Toxicity testing copper

Tests show that the presence of soil reduces the toxicity of copper to the soil-dwelling nematode Caenorhabditis elegans copper toxicity to nematodes increases with increasing densities of bacteria and increasing concentrations of sodium chloride or potassium chloride (Donkin and Dusenbery 1993). Terrestrial isopods efficiently assimilate and store copper as detoxihed granules in the hepatopancreas this activity is in contrast to many species of marine crustaceans that are unable to assimilate, detoxify, or otherwise regulate copper (Weeks and Rainbow 1993). 

Jacobson, P.J., J.L. Farris, D.S. Cherry, and R.J. Neves. 1993. Juvenile freshwater mussel (Bivalvia Unionidae) responses to acute toxicity testing with copper. Environ. Toxicol. Chem. 12 879-883. 

McKim, J.M. and D.A. Benoit. 1974. Duration of toxicity tests for establishing no effect concentrations for copper with brook trout (Salvelinus fontinalis). Jour. Fish. Res. Bd. Can. 31 449-452. 

Chitosan is a polymer with metal-binding properties that is derived from naturally occurring chitin. Research has been conducted on the potential use of chitosan in hazardous waste remediation. While chitosan does bind transition metals, it favors iron, a nonhazardous metal, which competes and interferes with chitosan s binding of toxic metals. Copper also tends to be highly bound, while the amount of cadmium and lead removed is lower. The technology is still undergoing testing and is not yet commercially available. 

Thus the total copper added to a toxicity test or measured as the exposure (e.g., by atomic absorption spectroscopy) may be much greater than that which is available to an organism to induce toxicological effects. 

Chapman, K.K., Benton, M.J., Brinkhurst, R.O. and Scheuerman, P.R. (1999) Use of the aquatic oligochaetes Lumbriculus variegatus and Tubifex tubifex for assessing the toxicity of copper and cadmium in a spiked-artificial-sediment toxicity test, Environmental Toxicology 14 (2), 271 -278. 

The majority of toxicity test data are generated using species from the northern hemisphere (i.e., Holarctic). For example, 9 of the 12 freshwater fish species used in the ecological risk assessment of atrazine (Solomon et al. 1996) and 27 of the 40 freshwater fish species used in the risk assessment of copper (Brix et al. 2001) are from Holarctic habitats. Relatively few data are available for southern hemisphere species, and consequently risk assessments conducted to protect southern hemisphere ecosystems have to utilize toxicity data obtained using northern hemisphere species (Muschal and Warne 2003). Does this matter Based on the limited data currently available, it would appear not. 

See also Copper Mercury Silver Toxicity Testing, Dermal Toxicity Testing, Inhalation. 

Bogomolov, D.M., Chen, S.K., Parmelee, R.W., Subler, S. and Edwards, C.A. (1996) An ecosystem approach to soil toxicity testing a study of copper contamination in laboratory soil microcosms. Applied Soil Ecology, 4, 95-105. 

Lock, K. and Janssen, C.R. (2001) Test designs to assess the influence of soil characteristics on the toxicity of copper and lead to the oligochaete Enchytraeus albidus. Ecotoxicology, 10, 137-144. 

Van Gestel, C.A.M., Van Dis, W.A., Van Breemen, E.M. and Sparenburg, P.M. (1989) Development of a standardized reproduction toxicity test with the earthworm species Eisenia andrei using copper, pentachlorophenol and 2,4-dichloroaniline. Ecotoxicology and Environmental Safety, 18, 305-312. 

Examples showing that metal speciation is important to metal toxicity include arsenic, copper, selenium, and chromium. While ionic copper (Cu2+) and CuClj are highly toxic, Q1CO3 and Cu-EDTA have low toxicity (Morrison et al, 1989). Toxicity tests show that As(III) is about 50 times more toxic than As(VI). Trivalent chromium is much less toxic than hexavalent chromium, probably because Cr(VI) is much smaller and the chemical structure of chromate is similar to sulfate. A special channel already exists in biomembranes for sulfate transport. While modeling metal speciation is not always possible, and redox equilibrium is not achieved in all natural waters, geochemical modeling of equilibrium species distribution remains one of the methods of discerning metal speciation. 

Studies investigating the effects of pesticides on crustaceans should be of high priority. Crustaceans are very important consumers and prey in various aquatic systems and there are delicate relationships between crustacean plankton prey and fish predators in the pelagic zone that can and have been shown to be disturbed. It is known that pesticides are present in surface waters and it is especially urgent to study the effects of insecticides on freshwater species and species that are present in estuaries and coastal waters with high risks of contamination due to vicinity to the sources. In acute toxicity tests crustaceans were much more (often 10-times more) sensitive to insecticides than fish (Maltby et al. 2005), and some of the chemicals probably affect behaviors at very low concentrations. As there are very few studies done on pesticide effects on crustacean chemoreception it is not possible to compare their sensitivity with fish, but it is likely that there are differences. The few crustaceans studied concerning effects of copper indicate that they are less sensitive to the metal compared with fish. 

In the case of copper, it was also reported that a rise of pH is accompanied by an increase of the toxicity in rainbow trout [15]. On the other hand, acute toxicity tests of aluminum for smallmouth bass (Micropterus dolomieui) showed that the rise of pH weakens its toxicity [19]. When pH is elevated, toxic Al ", AlCOH) ", and A1 (OH)" would decrease, and less toxic hydroxide precipitate would increase. These changes of speciation could explain the weakened toxicity. 

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