(366d) Modeling the Impacts of International Food Trade on Contaminant Transport and Human Exposure

Introduction: Quantifying and addressing the implications of the transfer of resources across borders is a hallmark of research on the food, energy and water (FEW) nexus. International trade in goods can result in severe imbalances in the water stress, green house gas emissions, and energy consumption experienced by or attributed to producing and receiving countries^1,2. Yet an important component of food trade—that is, the potentially hazardous chemicals contained in foods as a result of accumulation from production environments, processing, transport, or storage—is still poorly quantified^3–5. Here, we investigate the importance of international food trade on the dietary exposure of the Swiss population to polybrominated diphenyl eithers (PBDEs). PBDEs are lipid soluble compounds used as flame retardants in synthetic fibers and molded plastics. Of major concern is PBDE exposure through the diet. Studies have confirmed that fish, meat, and dairy products contribute most to the daily PBDE intake⁶. Like other countries, Switzerland has reported a gradual shift in dietary patterns over the past few decades, with increasing consumption of fish reported, reaching a peak value of 17.6 kg in 2010, and with a shift in the origin of fish. We therefore constructed a model to quantify the exposure of the Swiss population to PBDEs from local and imported fish and seafood.

Methodology:

Model boundaries: Our study focused on Switzerland as a geographical case study. All calculations referred to fish imports for the year 2016. Fish, shrimp/prawn, and mussels were selected as key fish and seafood types to include in the study, as they are among the most highly consumed.

Data collection: An extensive literature review was conducted to derive useful input data for our model, including PBDE concentrations in fish, shrimp and mussels from different countries, and to estimate daily per capita fish consumption in Switzerland. Trade data (imports, exports, and re-exports) for fish, crustaceans (shrimp and prawns) and mollusks (mussels) was extracted from the UN Comtrade Database. Data were collected for fresh, frozen, fresh fillet, and frozen fillet categories of the respective commodities.

Model Structure: The model consists of four primary components. These are: (i) PBDE concentrations in fish from different origins, resulting from bioaccumulation from their environment and/or food; (ii) food trade data for Switzerland; (iii) local fish production; and (iv) dietary intake to the Swiss population via fish and seafood consumption.

Results and Discussion: Based on the difference between average per capita fish consumption, production, imports and re-exports, we estimate that Switzerland imports approximately 66% of fish consumed, while only 34% is locally caught. Of the imported fish, Norway, Denmark and the UK are the largest exporters of salmon to Switzerland. For shrimp and prawn, the majority is from Vietnam. For other fish, Norway, Denmark, the Netherlands, Vietnam, France, Germany, Italy, and China are the largest exporters. Within the locally produced fish, whitefish (Coregonus sp.) is the most common fish contributing to 60% of local the catch, followed by perch (19%), pike (7%) and roach (7%)⁷. Using an average of 23g/day fish consumption, results show that from 70000 metric tons fish consumed in Switzerland in 2016, 66 % (46000metric tons) was imported corresponding to 34 % locally caught fish (24000 metric tons).

Based on published studies of PBDEs in fish, the highest concentrations were detected in whitefish (Coregonus spp.) in Switzerland⁸. Norway also reported high levels of PBDEs in whitefish⁹. The US reported PBDEs as high as 3078 pg/g wet weight in salmon¹⁰. Compilation of country-specific PBDE body burdens in fish continues. In addition, we are employing modeling approaches to estimate PBDE body burdens in key species from exporting countries where data are lacking. These data will aid in forming a comprehensive source-receptor relationship for Swiss population exposure to PBDEs via seafood and fish.

References Cited

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(7) Swiss fact: around 1.8 million kilograms of fish are caught in Switzerland every year https://lenews.ch/2017/01/04/swiss-fact-around-1-8-million-kilograms-of-... (accessed May 31, 2018).

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(10) Schecter, A.; Päpke, O.; Tung, K.-C.; Staskal, D.; Birnbaum, L. Polybrominated Diphenyl Ethers Contamination of United States Food. Environ. Sci. Technol. 2004, 38 (20), 5306–5311.