DDT methoxychlor

The commonly used organic insect toxicants do not interfere in the analysis of Compound 118 by this new procedure. Hexane solutions of chlordan, DDT, methoxychlor, hexachlorocyclohexane (BHC), and toxaphene treated according to the procedure for determining Compound 118 gave a pale yellow color similar to that of the blank. 

Aspila et al. [338] reported the results of an interlaboratory quality control study in five laboratories on the electron capture gas chromatographic determination of ten chlorinated insecticides in standards and spiked and unspiked seawater samples (lindane, heptachlor, aldrin, 5-chlordane, a-chlordane, dield-rin, endrin, p, p -DDT, methoxychlor, and mirex). The methods of analyses used by these workers were not discussed, although it is mentioned that the methods were quite similar to those described in the water quality Branch Analytical Methods Manual [339]. Both hexane and benzene were used for the initial extraction of the water samples. 

Figure 15.4 Structures of DDT, methoxychlor, and their major metabolites, and toxicological and key physicochemical properties. Data from [132, 135, 141, 210].

Biocides most often found in the indoor environment are chlorinated hydrocarbons like chlordane, DDT, dieldrin, lindane, heptachlor and methoxychlor, pyrethroids like cyfluthrin, cypermethrin, and permethrin, organophosphates like chlorpyrifos, diazinon, dichlorvos, isofenfos, and malathion, carbamates like ben-diocarb, carbaryl and propoxur and chlorophenols like pentachlorophenol (PCP), chlorocresol (4-chloro-3-methylphenol) and o-phenylphenol. Residues formed in house dust may vary in different countries (Butte, 2003), but biocides like chlorpyrifos, DDT, methoxychlor, permethrin, pentchlorophenol and propoxur seem to be the active compounds in biocide formulations even in different continents, as they are found equally in house dust samples form Germany and the USA (Becker et al., 2002 Butte, 2003 Camann, Colt and Zuniga, 2002). Concentrations of biocides in house dust are mostly in the milligram per kilogram range, they seldom exceed a microgram per cubic meter in indoor air. 

The physical properties of these compounds are somewhat different from prolan, DDT, methoxychlor, perthane, and other related chemicals. Water solubility and polarity are considerably... 

Pyrethroid insecticides (deltamethrin, NRDC 157, cismethrin), DDT analogs ( p,j> -DDT, (>,j> -DDT, methoxychlor, EDO), and a DDT-pyrethroid hybrid compound (GH401) enhanced veratridine-dependent sodium uptake by mouse brain synaptosomes The effectiveness of these compounds in the sodium uptake assay was in good agreement with their acute mammalian toxicities. , -DDT also enhanced veratridine-dependent sodium uptake by fish brain synaptosomes These findings demonstrate the utility of ion flux assays to study interactions of insecticides with sodium channels in the central nervous system and to explore species differences in insecticide target site sensitivity ... 

For chlorpyrifos and lindane, no differences were observed between the dust of homes where biocides had been used ( users ) and dust without application of any biocide by the occupants ( non-users ). DDT, methoxychlor and PBO concentrations in the dust of users of insecticides were significantly higher than in that of non-users (see Fig. 3.5-2 for methoxychlor). Users of wood preservatives showed higher concentrations of PCP and users of biocides against insects and fleas showed higher concentrations of propoxur. 

Through microbial activities, a reducing environment can be created, particularly in a flooded soil. Many pesticides are degraded by reductive reactions that proceed nonenzymatically under anaerobic conditions. DDT, methoxychlor, and heptachlor readily break down in an anaerobic flooded ecosystem (Sethunathan, 1973). 

Aldrin, chlordecone (Kepone), 2,4-D, DDT and metabolites, dieldrin, endosulfan, endrin, f]- and y-HCH (lindane), linuron, methoxychlor, mirex... 

Schwack W (1988) Photoinduced additions of pesticides to biomolecules. 2. Model reactions of DDT and methoxychlor with methyl oleate. J Agric Eood Chem 36 645-648. 

The degradation of DDT by organisms designated Aerobacter aerogenes (possibly Klebsiella aerogenes) (Wedemeyer 1967) (Figure 2.6), and the partial reductive dechlorination of methoxychlor by K. pneumoniae (Baarschers et al. 1982). 

Arsenic, methoxychlor, benzene hexachloride, ethylene chlorohydrin, carboii tetrachloride, DDT phenols... 

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. 

New York has experienced a rather widespread breakdown in housefly control with the use of DDT. Schwardt of the Cornell University staff first noticed this failure of DDT in 1948. In 1949 the fly problem was very bad. Farmers, remembering the exceptional control of the past few years with DDT residual sprays, were greatly disturbed when DDT was first withdrawn from use in dairy bar ns because of the danger of DDT contamination in milk. Methoxychlor under conditions in 1949 did not measure up to the performance of DDT in other years neither did DDT. Lindane (gamma isomer of hexachlorocyclo-hexane) has been hailed by many dairymen as the successor to DDT, and by some farmers the question is raised— What is the successor of lindane to be ... 

A need has arisen for a sensitive and specific method of estimating microgram quantities of the insecticide methoxychlor in plant and animal products.. Methoxychlor, l,l,l-trichloro-2,2-bis(p-methoxyphenyl)-ethane, is an analog of DDT and therefore procedures for the determination of DDT should be applicable to methoxychlor as well. Such has actually been found to be the case. 

The pyridine-xanthydrol method of Stiff and Castillo (4) and Claborn (1) will indicate the presence of methoxychlor, but it has a low order of sensitivity and does not distinguish between methoxychlor and DDT. 

Much more promising is the method of Schechter and Haller (3), which depends upon the coupling of the tetranitro derivative of DDT with methanolic sodium methylate. Under conditions of intensive nitration methoxychlor will yield by this procedure a red color with an absorption maximum at 535 m/z. 

It may be generally stated that the Schechter-Haller procedure will distinguish methoxychlor from p,p -DDT, because the latter compound gives a blue color. However, o,p -DDT and various breakdown products of DDT yield red colors with absorption maxima close to that of methoxychlor, so that for practical purposes it is impossible to distinguish between them. 

In order to prepare the methoxychlor for analysis, it must be removed from the material under examination by means of a solvent extraction. The procedures used for the stripping of DDT are applicable to methoxychlor (2, 5, 6). The solvent chosen should readily dissolve methoxychlor, be sufficiently volatile to be evaporated by an air current at room temperature, and leave no residue upon evaporation that will interfere with the analysis. 

A procedure for the determination of 7-benzene hexa-chloride and DDT in benzene hexachloride-DDT-sul-fur formulations, employing partition chromatography, is described. The procedure has also been applied to the assay of 1,1,1 -trichloro-2,2-bis(p-methoxyphenyl)-ethane in technical methoxychlor. Results of separation of other insecticidal ingredients are discussed. 

The carcinogenic activity of chemical substances is important as well. They are present in pesticides of different classes OCPs (DDT, aldrine, heptachlor, methoxychlor), thiocarbamates (thiram, zineb, ziram), carbamides (monuron) [3], etc. Even if the official description of a given pesticide does not denote its carcinogenic (mutagenic, teratogenic, embryotoxic, etc.) activity, this merely means that this particular pesticide was not studied sufficiently. 

In general, the control of insect pests of cacao has been neglected. Also, little is known regarding the effect of insecticides on cacao. Cardona (9) in Colombia has studied the influence of some insecticides on the pollination and fruit setting. He used various preparations of BHC Agrocide, chlordan, DDT, dieldrin, dieldrex, methoxychlor [l,l,l-trichloro-2,2-bis(p-methoxyphenyl) ethane], and toxaphene. 

---