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Metabolism of a dicofol impurity alpha-chloro-DDT, but not dicofol or dechlorodicofol, to DDE in mice and a liver microsomal system.

1. The important acaricide dicofol and two related compounds, alpha-chloro-DDT (an impurity in dicofol) and dechlorodicofol (DCD) (a photolysis product of dicofol), as [phenyl-14C]-labelled preparations, were administered i.p. to male mice (30 mg/kg) and incubated with rat-liver microsomes alone and with NADPH, both aerobically and anaerobically, and with rat-liver cytosol alone and with glutathione. 2. alpha-Chloro-DDT is metabolically dechlorinated to DDE in the following systems: in vivo, based on analyses of mouse brain, fat and liver; in vitro, with anaerobic rat-liver microsomes plus NADPH; and with reduced haematin. Trace amounts of DDT are also detected in vivo in mouse liver. 3. Dicofol is reductively dechlorinated to DCD, and both compounds are metabolized to dichlorobenzophenone and dichlorobenzhydrol in vivo in the mouse tissues examined, and also in vitro exclusively with anaerobic rat-liver microsomes in the presence of NADPH. Liver cytosol with glutathione is less effective or inactive. 4. The in vivo metabolic dechlorinations of alpha-chloro-DDT and dicofol probably involve a reduced porphyrin in liver microsomes.

Adipose Tissue

Combined extraction-cleanup column chromatographic procedure for determination of dicofol in avian eggs.

Dicofol in avian eggs was completely oxidized to dichlorobenzophenone (DCBP) when a hexane Soxhlet extraction procedure was used. This degradation did not occur with other avian tissues (muscle and liver). For this reason, a combined extraction-cleanup column chromatographic procedure, without added heat, was developed for the determination of dicofol in avian eggs. Homogenized subsamples of eggs were mixed with sodium sulfate, and the mixture was added as the top layer on a column prepacked with Florisil. The dicofol and other compounds of interest were then eluted with ethyl ether-hexane. The extracts, relatively free from lipids, were quantitated on a gas chromatograph equipped with a 63Ni electron-capture detector and a methyl silicone capillary column. Recoveries from chicken eggs, fortified with dicofol and other DDT-related compounds, averaged 96%. Analysis of eggs of eastern screech-owls, fed a meat diet containing 10 ppm technical Kelthane, showed that both dicofol and DCBP were present. Results were confirmed by gas chromatography/mass spectrometry. This method is rapid and reliable, involves a minimum of sample handling, and is well suited for high volume determination of dicofol in eggs and other avian tissues.

Animals

Chromatographic determination of dicofol and metabolites in egg yolks.

Egg yolk was spiked with p,p'-dicofol (p,p'-DCF) (0.1-2.0 micrograms/gm), p,p'-dichlorobenzophenone (p,p'-DCBP) (0.1-2.0 micrograms/gm), and 1,1-bis(4-chlorophenyl)-2,2-dichloroethylene (p,p'-DDE) (0.05-1.0 micrograms/gm). The fortified egg yolk (2-5 g) was mixed with acetonitrile to extract non-fat organic materials. After removal of acetonitrile, the spiked chemicals were separated with a column chromatograph packed with acid alumina. Recovery efficiencies for p,p'-DCBP and p,p'-DDE were determined by gas chromatography, and for p,p'-dicofol by high performance liquid chromatography. The recovery efficiencies for p,p'-dicofol, p,p'-DCBP and p,p'-DDE were 77.2-93.8%, 84.1-101.1%, and 88.5-96.0%, respectively.

Animals

Survey of DDT-like compounds in Dicofol formulations.

The levels of o,p'-DDE, p,p'-DDE, o,p'-DDT, p,p'-TDE (DDD), and p,p'-DDT were determined in 19 samples of Dicofol formulations commercially available in Italy. The total of DDT-like compounds, calculated on a Dicofol content basis, was in the range 0.63-23.19%, with an average of 8.28%. Setting a requirement of minimum purity for Dicofol technical products is proposed.

Chromatography, Gas

Residues of dicofol on cucumber grown under plastic covers in Jordan.

Residues of dicofol were determined on cucumber leaves and fruits under plastic house (PH) and plastic tunnels (PT). Five sprays, 8 d apart, were applied at 0.15% concentration. Initial deposits on leaves were 48 and 58 ppm under PH and PT, respectively. In the last sampling date of leaves, the amounts of 191 and 135 ppm were detected under both cultures, respectively. There was a continuous increase in the initial residue after each spray. The highest amount of dicofol (401) was determined 1 d after the fifth spray under PH. The exposure to high residues may pose a risk to fieldworkers. On cucumber fruits, residues of 0.95 and 1.60 ppm were determined 1 d after the fourth spray under PH and PT, respectively. These residues decreased after 4 d to 0.40 and 1.49 ppm, respectively. Almost no detectable residues could be determined 8 d after sprays number 4 and 5 under both cultures. All dicofol residues on the fruits were below the tolerance level of 2 ppm.

Chromatography, Gas

Enhanced activation is the mechanism of negative cross-resistance to Chlorpyrifos in the Dicofol-IR strain of Tetranychus urticae (Acari: Tetranychidae).

The mechanism responsible for negative cross-resistance to chlorpyrifos was examined in isogenic dicofol susceptible (Orchard-12) and resistant (Dicofol-IR) two-spotted spider mites, Tetranychus urticae Koch. The acetylcholinesterase of both strains was equally sensitive to inhibition by chlorpyrifos oxon. However, the Dicofol-IR strain showed increased oxidative activation of chlorpyrifos to chlorpyrifos oxon relative to the Orchard-12 strain, suggesting this mechanism is responsible for the observed negative cross-resistance.

Animals

Neurotoxicities and behavioral changes in a 12-year-old male exposed to dicofol, an organochloride pesticide.

The case of a 12-yr-old male exposed to a substantial amount of dicofol, a DDT analog, is presented. The patient was still contaminated 3 wk after exposure. Blood and fat analysis documented the presence of dicofol. The patient demonstrated subjective and objective evidence of neurological injury, which resolved. Other organ injury was not present. Cognitive and emotional difficulties persisted over an 18-mo period.

Child

Dicofol residues in United States soils having a known history of its use as a miticide, 1974.

Soil samples were collected from a total of 21 sites in California, Washington, Florida, Pennsylvania, and Michigan. Dicofol (Kelthane) miticide had been applied at various times over a 5-year period to 17 of the sites; four sites had received no applications. Samples were collected at 0-75-mm and 75-150-mm depths, and submitted to gas-liquid chromatographic analysis. Samples from only four of the 17 treated sites contained mean residues equal to or exceeding 2.00 ppm. Residues in all cases were only a small fraction of the total amount applied. Apparently, a mechanism for the dissipation of dicofol exists, but it is unidentified at this time.

Dicofol