Screening toxic chemicals

Haque, R., Falco, J., Cohen, S., Riordan, C. (1980) Role of transport and fate studies in exposure, assessment and screening toxic chemicals. In Dynamics, Exposure and Hazard Assessment of Toxic Chemicals. Haque, R., Editor, pp.47-67. Ann Arbor Science Publishers Inc., Ann Arbor, MI. 

Information from transport and fate processes can be utilized to screen toxic chemicals as to their environmental behavior using (i) the bench-mark concept and (ii) the structure-activity relationship. 

Identification of stmctures of toxic chemicals in environmental samples requires to use modern analytical methods, such as gas chromatography (GC) with element selective detectors (NPD, FPD, AED), capillary electrophoresis (CE) for screening purposes, gas chromatography/mass-spectrometry (GC/MS), gas chromatography / Fourier transform infra red spectrometry (GC/FTIR), nucleai magnetic resonance (NMR), etc. 

The Toxic Substances Control Act of 1976 was enacted by Congress to test, regulate, and screen all chemicals produced or imported into the U.S. Many thousands of chemicals and their compounds are developed each year with unknown toxic or dangerous characteristics. To prevent tragic consequences, TSCA requires that any chemical that reaches the consumer market be tested for possible toxic effects prior to commercial manufacture. Any chemical that poses health and... 

Bioassays can be used for cost-effective biomonitoring and rapid screening of environmental samples to detect the presence of mixtures of toxic chemicals and to identify hot spots. 

Selecting an approach A nearby lab specializes in mass spectrometric analysis and can perform the EPA screening method for pesticides and other toxic chemicals. Your own lab just bought an inductively coupled plasma emission spectrometer and can analyze the water for heavy metals. 

EPA. 1986c. Final report on the evaluation of four toxic chemicals in an in vivo/in vitro toxicological screen Acrylamide, chlordecone, cyclophosphamide, and diethylstilbestrol. Research Triangle Park, NC U.S. Environmental Protection Agency, Health Effects Research Laboratory. EPA-600-1-86-002. 

Persoone, G. Cyst-based toxicity tests. I. A promising new tool for rapid and cost-effective toxicity screening of chemicals and effluents. Zeitschr. Fiir Angewandte Zoologie 1991, 78, 235-241. 

Liss-Suter D, Villaume JE, Goldstein FJ. 1978. A literature review - problem definition studies on selected toxic chemicals. Volume 8 Environmental aspects of diesel fuels and fog oils SGF no. 1 and SGF no. 2 and smoke screens generated from them. Philadelphia, PA Franklin Institute Research Laboratories. Final report. Contract no. DAMD 17-77-C-7020. ADAO56021. 

The first two chapters describe the two most widely recognized techniques for the rapid biological screening of chemical substances for potential mutagenicity and carcinogenicity. The remaining chapters present instrumental analytical techniques for monitoring toxic substances. 

In Chapter 1 Bruce N. Ames, the plenary speaker at the symposium, describes the development of the Salmonella/microsome assay, which is better known as the Ames Test. This test was the first proven rehable and rapid in-vitro method for the mutagenic and carcinogenic screening of chemicals. Included is an excellent overview of the potential problem of human exposure to toxic substances as well as a description of how this important method is being used to test chemical substances. 

Not all agents can be readily metabolized. The toxic metals lead and mercury are elements that cannot be degraded but must still be removed from the body. Another important mechanism of detoxification is the attachment or binding of another compound to a toxic chemical to make it easier for the kidney to filter the compound out of the blood and excrete it in the urine. A primary purpose of the kidney is to screen the blood for waste products and concentrate them in the urine for excretion, as occurs, for example, with mercury. Caffeine is excreted in the urine at approximately the same concentration as the blood because the kidney cannot concentrate caffeine. Vitamins, however, are readily concentrated and excess quickly eliminated in the urine. 

Verschaeve, L., Van Compel, J., Thilemans, L., Regniers, L., Vanparys, P. and van der Lelie, D. (1999) VITOTOXD bacterial genotoxicity and toxicity test for the rapid screening of chemicals. Environmental and Molecular Mutagenesis, 33, 240-248. 

Bolon B et al (1997) Differential follicle coimts as a screen for chemically induced ovarian toxicity in mice results from continuous breeding bioassays. Fimdam Appl Toxicol 39 1-10... 

RL SOP No. 70-3, dated June 1, 1967, describes methods used at Edgewood for searching for and selecting toxic chemicals. Some of the details In connection with exposure of human volunteers to experimental irritant chemicals are described. Human volunteers were exposed to compounds after review of animal screening data and approval by committees based on a conclusion that the experimental chemicals were safe for human use. Generally, two volunteers were exposed to each substance. Subjects were exposed in a wind tunnel at an airspeed of 5 mph and were asked to resist leaving the test atmosphere (up to 1 min) until exposure was unbearable. 

Bolon, B., Bucci, T.J., Warbritton, A.R., Chen, J.J., Mattison, D.R. Heindel, J.J. (1997) Differential follicle counts as a screen for chemically induced ovarian toxicity in mice results from continuous breeding bioassays. FanJam. appl. Toxicol, 39, t-tO... 

Ishidate, M., Jr Odashima, S. (1977) Chromosome tests with 134 compounds on Chinese hamster cells in vitro—a screening for chemical carcinogens. Mutat. Res., 48, 337-354 Izmerov, N. F. (1984) Pyridine (IRPTC Scientific Reviews of Soviet Literature on Toxicity and Hazards of Chemicals), United Nations Environmental Programme, Moscow, Centre of International Projects, GKNT... 

Walker, J.D., Knaebel, D., Mayo, K., Tunkel, J. and Gray, D.A. (2004) Use of QSARs to promote more cost-effective use of chemical monitoring resources. 1. Screening industrial chemicals and pesticides, direct food additives, indirect food additives and pharmaceuticals for biodegradation, bioconcentration and aquatic toxicity potential, Water Quality Research Journal of Canada 39, 35-39. 

Contrera, J.F., Matthews, E.J., Kruhlak, N.L., Benz, R.D. (2008). In silico screening of chemicals for genetic toxicity using MDL-QSAR, nonparametric discriminant analysis, e-state, connectivity, and molecular property descriptors. Toxicol. Mech. Meth. 18 207-16. 

Hontzeas N, Hafer K, Schiestl RH. Development of a microtiter plate version of the yeast DEL assay amenable to high-throughput toxicity screening of chemical libraries. MutatRes. 2007 634(l-2) 228-234. 

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