Long-term effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin on the peripheral nervous system. Clinical and neurophysiological controlled study on subjects with chloracne from the Seveso area.

This work was set up to investigate the possible presence of peripheral nervous system involvement as a long-term effect of the exposure to dioxin in 152 subjects with chloracne from the Seveso area; 123 age- and sex-matched subjects living in nearby towns with similar environmental pollution formed the control group. The accident in Seveso took place in July, 1976, and this study was carried out from October, 1982, to May, 1983. Although a peripheral neuropathy was not found in any of the subjects, a significant increase of the number of individuals presenting at least two bilateral clinical signs (p less than 0.05) or one abnormal electrophysiological parameter (p less than 0.02) was found in the Seveso group. Principal component analysis did not show any subdivision between these two groups. The Fisher approach to discriminant analysis reveals a clear subdivision between the group of the most exposed subjects and randomly selected subgroups of control subjects. In conclusion, clinical and electrophysiological signs of peripheral nervous system involvement occur with a statistically increased frequency in the Seveso population 6 years after the accident, although a peripheral neuropathy was not evident in any of the chloracne patients using the World Health Organization diagnostic criteria.