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What Is Yusho Disease? – Full Analytical Study about the Disease

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What Is Yusho Disease – In 1968, a mass food poisoning incident occurred in western Japan, involving more than 1,800 patients. The incident was hailed as yusho (oil sickness in Japanese) because it arose from the ingestion of rice bran oil contaminated with polychlorinated biphenyls (PCBs), polychlorinated dibenzofurans (PCDFs), and other dioxin-related compounds. With Yusho patients suffering from various symptoms. Including comedones, acneiform rash, and pigmentation of the conjunctiva, skin, and gums.

After the Yusho Incident, a similar incident of mass food poisoning, Yucheng (oil sickness in Chinese), occurred in central Taiwan in 1979, also caused by ingestion of cooking oil contaminated with PCBs and dioxins.  Therefore, the Yusho and Yucheng incidents use to assess the long-term adverse health effects associated with PCB and PCDF ingestion.

Our 40-year follow-up training of the Yusho cohort showed increased mortality from all cancers, including lung and liver cancer in males. The Yusho and Yucheng cohorts also presented higher mortality from all cancers, lung cancer, heart and liver disease in men, and liver cancer in women. Additional longer-term research to determine whether cancer risk remains high could improve our understanding of the disease, but a 50-year follow-up of Yusho patients has not yet report.

What Is Yusho Disease – Data Sources

The Yusho Registry began in 1968, and Yusho patients for this report were followimg up until December 2017 or until death. For patients misplaced to follow-up, vital status data collect on the last day they recognize to be working. In Japan, registering yusho data is required under the Yusho Patient Policy Comprehensive Promotion Act. And it is considered indifferent and complete in various prefectures and years.

We excluded 654 subjects registered after 1977 who had not diagnose with a yusho since the beginning of the yusho incident. Because the yusho diagnostic criteria revise several times after the yusho incident. And also, these factors could lead to the possible affected patient’s omittes. Who died before the official registration period and may introduce bias. After excluding these cases, 1664 subjects met the inclusion criteria. None of the subjects was enrolled in a specific medical surveillance program for early detection of PCB/PCDF-related diseases or received special treatment.

What Is Yusho Disease Background

In 1968, the Yusho incident led to accidental exposure to polychlorinated biphenyls (PCBs), polychlorinated dibenzofurans (PCDFs), and related compounds in Japan. This study updated the mortality risk in Yusho patients.


We obtained efficient cohort data for all Yusho patients over the period 1968-2017. We calculated consistent mortality ratios (SMRs) for all-cause and cause-specific mortality. Over a 50-year follow-up period compared to the general population in Japan.

Statistical analysis

Person-years at risk intend from the official registration date for each Yusho patient to the time of death or the end of follow-up, whichever recordes first. We chose the official registration date as the start date for determining person-years. Because it was difficult to identify target subjects at initial exposure. Contaminated oil was widespread in western Japan, and exposure to PCBs. And PCDFs could not be determines at the time of the Yusho incident.

Therefore, some potential person-years could lose between the date of exposure and the date of registration. For patients not available for follow-up, person-years censore to the last date they known to stay alive. Person-years were stratified by sex, 10-year age groups, and 10-year calendar periods. The predictable number of deaths from all causes and cause-specific diseases calculate using life-table methods. And also, using reference mortality rates for the general Japanese population by age attained and calendar period. National sex-specific mortality rates for 10-year and 10-calendar-year intervals use as reference figures.

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