Prime Tanning and others are disputing claims that chromium 6 is to blame for an outbreak of tumors.

Environmental activist Erin Brockovich told a group in Cameron, Mo., that sludge from Prime Tanning spread on farm fields could be linked to brain tumors and other health problems in the area. Two residents filed a lawsuit against the company on Wednesday.

Prime Tanning suspended land application of sludge pending the outcome of its investigation. The company takes the allegations seriously and will cooperate with state and federal agencies, Grover Elliott, vice president and chief financial officer, said in a statement Thursday.

“Based on our preliminary investigation, we believe there is no basis for the claims made in the litigation,” Mr. Elliott said.

The leather tannery on Stockyards Expressway in St. Joseph appeared to be in operation Thursday. The company was recently purchased by National Beef Packing.

The charges center around a practice where sludge from Prime Tanning was given to farmers to spread on crop fields. The material, which contains hair, fat and proteins from the tanning process, adds nutrients to the soil.

The lawsuit, filed by William Kemper of Cameron and Janet Lasher of Gallatin, claims that hexavalent chromium, also known as chromium 6, was used by Prime Tanning to remove hair from hides. Chromium remained in the sludge, became airborne and exposed residents to a known carcinogen, the lawsuit states.

Defendants in the case include National Beef Leathers Co., Prime Tanning and Rick Ream, identified as a Prime Tanning employee who oversaw land application.

Mr. Kemper’s wife died of a brain tumor in May 2008. Mrs. Lasher was diagnosed with lung cancer in February.

Chromium 6 has been determined to cause cancer of the lungs and stomach, according to the Centers for Disease Control and Prevention.

But chromium 6 is not used in the tanning process, says a scientist from the Leather Research Laboratory at the University of Cincinnati. Dr. Nicholas J. Cory, director of the lab, was referred to the media by Prime Tanning.

In an e-mail to the News-Press, Dr. Cory said only chromium 3, which is a safe product, is used to tan hides. The lab’s Web site at www.leatherusa.org, states that chromium 3 may be converted to chromium 6 in the industrial process.

Others see problems linking an apparent outbreak of tumors in Cameron with the sludge. Bob Kelly, agriculture business specialist with Buchanan County Extension, said the product has been spread on land in Andrew, Buchanan, Clinton and DeKalb counties for many years.

“Why aren’t we seeing more of this in a widespread area if this is the case?” Mr. Kelly said.

He said when farmers receive the sludge, it should be tested to determine it is safe to use. The soil is tested to determine how much can be applied to raise a crop.

Based on research and technology available, the sludge appears to be safe, Mr. Kelly said, and a responsible way to reuse material instead of sending it to a landfill.

“For years we have used it as a nutrient and haven’t seen problems until this perceived problem,” he said.

Prime Tanning has not had a history of environmental violations, said Andy Clements, assistant director of public works for the city of St. Joseph.

“They’ve been a very good industry in St. Joe,” Mr. Clements said.

Sludge from the city’s own wastewater treatment facility is applied to fields that the city owns and leases to farmers, Mr. Clements said.

Prime Tanning has a primary wastewater treatment facility at its factory.

Dr. Cory said the sludge from Prime Tanning contains organic nutrients, such as manure and proteins, and calcium hydroxide, which is known as lime and is applied to soil to make it less acidic.

“Chromium 6 is not added to the soil,” he said. “If it were, it would rapidly be converted to harmless chromium 3 by the extremely high organic content.”

Mr. Kelly said the sludge is applied to the same fields every two to three years.

“I understand the desire to want to know what’s causing the problem, but I think we’re clutching at straws here,” he said.

Susan Mires can be reached

at susanm@npgco.com.