A Critical Review: 2,3,7,8 –Tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD) Effects on Gonad Development in Bivalve Mollusks

Abstract

Bivalve mollusks are equally sensitive to 2,3,7,8-tetrachlorodibenzo-p-dioxin's (2,3,7,8-TCDD) effect on gonad development, embryonic development, and epithelial lesion occurrence as higher vertebrates. 2,3,7,8-TCDD alters normal development of reproductive organs and early development in bivalve mollusks at 2 to 20 pg/g wet weight. In both Crassostria virginica and Mya arenaria, 2,3,7,8-TCDD preferentially accumulates into the gonads. The sensitivity of gonad maturation is likely due to disruption of cross-talk between highly conserved steroid, insulin, and metabolic pathways involved in gonad differentiation. The altered gonad development and decreased veliger larval survival can partially explain the lack of self-sustaining bivalve populations in 2,3,7,8-TCDD contaminated estuaries.

Poison in paradise: increase of toxic effects in restored sections of two rivers jeopardizes the success of hydromorphological restoration measures

“…2b, 4f, Table 2, Additional file 5: Figure S4a), for which an increase in reproduction with rising estrogenic activities has already been reported [41,47,80,93,95]. Since only reduced reproduction and increased mortality of invertebrates by dioxin-like substances are described in the literature [83,[88][89][90][91] but no increased reproduction, it can be assumed that the significant positive correlation between dioxin-like activities and the reproduction of snails only reflects the wastewater load and thus the estrogenic activity ( Table 2, Additional file 5: Figure S4b). This results mainly from the correlation between estrogenic and dioxin-like compounds in water samples and is supported by the significant negative correlation between dioxin-like activities in sediment samples and the reproduction of P. antipodarum ( Table 2, Additional file 5: Figure S4c, i).…”

“…Although most invertebrates do not express the aryl hydrocarbon receptor (AhR) and are, therefore, relatively unresponsive to dioxin-like compounds [85], PAHs and dioxins as potent agonists at the AhR [85][86][87] negatively affect reproduction and mortality of invertebrates [74,[88][89][90][91][92][93]. The correlation analyses also revealed that increasing dioxin-like activities lead to a decrease in the reproduction of G. fossarum ( Table 2, Additional file 5: Figure S4h) but do not have a lethal effect on G. fossarum and P. antipodarum.…”

Hormones and Endocrine-Disrupting Chemicals: Low-Dose Effects and Nonmonotonic Dose Responses

“…Similarly, perchlorate affects fish (650 -653), amphibians (654 -658), and birds (659 -661) via mechanisms consistent with those described for humans, and some of the earliest reports on perchlorate's effects on thyroid function were conducted in amphibians (661,662). Finally, ecological studies of dioxin and dioxin-like chemicals reveal effects on a range of exposed wildlife including birds (663,664), fish (665,666), and invertebrates (667). Although these studies have highlighted some of the species-specific effects of dioxin (389), and orders of magnitude differences in toxic equivalency factors between species (668), they also indicate the conservation of mechanisms for the effects of dioxin on a range of biological endpoints in wildlife, laboratory animals, and humans (384).…”

An Overview of the Effects of Dioxins and Dioxin-Like Compounds on Vertebrates, as Documented in Human and Ecological Epidemiology

“…However, some of the same congeners, such as PCB 114, 156, and 157, have higher TEF values in birds than in humans and other mammals. This congener-specific sensitivity suggests that for certain dioxins, not all exposed species will serve as sentinels for the health of humans or other species, including invertebrates, such as the eastern oyster, which may be the most dioxin-sensitive species with respect to developmental endpoints [44]. Furthermore, the matter is complicated by the fact that different congeners dominate different environments and trophic levels,…”