We studied chlorpyrifos, an insecticide present in a commercial dip for treating ectoparasites in dogs, to estimate the amount of transferable residues that children could obtain from their treated pets. Although the chlorpyrifos dip is no longer supported by the manufacturer, the methodology described herein can help determine transferable residues from other flea control insecticide formulati...

Organophosphorus insecticide, chlorpyrifos, and heavy metal, lead, were studied for their interactive effects on neurobehavioral aspects in Wistar rats when exposed for a period of 90 consecutive days through experimental diet. The tests used for the assessment of neurobehavioral changes were include functional observation battery, grip strength measurement, foot splay measurement and motor act...

The insecticide chlorpyrifos has been tested in numerous toxicological studies in the past. On the basis of these studies, the EU-evaluation of the active ingredient was finalized in 2005. Since then, new studies and data on the toxicity of chlorpyrifos have been published. The US American Environmental Protection Agency EPA has evaluated these studies and derived new toxicological reference va...

Chlorpyrifos (see Figure 1) is the most widely used insecticide in the United States, both in crop production and in nonagricultural applications.1 Its nonagricultural use in the United States is estimated at between 9 and 12 million pounds per year.1 Agricultural use estimates vary: the U.S. Environmental Protection Agency (EPA) estimates that between 10 and 15 million pounds are used annually...

BACKGROUND Organophosphorus pesticides such as chlorpyrifos and malathion are widely used insecticides. They do not bioaccumulate appreciably in humans and are rapidly metabolized and excreted in the urine. In nonoccupational settings, exposures to these pesticides are typically sporadic and short-lived because the pesticides tend to degrade in the environment over time; however, dietary exposu...

Chlorpyrifos is a common agricultural insecticide and has been used residentially in the United States until the year 2000 when this use was restricted by the U.S. Environmental Protection Agency (U.S. EPA). A chlorpyrifos metabolite, 3,5,6-trichloro-2-pyridinol (TCPy) has been found in urine samples collected during exposure field studies. In this work, we use urinary biomarker data and the in...

Development of resistance to chlorpyrifos in Culex pipiens population from Tunisia under temephos selection pressures was investigated. The objective of this study was to follow the evolution of resistance responses in Culex pipiens larvae under laboratory conditions. The selection to temephos caused a significant increase of resistance to chlorpyrifos levels. Indeed, the LD50 resistance rate i...

Paraoxonase (PON1) is a calcium dependent enzyme that is capable of hydrolyzing organophosphate anticholinesterases. PON1 activity is present in most mammals and previous research established that PON1 activity differs depending on the species. These studies mainly used the organophosphate substrate paraoxon, the active metabolite of the insecticide parathion. Using serum PON1 from different ma...

The aim of the study was to investigate the influence of administration of chlorpyrifos and/or enrofloxacin on the activity of chosen antioxidative enzymes i.e.: superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) in erythrocytes of rats. Chlorpyrifos was administered by stomach tube during 28 days at a dose of 3 mg/kg bw (0.02 LD50), and enrofloxacin was administered by...

Chlorpyrifos is one of the most popular pesticides used for agriculture crop protection, and widespread contamination is a potential concern. However, chlorpyrifos is hydrolyzed almost 1,000-fold slower than the preferred substrate, paraoxon, by organophosphorus hydrolase (OPH), an enzyme that can degrade a broad range of organophosphate pesticides. We have recently demonstrated that directed e...