Pesticides Flashcards
What do organophosphates activate or inhibit? What are the signs/symptoms of exposure?
Organophosphates inhibit acetylcholinesterase. This inhibition causes a build of acetylcholine at the nerve synapse, thereby stimulating muscarinic and nicotinic cholinergic receptors.
This leads to cholinergic syndrome (parasympathetic effects). This includes miosis, hypersalivation, flaccid paralysis, over secretion in the gastrointestinal tract.
What muscarinic receptor antagonist is used to treat organophosphate toxicity? Also, what are the signs that sufficient activity of this reversal agent is achieved?
Atropine
Atropinization is characterized by sympathetic nervous system responses such as: dry mouth, pupil dilation, bronchodilation, flushing.
Which pesticide creates a slower reactivation of cholinesterase: organophosphates or carbamates? Why?
Carbamates
What do carbamates activate or inhibit? What are the signs/symptoms of exposure?
Carbamates inhibit acetylcholinesterase activity.
The effects are miosis, urination, salivation, diarrhea, muscle fasciculation.
What do pyrethroids activate or inhibit? What are the signs/symptoms of exposure?
Pyrethroids activate sodium channels, preventing closing and reopening of the sodium channel. Subtypes II inhibit GABA-dependent chloride channels.
Symptoms and signs include tremors, seizures, salivation and altered behavior. Occupational exposure is associated with paresthesia, and chronic exposure is associated with liver enlargement.
Chlordane, aldrin, DDT, heptachlor, endrin, and toxaphene are all examples of which pesticide class?
Organochlorines
What do organochlorines activate or inhibit? What are the signs/symptoms of exposure?
Organochlorines likely act on sodium channels, with some variants affecting calcium-ATPase.
Symptoms vary across this class, but primary include CNS effects and tremor,
What do neonicotinoids activate or inhibit? What are the signs/symptoms of exposure?
Neonicotinoids are agonists for nicotinic acetylcholine receptors. This leads to an initial activation followed by prolonged depolarization period.
Signs and symptoms are consistent with parasympathetic simulation: salivation, miosis, muscle fasciculation, GI secretions.
What do avermectins activate or inhibit? What are the types of toxicity observed?
Avermectins (antiparasitic) activates glutamate-gated chloride channels in invertebrates, but also modulates GABA receptor-mediated chloride channels in mammals.
Neurotoxicity, developmental toxicity and some unique immune reactions related to high doses of ivermectin.
Which type of insecticide has toxicity that is mediated by the formation of an oxon metabolite?
organophosphates
2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) was a contaminant of concern in which 1970’s herbicide?
Agent Orange
Bipyridyl herbicides include which two noteworthy products?
Paraquat and diquat
What is the chemical basis for paraquat’s mechanism of toxicity?
Paraquat is reduced to form a free radical that, in the presence of oxygen, leads to superoxide (O2 with a free free electron) formation.
Alachlor, acetochlor and metolachlor are a part of what pesticide family?
Chloroacetanilides
What product changes were made to paraquat to avoid acute exposures?
Addition of a blue dye, a stenching agent and an emetic to reduce oral absorption
