Science / Medicine : Dioxin’s Link to Cancer

A study of more than 5,000 chemical workers has uncovered new evidence suggesting that dioxin, a substance found in the defoliant Agent Orange, may cause some cancers but not the types of cancer commonly associated with the chemical.

The study, conducted by the National Institute for Occupational Safety and Health and published last week in the New England Journal of Medicine, is not expected to resolve the longstanding controversy over the health effects of dioxin.

Some Vietnam War veterans said they suffered health disorders from the dioxin in Agent Orange, used to defoliate areas where Viet Cong guerrillas hid, and filed a class-action suit against the herbicide manufacturers for compensation.

The Journal study reported that among workers exposed to dioxin for a year or more, researchers found a ninefold increase in risk of soft-tissue sarcoma, a 42% increase in cancers of the respiratory tract and a 46% increase in all cancers compared to the general population. But because the actual number of cancers was small, the results may have been the result of statistical flukes, researchers said. However, they added, the results “must be taken seriously as a flag of a probable human risk.”