Coexposure of Dioxin-like Polychlorinated Biphenyls and Polychlorinated Dibenzo-p-dioxins and Dibenzofurans in Free-Range Hens and Implications Derived from Congener Profile Analysis Chingju Lin, †,# Jing-Fang Hsu, ‡,∥,⊥,# and Pao-Chi Liao* ,‡,§ † Department of Physiology, College of Medicine, China Medical University, 91 Shueh-Shih Road, Taichung 404, Taiwan ‡ Department of Environmental and Occupational Health, College of Medicine, National Cheng Kung University, 138 Sheng-Li Road, Tainan 704, Taiwan § Center for Micro/Nano Science and Technology, National Cheng Kung University, 1 University Road, Tainan 701, Taiwan ∥ L5 Research Center, China Medical University Hospital, Taichung 404, Taiwan ⊥ China Medical University, 91 Shueh-Shih Road, Taichung 404, Taiwan ABSTRACT: The consumption of free-range eggs is becoming more popular worldwide. We analyzed the levels of 12 dioxin- like polychlorinated biphenyls (dl-PCBs) and their congener profiles from 6 free-range and 12 caged egg samples. The mean levels of dl-PCBs in the free-range samples were 5.4 times higher than those in caged eggs. All egg samples exhibited at least two characteristic dl-PCB congener patterns, which reflected distinctive contamination sources. Additionally, for the first time, we demonstrated that the dl-PCB levels in the free-range eggs were highly correlated with elevated levels of 17 polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) (r = 0.986; p < 0.001), indicating a coexposure scenario in free-range hens. Cluster analysis of congener patterns implied that this coexposure scenario could be attributed to distinct dl-PCB and PCDD/F sources. This congener profile information provides insights from a different perspective for further identifying potential dl-PCB and PCDD/F sources in the polluted free-range eggs. KEYWORDS: free-range egg, PCB, PCDD/F, congener profile, coexposure ■ INTRODUCTION Polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and polychlorinated biphenyls (PCBs) are three classes of chemically and structurally related polyhalogenated aromatic hydrocarbons originated from industrial activities and wastes. These ubiquitous compounds can be persistent in soils and sediments as well as in waste repositories for decades to centuries. For example, although the manufacture and use of PCBs were banned in the 1970s, PCB contamination is still a continuing concern due to the long half- lives of these compounds and their production through certain industrial activities. 1 Acute and long-term exposure to PCDD/ Fs and PCBs can be hazardous to health. Exposure to PCDD/ Fs can lead to carcinogenic concerns, 2 developmental defects, 3 and hormonal disruption, 4 while exposure to PCBs has been reported to be associated with chloracne and related dermal lesion, 5 cancer risk, 6,7 disruption of the nervous function, 8−10 and immune system dysfunction. 11 The toxic effects of these substances are mainly attributed to a subset of 17 PCDD/F congeners and 12 dioxin-like PCB (dl-PCBs) congeners. Because these pollutants occur as a mixture of congeners in the contaminated environments, human subjects normally take in dozens of congeners upon exposure. For example, different congener patterns of highly toxic PCDD/Fs and dl-PCBs can be found in the tissues, blood, and milk of exposed subjects. 12,13 Therefore, rather than analyzing only one or a few congeners, risk assessment of human exposure always includes analysis of a mixture of PCDD/F or dl-PCB congener profiles. Chicken eggs are one of the most important nutrition sources in many areas including Taiwan. Because eggs contain almost 10% fat, dioxins are likely to accumulate in the fat of the yolk. 14 It has been estimated that the contribution of eggs to the daily dioxin intake of humans is approximately 4% in many European countries. 14 In a Spanish county near a hazardous waste incinerator, the contribution percentage was as high as 17%. 15 Thus, it is important to monitor the levels of PCDD/Fs and dl-PCBs in eggs. For example, one of the strategies implemented by the Commissions of the European Commun- ities (EC) to reduce the health risks associated with PCDD/Fs or dl-PCBs exposure is to regulate the maximum concentration of PCDD/Fs to 3 pg World Health Organization Toxic Equivalents (WHO 1998 -TEQ)/g lipid and the sum of dioxin and dl-PCBs to 6 pg WHO 1998 -TEQ/g lipid in eggs. 16 Hen eggs have been estimated to contribute as much as 7% of monthly intake of PCDD/Fs and dl-PCBs in both male and female Taiwanese individuals. 17 Traditionally, the majority of consumed eggs are produced by caged hens. In recent years, the consumption of eggs produced by free-range hens or by organic farming has gradually increased in the pursue of natural and better nutritional qualities in eggs. 18 The demand for free-range or organic eggs is continuing to grow in Taiwan. Nevertheless, Received: November 2, 2011 Revised: February 3, 2012 Accepted: February 6, 2012 Published: February 6, 2012 Article pubs.acs.org/JAFC © 2012 American Chemical Society 1963 dx.doi.org/10.1021/jf204468s | J. Agric. Food Chem. 2012, 60, 1963−1972