Persistent Blood Dioxins and Sensory Impairment Assessed by Quantitative Sensory Testing in 115 Yusho Patients...

Yusho patients continue to experience sensory symptoms such as pruritus and numbness even decades after dioxin exposure. However, objective assessment of long-term sensory impairment remains limited. Using a minimally invasive quantitative sensory assessment method, we conducted an exploratory investigation into the relationship between sensory thresholds and dioxin exposure in Yusho patients. Minimum perceived current (MPC) values were modestly higher in Yusho patients than in controls. Patients with pruritus or numbness tended to show lower MPC values than those without these symptoms, although correlations between MPC and pruritus and numbness visual analog scale (VAS) were not consistently observed. Although a weak positive correlation was observed between MPC and PCDF levels and a similar trend was noted in the categorical comparison, this association was attenuated after adjustment for age and sex. Importantly, the high-exposure group included a significantly greater proportion of women, who typically exhibit lower MPC values. These findings are consistent with persistent sensory impairment that cannot be fully explained by exposure intensity. This study provides valuable insight into the long-term health effects of chronic dioxin exposure.