Toxicokinetics of Methyl Parathion in Lactating Goats

Baynes, Ronald E.; Bowen, John M.

doi:10.1021/jf00054a034

Cited by 4 publications

(2 citation statements)

References 14 publications

(18 reference statements)

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“…These chemicals are characterized by their ability to inhibit acetylcholinesterase activity [1][2][3][4]. They are lipidsoluble and are capable of penetrating the skin, the placenta, and into the fetus [5][6][7][8][9][10][11][12][13][14].…”

Section: Introductionmentioning

confidence: 99%

Environmental Toxicology and Health Effects Associated with Methyl Parathion Exposure – A Scientific Review

Edwards

Tchounwou

2005

IJERPH

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Methyl parathion - MP (C[8]H[10rsqbNO[5rsqbPS) is a restricted-use pesticide that has been widely used as an agricultural insecticide. It belongs to the class of organophosphate chemicals characterized by their ability to inhibit acetylcholinesterase activity. The main route of human exposure is inhalation, but dermal contact and inadvertent ingestion can also be substantial. Populations that are susceptible to MP exposure primarily are applicators, manufacturers and individuals living near application and/or disposal sites. Exposure has also been reported as a result of illegal indoor application. MP related health effects include headaches, nausea, night-waking, diarrhea, difficulty breathing, excessive sweating and salivation, incoordination, and mental confusion. Other symptoms including behavior problems, motor skill problems and impairment of memory recall have also been reported. The primary targets of toxicity are the hematopoietic system (serum cholinesterase inhibition), the cardiovascular system (cardiovascular lesions, abnormalities in heart rate and increase in heart-to-body ratio), the reproductive system (placental morphology, fibrosis and hemorrhage, and inhibition of DNA synthesis in seminiferous tubules), and the nervous system (headache, muscle weakness, insomnia, dizziness, and impaired memory). MP is believed to not have any carcinogenic effects. In an attempt to update its toxicologic profile, we hereby provide a critical review of MP-related environmental and toxicologic effects, with a special emphasis on their potential implications for public health.

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Section: Introductionmentioning

confidence: 99%

Environmental Toxicology and Health Effects Associated with Methyl Parathion Exposure – A Scientific Review

Edwards

Tchounwou

2005

IJERPH

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“…The pharmacokinetic profile of organophosphorus insecticides is affected by factors such as route of administration (Carver and Riviere, 1989) and animal species (Qiao et al, 1994). These insecticides are lipid-soluble and are capable of penetrating biological membranes, including the skin (Baynes and Bowen, 1995;Carver and Riviere, 1989;Draper and Street, 1981;Nolan et al, 1984;Wester et al, 1993) and the placenta, and into the fetus (Salama et al, 1992 a,b;Villeneuve et al, 1972). Physiological and biochemical changes associated with pregnancy may result in alterations in the pharmacokinetics of methyl parathion, with subsequent modifications of its pharmacodynamics and toxicity.…”

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confidence: 99%

Placental Transfer and Pharmacokinetics of a Single Dermal Dose of [14C]Methyl Parathion in Rats

Abu-Qare

Abdel-Rahman

Kishk

et al. 2000

Toxicological Sciences

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The pharmacokinetics and placental transfer of a single dermal 10.0 mg (10microCi)/kg dose of uniformly phenyl-labeled [14C] methyl parathion (0,0-dimethyl 0-4-nitrophenyl phosphorothioate) were investigated in pregnant Sprague-Dawley rats at 14-18 days of gestation. Three rats were killed at each time interval: 1, 2, 4, 12, 24, 48, 72, and 96 h after dosing. Radioactivity disappeared biexponentially from the administration sites, which retained 50% and 3% of the dose after 1 h and 96 h, respectively. Most of the absorbed radioactivity was excreted in the urine (91%). Only 3% of the 14C was recovered in the feces. One h after the administration, radioactivity was detected in all tissues, including fetal tissue. The peak maternal plasma concentration of radioactivity (ng methyl parathion equivalent/ml) was 1005 at 2 h, compared to 318 ng for fetal plasma at 12 h. The maximum concentrations of radioactivity (ng methyl parathion equivalent/g), detected in most tissues within 12 h of dosing, were, in descending order: adipose tissue (67,532), kidney (1,571), spleen (1,256), spinal cord (1,004), heart (729), liver (706), brain (546), placenta (389), and fetus (256). The metabolism studies showed that methyl parathion, detected by HPLC, was the major compound identified in plasma and tissues. The maximum concentration detected was in plasma, at 513 ng/ml, and in the following tissues (ng/g fresh tissue): kidney (819), fetus (668), placenta (394), liver (375), and brain (282). The metabolite methyl paraoxon was detected in maternal brain and liver at maximum concentrations (ng/g fresh tissue) of 135 and 64 after 12 h and 4 h respectively, while p-nitrophenol was only detected in liver at a maximum concentration of 21 ng/g 72 h after dosing. Pharmacokinetic studies showed that methyl parathion disappeared monoexponentially from plasma and tissues. The half-life of elimination of methyl parathion from plasma was 11 h corresponding to a constant rate value of 0.06 h(-1). The results indicate that skin and placenta are poor barriers against methyl parathion permeability, resulting in a rapid and extensive dermal absorption of this insecticide and extensive placental transfer. This is indicated by the relative residence (R(R)) of methyl parathion in the plasma, which was largest in the placenta followed by the fetus. This study suggests that pregnant women and fetuses may be at risk of cholinergic toxicity following dermal exposure to methyl parathion.

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Absorption

Baynes

Riviere

2012

Pesticide Biotransformation and Disposition

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Toxicokinetics of Methyl Parathion in Lactating Goats

Cited by 4 publications

References 14 publications

Environmental Toxicology and Health Effects Associated with Methyl Parathion Exposure – A Scientific Review

Environmental Toxicology and Health Effects Associated with Methyl Parathion Exposure – A Scientific Review

Placental Transfer and Pharmacokinetics of a Single Dermal Dose of [14C]Methyl Parathion in Rats

Absorption

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