Experimental toxic substances

numerous other dangerous toxic and hazardous substances have been experimented with by the miUtary, and their presence is possible at laboratory and similar faciUty remediation sites. The following is a list of those substances known to have been actually used in experimentation, including chemical warfare agents, pyrotechnics, and chemicals with other industrial appUcations  

Acrolein Acetyl chloride Acetylene-arsenic trichloride Acetyl fluoride Aluminum chloride Aluminum arsenide Ammonium cyanide 

AniUte (toxic) CCI4 added to nitrobenzol and nitrogen peroxide produces up to 40% phosgene on detonation Anthracene 

Arsenic trifluoride Benzyl chloride Benzyl cyanide Boron trifluoride Bromine trifluoride Butyl lithium Butyl mercaptan Calcium arsenide Carhon bisulfide Carhon monoxide Carhonyl fluoride Carhonyl sulfide Chlorine monofluoride Chlorine trifluoride Chloroacetic anhydride Chloroacetyl chloride Chloroform Chrysarohin Coal tar Cyanogen 

Ethylaluminum chloride Ethyldibromoacetate Ethylene oxide Eluorine 

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Fourteen formulations of chemical alternatives were submitted to EPA under confidentiality and they were assessed based on numerous human health and ecotoxicity endpoints in addition to bioaccumulation potential and environmental persistence. They were also screened for potential exposure to workers, users and the aquatic environment. Where data gaps existed, EPA experts used models and chemical analogs to estimate the hazard for a particular endpoint. The literature and test data reviews were published in the final report, Environmentally Preferable Options for Furniture Fire Safety Low Density Furniture Foam . In addition, each hazard endpoint was ranked with a concern level (High, Moderate or Low) based on the criteria used by the EPA s New Chemicals Program to rate the concern level of new chemicals submitted under the Toxic Substance Control Act (TSCA). As seen in Figure 8.2, where the hazard endpoint rankings are bold, the value is based on experimental data. Where the hazard endpoints are presented in italic font, the value is estimated based on models or chemical analogs. In this way, detailed hazard information was summarized and presented in a clear and concise format. 

The effect depends on species. Animals used for experimental purposes do not all react in the same way and with the same sensitivity to toxic substances. The reaction depends on the species. Within the same species, members have different degrees of resistance this has been particularly obsenred in situations of human poisoning. 

Dandruff shampoos, 7 850-851 Dangerous drugs, testing for, 12 98-99 Dangerously toxic substances, 23 113 Dangerous substances, substitute chemicals for, 24 194 Dangling bond (DB) density, 22 132 Daniel experimental design text ... 

The physico-chemical properties may provide indications about the absorption of the substance for various routes of exposure and may therefore be of importance in the evaluation whether an appropriate administration route has been applied in the available experimental toxicity studies. In order for a substance to be absorbed, it must cross biological membranes. Most substances cross biological membranes by passive diffusion. This process requires a substance to be soluble both in lipid and water. The most useful parameters providing information on the potential for a substance to diffuse across biological membranes are the logPoctanoi/water and the water solubility. 

The minimum dose of a toxic substance that is lethal when assayed with various experimental animals. It is usually followed by a subscript number equal to the percentage of the animals that died under the assay conditions (e.g., LDso). 

Information regarding the health effects of diazinon following ingestion in laboratory animals is substantial, but less information is available on the effects of inhalation and dermal exposures (see Figure 2-4). Furthermore, the health effects of acute- and intermediate-duration exposures to diazinon are more fully characterized than those associated with chronic-duration exposures. The available information indicates that diazinon is a toxic substance to all species of experimental animals, deriving its toxicity from acetylcholinesterase inhibition. 

The dehalogenation process has been approved by the EPA s Office of Toxic Substances for PCB treatment and has been experimentally implemented for the cleanup of PCB-contaminated soil at the following three Superfund sites Wide Beach in Erie County, New York (1985) Re-Solve in Massachusetts (1987) and Sol Lynn in Texas (1988). The glycolate process has been used to successfully treat contaminant concentrations of PCBs from less than 2 ppm to reportedly as high as 45,000 ppm. Using this technology, Helland et al. (1995) investigated reductive dechlorination of carbon tetrachloride with elemental iron and found that the rate of dechlorination to chloroform and methylene chloride was a fast first-order process. 

From the analysis of the various respirometric curves recorded in both normal conditions and after exposure of the system to the toxic substance at several concentrations, we obtained a calibration curve to which reference can then be made to determine the toxicity of the selected sample. In practical terms, for each measurement record two different respirometric curves one in the presence of substrate alone and the other in the presence of substrate but after initial incubation with the toxic substance (for 8 min) the results can be processed using one of the two following experimental data ... 

Khanin, AC. 1969. [Histopathological changes in the central nervous system and internal organs of experimental animals after chronic 24-hour inhalation of toxic substances.] Tr Tsent Inst Vsoversh Vrachei 135 97-106 (Russian). 

HPV-lnerts data set — It contains 623 high production volume inerts (human papilloma virus-[HPV] Inerts), which is a subset of the Toxic Substances Control Act (TSCA) Inventory. The EPA is including HPV-lnerts in version 2 of the Endocrine Disruption Priority Setting Database (EDPSD2), and there was a need to prioritize HPV-lnerts for further experimental evaluation. Of 623 chemicals, 166 chemicals were either mixtures or their structures were not available, excluding them from prediction. The activities (or otherwise) of457 chemicals were predicted by this system. 

Lethal concentration-50 (LC50) concentration of a potentially toxic substance in an environmental medium that causes death of 50% of the experimental organisms over a certain period of exposure. 

Lauwerys RR. 1989. Metals — Epidemiological and experimental evidence for carcinogenicity Biological monitoring of exposure and the response at the subcellular level to toxic substances. Arch Toxicol Suppl 13 21-27. 

For the derivation of EQSs (and similar benchmarks), experimental toxicity data are considered essential. However, for many substances there will be insufficient reliable toxicity data available to meet the prescribed minimum data requirements. In their absence (or to supplement an existing data set), several extrapolative methods may potentially be of assistance. Nevertheless, we recommend extreme caution when extrapolating from calculated values to predicted real toxicity data. Most suggested calculation methods to supplement missing toxicological data are considered unacceptable in EQS derivation. 

Neurotoxicity caused by chemical substances requires careful interpretation based on well confirmed data on experimental animals and surveys of workers and the general population. Neurotoxicity is one of several noncancer end-points that share common default assumptions and principles. The interpretation of data as indicative of a potential neurotoxic effect involves the evaluation of the validity of the database. Attention should be given to the existing gaps—for instance, (1) identification of the specific toxic substance, (2) knowing the observed effects and significance in terms of neurotoxicity, and (3) whether the conclusions made agree... 

An account of the safe disposal of laboratory chemicals is given in Pitt, M. J., et al., Handbook of Laboratory Waste Disposal (Chichester Ellis Horwood, 1985). Detailed experimental procedures have been published on how to convert particularly reactive and toxic substances into less harmful products before their disposal see, for example. Hazardous Laboratory Chemicals Disposal Guide, 3rd ed., ed. M.-A. Armour (Boca Raton, FL CRC Press, 2003). Destruction of Hazardous Chemicals in the Laboratory, 2nd ed., ed. G. Lunn et al. (New York Wiley, 1994) contains methods for the degradation and disposal of the following chemicals ... 

Experimental results showed that carbonmineral composites are much better than others adsorbents, for example, the mineral one. A good selectivity of carbon materials made us to assume that it is a carbon substance is responsible both for selectivity and synergistic effect of adsorption too. From our point of view one of the reason of such a behavior could be specially organized carbon structures such as intermediate complexes (clusters), which possess peculiar electron properties only to them. Probably similariy toxic substances are adsorbed, such as phenols, cresols, quaiacol, aldehydes, polyatomic alcohols, ethers etc. (Table 1). 

In most toxicity studies, the concentration of the toxic substance is raised in one step to the level to be studied, leaving little chance for acclimation to take place. This experimental situation is not adequate for toxicity studies in waste treatment systems because in most of these systems acclimation will probably occur. This is true because if a toxic substance is present in a waste, its concentration in the reactor will usually build up slowly rather than suddenly. Thus, adequate delineation of toxicity in waste treatment requires an allowance for acclimation. 

EPL The substance known as essential phospholipid is the highly purified fraction of phosphatidylcholine with polyunsaturated fatty acids in positions Ci and C2 (= PPC), whereby 1,2 dilinoleylphosphatidylcholine is the main active ingredient. This exact biochemical definition is important, since similar substances do not display the effects of EPL as far as cell protection against toxic substances and inhibition of fibrosis are concerned — as was shown in many experimental and clinical studies. Recommended dosage 3 X 300 mg/day over a longer period of time. (72, 74) (s. p. 865)... 

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