contribution of meat and meat mixtures to the total DLC exposure for these groups was approximately 37 and 35 percent, respectively, for pregnant and lactating women compared to children aged 1–5 years (IOM, 2003).
Polybrominated diphenyl ethers (PBDEs) are synthetic compounds that are added to a variety of materials to increase their fire resistance. PBDEs are structurally similar to PCBs, and can exist, theoretically, as 209 distinct isomers. PBDEs are released into the environment as emissions from facilities manufacturing them and as a result of degradation, recycling, or disposal of products that contain them. The patterns of use of PBDEs are changing rapidly.
Bioaccumulation of PBDEs As with other persistent organic pollutants, PBDEs are cycled globally (de Wit et al., 2004). PBDE levels in aquatic wildlife have increased rapidly in recent decades (Ikonomou et al., 2002; Law et al., 2003), with doubling times of between 1.6 years and 6.0 years (Lunder and Sharp, 2003; Rayne et al., 2003; Hites et al., 2004a). PBDE tissue (blood, milk, and adipose) levels in humans have followed a time course similar to that in wildlife. The concentrations in human milk samples in Sweden, British Columbia, and the United States have increased manyfold over recent decades (Darneud et al., 2001; Ryan et al., 2002; Hites, 2004; Sjodin et al., 2004a; Schecter et al., 2005), with doubling times of 10 years or less (Meironyte et al., 1999; Ryan et al., 2002). For reasons that are not known, the concentrations of PBDEs in biological tissues collected in North America are at least 10 times greater than those collected in Europe or Japan (Peele, 2004). Although ingestion is considered to be an important route of exposure to PBDEs, the importance of other routes, such as indoor air and dust, are poorly characterized and could be important in certain settings (Sjodin et al., 2004b).
Although the concentrations of PBDEs have been found to vary widely across countries, market basket surveys, total diet studies, duplicate diet studies, and commodity-specific surveys have repeatedly shown that, within a region, fish and shellfish tend to have PBDE concentrations that are greater than those found in dairy products, eggs, fats, and oils, and other meat products are important sources of exposure to PBDEs. This has been found in Canada, Finland, Germany, Japan, the Netherlands, Sweden, and the United States. In terms of total intake of PBDEs, fish and shellfish are the major contributors in Europe and Japan, while meats and poultry are the major contributors in the United States and Canada (FAO/WHO JECFA, 2005). The PBDE concentration tends to be greater in fish at higher trophic levels, i.e., predatory fish (Rice, 2005). In a market basket survey