PLANT CITY – A national expert in environmental medicine and toxicology calls the state health department’s recent investigation into cancer rates near Coronet Industries “meaningless” and “irrelevant.”

James Dahlgren, a clinical professor of medicine at the University of California at Los Angeles, has testified on behalf of plaintiffs in a number of lawsuits involving pollution- related illness, taking on corporate giants such as DuPont and Kerr-McGee.

Dahlgren’s research also helped secure a $333 million judgment in a case made famous by the hit film “Erin Brockovich.” Masry & Vititoe, the California law firm that employs Brockovich, is one of several representing local residents who blame Coronet for a variety of illnesses, including cancer.

Health officials on Thursday released the results of an analysis that concluded that eight types of cancer were no more prevalent in census tracts surrounding the phosphate processing plant than in the rest of the state. In fact, they were slightly lower.

“It is meaningless to do a census tract study if you are attempting to determine whether or not cancer in an individual was caused by pollution exposure,” Dahlgren said in a statement released Monday. “In fact, if you want to design a study to confuse the issue and not get results, you do exactly what the Florida Health Department has done here.”

State health officials and epidemiologists are aware of the limitations of a study conducted in a sparsely populated area with no clear route of exposure to contaminants.

Casting a wide enough net to include a statistically significant sample – in this case a 48-square-mile area around Coronet – means diluting the results with residents not likely exposed to the suspected source of pollution.

In the case of the yearlong Coronet inquiry, investigators have been looking at the phosphate processing plant as well as nearby abandoned landfills.

Environmental testing of water, air and soil has produced mixed results. The analysis of cancer rates is the latest piece in the puzzle being assembled in an effort to address widespread health complaints in communities near the century-old plant, which will close at the end of the month.

“Unquestionably there are some issues,” Hillsborough County Medical Director Doug Holt said. “If you go back and try to figure out individual cause and effect, this data will not tell you that.”

Coronet officials have maintained that there is no scientific evidence linking the plant to illness or disease in the community.

There are more than 1,000 cases reported to health departments each year where a group of people in a community are concerned about a source of pollution, according to Michael Thun, vice president of epidemiology and research for the American Cancer Society.

“Even the ones investigated extensively don’t provide answers,” he said.

A recent investigation into a childhood cancer cluster in the small town of Fallon, Nev., failed to turn up a cause, despite evidence of wells contaminated with arsenic and other toxins.

“In the case of Fallon, there was an extraordinary increase in leukemia – incredibly statistically significant,” Thun said. “What’s missing there is a clear explanation of why.

“It’s not that epidemiology is not a very strong tool, because it is,” he said. “But it is not well-equipped to provide answers in these situations.”

Epidemiology, the study of epidemic diseases, is an extraordinary tool in looking at strong risk factors, he said.

In cases of a single rare cancer linked to intense, prolonged exposure to a known contaminant, such as asbestos, radium, vinyl chloride and other carcinogens in the workplace, it has proved invaluable in identifying cancer-causing agents.

But the reality is that none of the tools currently available is likely to provide a clear link between the disease and the localized exposure in a community such as the one near Coronet, Thun said.

“The population is not large enough, and the tools are too crude.”

The approach used by health officials in Florida is one used across the country, he said.

“The limitation is it almost never satisfies people whose claim is not upheld by the analysis.

“These situations are almost uniformly frustrating and unsatisfying to everyone involved.”

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