Dioxins and Dioxin-Like Compounds
In the U.S. Domestic Meat and Poultry Supply
Between May 2002 and May 2003, the U.S. Department of Agriculture’s (USDA)
Food Safety and Inspection Service (FSIS) conducted a survey to gather information on
dioxins, furans, and dioxin-like PCBs in U.S. meat and poultry products as part of a
continuing effort to understand and characterize potential contaminants in the food
supply. In this report, the dioxins, furans, and dioxin-like polychlorinated biphenyls
(PCBs) included in the survey are referred to as dioxin-like compounds (DLCs).
DLCs are a group of compounds that share a similar chemical structure and
common characteristics such as exerting biological effects through a common receptor-
mediated mechanism of action (Ah-receptor). Each compound in this group is referred to
as a congener. DLCs almost always occur as mixtures of individual congeners.
Low levels of DLCs are ubiquitous in the environment. DLCs are released into
the environment through natural processes, such as forest fires and volcanic eruptions,
and through industrial processes, such as combustion or incineration of industrial waste,
or chemical manufacturing. These compounds can remain in the environment for
DLCs accumulate in the fatty tissues of food animals and the primary means of
human exposure is believed to be through the consumption of animal fats in food. DLCs
also accumulate in fatty tissue in the human body. Studies indicate that prolonged
exposure to elevated levels of dioxin may have long term, adverse health effects.
Samples collected for analysis are adipose (fat) samples from carcasses. The
percentage of carcass fat actually varies by species, thus all findings are converted to a
100% fat level. These results are referred to as fat-based or lipid-based results.
DLCs are not toxicologically equal. Toxic equivalency factors (TEFs) are used to
characterize the relative potency of various DLC congeners. The most recent and