Cadmium, toxicity

Divalent metal transporter 1 was identified in the enterocytes of the small intestine and in other cells as a proton symporter, favoring the transport from more acidic media, and it was assigned a major role in the assimilation of iron from the animal diet [54]. But its lack of selectivity in reconstituted systems soon became apparent, showing that Cd is efficiently transported by DMTl in vitro [54,55]. This observation was extended to include a correlation of DMTl expression and Cd transport, both in cellular models [56-58] and in animals with iron-manipulated diets [59,60]. Furthermore, animal [61], and human [62] studies comparing iron status and cadmium burden fully corroborated the association of Cd transport with the plasma membrane form(s) of DMTl. Hence, there is no doubt that DMTl transports Cd in cells that produce this transporter. This conclusion is relevant to an individual s susceptibility to cadmium toxicity since DMTl is strongly iron-regulated and cadmium transport thus depends on the nutritional and (patho)physiological iron status, in particular for intestinal absorption. 

Another ZIP transporter, ZIP14, allows Cd to permeate the plasma membrane of ZIP14-transfected mouse fibroblasts and canine kidney epithelial cells [67]. ZIP14 also transports non-transferrin bound ferrous iron [6S,69], but the impact of ZIP14 regulation on permeation of different metal ions may be indirect, involving distant signaling events [70], such as crosstalk with other transporters. 

The above and other transporters involved in the uptake of essential metal cations for animals are subject to extensive regulation [71]. The regulatory mechanisms can be sophisticated and they can involve networks of essential and toxic metals as recently demonstrated and reviewed [7,70,72]. Since increased hepatic accumulation of ingested cadmium is associated with upregulation of several intestinal transporters in mice fed diets deficient in essential metals, it follows that Cd entry into cells, and its intestinal absorption in particular, strongly depends on the status of the animal or human with respect to these essential metals. 

The fact that metal cation importers mediate cadmium entry into cells whereas Cd does not appear to be a substrate for exporters of essential transition metals points at an important issue of cadmium speciation in biological systems. Upon exposure of cells, particularly those protecting the body from its envirmunent, such as epithelial cells, Cd is presented in relatively weak complexes allowing Cd to easily dissociate and bind to cadmium transporters, and it may cross membranes as a free ion. In contrast, once inside cells, strong Ugands of Cd are generally 

1 Exposure of Humans to Cadmium and Patho-Physiological Consequences 

---

The future of cadmium plating is in question because of cadmium toxicity (83). Cyanide-free cadmium plating systems have experienced some growth. Acid cadmium, based on cadmium sulfate compositions, is replacing some cyanide baths in the United States. The fluoborate cadmium is reported in use in the UK, especially in barrel plating (84). Cadmium plating is covered by ASTM (85), U.S. government, and ISO specifications (86). 

Morin S, Duong TT, Herlory O, Feurtet-Mazel A, Coste M (2008) Cadmium toxicity and bioaccumulation in freshwater biofilms. Arch Environ Contam Toxicol 54 173... 

Wang, A. and Crowley, D.E., Global gene expression responses to cadmium toxicity in Escherichia coli, J Bacteriol, 187 (9), 3259-3266, 2005. 

Worden, C., Kovac, W., Dorn, L., and Sandrin, T., Environmental pH affects transcriptional responses to cadmium toxicity in Escherichia coli K-12 (MG1655), FEMS Microbiol Lett, 293 (1), 58-64, 2009. 

Sandrin, T.R., Chech, A.M., and Maier, R.M., A rhamnolipid biosurfactant reduces cadmium toxicity during naphthalene biodegradation, Appl Environ Microbiol, 66 (10), 4585-4588, 2000. 

Sandrin, T. and Maier, R., Effect of pH on cadmium toxicity, speciation, and accumulation during naphthalene biodegradation, Environ Toxicol Chem, 21 (10), 2075-2079, 2002. 

Reduced with NiMH because of elimination of cadmium toxicity concerns... 

PDT candidate. Indeed, it is effective against human leukemia cells,128 284 and as a photobactericide.128 285 286 However, concerns about solubility and cadmium toxicity led to a discontinuation of biological work,128 and in any case the cadmium(II) complex was soon overtaken as a PDT sensitizer by the lutetium(III) derivative (32) (Section 9.22.7.1). 

Brown, V., D. Shurben, W. Miller, and M. Crane. 1994. Cadmium toxicity to rainbow trout Oncorhynchus mykiss Walbaum and brown trout Salmo trutta L. over extended exposure periods. Ecotoxicol. Environ. Safety 29 38-46. 

Eaton, J.G. 1974. Chronic cadmium toxicity to the bluegill (Lepomis macrochirus Rafinesque). Trans. Amer. Fish. Soc. 103 729-735. 

Giesy, J.P., Jr., G.J. Leversee, and D.R. Williams. 1977. Effects of naturally occurring aquatic organic fractions on cadmium toxicity to Simocephalus serrulatus (Daphnidae) and Gambusia affinis (Poeciliidae). Water Res. 11 1013-1020. 

Rombough, P.J. and E.T. Garside. 1982. Cadmium toxicity and accumulation in eggs and alevins of Atlantic salmon, Salmo salar. Canad. Jour Zool. 60 2006-2014. 

Howell, R. 1985. Effect of zinc on cadmium toxicity to the amphipod Gammarus pulex. Hydrobiologia 123 245-249. 

Yu, H.S. and S.T.H. Chan. 1988. Zinc amelioration of cadmium toxicity on preimplantation mouse zygotes in vitro. Teratology 37 13-19. 

Primary hepatocyte cultures have been used as a tool to predict the hepatotoxicity of many compounds such as nonsteroidal anti-inflammatory drugs (Castell et ah, 1988), psychotropic drugs (Boelsterli et ah, 1987), immunosuppressant drugs (Boelsterli et ah, 1988), and salicylates (Tolman et ah, 1978). Rat primary hepatocyte cultures have also been shown to be a good model for examining the mechanisms of metallothionein-induced tolerance to cadmium toxicity (Liu et ah,... 

Liu, J., Kershaw, W.C. and Klaasen, C.D. (1990). Rat primary hepatocyte cultures are a good model for examining metallothionein-induced tolerance to cadmium toxicity. In Vitro Cell. Dev. Biol. 26 75-79. 

Martelli, A., Rousselet, E., Dycke, C., Bouron, A. and Moulis, J.-M. (2006) Cadmium toxicity in animal cells by interference with essential metals, Biochimie, 88, 1807-1814. 

Marshall, J.S. Cadmium toxicity to laboratory and field populations of Daphnia galeata mendotae, Bull. Environ. Contam. 

It is also used extensively in semiconductors and in plastics as a stabilizer. Cadmium smelting is often done from residual dust from lead smelting operations, and cadmium smelter workers often face both lead and cadmium toxicity. 

---