Yushō disease

Diagram of deodorization tower
The PCB that was used as the heating medium leaked from the pipes and mixed into the rice bran oil.

Yushō disease is a severe mass poisoning event resulting from the contamination of rice bran oil with polychlorinated biphenyls (PCBs) and polychlorinated dibenzofurans (PCDFs). The incident, which transpired in northern Kyūshū, Japan, in 1968, is one of the hallmark episodes in environmental medicine, highlighting the dangers of industrial chemicals when they inadvertently enter the human food chain.

History

In January 1968, rice bran oil manufactured by the Kanemi Company in Kyushu became adulterated with PCBs and PCDFs during its production process. The contamination arose when the oil, during its deodorization phase, was heated using PCB circulating through pipelines. Pipe damages led to PCB leakage into the rice bran oil. This tainted oil was subsequently sold for cooking purposes to consumers and to poultry farmers as a feed enhancer. Between February and March of that year, poultry farmers began to report extensive bird deaths, with the cause identified as respiratory difficulties. The total death toll reached 400,000 birds. Human exposure soon became evident when about 14,000 individuals who had consumed the tainted oil exhibited symptoms. The aftermath witnessed over 500 fatalities.

Clinical Manifestations

Patients affected by Yushō disease presented a range of symptoms:

• Dermal and ocular lesions
• Menstrual cycle irregularities
• Diminished immune responses
• Fatigue and headaches
• Persistent cough
• Distinctive skin ulcers

Furthermore, among the pediatric population, there were accounts of:

• Impaired cognitive development
• Neurological disturbances

Global Resurgence: Yu-cheng disease in Taiwan

Regrettably, a little over a decade after the Yushō tragedy, a strikingly similar incident occurred in Taiwan in 1979. Termed the Yu-cheng disease (Chinese: 油症; pinyin: yóuzhèng; Wade–Giles: Yu2 cheng4), rice oil was again the contaminant medium. This event reaffirmed the persistent dangers of PCBs and PCDFs, especially in children, with analogous symptoms being reported.

Scientific Exploration

Numerous animal studies have been conducted to demystify the mechanisms underlying the effects of PCBs and PCDFs. Findings illustrated that even minuscule amounts of PCBs have the potential to decimate fish and other wildlife populations. Consequently, these revelations prompted a significant reduction in the utilization of PCBs in industrial processes.

Other Global Episodes

Highlighting the global repercussions of toxic contaminants in the food chain, 2008 saw a dioxin contamination incident that sparked the Irish pork crisis, leading to a worldwide recall of Irish pork.

See also

• Four Big Pollution Diseases of Japan
• 2008 Irish pork crisis
• Seveso disaster

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