Pigmentation of the oral mucosa by PCB poisoning in Yusho patients

Toxins, such as PCBs, dramatically affect patients even decades after exposure. Although 40 years have passed since the accidental poisoning with polychlorinated biphenyl (PCB) in Western Japan in 1968, high concentrations of PCBs are still detected in the serum of the "Yusho" (oil disease) patients. In this study, an epidemiological examination was carried out to reveal the prevalence of the oral pigmentation and blood concentrations of PCBs and polychlorinated quaterphenyl (PCQ) in Yusho victims.

We performed a group examination of patients (Yusho victims) from 2004 to 2006, including 72 Yusho victims and 15 control subjects. The oral examination was performed by two oral and maxillofacial surgeons. The serum concentrations of PCB and PCQ were determined using gas chromatography; blood samples from Yusho victims were analyzed for PCB and PCQ by saponification in 1M NaOH ethanol solution, extraction with n-hexane column chromatography on silica gel, and then gas chromatography with electron capture detection.

The mean Yusho victim's serum PCB and PCQ concentrations were 3.3ppb and 0.9ppb, respectively. In controls, these were 0.7ppb and 0ppb, respectively. Oral pigmentation was observed in 24 out of 72 Yusho patients. In controls, oral pigmentation was observed in one out of 15 persons. Oral pigmentation was most frequently observed in the buccal mucosa, followed by gingival mucosa. The blood concentration of PCB in Yusho patients with oral pigmentations was significantly higher than that in Yusho patients without oral pigmentation.

These results indicated that PCB-related compounds may be responsible for the higher prevalence of oral pigmentation in Yusho victims, even though a long time has passed since the Yusho poisoning accident.