Insecticides: Agricultural Use and Human Health Implications

1. Insecticides: Agricultural Use and Human Health Implications By: Tristan J. Van Voorhis

2. Insectides Def: pesticides that are used to kill insects Uses: • In the agriculture industry, they are used in combination with fungicides and herbicides • Prevent insects from eating crops • Control insect-borne disease

3. Indoor Application • Common insecticides: flea powder and cockroach spray • Can be tracked indoors (on shoes, gloves, pets, airborne dust) • Indoor insecticides have longer half life than in the outdoor environment due to less water, UV and biological exposure and breakdown

4. Classifications • Organic: synthetic chemicals that account for large number of pesticides • Inorganic: manufactured with metals • Arsenates, sulfur, fluoride, and copper-compounds • Contact: toxic to insects by direct contact • Aerosols • Natural: composed of plants to defend against insects • Pyrethrum and nicotine • Systemic: incorporated with treated plants

5. Agricultural Application Spray application – most common method • Applied manually by mounted tractor sprayers or hand held equipment • Aerial application as well • Targets insects that dwell on vegetation and soil

6. Environmental Considerations • Water pollution by various routes • Pesticide drift • VOC (volatile organic compounds) • Soil contaminants • Non-target organisms • Pest resistance

7. Environmental Considerations • Prior to the use of a pesticide in the United States, the Environmental Protection Agency studies the ecological effects of a pesticide and its degradation products to various terrestrial and aquatic animals and plants. • The EPA also studies the chemical fate and transport of a pesticide in soil, air, and water resources

8. Organophosphorus Insecticides • Class of chemicals composed of an organic radical bound to a phosphorus containing radical that kill insects. • Classified as non-persistent because upon hydrolysis with air, soil, or sunlight, these compounds are rapidly degraded • Widely used for agricultural, residential, and community health purposes • Examples: chlorpyrifos, diazinon, dichlorvos, fenthion, malathion, methyl-parathion Functions- • Irreversibly inactivate acetylcholinesterase • Disrupt insect nervous impulses which results in death or impairment of normal function • Replaced organochlorine insecticides that were known to be persistent in the environment

9. Adverse Health Effects • Acute toxicity for mammals • Pose as addictive toxic effects that are amplified by multiple exposures • Metabolize quickly and excreted in urine • Potential chronic health risks • Respiratory depression, seizures, loss of consciousness • Absorbed by inhalation, skin penetration, and ingestion

10. Other Effects • Psychiatric effects • Cancer • Eye defects • Birth defects • Cardiac effects • Neurological

11. Poisoning • Signs and symptoms: headache, nausea, muscle twitching, diarrhea, hypersecretion • Treatment: Clear airways to improve tissue oxygenation, administer atropine sulfate intravenously, decontaminate skin

12. Alternatives and Considerations • Methods of cultivation • Other organisms to kill pests • Genetic engineering • Insect breeding interference

13. Insecticide Summary • Research safer ways to handle and apply insecticides • Minimize human exposure by introducing new or improved personal protective equipment • Investigate how home design and household cleaning practices affect indoor pesticide levels • Implement simple preventative measures like removing shoes at the door or installing walk off mats • Wash and peel food crops