Chlorinated cyclodienes

A second organochlorine pesticide, heptachlor (HEP), a chlorinated cyclodiene that was used primarily as an agricultural and domestic insecticide, was evaluated for its potential to suppress the immune system of rats. Rats were exposed to HEP pre-and postnatally, as described above for MXC. The IgM antibody response to SRBCs was suppressed at all doses in males but not females at 8 weeks of age. At 26 weeks of age, the IgG anti-SRBC response was suppressed in all of the HEP-exposed males, but not females.131... 

DDT Metabolism.-- The metabolism of DDT has been studied in R and S fish, following similar protocols to chlorinated cyclodiene metabolism organic extraction (acetonitrile), thin layer chromatography of organic extracts, and liquid scintillation counting of the resultant spots (4). When S and R fish were exposed to 60 yg/l of 14C-labelled , -DDT for 4 hr, radioactivity was found in the spots which co-chromatographed with... 

Ivie, G.W. and Casida, J.E. Photosensitizers for the accelerated degradation of chlorinated cyclodienes and other insecticide chemicals exposed to sunlight on bean leaves, / Agric. Food Chem., 19(3) 410-416, 1971a. 

Below-grade bioremediation is an ex situ technology designed to treat soil, sludge, and sediment impacted with chlorinated cyclodiene insecticides such as chlordane and heptachlor. Naturally occurring fungi are added to pesticide-contaminated soil, which is then treated in a below-grade actively aerated bioremediation cell. 

Falandysz, J., Strandberg, L., Puzyn, T., Gucia, M., 2001. Chlorinated cyclodiene pesticide residues in blue mussel, crab and fish in the Gulf of Gdansk, Baltic Sea. Environ. Sci. Technol. 35, 4163-4169. 

Manclus, J.J., A. Abad, M.Y. Lebedev, et al. 2004. Development of a monoclonal immunoassay selective for chlorinated cyclodiene insecticides. J. Agric. Food Chem. 52 2776-2784. 

As seen from the structural formulas in Figure 16.4, the organochlorine insecticides are of intermediate molecular mass and contain at least one aromatic or nonaromatic ring. They can be placed in four major chemical classes. The first of these consists of the chloroethylene derivatives, of which DDT and methoxychlor are the prime examples. The second major class is composed of chlorinated cyclodiene compounds, including aldrin, dieldrin, and heptachlor. The most highly chlorinated members of this class, such as chloredecone, are manufactured from hexachlorocyclo-pentadiene (see Section 16.3). The benzene hexachloride stereoisomers make up a third class of organochlorine insecticides, and the third group, known collectively as toxaphene, constitutes a fourth. 

Heptachloronorbornene (l,2,3,4,5,7,8-heptachlorobicyclo[2,2,l]hept-2-ene) is produced by the Diels-Alder reaction by addition of vinylchloride to cyclopen-tadiene. This product is converted by dehydrochlorination to hexachloronor-bornadiene (l,2,3,4,7,7-hexachlorobicyclo[2,2,l]hepta-2,5-diene) which is an intermediate in the syntheses of the stable chlorinated cyclodiene insecticides. Hexachloronorbornadiene (HCND) and heptachloronorbornene are very hydrophobic chemical intermediates with very high log Kqw values of 5.15... 

Carbamates Chlordecone Chlorinated cyclodienes Methyl bromide... 

Chemical/Pharmaceutical/Other Class Organo-chlorine cyclodiene insecticide... 

The chlorinated cyclodienes were used in diverse formulations for different purposes such as spraying of crops and vectors of disease, for the control of ectoparasites on animals, for dressing of seed, etc. Their use was more or less phased out during the 1980s and today the uses are very few (Walker et al., 2001). 

Epoxidation or the insertion of an oxygen atom into a carbon-carbon double bond can frequently result in the formation of products with greater environmental toxicity. Various microorganisms can catalyze the reaction of the chlorinated cyclodiene insecticides aldrin, isodrin, and heptachlor to their more toxic epoxide derivatives. 

A rapid, competition immunoassay has been developed that detects chlorinated cyclodiene insecticides in meat, fish and milk products. The assay, a competition enzyme-linked inununosorbent assay, employs a monoclonal antibody that recognized all of the cyclodiene insecticides it was tested against. A simple method to extract heptachlor and related cyclodiene insecticides that is compatable with the immunoassay is described. The sensitivity of the immunoassay is sufficent to detect cyclodienes at the tolerance level in beef. We anticipate initial application of this assay as a screening aid. 

Table II. Recovery efficiency of chlorinated cyclodienes from beef fat...

The use of chlorinated, cyclodiene insecticides in agricultgure production by and large has been phased out with the exception of endosulfan. 

A cELISA using LLNL-Hept-2. capable of detection heptachlor and other related chlorinated cyclodiene insecticides in spiked meat, fish and dairy samples was developed. Our cleanup method did not remove all of the substance(s) that interfered with the cELlSA. Such substances were observed in the hexane extracted material from all three matrixes investigated. Our data suggests that the beef fat has the highest level of interfering substances and heavy dairy cream the lowest level. The exact nature of these substances are not known. 

Since LLNL-Hept-2 binds all of the chlorinated cyclodiene insecticides tested, a positive response in the cELISA represents an integrated value and does not identify a specific insecticide. Uncertainty about the exact composition of the contamination is a result of cross-reactivity with related chemicals and occurs even with monoclonal antibodies. However, monoclonal antibodies are invariant reagents that need to be extensively characterized only once to determine the range of compounds detected and their relative sensitivities. In contrast, polyclonal antibodies need to be... 

Further studies of spiked and incurred tissues using both the cELISA and a more traditional chemical assay for chlorinated cyclodiene insecticides are needed to demonstrate the reliability of the cELISA. Such studies also will permit an evaluation of the level of false negatives and/or false positives detected by the immunoassay. This latter point is of key importance for defining a useful screening method. 

After examination of 106 chlorinated cyclodiene insecticides on six selected types of insect. Soloway (1965) concluded that a strict geometry governs ability to react with insect receptors. Two electron-rich sites are required (Cl, O, N, S, or double bond) for electrostatic adsorption (dihydro-aldrin has only one such site, and has only a low toxicity to insects). Aldrin 6.46) is a typical example. Chemically it is efo- wrf(9-l,2,3,4,10,10-hexachloro-l,4 5,8-dimethano-hexa-hydronaphthalene. The critical outline which these nearly spherical molecules require for activity is shown in 6,47), it was produced by viewing molecular models along a line joining the bridgehead (methano) atoms. Lindane, which has a similar mode of action, has a similar outline. For further details of structure—action relationships, see Brooks (1974). 

From the massive rejection of the chlorinated cyclodienes, two survivors emerge, both recommended by IPM (p. 244). The first of these is endosulfan 6,48) with inbuilt biodegradability. The second is campheclor (formerly called toxaphene) said to be a mixture of about 175 polychloro derivatives of cam-phene 6.49) with an overall empirical formula ofCioHjoClg, and no double bond (Casida et al., 1974). It, too, is biodegradable. 

The modes of action of lindane (6.45) and the chlorinated cyclodienes (the dieldrin—aldrin family) seem to be identical, but quite different from that of DDT. They act presynaptically at cholinergic junctions in the central nerve system of insects, facilitating both spontaneous and evoked release of acetylcholine from an excess of which the insect appears to die. They do not block acetylcholinesterase (distinction from the organophosphorus insecticides, described in Section 13.3) (Beeman, 1982) and their action is not lessened by heat, as is that of DDT. 

The chlorinated cyclodiene insecticides act in a biologically different way from the DDT—pyrethrin group of insecticides and have different steric requirements. Soloway (1965) examined 106 cyclodienes and concluded that, for high activity, they should be nearly spherical. Proceeding to detail, he projected a model of aldrin on to a plane and obtained the outline of a highly modulated circle. Molecules which could just traverse through an aperture of these dimensions, see 6.47), scored well as insecticides. In addition, the presence of two electron-attracting substituents (usually chlorine atoms) was necessary. 

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