title: Contamination by polybrominated diphenyl ethers and persistent organochlorines in catfish and feed from Mekong River Delta, Vietnam.
abstract: Commercial feeds for aquaculture and catfish samples were collected from the Mekong River Delta, Vietnam, for determination of polybrominated diphenyl ethers (PBDEs) and selected persistent organochlorines, including polychlorinated biphenyls (PCBs), DDT and its metabolites (DDTs), chlordane-related compounds (CHLs), hexachlorocyclohexane isomers (HCHs), and hexachlorobenzene (HCB). The most abundant contaminants were DDTs, with concentrations ranging from 10 to 700 ng/g lipid weight, followed by PCBs (1.0-80 ng/g), CHLs (<0.01-8.2 ng/g), PBDEs (0.12-3.7 ng/g), HCHs (<0.03-5.1 ng/g), and HCB (<0.07-3.2 ng/g). Polybrominated diphenyl ethers were detected in all samples, suggesting their widespread contamination in the region. However, PBDE contamination levels in the present catfish specimens were low in comparison to levels worldwide. Interestingly, residue levels of all the contaminants were significantly higher in catfish collected near a municipal dumping site compared to farmed catfish. This suggests that runoffs from the dumping site during floods and rains may have brought pollutants to the surrounding areas. Contamination pattern in aquaculture feeds revealed elevated levels of PCBs and PBDEs in samples from foreign companies, perhaps implying their higher residues in some imported ingredients. Congener profiles of PBDEs and PCBs demonstrated similarity between the farmed catfish and the aquaculture feeds, suggesting these feeds as a major source of pollution to the farmed catfish. On the other hand, the PBDE and PCB profiles in the dumpsite catfish are clearly different from those of the farmed catfish, revealing their exposure to different sources. Risk assessment showed significantly higher intake of the contaminants by people who eat catfish cultured near the dumping areas. Further investigation regarding fate and occurrence of the contaminants in dumping sites is necessary.
authors.affiliation: Center for Marine Environmental Studies, Ehime University, Bunkyo-cho 2-5, Matsuyama 790-8577, Japan.
authors.forename: Nguyen Hung
authors.initials: NH
authors.lastname: Minh
authors.forename: Tu Binh
authors.initials: TB
authors.lastname: Minh
authors.forename: Natsuko
authors.initials: N
authors.lastname: Kajiwara
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Kunisue
authors.forename: Hisato
authors.initials: H
authors.lastname: Iwata
authors.forename: Pham Hung
authors.initials: PH
authors.lastname: Viet
authors.forename: Nguyen Phuc Cam
authors.initials: NP
authors.lastname: Tu
authors.forename: But Cach
authors.initials: BC
authors.lastname: Tuyen
authors.forename: Shinsuke
authors.initials: S
authors.lastname: Tanabe
mesh_terms: D000821:Animal Feed / Q000032:analysis*; D000818:Animals; D017756:Aquaculture; D002397:Catfishes; D006843:Hydrocarbons, Chlorinated / Q000633:toxicity*; D011075:Polybrominated Biphenyls / Q000633:toxicity*; D014744:Vietnam; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D006843:Hydrocarbons, Chlorinated; D011075:Polybrominated Biphenyls; D014874:Water Pollutants, Chemical