Toxicity of 2-(2-Halogen-4-Chlorophenyl)-2-(4-Chlorophenyl)-1,1,1-Trichloroethanes to Normal and to DDT-Resistant House-Flies

Century of DDT

“…o-Chloro-DDT. o-Chloro-DDT (2-(4-chlorophenyl)-2-(2',4'-dichlorophenyl)-1,1,1-trichloroethane , VII) is highly toxic to both S and R flies (Hennessey et al, 1961). The bulky 0 substituent evidently interferes sterically with dehydrochlorination as the compound (k X 105 = 1.07 X 103 l./mol/min) undergoes OH~-catalyzed dehydrochlorination only about 0.17 as rapidly as , '-DDT (k X 105 = 6.1 x 103) (Metcalf and Fukuto, 1968).…”

Structural systematics for 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane-type compounds: crystal structures of five analogs and comments on mode of action

“…Therefore, it is probably relatively stable toward the enzyme fly DDT dehydrdchlorinase. However, the equivalent enzyme in Aedes aegypti actively dechlorinates it (Hennessy et al, 1961). The torsion angles and t2 (+130.4°, -77,3°) and dihedral angle X (87.0°) are comparable to those of o,p -DDT (+133.4°, -85.7°, 80.3°and +147.7°, -76.3°, 88.9°) for the two independent molecules and to p,p'-DDT (+134.3°, -94.8°, 64.9°) (DeLacy and Kennard, 1972a).…”

DDT substitutes

“…Methoxychlor does not produce the characteristic tremors and other nervous manifestations characteristic of DDT intoxication (Von Oettingen and Sharpless, 1946). Chronic two-year feeding studies in rats showed no growth retardation or tissue damage at 5 to 10 ppm (Hodge et al, 1952). Methoxychlor fed to monkeys at daily oral dosages of 2.5 g/kg had no detectable effect in general health and produced no enzyme-inducing effects on microsomal oxidases.…”

“…These compounds have been studied by Stringer et al (1955), Rogers et al (1953), andHolan (1971). Such compounds, e.g., DANP, although less active than DDT to susceptible flies, are obviously not susceptible to dehydrochlorination by DDT'ase and, as shown in Table 4, are effective against DDT-resistant flies (Metcalf and Fukuto, 1968 (1969), is another example of "resistance proofing," as it contains no a-H for attack by DDT'ase.…”

“…o-Cl-DDT, as shown by Hennessy et al (1961), retains both a high toxicity to susceptible houseflies and is highly toxic to DDT-resistant flies ( Table 4). The bulky o-Cl-substituent evidently interferes sterically with dehydrochlorination, as this compound is dehydrochlorinated only about 0.2 as rapidly as DDT (Metcalf and Fukuto, 1968).…”