In the same federal courthouse here where two class-action lawsuits were filed against Union Carbide Corp., seeking $17.5 billion in damages as the result of the deaths from methyl isocyanate at its plant in Bhopal, India, another chemical giant, Monsanto Co. is on trial, accused of exposing its workers to a variety of toxic substances.

The 176 plaintiffs -- Monsanto retirees, employes or their relatives -- contend that exposure to harmful chemicals at Monsanto's Nitro, W.Va., plant over the years caused bladder cancer, heart and kidney ailments and skin disease, resulting in permanent injury and premature death.

"For years," according to workers' lawyer, W. Stuart Calwell, "there were no regulations, federal or state, and the chemical plants polluted our rivers and air with 300 different chemicals." Calwell said the workers "didn't get sick on any given day, but gradually they got sicker and sicker as the result of day-to-day exposure" to the substances.

The lawsuits were brought under West Virginia's wrongful-death act.

Among the chemicals formerly produced at the plant are para-aminobiphenyl (PAB), which causes bladder cancer, and 2,4,5-trichlorophenoxyacetic acid (2,4,5-T), suspected of causing a variety of liver and heart ailments. The plant still produces chlorinated phenols; chlorodibenzo-para-dioxin, carbon disulfide, hydrogen sulfide, analine and chlorine, all of which, the plaintiffs allege, are harmful to workers. Monsanto lawyer Charles Love said the accusations "aren't true, and if they are, it was not deliberate or intentional."

He said Monsanto stopped making PAB in 1955, shortly after discovering its carcinogenic effect, and that employes who contracted bladder cancer as a result "are being taken care of by Monsanto."

In an explosion at the plant on March 8, 1949, a number of workers producing 2,4,5-T were exposed to what later was thought to be dioxin. As a result, those workers contracted a skin condition called chloracne. Love said it was not until 1957 that a German scientist discovered that dioxin was a byproduct of making 2,4,5-T, and no one knew how to measure it until the mid-1960s. Calwell said Monsanto should have stopped making 2,4,5-T at the time of the accident, and certainly after 1957, but instead produced it until 1969.

The trial began in June and is expected to run through March.