Herbicides, Insecticides, Fungicides

2,4-dinitrophenol

- once used as an anti-obesity agent OTC -inhibits ATP synthesis, leads to rapid breathing, tachycardia, sweating, chronic anxiety, fatigue, weight loss. -cataract causing carcinogen

Glyphosate

-"Round Up" -non-selective broad spectrum, kills weeds and grass. -inhibits an enzyme involved in aromatic amino acid formation. -rapidly inactivated in most soils.

Triazenes

-Atrazine -used extensively in corn fields, often found in drinking water. -interferes with photosynthesis so carbon dioxide fixation is stopped. -banned in Europe.

DDT

-OC pesticide -high chemical stability, metabolites (DDD, DDE) are also persistent. -lipid soluble, promotes accumulation in organisms, readily stored in fat.

Sarin

-OP pesticide -nerve gas 1995 Subway Attack in Japan.

Carbamate Pesticides

-aldicarb, carbaryl, porpoxur -binds reversibly to to AchE, competitive inhibition. -Ach eventually gets broken down. -generally used on vegetables, fruit crops, anti-parasitic in farm animals. -neurotoxicity in humans is short lived because hydrolysis of cholinesterase molecule. -same route as OP pesticide, but less toxic to humans. Detoxified rapidly and excreted in urine.

Imidacloprid

-carbamate pesticide -possible contributor to colony collapse disorder in honeybees. -neonicotinoid, "nicotine" like -mimics acetylcholine. Binds to ACH receptors, but it is not broken down by AchE, constant nerve firing.

2,4,5-T

-chlorophenoxy compoud -used in woody perennials 50:50 mix with 2,4-D forms Agent Orange

2,4-D

-chlorophenoxy compound -mimics auxin, which is a plant hormone that controls shoot growth. -developed in WWII

Bipyridils

-diquat, paraquat -class of herbicides that damage the antioxidant system of plants leading to damage by free radicals.

Hexachlorobenzene

-formerly used as fungicide, led to human deaths in Turkey when treated seed grain was accidentally used in food production in late '50's. -skin blisters, arthritis, bone inflammation. -persistent and can be bio-magnified.

Paraquat

-herbicide that is exception to the rule that most herbicides are less dangerous to humans than other types of pesticides. -causes irreversible lung damage.

Biomagnification

-level of toxicant is magnified as it moves through the food chain to higher trophic levels.

Organophosphate Pesticides

-mimin acetylcholine, non-competitive inhibition. -binds irreversibly to acetylcholinesterase. Ach keeps working, causing constant nerve impulse.

Organochlorine Pesticides (OC's)

-modern synthetic pesticides, started with DDT. -strong ability to biomagnify 1940-1970- millions of tons poured into environment, beginning of ban. 1940's- used to control malaria, yellow fever, protected millions. -Used in WWII to protect troops from malaria, typhus. **kills insects by opening sodium channels in axons, disrupts sodium/potassium balance and neurons continue firing inappropriately.

General Pesticide Info

-most are neurotoxins, disrupt transmission of nerve impulses either along axon or at the synapse. 1st Generation: 1800's: Paris Green (arsenic, copper) London Purple (calcium, arsenic-organic matter) -These do not degrade, "legacy contaminants".

Diquat

-most toxic of commercial herbicides. -used large scale in Canada to destroy coca and cannabis plants.

Organophosphate Pesticides (OP's)

-parathion, malathion, diazinon -inhibit AchE -can cross skin, lungs, GI tract, BBB -exposure causes vomiting, nausea, excessive bronchial secretions. -skeletal muscle weakness, paralysis, mental confusion, fatigue. -generally biodegraded, does not accumulate in body

Biomagnification Factor

BCF= concentration in organism/concentration in environment.