Polychlorinated dibenzo-p-dioxins and furans PCDD/Fs

Many of the toxic and biological effects induced by polychlorinated dibenzo-p-dioxins and furans (PCDD/Fs) and PCBs such as carcinogenesis, reproductive disturbances and immunotoxic effects are believed to be mediated via the hepatic cytosolic aryl hydrocarbon receptor (Ah receptor) [254,255]. Based on in vitro and in vivo studies, the toxicity of individual organochlorines have been determined relative to 2,3,7,8-tetrachlorodibenzo-p -dioxin (TCDD) and expressed as toxic equivalency factors (TEFs) [254, 256]. In addition to PCDD/F, structurally related PCBs and PCNs bind to the Ah receptor. After binding to the Ah-receptor, the receptor-ligand complex is transferred into the nucleus where it binds to specific DNA sequences and causes transcription of structural genes, which in turn causes synthesis of various cytochrome P4501A1-dependent enzymes such as ethoxyresorufin O-deethylase (EROD) and aryl hydrocarbon hydroxylase (AHH). TEFs for PCNs have been estimated from enzyme-induction assays of EROD and AHH [10, 257] and Luciferase assays in rat cells [12] cf. Table 4. 

In June 1997, an expert meeting was organized by the World Health Organization (WHO) to reach a consensus about TEFs for human and wildlife of polychlorinated dibenzo-p-dioxins and -furans (PCDD/Fs) and PCBs. " " Twenty-nine congeners of these compound classes were... 

A large number of pubUcations have resulted from research on environmental appHcations of GC-MS. The compounds most commonly analyzed include alkanes, PAHs, pesticides, volatile organic compounds (VOCs) including off-flavor and water disinfection by-products (DBPs), PCBs, polychlorinated dibenzo-p-dioxins, and furans (PCDDs/Fs), as well as other ED chemicals such as phthalates and short ethoxy alkylphenol ethoxylate. GC-MS is also the technique of choice for the analysis of emerging contaminants, such as polybrominated diphenyl ethers (PBDEs) or polychlorinated alkanes, as well as for the analysis of some pharmaceuticals and organo-metallic compounds. 

MS has been the leading technique used in dioxin analysis. Until the 1990s, ultratrace determinations of polychlorinated dibenzo-p-dioxins and furans (PCDDs/Fs) were routinely performed using GC-HRMS, operating in the El mode (electron energy... 

The most studied organic compounds in the aerosol are the persistent organic compounds (POPs) as polychlorinated dibenzo-p-dioxins and furans (PCDD/Fs), polychlorinated biphenyls (PCBs), polychlorinated naphthalenes (PCNs), polybrominated diphenyl ethers (PBDEs) and polycyclic aromatic hydrocarbons (PAHs). 

In addition, the concern about e-waste not only focuses on its vast quantity generated daily, but also more on the need to handle the toxic chemicals embedded in it. It is well known that e-waste contains lead, beryllium, mercury, cadmium (Cd), and brominated flame retardants (BFRs) among other chemical materials [3]. Furthermore, highly toxic chemicals such as polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and polybrominated dibenzo-p-dioxins and dibenzo-furans (PBDD/Fs) can be formed during the recycling process [4]. 

These chemicals have received intense international attention in recent years because of their ubiquity, persistence, high bioaccumulation potential and harmful biological effects. Under the Stockholm Convention on POPs (see Chapter 1), 12 chlorinated chemical substances have been banned or severely restricted. These include dioxins and furans (polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans, PCDD/Fs),... 

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