Page 727 - Veterinary Toxicology, Basic and Clinical Principles, 3rd Edition

692 Section |IX Gases, Solvents and Other Industrial Toxicants

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FIGURE 52.1 Chemical structures of brominated flame retardants.
Structural similarities between polybrominated diphenyl ethers (PBDEs),
polychlorinated biphenyls (PCBs), and polybrominated biphenyls (PBBs)
are shown that are relevant to their mode of action. The letters “o,” “m,”
and “p” respectively indicate ortho, meta, and para substitutions for
chlorines or bromines. The numbers indicate the positions of halogens.

Plus. These compounds are used in furniture, textiles,
polyurethane foam, plastics used in electric and electronic
equipment, printed circuit boards, curtains, carpets, etc. to
meet fire safety standards (Alaee et al., 2003; Stapleton
et al., 2009; De Wit et al., 2010; Guo et al., 2011). The
high production volume and the structural similarities of
these brominated chemicals to other well-known toxic
environmental contaminants such as DDTs and PCBs are
the main concerns for environmental and human/animal
health. Furthermore, polybrominated dioxins (PBDDs)/
dibenzofurans (PBDFs), formed during heating or inciner-
ation of BFRs, have toxicological profiles similar to those FIGURE 52.2 Chemical structures of predominant PBDEs found in
of their chlorinated homologs (Birnbaum et al., 2003; commercial mixtures as well as biological and environmental samples.
DiGangi et al., 2010), but they are more toxic than
PBDEs. Like other organohalogens, BFRs are ubiquitous include heat-, chemical-, and abrasion-resistive coatings
in the environment, bioaccumulate, and are toxic to ani- on utensils; they are also used as dispersion, wetting, or
mals and humans (Dye et al., 2007; Kodavanti et al., water protection for paper and surface treatments. In
2008; Kierkegaard et al., 2009; Ounnas et al., 2010; Shaw particular, PFCs are used in metal-plating baths, surfac-
et al., 2010; Guo et al., 2011). A recent study pointed out tants, cleaning products, rust inhibitors, fire-fighting
that the contribution of diet to total intake is high in applications, starting materials for polymers, herbicide
Germany and the United Kingdom, while in the United and insecticide formulations, cosmetics, shampoos, phar-
States, the high concentrations of PBDEs in dust resulted maceuticals, lubricants, paints, polishes, upholstery, tex-
in a notably smaller proportion of the intake being attrib- tiles, carpets, soil/stain resistance coatings, mining and
uted to diet as far as toddlers and adult exposures are con- oil well surfactants, acid mist suppressants, electronic
cerned (Fromme et al., 2016). etching baths, alkaline cleaners, floor polishes, photo-
PFCs are another class of persistent organohalogens. graphic film, and denture cleaners and adhesives
PFCs differ from brominated and chlorinated organoha- (Senthilkumar, 2005; Kodavanti et al., 2008; Yamashita
logens by virtue of all hydrogen atoms, except those in et al., 2011). PFCs are also used in paper protection,
the functional groups being substituted by fluorine including food contact applications (plates, food contain-
atoms (Fig. 52.3). PFCshavebeenused inavarietyof ers, bags, and wraps) and nonfood contact applications
specialized consumer and industrial products for more (folding cartons, carbonless forms, and masking papers)
than 60 years (Lau, 2015). The applications of PFCs (Kannan et al., 2002).