Effects of environmental toxicants

A fundamental requirement for a toxic effect to occur is the establishment of chemical contact between the enviro toxic ant and some endogenous molecule at the site of action for the toxicant - it always starts with a reaction between two molecules . This, of course, requires exposure, bioavailability and absorption of the substance, as well as distribution within the organism to the site of action. 

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Foster, J.R. In Ecological Exposure and Effects of Airborne Toxic Chemicals An Overview, Moser, TJ. Barker, J.R. Tingey, D.T. Eds. U.S. Environmental Protection Agenty Environmental Research Laboratory, Corvallis, 1991 pp 60-89 EPA/600/3-91/001. 

Scott, G.R. and Sloman, K.A. (2004). Effects of environmental pollutants on complex fish behaviour integrating behavioural and physiological indicators of toxicity. Aquatic Toxicology 68, 369-392. 

After the four ranks for levels of risk for fire, instability, toxicity and reactivity are established, other ranks will appear - dedicated to the operators involved (are they able to cope with potential dangers ), the peculiarities involved in setting up the apparatus (detecting weak points eg), effect of environmental conditions (lighting, supervision etc), and any rank likely to be involved in the globai security of the process. 

Sandrin, T. and Hoffman, D., Bioremediation of organic and metal co-contaminated environments Effects of metal toxicity, speciation, and bioavailability on biodegradation, in Environmental Bioremediation Technologies, Singh, S.N. and Tripathi, R.D., Eds, Springer, Berlin, Germany, 2007, pp. 1-34. 

The increase in environmental awareness and the acute effects of some toxic compounds have raised questions over the safety of using many chemicals invented for agricultural and industrial applications. A great deal of current research addresses the management and remediation of old contaminated sites. Recent concerns regard the safety of consumer chemicals, especially nanomaterials the effect of pharmaceuticals on ecosystems and the combined effect that chemical cocktails have on human and ecosystem health. 

Coglianse, M.P. and M. Martin. 1981. Individual and interactive effects of environmental stress on the embryonic development of the Pacific oyster, Crassostrea gigas. I. The toxicity of copper and silver. Mar. Environ. Res. 5 13-27. 

Host resistance to disease has been used as an effective measure of the impact of environmental toxicants on immune function. To date, for virtually every agent examined,... 

This chapter presents specific information with regard to the effects of environmental and occupational exposure to arsenic on inflammatory processes, the immune system, and host defense. While the focus is on the in vivo and in vitro effects of arsenic on host immune responses (e.g., immunotoxicity and hypersensitivity) and their relationship to clinically observed manifestations of arsenic toxicity (e.g., inflammation and skin cancer), information on the potential mechanisms through which arsenic may exert its biological effects is also provided. 

Toxic Effects of Environmental Contaminants on Immune Organs,... 

The data presented in this paper indicate that excess levels (0.75%) of dietary zinc result in decreases in the bioavailability of calcium and phosphorus in rats and interfere with normal bone mineralization. High dietary levels of calcium or zinc appeared to cause a shift in the excretion of phosphorus from the urine to the feces, while the presence of extra phosphorus tended to keep the pathway of phosphorus excretion via the urine. The presence of large amounts of phosphorus in the Intestinal tract due to high intakes of zinc would increase the possibility of the formation of insoluble phosphate salts with various cations, including calcium, which may be present. A shift in phosphorus excretion from the feces to the urine, however, could result in an environmental condition within the system which would tend to increase the bioavailability of cations to the animal. The adverse effect of zinc toxicity on calcium and phosphorus status of young rats could be alleviated with calcium and/or phosphorus supplements. 

Glucuronidation of the resulting hydroxyl derivatives is also induced by phenobarbital pretreatment. Consequently, pretreatment of animals with both these agents reduces the carcinogenicity of acetylaminofluorene. This illustrates the difficulty of predicting the effect of environmental influences on toxicity when multiple metabolic pathways are involved. 

Again, the environmental and testing conditions for many wild mammalian and avian species are compatible with the domestic mammalian studies that have been done in some laboratories for years. Since some of the ecotoxicology studies concentrate on the nonlethal effects of the test substance on the test organisms, it is important that the test conditions and evaluation criteria be accurately described and the staff be very aware of sublethal effects of the toxicant on the test species. 

Thomulka, K.W., Schroeder, J.A. and Lange, J.H. (1997) Use of Vibrio harveyi in an aquatic bioluminescent toxicity test to assess the effects of metal toxicity Treatment of sand and water-buffer, with and without EDTA, Environmental Toxicology and Water Quality 12 (4), 343-348. 

Tsui, M.T.K. and Chu, L.M. (2003) Aquatic toxicity of glyphosate-based formulations comparison between different organisms and the effects of environmental factors, Chemosphere 52 (7), 1189-... 

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