Hexachlorocyclohexane study

The performance of SCWO for waste treatment has been demonstrated (15,16). In these studies, a broad number of refractory materials such as chlorinated solvents, polychlorinated biphenyls (PCBs), and pesticides were studied as a function of process parameters (17). The success of these early studies led to pilot studies which showed that chlorinated hydrocarbons, including 1,1,1-trichloroethane /7/-T5-6y,(9-chlorotoluene [95-49-8] and hexachlorocyclohexane, could be destroyed to greater than 99.99997, 99.998, and 99.9993%, respectively. In addition, no traces of organic material could be detected in the gaseous phase, which consisted of carbon dioxide and unreacted oxygen. The pilot unit had a capacity of 3 L/min of Hquid effluent and was operated for a maximum of 24 h. 

Although quite extensive use of has been made in studies on the degradation of alkyl sulfonates (Hales et al. 1986), C1 has achieved only limited application on account of technical difficulties resulting from the low specific activities and the synthetic inaccessibility of appropriately labeled substrates. One of the few examples of its application to the degradation of xenobiotics is provided by a study of the anaerobic dechlorination of hexachlorocyclohexane isomers (Jagnow et al. 1977), the results of which are discussed in Chapter 7, Part 3. 

A pioneer study of the distribution of this substance in the tissues of rats to which it had been fed was made by Laug (3). He evaporated ether extracts in Erlenmeyer flasks, so that a deposit was left over the bottom. Female houseflies were confined in the flasks, and the mortalities after 20 hours were compared to those obtained with known amounts of 7-hexachlorocyclohexane. Because most of the inner surface of the flask was untreated, the flies were out of contact with the toxicant during an unknown fraction of the exposure period. The exposure period was so long that the insects had to be fed dur-... 

Schechter et al. (7) in their studies on DDT in milk found that interfering extractives are largely removed by treatment with strong sulfuric acid. Furman and Hoskins (2) found the same treatment effective when hexachlorocyclohexane was the contaminating substance, and it has been applied in later work to numerous extracts of plants and animals. The procedure now used when either DDT or hexachlorocyclohexane is suspected is as follows ... 

Laboratory studies showed the pure gamma isomer of hexachlorocyclohexane to have residual life equivalent to that of the normal mixed isomers. The material does not break down in normal storage, as do mixed isomers. 

For some important insect pests there are still no satisfactory chemical controls. Such problems should be given due consideration in the development program. Many of these problems appeared to be solved with the discovery of DDT, benzene hexachlo-ride (hexachlorocyclohexane), and some of the more recent insecticides. Further studies of the toxicity of some of these products to warm-blooded animals have raised the important question of the advisability of continuing their use where food and feed products are concerned. Considerable attention is being centered on finding safer analogs, such as TDE and methoxychlor, and new and better insecticides. 

There is a potentially dangerous reaction of carbon tetrachloride with dimethylformamide in presence of iron. The same occurs with 1,2,3,4,5,6-hexachlorocyclohexane, but not with dichloromethane or 1,2-dichloroethane under the same conditions [1], A quantitative study of the reaction by DSC and ARC techniques shows that in a 1 1 wt. mixture with carbon tetrachloride in absence of iron, an exothermic reaction sets in below 100°C. Under adiabatic conditions, the heat release (207.6 J/g) would take a runaway reaction to over 240°C. In presence of 3% of iron powder, the same mixture shows 2 exotherms, one at 56°C (108 J/g) and the second at 94°C (275 J/g), a final adiabatic temperature exceeding 285°C being possible [2], Dimethylacetamide behaves similarly but more so. 

Chlorination of aromatic compounds under irradiation has been studied extensively (Wagner, 1969). With benzene, the product is a mixture of stereoisomeric hexachlorocyclohexanes with yields 104pmol.J 1. This certainly points to chain reaction with the initiation either from a dissociation, Cl2 2C1, or from the participation of the first excited singlet state of benzene 0B2u) giving... 

Fig. 5 Scientific studies in biota. DDTs dichloro diphenyl trichloroethane HCB hexachlorobenzene HCHs hexachlorocyclohexanes OCs organochlorine pesticides OPs phosphorate pesticides PCBs polychlorinated biphenyls HBCD hexabromocyclododecane...

In another AT study, Terrado et al. [15] characterised pollution patterns in different parts of the Ebro catchment. In the upper part of the Ebro, pollution was found to be mainly in the form of heavy metals (Zn, Cu, Cr, Pb, Cd and Hg), polycyclic aromatic hydrocarbons (PAHs), hexachlorocyclohexanes (HCHs) and trichlorobenzenes (TCBs). Etrophic conditions were also found. Pollution was found to source mainly from industry and urbanisation. The central Ebro was characterised by nutrient pollution such as the accumulation of Ca, Na, Mg and K, which highlighted the importance of salinisation effects from intensive irrigation and soils with high salt content. In the lower Ebro, organic [DDTs, hexachlorobenzene (HCB) and hexachlorobutadiene (HCBu)] and heavy metal (Hg, Cd, Zn and As) contamination was found to derive mainly from industrial and agricultural activities. 

Canton, J.H., Wegman, C.C., Vulto, T.J.A., Verhoef, C.H., and van Esch, G.J. Toxicity, accumulation, and elimination studies of a-hexachlorocyclohexane (a-HCH) with saltwater organisms of different trophic levels. Water Res., 12(9) 687-690,1978. 

Oliverira-Filho, E.C. and Paumgartten, F.J.R. Comparative study on the acute toxicities of a, p, y, and 8 isomers of hexachlorocyclohexane to freshwater fishes, Bull Environ. Contam. Toxicol, 59(6) 984-988, 1997. 

Five of the eight theoretically possible 1,2,3,4,5,6-hexachlorocyclohexanes have been studied and their preferred gas phase conformations determined325. ... 

Hexachlorocyclohexane -hexachlorobenzene - - Study of analysis conditions Ultra low [118] level ... 

Figure 5.2 Air concentrations (pg/m ) of a-HCH (hexachlorocyclohexane), y-HCH, endo-sulfans (sum ofendo I, endo II andendosulfan sulfate) and chlordanes (sum of trans-chlordane, cis-chlordane, and trans-nonachlor) between December 2004 and March 2005 at GAPS sites around the world. (Reproduced with permission from Environmental Science and Technology, Toward a Global Network for Persistent Organic Pollutants in Air Results from the GAPS Study, by Karia Pozo, Tom Harner et a ., 40(16), 4867-4873. Copyright (2006) American Chemical Society)...

Other radiolysis studies on chlorine and bromine compounds have included ethyl chloride , 1,3-dichloropropane , allyl halides , trichloroethylene and hexachlorobutadiene , hexachlorocyclopentadiene and other unsaturated chlorinated hydrocarbons - , hexachlorocyclohexane , chloro- and bromo-benzenes - - , phenyl ethyl bromides , polyvinyl chloride - - and... 

A large number of ubiquitous environmental pollutants are very toxic to the hypothalamic-pituitary-thyroid (HPT) axis when administered at high (greater than environmental) levels. To study low level effects on the HPT axis, laboratory animals were administered a mixture of 16 organochlorine pesticides and other chlorinated hydrocarbons and heavy metals, all at levels similar to those found environmentally, so as to simulate environmental exposure. The chemicals included DDT (6.91), HCB (5.73), TCDD (6.80), PCBs (6.29), methoxychlor (5.08), endosulfan (3.83), heptachlor (6.10), hexachlorocyclohexane (3.80), dieldrin (5.40), aldrin (6.50), mirex (7.18), several chlorinated benzenes (2.84-3.44), cadmium (-1.65), and lead (1.35). Effects were measured by monitoring thyroid activity. The study found that this mixture of environmental pollutants was toxic and can alter HPT physiology in sexually mature malesJ50 ... 

Unequivocal evidence for the re-emission of POPs has been demonstrated in an elegant study of the Great Lakes that border the USA and Canada. This study focused on the POP a-hexachlorocyclohexane (a-HCH), a chiral compound (Box... 

Wester, P. and J. Canton. Histopathological study of Oryzias latipes (medaka) after long-term /3-hexachlorocyclohexane exposure. Aquat. Toxicol. 9 21-45, 1986. 

In a study of 89 women (87% German) with repeated ( 2) miscarriages, Gerhard et al. (1998) found that blood concentrations of PCBs were higher than the reference level in 22% of the cases. The effect cannot be specifically attributed to PCBs because blood levels of other organochlorine compounds (pentachlorophenol, DDE, p- and y-hexachlorocyclohexanes, HCB) were higher than reference ranges in... 

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