Pesticide Formulations, Toxicity, and Human Safety
Formulations and adjuvants
Know the common letters and their behavior: EC (emulsifiable concentrate - solvent-heavy, high phytotoxicity risk, can damage tender foliage and certain plastics), WP/WDG (wettable powder, water-dispersible granule - good on dusty or waxy surfaces, requires agitation), SC/flowable, SL (solution), G (granule - applied dry, risk to birds), D (dust), M (microencapsulated - prolonged residual, high hazard to bees), and RTU (ready-to-use). Adjuvants (surfactants, stickers, spreaders, drift-control agents) are not pesticides and are not regulated as such, but the label may require or forbid them. Always follow the label's mixing order; adding incompatible products (an EC into a WP slurry) can cause sludge or clogged screens.
Toxicity and signal words
Toxicity is measured by LD50 (oral, dermal) and LC50 (inhalation) - the dose or concentration killing 50 percent of test animals. Lower LD50 means more toxic. Acute effects appear quickly; chronic effects (cancer, reproductive harm, cholinesterase inhibition) follow repeated exposure. Signal words on the label: DANGER–POISON with skull and crossbones (Category I), DANGER, WARNING (Category II), CAUTION (III and IV). The word reflects the most severe of oral, dermal, inhalation, eye, and skin irritation hazards, so a product that is low-oral but corrosive to eyes still reads DANGER.
Exposure and first aid
Routes are dermal, inhalation, oral, and ocular - dermal dominates in agriculture. Choose chemical-resistant gloves from the label's glove chart; leather and cotton absorb and hold pesticides. Organophosphate and carbamate poisoning shows cholinergic signs (salivation, lacrimation, sweating, miosis, vomiting, diarrhea) and is treated medically with atropine - call emergency services, do not induce vomiting with a solvent-based product.
Rule of thumb: when comparing labels, the smaller LD50 wins the toxicity comparison, and the more restrictive PPE statement governs.