A novel method was used to estimate assimilation efficiencies (AEs) of dissolved and food associated PCBs (IUPAC 31, 49, and 153) by the Baltic Sea blue mussel (Mytilus edulis). Mussels were exposed to radiolabeled PCBs in a series of short-term toxicokinetic experiments at different algal food concentrations, both at apparent steady-state (ASS) and non-steady-state (NSS) conditions in respect to PCB partitioning between water and algae. The PCB AEs were calculated using a physiologically based bioaccumulation model where experimentally determined uptake and exposure rates at ASS and NSS conditions were combined into linear equation systems, which were solved for PCB AE from water and food. A positive relationship between PCB uptake and algae clearance by the mussels was observed for all three PCBs. The PCB AEs from both water and food increased with congener hydrophobicity (octanol/water partition coefficient [K(ow)]), but AEs decreased with increases in water pumping and filtration rate of the mussels, respectively, The average contribution of food-associated PCB to the total uptake also increased with K(ow) from approximately 30% for PCB 31 and PCB 49 to 50% for PCB 153, mainly as a consequence of increased sorption to the algal food.

Aquaculture, which is growing 3–5 times faster than terrestrial agriculture, will play an important role to meet future global food production needs. However, over 80% of global sewage production is returned to the environment untreated or poorly treated. In developing nations, these nontraditional waters of diverse quality are being recycled for aquaculture, yet chemical residues are differentially studied. Here, we examined pharmaceuticals, pesticides, polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), polycyclic aromatic hydrocarbons (PAHs), and flame retardants in marine bivalves using isotope dilution liquid chromatography-tandem mass spectrometry (LC-MS/MS) and low-pressure gas chromatography-tandem mass spectrometry (LP GC-MS/MS). Green-lipped mussels from the field and oysters from aquaculture net pens, which are harvested as food products, were collected adjacent to point source municipal wastewater and landfill leachate effluent discharges, respectively, in Hong Kong, the fourth most densely populated country in the world. Multiple classes of pharmaceutical, pesticides, PAHs, and phosphorus-based flame retardants were detected at low μg/kg levels. Acceptable servings per week indicated minimal risk for a number of chemicals; however, such calculations could not be performed for other contaminants of emerging concern. Future efforts are needed to better understand contaminant influences on marine bivalve populations and aquaculture product safety, particularly in rapidly urbanizing regions of developing countries with limited wastewater infrastructure.