Endocrine-Disrupting Chemicals and Their Environmental Impacts - Organic Pollutants: An Ecotoxicological Perspective - page 281

et al. 1999). Concentrations of PBDEs in invertebrates derived from industrial areas
have been recorded up to 480 ng/g lipid (Yunker and Cretney 1996), and in fish at
concentrations of up to 27,000 ng/g lipid in muscle tissue and 110,000 ng/g lipid in
liver (Andersson and Blomkvisit 1981). Tetrabromodiphenyl (TeBDE) is consistently
the predominant congener in body tissues (Jansson et al. 1993; Sellström et al. 1993;
Luross et al. 2002). As a measure of their ubiquity in the environment, 90% of fresh-
water fish in the study by Hale et al. (2001) had detectable levels of TeBDE exceeding
those of PCB-153, typically the most abundant PCB congener.
Public concern about PBDE levels in the environment was heightened when it
was shown that a sharp increase in the concentration of certain PBDEs had occurred
in human breast milk over only a 10-year period (Meironyté et al. 1999; Norén
and Meironyté 2000), and the levels of exposure in some infants and toddlers were
similar to those shown to cause developmental neurotoxicity in animal experiments
(Costa and Giordano 2007). As a result of these concerns, the majority of commer-
cial PBDE mixtures have been banned from manufacture, sale, and use within the
European Union.
15.6.6 b i s p h e n of l s
Bisphenol A (BPA) was first discovered as an estrogen back in the 1930s, when it was
developed as an estrogen for clinical use (Dodds and Lawson 1938). The discovery
of DES, however, a far more effective synthetic estrogen, meant that the use of bis-
phenol A as a clinical estrogen was quickly superseded. Then, in the 1950s, BPA was
reacted with phosgene by a Bayer chemist, Hermann Schnell, to produce polycarbon-
ate plastic and, subsequently, to synthesize epoxy resins, which are now used widely,
including as lacquer preservatives in the lining of food cans, in automotive parts,
and in compact discs (reviewed in Oehlmann et al. 2008). The estrogenic activity of
bisphenol A was “rediscovered” in 1993 when it leached out of polycarbonate flasks
during autoclaving and subsequently had a stimulatory effect in an estrogen-depen-
dent cell culture system (Krishnan et al . 1993). Through in vitro screenings, a wide
range of other bisphenols have been shown to be estrogenic (Brotons et al. 1995;
Fernandez et al. 2001). Bisphenols are only weakly active as estrogens in in vitro
assays, with a potency of approximately 1:5000 compared to that of E 2 (Krishnan
et al . 1993). In vivo effects in rats occur at doses of tens of µg BPA/d. In the United
States, concentrations of BPA in surface waters have been recorded up to 8 µg/L
(Staples 1998). In vivo studies in fish have shown that concentrations of 16 µg/L in
the water can affect the progression of spermatogenesis, and inhibition of gonadal
growth occurred in both males and females at concentrations of 640 and 1280 µg/L
(Sohoni et al. 2001). BPA has also been shown to invoke an antiandrogenic response
in the A-SCREEN (Sohoni and Sumpter 1998).
15.6.7 a l k y l p h e n of l s
Alkylphenol ethoxylates (APEs) are nonionic surfactants that are used in the manu-
facturing of plastics, agricultural chemicals, cosmetics, herbicides, and industrial
detergent formulations. Alkylphenols such as nonylphenol (NP) are the products of