Survey of polychlorinated dibenzo--dioxins, polychlorinated dibenzofurans and non--polychlorinated biphenyls in U.S. meat, poultry, and siluriform fish from 2018-2019: toxic equivalency levels, temporal trends, and implications.

The U.S. Department of Agriculture (USDA) conducted a survey of domestic animal products including beef fat, pork fat, chicken fat, turkey fat, dairy cow fat, and siluriform fish muscle (i.e. catfish) to determine the current residue levels of polychlorinated dibenzo--dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and non--polychlorinated biphenyls (-PCBs). The following types of fat samples were analysed: beef from heifers and steers (referred to as "beef"), pork, chicken, turkey, dairy cow (referred to as "dairy cow"), and siluriform fish muscle, which includes catfish. The survey is conducted every 5 years. Fat samples for each slaughter class and siluriform fillets were collected from U.S. federally inspected slaughter facilities, processed, and analysed for 17 PCDD/Fs and 3 -PCBs. Toxic equivalency concentrations were calculated using 2005 toxic equivalency factors and summed (sum-TEQ) for all slaughter classes. The sum-TEQs ranged from non-detect (nd) to 16.5 pg TEQ/g lipid. The median sum-TEQs, when nd = ½ LOD, for beef, pork, chicken, turkey, dairy cow, and siluriform fish were 0.48, 0.08, 0.07, 0.21, 0.38, and 0.62 pg TEQ/g lipid (wet weight for siluriform fish), respectively. A comparison of the current and previous surveys typically depicts a significant declining trend depending on the slaughter class (such as chicken and turkey), however, beef and pork fat median values slightly increased and decreased, respectively, but neither were significant compared to the previous survey. The congener patterns for some high concentration beef and pork fat samples suggested that pentachlorophenol treated wood continues to be a likely on-farm dioxin exposure source.