Pesticides Domina Petric, MD

Pesticides can be devided into: Organochlorine Pesticides Organophosphorus Pesticides Carbamate Pesticides Botanical Pesticides

Organochlorine Pesticides DDT (chlorophenothane) and its analogs Benzene hexachlorides Cyclodienes Toxaphenes

Organochlorine Pesticides They can be absorbed through the skin and by inhalation or oral ingestion. They cause severe environmental damage and have been largely abandoned.

Organochlorine Pesticides DDT continues to have very restricted use for domestic mosquito elimination in malaria-infested areas of Africa. Organochlorine pesticide residues in humans, animals and environment.

Human toxicology These agents interfere with inactivation of the sodium channel in excitable membranes and cause rapid repetitive firing in most neurons.

Human toxicology Calcium ion transport is inhibited. These events affect repolarization and enhance the excitability of neurons. DDT causes tremor, as first manifestation, and convulsions.

Human toxicology There is no specific treatment for the acute intoxicated state. Management is symptomatic.

Human toxicology There is association between prepubertal exposure to DDT and brain cancer. The risk of testicular cancer is increased in persons with elevated DDT levels.

Human toxicology The risk of non-Hodgkin´s lymphoma is increased in persons with elevated oxychlordane residues.

Environmental toxicology The organochlorine pesticides are persistent chemicals. Degradation is quite slow. Bioaccumulation is well documented, especially in aquatic ecosystems.

Environmental toxicology The presence of organic matter in the soil favors the adsorption of these chemicals onto the soil particles. Adsorption is poor in sandy soils. These compounds induce significant abnormalities in the endocrine balance of sensitive animal and bird species.

Organophosphorus pesticides

Organophosphorus pesticides azinphos-methyl chlorfenvinphos diazinon dichlorvos dimethoate malathion parathion…

Organophosphorus pesticides Useful pesticides and plant systemics. They are based on soman, sarin and tabun, which were developed for use as war gases. Also used in human and veterinary medicine as local or systemic antiparasitics.

Organophosphorus pesticides The compounds are absorbed by the skin and by the respiratory and gastrointestinal tract. Biotransformation is rapid.

Human toxicology The major effect is inhibition of acetylcholinesterase through phosphorylation of the esteratic site inhibition of acetlycholinesterase accumulation of acetylcholine direct cholinergic activity (some of agents)

Human toxicology Exposure to organophosphorus pesticides cause altered neurologic and cognitive functions, as well as psychological symptoms of variable duration.

Human toxicology Some of these agents are capable of phoshporylating another enzyme present in neural tissue: neuropathy target esterase. This results in progressive demyelination of the longest nerves.

Human toxicology Organophosphorus ester-induced delayed polyneuropathy (OPIDP): paralysis and axonal degeneration. Delayed central and autonomic neuropathy may occur in some poisoned patients.

Human toxicology Neurotoxicity has been observed with: triorthocresyl phosphate (TOCP) dichlorvos trichlorfon leptophos methamidophos mipafox trichloronat

Human toxicology Polyneuropathy begins with burning and tingling sensations, particularly in the feet, with motor weakness few days later. Sensory and motor difficulties may extend to the legs and hands.

Human toxicology Gait is affected. Ataxia may develop. Central nervous system and autonomic changes may develop later. There is no specific treatment for delayed toxicity.

Acute treatment Atropine! In order to achieve adequate atropinization quickly, a doubling approach is typically used: escalation of doses from 1 mg to 2 mg, 4 mg, 8 mg, 16 mg…

Environmental toxicology Organophosphorus pesticides are not persistent pesticides. They are relatively unstable and break down in the environment: hydrolysis and photolysis. They have a small impact on the environment.

Carbamate pesticides Adicarb Aminocarb Carbaryl Dimetan Dimetilan Isolan Methomyl Propoxur Pyramat Pyrolan Zectran

Carbamate pesticides They inhibit acetylcholinesterase by carbamoylation of the esteratic site. They possess the toxic properties associated with inhibition of acetylcholinesterase.

Carbamate pesticides The clinical effects due to carbamates are of shorter duration than in the case of organophosphorus compounds. Spontaneous reactivation of cholinesterase is more rapid after inhibition by the carbamates.

Carbamate pesticides Carbamates are non persistent pesticides and have a small impact on the environment.

Nicotine, rotenone, pyrethrum Botanical pesticides Nicotine, rotenone, pyrethrum

Botanical pesticides Nicotine is obtained from the dried leaves of Nicotiana tabacum and Nicotiana rustica. It is rapidly absorbed from mucosal surfaces. Free alkaloid is readily absorbed from the skin.

Botanical pesticides Nicotine reacts with the acetylcholine receptor of the postsynaptic membrane: sympathetic and parasympathetic ganglia neuromuscular junction

Botanical pesticides Nicotine results in depolarization of the membrane. Toxic doses cause stimulation rapidly followed by blockade of transmission.

Botanical pesticides Rotenone is obtained from Derris elliptica, D. mallaccensis, Lonchocarpus utilis and L. urucu. The oral ingestion of rotenone produces gastrointestinal irritation.

Botanical pesticides Rotenone can also cause conjunctivitis, dermatitis, pharyngitis and rhinitis. Tretment is symptomatic.

Pyrethrum Consists of 6 known insecticidal esters: pyrethrin I pyrethrin II cinerin I cinerin II jasmolin I jasmolin II

Pyrethrum It may be absorbed after inhalation or ingestion. Absorption from the skin is not significant. The esters are extensively biotransformed.

Pyrethrum When absorbed in sufficient quantities, the major site of toxic action is central nervous system: excitation convulsions tetanic paralysis

Pyrethrum Voltage gated sodium, calcium and chloride channels are targets. Peripheral type of benzodiazepine receptors are also important targets of pyrethrum.

Pyrethrum Treatment: management of symptoms. Ivermectin, the chloride channel agonist may be used. Pentobarbital and mephenesin are also usefull.

Pyrethrum The pyrethroids are highly irritating to the eyes, skin and respiratory tree. They may cause irritant asthma, reactive airways dysfunction syndrome (RADS) and anaphylaxis.

Pyrethrum Workers spraying synthetic pyrethroids may have cutaneous paresthesias. Flight attendants and other aircraft workers use synthetic pyrethroids for aircraft disinfection and may have respiratory and skin problems and neurologic complaints.

Katzung, Masters, Trevor. Basic and clinical pharmacology. Medcape.com