Pesticides are chemical or biological agents used to kill, repel, or control pests that damage crops, spread disease, or affect human environments. While they increase agricultural productivity and control vector-borne diseases, they also raise concerns about environmental impact, food safety, and human health.
🧪 Types of Pesticides
| Class | Targets | Examples |
| Insecticides | Insects | DDT, malathion, permethrin |
| Herbicides | Weeds | Glyphosate, atrazine, 2,4-D |
| Fungicides | Fungi/molds | Mancozeb, chlorothalonil, azoxystrobin |
| Rodenticides | Rodents (rats, mice) | Warfarin, bromadiolone |
| Nematicides | Nematodes (worms) | Aldicarb, fluopyram |
| Bactericides | Bacteria | Copper sulfate, streptomycin |
| Larvicides | Insect larvae | Temephos, methoprene |
| Molluscicides | Snails, slugs | Metaldehyde, ferric phosphate |
🧬 Chemical Categories
| Chemical Class | Example Compounds | Mode of Action |
| Organochlorines | DDT, lindane | Nerve impulse disruption (sodium channels) |
| Organophosphates | Malathion, parathion | Acetylcholinesterase inhibitors |
| Carbamates | Carbaryl, aldicarb | Reversible cholinesterase inhibitors |
| Pyrethroids | Permethrin, cypermethrin | Disrupt sodium channels in nerves |
| Neonicotinoids | Imidacloprid, thiamethoxam | Bind nicotinic acetylcholine receptors |
| Phenoxy herbicides | 2,4-D | Mimic plant hormones (auxins) |
| Biopesticides | Bt toxin, neem oil | Natural or biological origin |
⚠️ Health and Environmental Concerns
- Acute toxicity: Skin, respiratory, neurological effects
- Chronic exposure: Cancer, endocrine disruption, neurotoxicity
- Bioaccumulation: Persistent chemicals like DDT in the food chain
- Resistance: Pests evolving resistance with repeated exposure
- Pollution: Water, soil, and non-target species contamination
✅ Regulation & Safety
- Monitored by agencies like EPA (U.S.), EFSA (EU), and WHO
- Maximum Residue Limits (MRLs) set for food safety
- Integrated Pest Management (IPM) recommended to reduce reliance