Toxico Lec - Pesticides

___can be defined as any substance or a mixture of substances intended for preventing, destroying, repelling, or mitigating pest

Pesticides

Pesticides be classified to ___

insecticides, herbicides, fungicides, rodenticides, acaricides, molluscicides, miticides, larvicides, and pediculicides

Pesticides exposure include

○ Occupational exposure (manufacturing, mixing/loading application, harvesting & handling crops)

○ Bystander exposure from spraying operations

○ General public who consumes food items containing pesticides residue

Most commonly used insecticides especially in farm areas

ACETYLCHOLINESTERASE INHIBITORS

ACETYLCHOLINESTERASE INHIBITORS examples

Organophosphate (Malathion, Parathion) and Carbamate pesticides

Unintentional exposure to insecticides around home or farm

ACETYLCHOLINESTERASE INHIBITORS

ACETYLCHOLINESTERASE INHIBITORS Most common exposure

gastrointestinal and unintentional exposure

MOA/MOT:

○ Binds to AchE (acetylcholinesterase) preventing degradation of Ach → excessive accumulation in the synapse → excessive parasympathetic stimulation

ACETYLCHOLINESTERASE INHIBITORS

ACETYLCHOLINESTERASE INHIBITORS S/SX:

○ Muscarinic stimulation: DUMBBELLS

○ Nicotinic stimulation: Hypertension, tachycardia

ACETYLCHOLINESTERASE INHIBITORS Dx

Base it on history and PE (know toxidromes that point out to a specific person

ACETYLCHOLINESTERASE INHIBITORS TX/ANTIDOTE

○ EMERGENCY & SUPPORTIVE MEASURES

○ ATROPINE

○ PRALIDOXIME (AChE regenerator)

EMERGENCY & SUPPORTIVE MEASURES of Acetylcholinesterase inhibitors

■ Decontamination (removal of exposed clothing, washing all exposed skin with soap & water)

■ Respiratory protective measures

Acetylcholinesterase inhibitors tx that Blocks muscarinic receptors

ATROPINE

Acetylcholinesterase inhibitors tx that:

■ Must give this 24-48 hours prior to the aging of the bonding (irreversible inhibition of ACh)

■ Breaks the bonds between the organophosphate & the enzyme (reactivating AchE) → effective only if used before bond ages and become permanent

PRALIDOXIME (AChE regenerator)

CHLORINATED HYDROCARBONS (DDT and analogs) are also known as

organochlorine pesticides

have largely been abandoned because they cause severe environmental damage (DDT)

Organochlorine pesticides

MOA/ MOT:

○ Blocks physiologic inactivation in the sodium channels of nerve membrane → uncontrolled firing of action potentials

CHLORINATED HYDROCARBONS

CHLORINATED HYDROCARBONS S/SX:

○ ACUTE: Tremors (1st sign) and may progress to seizure

○ CHRONIC: Associated with lymphoma & testicular CA

CHLORINATED HYDROCARBONS DX:

History & PE

CHLORINATED HYDROCARBONS TX

No specific treatment is available (Diazepam for seizure/convulsions)

○ Usually give CNS depressants like diazepam to prevent seizures

Most used in the market (present time)

BOTANICAL AGENTS

BOTANICAL AGENTS examples

PYRETHRINS AND PYRETHROIDS, nicotine, rotenone

Botanical agents that are derived from Chrysanthemum flower;

Pyrethrins

Botanical agents that are the synthetic derivatives

Pyrethroids

Most commonly used pesticides in the home (____ is the most common)

Permethrin

MOA/ MOT:

○ INSECTS: Prolongs the opening of Na+ channels → paralyzing the nervous system

○ MAMMALS: Generally metabolized rapidly thereby render them harmless

○ Toxicity is usually associated primarily with hypersensitivity reactions & direct irritants effects

■ Counter by giving corticosteroids

BOTANICAL AGENTS

BOTANICAL AGENTS S/SX:

○ Anaphylactic reactions

○ Inhalation: Bronchospasm

○ Skin: Burning sensation

○ Ingestion of large doses: CNS may be affected

BOTANICAL AGENTS TX

Decontamination; no specific treatment

●has the same effect on nicotinic cholinoceptors in insects as in mammals (excitation followed by paralysis of ganglionic, CNS, and neuromuscular transmission).

● Treatment is supportive

BOTANICAL AGENTS (NICOTINE)

● Plant alkaloid pesticide causes gastrointestinal distress when ingested and conjunctivitis and dermatitis after direct contact with exposed body surfaces.

● Treatment is supportive

BOTANICAL AGENTS (ROTENONE)

HERBICIDES examples

• CHLOROPHENOXY COMPOUNDS

• BIPYRIDYL COMPOUNDS

• CHLOROACETANILIDE

• TRIAZINES

• PHOSPHONOMETHYL AMINO ACIDS

CHLOROPHENOXY COMPOUNDS examples

2,4-dichlorophenoxyacetic acid (2,4-D), 2,4,5- trichlorophenoxyacetic acid

BIPYRIDYL COMPOUNDS

Paraquat, Diquat

CHLOROACETANILIDE examples

Alachor, Acetochlor, Metolachlor, Butachlor

TRIAZINES examples

Atrazine, Simazine, and Propazine

PHOSPHONOMETHYL AMINO ACIDS examples

Glyphosphate, Glufosinate