duke Energy coal sites. Officials this year decided that standard was too high. Williams and Reeder declared the water safe to drink in a March letter to well owners.

Rudo said in a statement first provided to The Associated Press that the cancer standard was set as required by a state law passed after the third-largest spill of toxic coal ash in U.S. history burst from a Duke Energy coal-ash pit in 2014. The law also launched groundwater testing for hexavalent chromium and other contaminants around all 14 of the company's North Carolina coal-burning plants, something that wasn't required previously.

More on this...

The state Department of Health and Human Services, where Rudo has worked for nearly 30 years, initially applied a far looser standard — a level for public water supplies set by the U.S. Environmental Protection Agency in the 1990s and required by a 2008 state law, Rudo said. But state law dictated a one-in-a-million cancer risk, so that's what health and environmental agencies calculated and eventually agreed upon, Rudo said. State agencies were required to follow the law, Rudo said, and he checked the calculations setting the stricter standard with federal health authorities based on the latest studies of cancer risk.

"This consensus, regarding what health protective values to use to protect the well water of the NC residents adjacent to the coal ash ponds, and how to communicate these to folks, was what Dr. Rudo followed," the scientist's statement said, "based on specific instructions from his superiors at DHHS."

But if the 2015 standard for hexavalent chromium were applied evenly, it would mean 900,000 other North Carolinians depending on well water would be urged against using it, Williams and Reeder said Tuesday.

Rudo said that's what the science shows.

"Dr. Rudo's request to extend this protection to all well water was denied, and is still denied," the statement said.

Coal ash is the byproduct of burning coal to generate electricity. Duke Energy denies its coal ash pits are the source of the contamination, noting hexavalent chromium occurs naturally as well as in industrial byproducts like coal ash.

McCrory worked for Duke Energy for nearly three decades prior to his election.