FUKUOKA -- A massive food poisoning incident caused by tainted rice bran oil more than half a century ago in Japan may still be affecting the health of not only patients but also their children and grandchildren, a survey by a research team has found.
The poisoning came to light in 1968, after rice bran oil produced by Kanemi Soko K.K. in Kitakyushu became contaminated with polychlorinated biphenyls during the production process and dioxins were generated due to heating, affecting about 14,000 people. In the early days of the incident, babies with dermatological abnormalities, or so-called "black babies," were born.
The research team, consisting of state-commissioned doctors, conducted a survey of next-generation victims of symptoms of the Kanemi oil poisoning, commonly referred to as "Yusho disease," in the fall of 2021. An interim report on their findings notes that the offspring of patients are complaining of symptoms similar to those of patients in many cases.
Parties concerned are calling for expanded relief measures for patients and their offspring, including revising the criteria for recognizing health damage from the poisoning, one of the largest food pollution cases in Japan.
"Up until now, it wasn't even known if the next generation was suffering from the disease, but I now know that there are many people with symptoms similar to mine," said Megumi Shimoda, 32, a resident of Isahaya, Nagasaki Prefecture. Shimoda's mother was recognized a Yusho disease patient.
Shimoda says she was surprised to see the interim report released in February, as it showed that about 40% of the 388 respondents had subjective symptoms of fatigue or headaches.
Since her childhood, Shimoda has suffered from headaches and stomachaches of unknown causes, as well as sudden nose bleeds. She grew suspicious about the connections between her symptoms and Yusho disease, and has undergone health checkups for the disease held by the local government almost every year since she was 17.
However, as to the dioxin concentrations in her blood samples are below the designated threshold, she has not been recognized as a Yusho disease patient. She worries that she might become unable to work someday, and has continued to visit the hospital.
Having cooperated in the latest survey, Shimoda said, "I want the criteria to be revised so that those who wish to be recognized as patients can be certified as such. I hope the survey will lead to authorities reaching out to next-generation patients who have yet to raise their voices."
The patients who suffered the poisoning firsthand are also deeply concerned about their children. It had already been known that there were children and grandchildren of patients who had complained of symptoms similar to those caused by Yusho disease.
A woman in her 70s living in the city of Fukuoka is one of those parents. She originally hails from the Nagasaki Prefecture city of Goto, where damage from the Kanemi oil poisoning was concentrated. She asked her children living in different parts of the country to respond to the survey, in the hope that "it will lead to them being recognized as patients."
Her children have dermatological conditions and other symptoms, and visit multiple hospitals, leaving work early to do so. The woman said, "It is hard to see my children suffering and working while feeling indebted to their workplaces. I think, 'If only I hadn't ingested the tainted oil,' and my regret keeps growing."
Tadashi Fujino, a doctor at Kikuyo Hospital in Kumamoto Prefecture, who has long examined Yusho disease patients, praised the survey, saying, "It is helpful that it has uncovered the actual situation." He underscored the need to further investigate the true picture of the damage, adding, "We must not forget that there are people who have yet to be recognized as patients, as well as patients in the next generation."
Gaku Tsuji, 45, head of the research team behind the survey, commented, "The number of subjective symptoms reported by respondents was extremely high. We've learned that most of them have health problems of some kind or the other."
Moving forward, the research group intends to compare and analyze the health conditions between certified Yusho disease patients and general people. The team is expected to compile a final report around the summer of 2023 by incorporating the results of health checks on the survey respondents in April or later, and report it to the Ministry of Health, Labor and Welfare.
Tsuji said, "It is necessary to clarify the characteristics of health damage among second-generation patients and create new recognition criteria that will lead to relief to them."
(Japanese original by Keiko Yamaguchi, Kyushu News Department)