Serum dioxin and peripheral neuropathy in veterans of Operation Ranch Hand

We studied whether exposure to Agent Orange and its contaminant, 2,3,7,8-te trachlorodibenzo-p-dioxin (dioxin), during the Vietnam War is related to pe ripheral neuropathy. The index subjects were veterans of Operation Ranch Ha nd, the unit responsible for aerial herbicide spraying in Vietnam from 1962 to 1971. We report peripheral nerve function assessed in 1982, 1985, 1987, 1992 and 1997, nerve conduction velocities measured in 1982, and vibrotact ile thresholds of the great toes measured in 1992 and 1997. We assigned eac h Ranch Hand veteran to one of three exposure categories named "background" , "low" and "high", based on his serum dioxin level. Other than the bilater al vibrotactile abnormalities, we consistently-found a statistically signif icant increased risk of all indices of peripheral neuropathy among Ranch Ha nd veterans in the high exposure category in 1997, and a statistically sign ificant increased risk of diagnosed peripheral neuropathy, incorporating bi lateral vibrotactile abnormalities of the great toes, in the high category in 1992. Restricting to the enlisted veterans did not alter these results. Cautious interpretation of these results is appropriate until the relations hip between pre-clinical diabetes mellitus and peripheral neuropathy is fur ther evaluated in future examinations. Published by Elsevier Science Inc.