Health related quality of life and polychlorinated biphenyls and dibenzofurans exposure: 30 years follow-up of Yucheng cohort
Introduction
Polychlorinated biphenyls (PCBs) and Polychlorinated dibenzofurans (PCDFs) are lipophilic pollutants and are known to cause multiple health outcomes in exposed animals and humans (Carpenter, 2011), including cancer, immune system suppression, decrements in cognitive and neurobehavioral function, disruption of sex steroid and thyroid function, and at least some of them increase the risk of chronic diseases. In 1978–1979, approximately 2000 people in central Taiwan were exposed to rice oil contaminated with heat-degraded PCBs (Hsu et al., 1985). The beginning of the outbreak with PCBs poisoning, covering four counties in central Taiwan, there were 1843 cases by the end of 1980. In the course of 3.5 years, 2061 persons were determined to be PCB poisoning victims. The PCBs involved in Yucheng had been repeatedly heated and cooled and were partially oxidized into PCDFs and other polychlorinated multiple ring structures. Patients used the contaminated cooking oil for an average of 8 months. They were estimated to have consumed approximately 1 g of PCBs and 3.8 mg of PCDFs (Primarily 2,3,4,7,8-pentaCDF and 1,2,3,4,7,8-hexaCDF) during an average of nine to ten months of consumption (Lan et al., 1981). An epidemiological study on polychlorinated biphenyls poisoning in Taichung area found that in exposed victims median serum PCBs concentrations were 40–60 ppb wet weight (ww) and serum PCDFs levels of approximately 2.7 ppt ww for pentaCDF and 10.8 ppt ww for hexaCDF. These levels are on the order of 10–20 times higher than background for PCBs and 100–1000 times higher for pentaCDF and hexaCDF. Some of these chemicals are extremely persistent in human tissue; 14 years after exposure, PCBs and PCDFs measurement in 56 women from the cohort showed that total PCBs were still 7-fold higher and PCDFs congeners were 50–180 times higher than that of pooled local controls (Guo et al., 1997). The victims developed symptoms included chloracne, hyperpigmentation, and peripheral neuropathy, and the illness was referred to as “Yucheng” (oil disease in Chinese). By 1983, a registry set up and maintained by the Taiwan Provincial Department of Health included 2061 subjects (Hsu et al., 1984).
Individuals poisoned in this incident had excess mortality from nonmalignant liver disease [standardized mortality ratio=2.7 and 95% confidence interval (CI), 1.3–4.9, based on 10 deaths] at 13 years of follow-up (Yu et al., 1997), although their overall mortality was not higher than that of the Taiwan general population (Standardized mortality ratio 0.8 and CI, 0.7–1.0, based on 83 deaths). Later follow-up of mortality found increase deaths due to systemic lupus erythematus in exposed women 8–24 years after the exposure event (Tsai et al., 2007). Lifetime prevalence of chloracne, abnormal nails, hyperkeratosis, skin allergy, goiter, headache, gumpigmentation, and broken teeth were observed more frequently in the PCBs/PCDFs-exposed men and women. The exposed women also reported anemia 2.3 times more frequently than controls. The exposed men reported arthritis and herniated intervertebral discs 4.1 and 2.9 times, respectively, more frequently than controls (Guo et al., 1999, Yu et al., 2000).
The World Health Organization (WHO) defines Quality of life (QOL) as “an individuals’ perception of his/her position in life in the context of the culture and value systems in which he/she lives, and in relation to his/her goals, expectations, standards and concerns (WHOQOL, 1994). WHOQOL evaluates a person's physical health, psychological state, level of independence, social relations, personal beliefs, and relationship to salient features of the environment. In addition, WHOQOL-BREF was the short form of the WHOQOL, which included 26 original questions, and two additional questions specific to Taiwanese population (Yao et al., 2002). It evaluates a person's physical health, psychological state, social relations, and relationship to the environment.
Although multiple health outcomes have been documented in Yucheng subjects, the health-related QOL has never been assessed. The only study on QOL effects among people exposed to environmental agent was conducted in people exposed to Cobalt-60 due to residing in homes using contaminated steel reinforcing bars (Yen et al., 2011, Yen et al., 2013). However, effects on QOL have never been studied among population exposed to chemical agents. We followed up exposed people to determine whether QOL was affected, as compared to the QOL obtained from background population selected from the National Health Interview Survey (NHIS) in 2001 in Taiwan.
This study aimed to determine whether QOL was affected in people exposed to PCBs/PCDFs, as compared to the QOL obtained from background population selected from the National Health Interview Survey (NHIS) in 2001 in Taiwan.
Section snippets
Study population
A total of 2061 subjects were exposed to rice oil contaminated with PCBs and PCDFs in 1979, and were defined the Yucheng registry. We loss some Yucheng people resulting from the wrong addresses recorded by the Yucheng registry and thus they could not be traced further. Therefore, a total of 1837 Yucheng subjects were traced in 1991 (Guo et al., 1999). Of these, 151 died during the follow-up period, and 381 could not be traced further due to moving, leaving 1305. In 2008, we conducted a
Results
In total, 267 Yucheng individuals completed the questionnaire satisfactorily. Those completed the questionnaire and those who did not were not statistically different in age (47.2 vs. 46.2, p=0.10) and gender distribution (percentage male=41.6% vs. 44.7%, p=0.35).
The demographic characteristics of both the exposed and the reference groups are shown in Table 1. Year of education (p=0.02), alcohol use (p<0.0001), and marital status (p<0.0001) were significant different between exposed and
Discussion
We show for the very first time that poisoning from persistent organic pollutants PCBs and PCDFs can affect QOL 30 years after the exposure. These observed effects were dose-related, as those who had skin manifestations had even lower HRQOL scores in all domains compared to those without skin lesions. Physical effects of exposure to PCBs/PCDFs have been reported, however, psychosocial health impact has not been well known.
Yucheng people had physical domain of QOL affected, likely due to
Conclusions
Exposure to persistent organic pollutants PCBs and PCDFs can affect QOL 30 years after the exposure, especially among those highly exposed.
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