Toxicology of Pesticides Flashcards
What is a pesticide?
any physical, chemical or biological agent that will kill an undesirable pant or animal pest
What is the amount of global pesticide poisoning cases that occur each year?
385 million cases each year, 11,000 deaths
What are some of the ways that humans can be exposed to pesticide poisoning?
Pesticide molecules in the air-from spraying
Runoff in ground water
Soil contamination
Dermal contamination
Grazing contamination by cattle leading to meat and dairy contamination
What are the some of the background pesticide exposure that humans are exposed to?
Humans have pesticide metabolites in 92% of childrens and 82% of adults urine samples
Detectable residues of at least one pesticide on 72% of fruits/vegetables
Residue in >90 of stream samples and in 50% of wells
What are the major types of insecticides?
organochlorine compounds, pyrethroids, organophosphates, carbamates and neonictotinoids
What are the organochlorine and pyrethroids MOA?
Disrupts ion channel functions at nerve cells
What are the organophosphates and the carbamates MOA?
Inhibits acetylcholineesterase
What is the MOA of neonicotinoids?
nAch receptor agonists
What are the four classes of organochlorine insecticides?
DDT, hexachlorocyclohexane, cyclodienes and polychloroterpenes
What are chemistry and kinetics of organochlorine insecticides?
synthetic compounds, some Cl substitutions, highly lipophilic, can biomagnify and resistance to biological/chemical breakdown
What is this LD50 and Logkow of DDT?
113-800 and 7
What are the chemistry and kinetics of pyrethroid?
synthetic analogs of naturally produced pyrethrins, low water solubility, rapid metabolism, mostly toxic to fish, some require synergists
What are pyrethroid synergists and MOA?
piperonyl butoxide and sesamex-inhibitors of CYP
What are the properties of Pyrethrum?
4 different plates compounds, unstable in sunlight and requires synergist
What are the properties of 1st and 2nd gen pyrethroids?
improved stability, greater efficacy, found in household uses, and still requires synergist
What are the properties of 3rd and 4th generation pyrethroids?
photostable, no synergist required and agricultural uses
What are the chronic effects of organochlorine insecticide poisoning?
Causes endocrine disruption, leading to reproductive failures, activates estrogen receptors and interferes with calcium metabolism leading to eggshell thinning
Where is organochlorine poisoning most prevalently seen?
Africa
What are some common examples of organophosphates?
Orthophosphoric acid, methyl parathion, diazinon, chlorpyrifos
What are some common examples of carbamates?
Carbamic acid, carbaryl, primcarb, carbofuran
What are the chemistry and kinetics of OPs?
derivatives of orthophosphoric acid, moderately water soluble
What are the chemistry and kinetics of carbamate insecticides?
synthetic derivatives of carbamic acid, typically more polar and water soluble than OPs, rapidly degrade in environment but not persistent.
What are the relative ranges of LogKow for the OPs and carbamaics?
2.4-3.8
What are the MOAs of OPs and carbamaics?
inactivates AChE, too much Ca2+ leading to cytochrome C and ROS activation, leading to apopotosis
