Also DDT

SAFETY PROFILE Confirmed carcinogen with experimental carcinogenic, neoplastigenic, and mmorigenic data. Poison by ingestion. Moderately toxic by skin contact. Mutation data reported. An insecticide. When heated to decomposition it emits toxic fumes of CT. See also DDT. 

Human Toxicity.- Slightly irritating to, but not absorbed appreciably through, skin. Estimated fatal oral dose 7.5 g/kg body wt. Continued ingestion over long periods may cause kidney damage. See also DDT. 

CCls CHO. A colourless oily liquid with a pungent odour b.p. 98°C. Manut actured by the action of chlorine on ethanol it is also made by the chlorination of ethanal. When allowed to stand, it changes slowly to a white solid. Addition compounds are formed with water see chloral hydrate), ammonia, sodium hydrogen sulphite, alcohols, and some amines and amides. Oxidized by nitric acid to tri-chloroethanoic acid. Decomposed by alkalis to chloroform and a methanoate a convenient method of obtaining pure CHCI3. It is used for the manufacture of DDT. It is also used as a hypnotic. 

Malaria affects an estimated 270 million people and causes 2—3 million deaths annually, approximately one million of which occur in children under the age of five. While primarily an affliction of the tropics and subtropics, it has occurred as far north as the Arctic Circle. The disease essentially has been eradicated in most temperate-zone countries, but some 1100 cases of malaria in U.S. citizens returning from abroad were reported to the Centers for Disease Control during 1990. Malaria is seen today in Southeast Asia, Africa, and Central and South America. It is on the increase in Afghanistan, Brazil, China, India, Mexico, the Philippines, Sri Lanka, Thailand, and Vietnam. Escalation of the disease is because of the discontinued use of the insecticide DDT which effectively kills mosquito larvae, but has been found to be toxic to Hvestock and wildlife. Also, chloroquine (6), a reUable dmg for the prophylaxis and treatment of falcipamm malaria, is ineffective in many parts of the world because of the spread of dmg-resistant strains. 

It is also clear that it is difficult to relate cause and effect to any specific chemical since, with the exception of point source effluents, many waterways contain a multitude of chemicals, of which the active endocrine disruptor may not be that which has been measured in the water or tissue. For such reasons, many studies have used in vitro experiments in which isolated tissue, either from a control animal or one captured in a polluted water system, is exposed to a single pollutant in the laboratory. Such experiments have shown significant disruption to testicular activity by a wide range of xenobiotics, including cadmium, lindane, DDT, cythion, hexadrin and PCBs. ... 

Although eggshell thinning attributable to DDE exposure has occurred in birds in the UK, the lethal and siiblethal effects of the cyclodiene pesticides aldrin, dieldrin and heptachlor are also believed to have contributed to the population effects, particularly in the case of the sparrowhawk and peregrine falcon. Following the withdrawal of DDT and the cyclodienes from use in the UK, Europe and North America, bird of prey populations that were severely affected have shown partial or complete recovery. ... 

There is some evidence for chemically mediated endocrine disruption in amphibians. The egg yolk protein, vitellogenin, is inducible in amphibians by exposure to DDT. " Males of the short clawed toad Xenopus laevis given 250 fig/g or 1 fig/g o,p -DDT for seven days have been shown to produce vitellogenin, although the induction was less than that achieved by treatment with 1 fig/g of either 17/1-oestradiol or diethylstilboestrol. Research has also shown that endocrine disrupting chemicals can alter sex ratios in wild populations of certain species PCB congeners and organochlorine compounds have been linked with male domination of sex ratios in polluted compared to unpolluted sites. ... 

Hurst (19) discusses the similarity in action of the pyrethrins and of DDT as indicated by a dispersant action on the lipids of insect cuticle and internal tissue. He has developed an elaborate theory of contact insecticidal action but provides no experimental data. Hurst believes that the susceptibility to insecticides depends partially on the cuticular permeability, but more fundamentally on the effects on internal tissue receptors which control oxidative metabolism or oxidative enzyme systems. The access of pyrethrins to insects, for example, is facilitated by adsorption and storage in the lipophilic layers of the epicuticle. The epicuticle is to be regarded as a lipoprotein mosaic consisting of alternating patches of lipid and protein receptors which are sites of oxidase activity. Such a condition exists in both the hydrophilic type of cuticle found in larvae of Calliphora and Phormia and in the waxy cuticle of Tenebrio larvae. Hurst explains pyrethrinization as a preliminary narcosis or knockdown phase in which oxidase action is blocked by adsorption of the insecticide on the lipoprotein tissue components, followed by death when further dispersant action of the insecticide results in an irreversible increase in the phenoloxidase activity as a result of the displacement of protective lipids. This increase in phenoloxidase activity is accompanied by the accumulation of toxic quinoid metabolites in the blood and tissues—for example, O-quinones which would block substrate access to normal enzyme systems. The varying degrees of susceptibility shown by different insect species to an insecticide may be explainable not only in terms of differences in cuticle make-up but also as internal factors associated with the stability of oxidase systems. 

Korotkov et al (Ref 67) also stress the importance of convective burning in DDT. They claim that the length of the run-up zone to detonation is determined by dp/dt in the burning zone. The value of dp/dt in turn is determined by the specific burning surface and the permeability, pore size and compressibility of the expl... 

Let us now examine DDT. The latest and also the most penetrating studies of DDT were with HE rather than SP. However, there is every expectation that DDT in HE and SP are similar, with only minor differences... 

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