Effect of dioxin-related compounds on oral pigmentation in patients affected by the Yusho incident

Toxins such as polychlorinated biphenyls (PCBs) and dioxins dramatically affect patients even decades after exposure. Patients with Yusho, a condition caused by exposure to PCBs and dioxins, have diverse mental and physical complaints, even though it is almost 50 years since the Yusho incident. Oral pigmentation is one of the major symptoms in Yusho patients.

A total of 183 participants in the Yusho health study were examined. Oral examinations, including recording the prevalence of oral pigmentation, were performed by two oral surgeons. Demographic and clinical characteristics, including blood concentration of PCB and 2,3,4,7,8-pentachlorodibezofuran (2,3,4,7,8-PeCDF), which are the major causes of Yusho, were obtained from the results of recent surveys conducted by the Yusho Study Group.

The mean serum PCB and 2,3,4,7,8-PeCDF levels of the 183 Yusho patients were 1.59 ± 1.25 ppb and 29.0 ± 42.9 pg/g lipid, respectively. There was a significant correlation between the levels of PCB and 2,3,4,7,8-PeCDF (r = 0.64, p < 0.01). The rate of oral pigmentation in Yusho patients (25.7%) was significant higher than among potential victims of Yusho (13 of 183, 7.1%) (p < 0.05).

The prevalence of oral pigmentation was still significantly higher in Yusho patients, even 50 years after exposure, although blood PCB levels have decreased in that time.