Scientists and health advocates slammed a new state report that concludes residents of St. Charles County are not at higher risk of developing leukemia due to radioactive waste stored at Weldon Spring.

The authors of the report diluted the data by looking at too many ZIP codes, made no correction for population growth in St. Charles County and didn't study other types of cancer known to have links to radiation, said Robert Criss, a Washington University geochemist who studies contamination of groundwater in Missouri river basins.

"I'm unconvinced by their report, and I put it in the category of pretty shoddy work," Criss said. "They've massaged and manipulated data, and when people do that it sets off my alarm bells. It might be that everything's fine, but they've not convinced me they've studied it well."

The most recent report's authors — Shumei Yun and Philomina Gwanfogbe of the Missouri Department of Health and Senior Services and Chester Lee Schmaltz of the Missouri Cancer Registry — declined to answer questions about their work, according to Gena Terlizzi, health department spokeswoman. The department's director, Margaret Donnelly, did not return several phone messages.

The report, a follow-up to a 2005 report on leukemia cases and deaths in St. Charles County, was posted on the department's website in December and available only through a search. The department received no public input and gave no notification to residents of the area.

"When you have something like this you don't hide it; you at least let people know because they paid for it, especially people in the affected areas," said Bob McCarty, who lives in the county and writes a political blog. "I'm not an environmentalist. I've never hugged a tree. If it's all good, so be it, but the one thing they need to do is communicate better."

The Weldon Spring site was contaminated through the production of explosives during the war effort of the 1940s and by the processing of uranium by the Mallinckrodt chemical company in the 1950s and 1960s.

About 3,500 people worked on atom bomb production at various sites in the St. Louis area, and many have since died of cancers tied to radiation exposure.

By the 1980s, water samples from at least seven wells near Weldon Spring were contaminated by radiation, according to government testing. The government's cleanup efforts ended in 2001 with a 42-acre site at Weldon Spring that contains 1.5 million cubic yards of radioactive material.

The latest Weldon Spring cancer report looked at leukemia incidence and death rates for the five ZIP codes 63301, 63303, 63304, 63366 and 63376 between the years of 1996 and 2004.

The choice of ZIP codes "leads to a great dilution of any possible problems that would have arisen with the site," Criss said. "They've included ZIP codes that are way north of I-70."

The report could also have been more useful if the data were separated out for each ZIP code, Criss said.

"It's unacceptable that they do not have those tables in there, you know they have those data," he said.

Criss also criticized the report for calculating cancer rates based on the 2000 census, when the population in St. Charles County was much greater than in the 1960s when the threat of chemical exposure was highest.

In the report, the number of leukemia deaths for residents older than 65 rated significantly higher than average. There were 151 deaths in that age group from 1996 to 2004, compared with an expected 121 deaths.

Denise Brock of O'Fallon, Mo., works with former Mallinckrodt workers as an ombudsman for the National Institute for Occupational Safety and Health.

"I deal with the workers who were employed at Weldon Spring and those workers are very, very ill," she said. "I don't see just leukemia, I see brain cancer, I see lots and lots of lung cancer, esophageal cancer, tongue cancer, pancreatic cancer."

Brock questioned why the report compares St. Charles County leukemia rates with the rest of Missouri, instead of the U.S.

"Mallinckrodt left a legacy of waste all across the state of Missouri," she said.

Leukemia was chosen as the focus of the study because of "historical community concerns," according to Terlizzi, the health department spokeswoman.

The data used in the report were collected by the Missouri Cancer Registry, which is co-sponsored by the state health department and receives information from hospitals, nursing homes, pathology labs and other sources when Missouri residents are diagnosed with cancer in or out of the state.

"The department of health is very open about responding to reports of excess cancer and never wants to have any environmental hazard that is there to be ignored," said Jeannette Jackson-Thompson, the registry's director.

Jackson-Thompson said she did not have permission from the state to talk about the Weldon Spring report, but said, in general, cancer rates at the ZIP-code level are not publicly available to protect patient privacy.

"I could go to jail," she said. "It's not that we're trying to hide something, we're trying to protect confidentiality and give you accurate information."

Jackson-Thompson cited a 2008 investigation of a cluster of 68 brain tumors around Cameron, in northwest Missouri, which residents thought could be linked to a former insulation fiber plant.

Federal and state environmental officials concluded there was no health risk and the cancer rates were not abnormal.

"A lot of agencies wasted a lot of time and resources trying to find something that didn't exist," she said. "In an election year, somebody jumped in and started an inquiry when there was nothing to be inquired about."