Chen-Chin Hsu

The Yu-cheng Rice Oil Poisoning Incident

As human beings, we hope to learn from past experiences and not repeat our mistakes. Unfortunately, 11 years after the Japanese Yusho incident (see Chapter 19), a similar tragedy happened in Taiwan in 1979. A Japanese-produced PCB mixture (Kanechlor 400, 500) was used as the heat-transfer medium in the process of deodorization and decolorization of rice oil by a rice oil company in central Taiwan. PCBs and their heat-degraded by-products, polychlorinated dibenzofurans (PCDFs), ter- and quaterphenyls (PCTs and PCQs), leaked into the rice oil and intoxicated 2000 people who had consumed the oil. The initial clinical symptoms consisted of acne, pigmentation of the nails and skin, and hypersecretion of the meibomian glands. Because the disease was caused by ingestion of rice oil, the syndrome was referred to as Yu-cheng (pronounced Yo-Jun), which translates to oil disease, and the exposed subjects were referred to as the Yu-cheng cohort.

Cognitive development in Yucheng children

We have been following up the biological and mental development of children exposed prenatally to polychlorinated biphenyls and their contaminants (Yucheng children). When we started this 12-year follow-up study in August 1985, 118 Yucheng children we assigned a non-exposed child matched by sex, age, locality of residence, mothers age, socio-economic status of the family. This article reports the cognitive aspect of the development of Yucheng children as compared to their matched controls. A consistent tendency which indicates that Yucheng children score lower in each kind of measurement tool at each age level has been observed. This seems to imply that congenitally exposure to PCBs and their contaminants has long-term adverse effects on the cognitive development of human being.

The immunologic evaluation of the yucheng children

The immunologic effects of in utero exposure to polychlorinated biphenyls (PCBs)/polychlorinated dibenzofurans (PCDFs) were evaluated in the Yucheng children in this study. The study subjects consisted of 105 Yucheng children and 101 control children. The Yucheng children were born, between July 1978 and June 1987, to women who had exposed to high dose of PCBs/PCDFs through consumption of contaminated rice bran oil in 1978-1979. These children had been reported to have higher frequencies of bronchitis than their controls in the first six months of life, and higher frequencies of respiratory tract and ear infection in a 6-year follow-up. The low resistance of the Yucheng children to infection suggested that their immune function was suppressed by the PCBs/PCDFs they had exposed to in utero. In the summer and fall of 1995, a thorough physical examination and blood draw were performed on the study children. The Yucheng children were reported by their parents to have higher frequencies of influenza attacks than the control children during the six months prior to the examination. The frequencies of other symptoms were similar between the two groups. The serum levels of various immunoglobulins were similar between the two groups. Fifty-one serum samples, 29 of Yucheng and 22 of control children, were available for cell-mediated immunologic analysis. The percentages of various T cell markers, CD3, CD4, and CD8, and B cell and NK cell markers were not different between the Yucheng and the control children. No dose-response relationship was found between 27 Yucheng childrens serum PCB/PCDF levels and any of their immunologic markers. WE concluded that 16 years after the Yucheng incident, Yucheng children exposed to high dose of PCBs/PCDFs in utero did not show, with the serum immunologic marker analyses, suppressed immunity when compared to their controls. To explain the consistent higher frequencies of upper respiratory tract infection in the Yucheng children, immune functional tests such as delayed hypersensitive skin reaction, in vitro lymphocyte proliferation, and antibody synthesis following immunization may be necessary.

Neonatal and childhood teeth in relation to perinatal exposure to polychlorinated biphenyls and dibenzofurans: observations of the Yucheng children in Taiwan.

In order to determine the effect of perinatal polychlorinated biphenyls and dibenzofurans (PCBs/PCDFs) exposure on neonatal and childhood teeth in Yucheng children, we carried out complete dental examinations on 73 Yucheng children born to mothers who ingested high levels of PCBs/PCDFs and 75 matched controls, aged 7-11 years, in 1992. Ten of 73 (10%) exposed children were reported to have borne teeth during the neonatal period, while none of the controls did. The exposed group also had a significantly higher percentage of teeth with congenitally missing tooth germ compared to the controls (29 vs 2.7%) or rotation (19 vs 2.7%). The percentages of developmental defects increased significantly with increasing maternal serum PCB levels, childhood PCB and PCDF levels, and the duration of breast feeding. The maternal PCB level clearly played a more important role in an increased risk of neonatal teeth and developmental defects. The defects were apparent from the lowest tertile, with a total PCB level of <10 ppb in maternal serum measured nearest to childbirth. The number of permanent teeth tended to be less in exposed children than in the control group from the age of 11 years onwards. Our present study has demonstrated for the first time a dose-response relationship between perinatal PCBs/PCDFs exposure and dental defects.

Blood serum levels of PCDFs and PCBs in Yu-Cheng children peri-natally exposed to a toxic rice oil

Children secondarily exposed through their mothers to a toxic rice oil containing PCDFs and PCBs in the Yu-cheng incident have shown developmental delay even a decade after the incident. Forty-five serum samples were collected from these children in February 1991 ad small amounts analyzed for their contaminant content using sample enrichment and isotope dilution mass spectrometry. In about one-half the samples, detectable levels of PCDFs and PCBs could still be determined with average values for 2, 3, 4, 7, 8-PnCDF and 1, 2, 3, 4, 7, 8-HxCDF of 300 and 620 ng/kg serum lipid, respectively. The mean of the total PCBs on a whole weight basis was 7.5 micrograms/kg. These concentrations of PCDFs and PCBs are still 10 to 25 times higher than those from a matched control population. Although the serum levels did not correlate with developmental delays, those for the two PCDFs but not the total PCBs correlated with duration of breast feeding indicative of postnatal exposure. The results of this study suggest that estimation of past prenatal exposure of children to PCDFs is best carried out using current mother and not current child blood concentrations.

Cytochrome P450IA2 in vivo induction: A potential biomarker of polyhalogenated biphenyls and their related chemical's effects on the human

Abstract The objectives of our studies have been to test the hypothesis that polyhalogenated biphenyls and related chemicals (PHB) can induce cytochrome P450 dependent mixed function monooxygenase family I enzymes (P450I) in the human, and the degree that a PHB induces P450I activity in the human correlates to the toxicity of the chemical. The P450I family enzyme, P450IA2, activity was monitored in the human by the caffeine breath test. The study subjects were exposed to high amounts of polybrominated biphenyls (PBB), polychlorinated biphenyls with polychlorinated dibenzofurans (PCB/DFs), or mirex. All the PHBs induced the P450IA2 activity of the exposed subjects as compared to the nonexposed control group. The capacity of each PHB to induce P450IA2 activity correlated with the known toxicity of each exposure ( PCB DF PBB >mirex ) in the human. P450IA2 activity as measured by the caffeine breath test may by a most useful biomarker in monitoring and understanding the effects of PHBs on the human population.