At least two dozen northwest Missouri landowners have filed a lawsuit against the former and current owners of a St. Joseph tannery that provided chromium-tainted sludge for use as fertilizer on their farm ground.

In a suit filed Thursday in Buchanan County Circuit Court, the plaintiffs accuse Prime Tanning Corp., which owned the tannery until March, and National Beef Co., the new owner, of causing damage to their farmland by providing the sludge and failing to warn property owners that it contained chromium.

The plaintiffs also are suing the Milwaukee-based chemical company Elementis LTP, which claims to be the world’s largest producer of chromium chemicals, and the Kansas City engineering firm Burns and McDonnell, which designed the system to produce the fertilizer.

Earlier this year, the tannery came under investigation to determine whether sludge provided to farmers in four northwest Missouri counties could have caused a cluster of brain tumors in the Cameron area.

The tannery had been giving sludge to farmers since 1983. Environmental studies conducted this year in three of the four counties found trace amounts of hexavalent chromium, a know carcinogen also known as chromium 6.

But investigators this summer said the chemical levels were not high enough to threaten human health.

Several other lawsuits have been filed against Prime Tanning and National Beef Leathers since April alleging the sludge caused brain tumors.

The latest suit claims the plant’s attempted conversion of chromium 6 into trivalent chromium, which is a neutral chemical often used in the process of tanning hides, failed and the chromium reverted to its previous, more dangerous form.

Because of the contamination, the plaintiffs said they will have to clean up their land.

Chromium 6 is the same carcinogen that led to a $333 million settlement from Pacific Gas & Energy in 1996 for exposing a California town to the chemical. The case spawned the movie “Erin Brockovich,” about a woman who fought the utility and helped with the settlement.