Edible clay inclusion in the diet of oysters can reduce tissue residues of polychlorinated biphenyls
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ORIGINAL ARTICLE
Edible clay inclusion in the diet of oysters can reduce tissue residues of polychlorinated biphenyls Meichen Wang1 · Timothy D. Phillips1 Accepted: 14 May 2020 © Korean Society of Environmental Risk Assessment and Health Science 2020
Abstract Objective Polychlorinated biphenyls (PCBs) are lipophilic and persistent environmental pollutants that are readily absorbed and accumulated in high concentrations in fatty tissues of humans and animals. Invertebrate animals, such as oysters, are vulnerable and sensitive to PCB contamination. Methods Previously, our in vitro isothermal studies have shown that acid processed montmorillonites (APM) can effectively bind PCBs and Aroclors. Therefore, in a novel application of this work, a dietary strategy for shellfish was developed using APM, and its parent clay to reduce exposures to PCBs in oysters. PCB residues in oysters with clay treatment at different dietary inclusion rates and durations were measured and compared to a washout treatment. Results The efficacy and safety of this strategy were supported by a significant reduction of PCB residues with the inclusion of a low level of APM (0.05%) during a 4-day treatment. Moreover, this sorbent strategy reduced PCB residues in oysters in a dose- and time-dependent manner. Conclusions Based on our results, it is possible that clay-based sorbents such as APM, can be included in the diet to significantly reduce exposures to PCBs. Keywords Toxicant sorption · Oysters · Polychlorinated biphenyls (PCBs) · Clay
Introduction Polychlorinated biphenyls (PCBs) are chlorinated aromatic hydrocarbons that were discovered and initially characterized in 1881. The physical and chemical properties of PCBs, such as stability, resistance to degradation, oxidation and chemical agents, low vapor pressures, and fire resistance have resulted in their widespread use as electrical insulators and their persistence in the environment [1]. An important environmental concern about PCBs is their incorporation into the food chain. The problem can be magnified after flooding which can mobilize contaminated sediment. Benthic invertebrates feeding on the bottom consume PCBs and later pass them in the food chain to fish, humans and other creatures (Fig. 1). Importantly, PCB exposure from seafood accounts for over 90% of PCB exposure to humans [2]. * Timothy D. Phillips [email protected] 1
Department of Veterinary Integrative Biosciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX 77843, USA
There are several means by which PCB concentration can be mitigated, such as hydrolysis under extreme conditions and photodegradation. However, due to the overall stability of PCBs, environmental conditions are not likely to promote these chemical reactions. Oysters are natural filter feeders that commonly grow in groups called an oyster reef (or bed) found in salt water or brackish water. They feed by pumping water through their gills, trapping particles of food as well as nutrients, and
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