body, Covaci says. “Ingestion of highly contaminated food, such as fish from polluted areas, would lead to a spike in serum levels of also reflect regulatory and food Three papers in this issue of ES&T PCBs, which would fall gradually safety changes made after the provide new information on huif the exposure stops,” he PCB/dioxin food incident in 1999, man exposure to PCBs and their suggests. such as strict “farm to fork” possible mechanisms of toxicity. Not all PCBs are the same, a monitoring for PCBs, he says. Two of the papers come from complexity taken on by Covaci The contribution of household Adrian Covaci’s group at the Uniand colleagues in Antwerp and at dust to overall exposure was relaversity of Antwerp. One, from CoAlexandru Ioan Cuza University of tively small. Compared with colvaci and colleagues at the Iasi (Romania) in their University of Antwerp, Asanalysis of serum samples siut University (Egypt), and from Belgium and Romania. the University of BirmingHighly chlorinated PCBs are ham (U.K.) (Environ. Sci. more resistant to modificaTechnol. DOI 10.1021/ tion enzymes such as cytoes9021427), analyzes the chrome p450s and are more contributions of diet and lipophilic than less-chlorihousehold dust to PCB and nated PCBs. In addition, DDT intake in Belgian colonly some PCBs adopt dilege students. The results oxin-like structures, and only suggest that changes in food PCB contamination in the Michalovce district of Slovasome hydroxylated PCBs are safety standards implekia has been linked to subtle hearing damage in children. thought to strongly perturb mented after the Belgian thyroid hormone pathways. PCB/dioxin crisis of 1999 As a result, PCB profiles may may have lowered dietary differ with regard to persisexposure levels there. A tence in the body and companion paper compares toxicity. the PCB congener profiles in In this study, the authors serum samples from Belsaw that serum samples gium and Romania (Environ. from subjects residing in the Sci. Technol. DOI 10.1021/ two countries had roughly es902149b). A third, from similar levels of all PCBs. Toma´sˇ Trnovec and colHowever, the Romanian leagues (Environ. Sci. Techsamples contained a smaller nol. DOI 10.1021/ proportion of hydroxylated es901918h), probes the PCBs, which they attribute relationship between PCB to the presence of a greater exposure in Slovakia and proportion of the more persubtle damage to children’s sistent, highly chlorinated hearing. PCBs in Romania than in One striking result from Three outer hair cells and one inner hair cell form Belgium. the Belgian student data is a column under the tectorial membrane (blue). Covaci and colleagues also that the levels of PCBs measured other compounds and lege students, infants and present in their diets are several found that the wood preservative children tend to have higher extimes less than previously repentachlorophenol (PCP) was posures, through dust and buildported values from Europe and more abundant in Belgian ing materials and also through the U.K. Some of the differences samples than in Romanian specibreast milk, notes Larry Robertmay stem from the methods that mens, even though PCP’s use has son, a toxicologist from the Uniare used to measure dietary expobeen restricted in European counversity of Iowa. sure, Covaci says. Rather than tries since the 1980s. In RomaIn the Belgian student data, sesampling participants’ meals, sevnian samples, the levels of the rum concentrations of PCBs did eral previous studies took a “marpesticide DDT and its main menot correlate with dietary expoket basket” approach, focusing on tabolite, ppDDE, were several sure. This suggests that serum fatty meats and dairy products, times higher than in samples levels may reflect past, rather and these studies did not account from subjects in Belgium. DDT than present, exposure because of for losses during food preparawas not banned in Romania until PCBs’ multiyear persistence in the tion. However, the decline may NIH
CIA/QUINN EASTMAN
Good, Bad News on European PCB exposure
10.1021/es100689d
2010 American Chemical Society
Published on Web 03/18/2010
April 15, 2010 / ENVIRONMENTAL SCIENCE & TECHNOLOGY 9 2755
1985, and agricultural stocks of the chemical may still be used illegally in some areas today, Covaci observes. The relationship between PCB exposure and hearing was examined by Trnovec and co-workers at Slovak Medical University, Military Aviation Hospital, and Hospital with Policlinics (all in Slovakia), and the U.S. National Institute of Environmental Health Sciences. In the Michalovce district in Slovakia, PCBs were produced between 1959 and 1984; this led to extensive contamina-
tion of sediments in the Laborec River. Monitoring of 12-year olds from this district revealed serum PCB levels several times those seen elsewhere in Slovakia. High serum PCB levels are linked to a loss of sensitivity for the outer hair cells of the cochlea, especially at low frequencies. The authors describe the damage as “subclinical”: detectable only through laboratory tests and not interfering with speech comprehension or daily activities. “The thresholds and mechanism of action for PCBs on hear-
2756 9 ENVIRONMENTAL SCIENCE & TECHNOLOGY / April 15, 2010
ing have not been previously addressed in humans, so this is a significant finding,” Robertson says. Studies in rodents suggest hearing damage comes from interference with thyroid hormone pathways, leading to neurotoxicity. However, the mechanism may be different in humans and rodents because the timing of cochlear development is not the same, Trnovec and colleagues state. —QUINN EASTMAN
