Pesticides methoxychlor

Blizard, D., T. Sueyoshi, M. Negishi, S.S. Dehal and D. Kupfer. Mechanism of induction of cytochrome P450 enzymes by the proestrogenic endocrine disruptin pesticide-methoxychlor interactions of methoxychlor metabolites with the constitutive androstane receptor system. Drug Metab. Dispos. 29 781-785, 2001. 

Substantial rate enhancement for the photolysis of the pesticide methoxychlor... 

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. 

A waste is toxic under 40 CFR Part 261 if the extract from a sample of the waste exceeds specified limits for any one of eight elements and five pesticides (arsenic, barium, cadmium, chromium, lead, mercury, selenium, silver, endrin, methoxychlor, toxaphene, 2,4-D and 2,4,5-TP Silvex using extraction procedure (EP) toxicity test methods. Note that this narrow definition of toxicity relates to whether a waste is defined as hazardous for regulatory purposes in the context of this chapter, toxicity has a broader meaning because most deep-well-injected wastes have properties that can be toxic to living organisms. 

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. 

Results of volatilization and leaching estimations are reported for six pesticides that span a wide range of the physical/chemical properties that affect fate at the soil/air interface. The pesticides are Mirex, toxaphene, methoxychlor, lindane, malathion, and dibromochloropropane (DBCP). These particular pesticides were chosen for discussion here because they illustrate the methods for assessing the fate of organics at the... 

Table I shows the results of calculating a soil diffusion coefficient and soil diffusion half-lives for the pesticides. The 10% moisture level specified means that the soil is relatively dry and that 40% of the soil volume is air available for diffusion. Complete calculations were not made for methoxychlor, lindane, and malathion because, based on Goring s criteria for the Henry s law constant, they are not volatile enough to diffuse significantly in the gas phase. This lack of volatility is reflected in their low values of X. These materials would move upward in the soil only if carried "by water that was moving upward to replace the water lost through evapotranspiration at the surface. Mirex has a very high Henry s law constant. On the basis of Goring s criteria, Mirex should diffuse in the soil air but, because of its strong adsorption, it has a very large a and consequently a very small soil air diffusion coefficient. The behavior of Mirex shows that Goring s criteria must be applied carefully.

Pesticides, TCDD, PCBs, PBBs, methoxychlor Pesticides... 

Pesticide wastes that are hazardous by reason of the characteristics are those which are either solvent based and have a flash point <60 °C are aqueous and have a pH <2.0 or >12.5 release HCN or H2S upon contact with acids or leach greater than threshold levels of one or more of the elements arsenic, barium, cadmium, chromium, lead, mercury, selenium and silver, or the pesticides endrin, lindane, methoxychlor, toxa-phene, 2,4-D or 2,4,5-TP. To date, these are the only pesticides for which thresholds have been established. 

Millions of pounds (1 lb = 0.454 k) of pesticides are used on croplands, forests, lawns, and gardens in the United States each year. A large quantity of hazardous pesticides is also released by the pesticide industry to the environment. These hazardous pesticides drain off into surface waters or seep into underground water supplies. Many pesticides pose health problems if they get into drinking water and the water is not properly treated. The maximum limits for pesticides in drinking water are (a) endrin, 0.0002 mg/L (b) lindane, 0.004 mg/L (c) methoxychlor, 0.1 mg/L (d) toxaphene, 0.005 mg/L (e) 2,4-D, 0.1 mg/L and (f) 2,4,5-TP silvex, 0.01 mg/L. 

Methoxychlor Pesticide - organochlorine - bioaccumulates - used as a replacement for DDT In the US, 3.7 million pounds manufactured in 1978. Use has declined significantly - regulated has a water contaminant... 

Pesticides Dibromochloropropane (DBCP), methoxychlor, linuron (herbicide)... 

The comparative figures for methoxychlor, a biodegradable pesticide, were 1343 and 206, respectively. Although it is... 

As indicated in Table VII, 13 of the 18 OCPs were retrieved in excess of 90% recovery during the first extraction. The remaining four OCPs, endrin, endosulfan n, endosulfan sulfate, and methoxychlor were recovered at levels between 10-57%. Since no significant amount of any OCP was recovered during the follow-up extraction, breakdown of some organochlorine pesticides endrin in the injection port of the GC was suspected. 

The phenomenal success of DDT stimulated further research, and by 1946 the two DDT analogs, DDD and methoxychlor (Table 1,A) had been produced (Tables are at the end of the chapter). The observation of greater insecticidal activity in those organochlorine compounds that lose their HC1 more easily led to yet another group of chlorinated derivatives, the condensed ring chlorocyclodienes (Table 1,B). Thus, nearly all of the chlorinated pesticides currently in use had been... 

The American Public Health Association [97,98] published an early gas chromatographic method for the solvent extraction and gas chromatographic determination of 11 chlorinated insecticides in water samples in amounts, down to 0.005mg L 1 p,p -DT)E, p,p -DDT, Aldrin, Dieldrin, Endrin, Heptachlor, Heptachlor epoxide, Lindane, Isodrin and Methoxychlor. The insecticides Carbophenothion, Chlordane, Dioxathion, Diazinon, Ethion, Malathion, Parathion methyl, methyl Trithion, Parathion, Toxaphene and VC-13 may be determined when present at higher levels. Also, the chemicals chlordane, hexachlorobicycloheptadiene and hexachlorocyclopentadiene, which are pesticide manufacturing precursors, may be analysed by this method. 

The pure form of methoxychlor is a gray to pale yellow powder with a fruity or musty odor, or a crystalline solid. Technical methoxychlor (88% to 90% pure) is a gray powder. Methoxychlor is a practically nontoxic compound, and the USEPA has grouped it under general use pesticide (GUP).14... 

Two organochlorine pesticides have also been evaluated in animal models using early life stage exposures. Methoxychlor (Chapin et al., 1997) and heptachlor (Smialowicz et al., 2001) were evaluated for immunotoxicity after perinatal plus juvenile exposure of rats. In the case of methoxychlor, T cell-dependent antibody responses were depressed persistently in males but not females (Chapin et al., 1997). For heptachlor, early exposure of Sprague-Dawley rats, using doses relevant to human exposure, produced persistent impairment of antibody responses in males but not females. No adult-exposure immunotoxicity was observed at the doses examined, suggesting that there is an increased susceptibility of the prenatal and/or early postnatal life stages to this pesticide (Smialowicz et al., 2001 Smialowicz, 2002). 

Over the last decades, large amounts of different man-made chemicals which can act as weak estrogens have been released into the terrestrial and aquatic environment and are distributed world-wide. Classical environmental estrogens are pesticides, such as o,p -DDT, and its metabohtes o,p -DDE and o,p -DDD, methoxychlor and its metabolites, chlordecone (Kepone ), dieldrin, Toxaphene, and endosulfan [126, 135, 136]. It is also known that many chemicals with very weak or no measurable estrogenic activity can be metabolized in organisms especially to hydroxylated compounds which may have much more estrogenic potency than the parent compound. Examples are methoxychlor and its mono- and di-demethylated derivatives [126,127] as well as the alkylphenol... 

The following are examples of priority pollutants arsenic, selenium, barium, cadmium, chromium, lead, mercury, silver, benzene, ethylbenzene, chlorobenzene, chloroethene, dichloromethane, and tetrachloroethene. The priority pollutants also include the pesticide and fumigant eldrin, the pesticide lindane, the insecticide methoxychlor, the insecticide and fumigant toxaphene, and the herbicide and plant growth regulator silvex. There are a total of 65 priority pollutants. 

Methoxychlor is very persistent in soil. Its half-life is 120 days. Methoxychlor degrades much more rapidly in aerobic conditions than in anaerobic conditions. Methoxychlor is tightly bound to soil and is insoluble in water. The risk to groundwater should be low. Movement of the pesticide is likely via adsorption to suspended soil particles. 

A large number of ubiquitous environmental pollutants are very toxic to the hypothalamic-pituitary-thyroid (HPT) axis when administered at high (greater than environmental) levels. To study low level effects on the HPT axis, laboratory animals were administered a mixture of 16 organochlorine pesticides and other chlorinated hydrocarbons and heavy metals, all at levels similar to those found environmentally, so as to simulate environmental exposure. The chemicals included DDT (6.91), HCB (5.73), TCDD (6.80), PCBs (6.29), methoxychlor (5.08), endosulfan (3.83), heptachlor (6.10), hexachlorocyclohexane (3.80), dieldrin (5.40), aldrin (6.50), mirex (7.18), several chlorinated benzenes (2.84-3.44), cadmium (-1.65), and lead (1.35). Effects were measured by monitoring thyroid activity. The study found that this mixture of environmental pollutants was toxic and can alter HPT physiology in sexually mature malesJ50 ... 

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