Pesticide Formulations and Hazards
Formulations and what they imply
A formulation is the active ingredient plus carriers, solvents, surfactants, and inert ingredients. Know the common types and their trade-offs:
- EC (emulsifiable concentrate): solvent-based; good coverage; can injure sensitive plants and degrade rubber/plastic; flammable solvents possible.
- WP/WDG (wettable powder / water-dispersible granule): must be mixed with water; WPs cause inhalation dust; WDG reduces dust.
- SC/flowable (suspension concentrate): liquid suspension; needs agitation.
- Soluble powders/liquids: dissolve fully; low agitation need.
- Dusts, granules, baits: dry; granules reduce drift but can be picked up by birds.
- Microencapsulated: slow release; can be hazardous to bees.
Hazard types
Candidates must separate acute (immediate) from chronic (long-term) toxicity and recognize routes of exposure: dermal, inhalation, oral, ocular. Learn LD50/LC50 as toxicity measures - lower number = more toxic. Understand signal words, SDS (Section 2 hazards, Section 4 first aid, Section 8 exposure controls), and carrier/solvent hazards distinct from the active ingredient.
Traps in questions
(1) Assuming a "natural" or "organic" product is low-hazard - botanicals can be highly toxic; (2) confusing LD50 direction (smaller is more toxic); (3) forgetting that the inert ingredients/solvents cause many poisoning signs; (4) thinking granules are harmless because they are dry - they still carry label hazards; (5) assuming all formulations mix the same way.
Rule of thumb
Read the number, not the word. For LD50, lower = more toxic. For signal words, DANGER is stronger than WARNING, which is stronger than CAUTION.
Worked example
Product A has an oral LD50 of 50 mg/kg; Product B has 5,000 mg/kg. Product A is far more acutely toxic (lower LD50), and would likely carry a stronger signal word.