9.4 Pesticide Stewardship: Spray Drift, Handler Safety & Worker Protection

9.4 Pesticide Stewardship: Spray Drift, Handler Safety & Worker Protection

Pesticides-herbicides, insecticides, and fungicides-are powerful tools that demand stewardship. The International CCA Performance Objectives pair environmental stewardship (keeping pesticides out of non-target areas) with health and safety (protecting the people who handle and enter treated fields). Both rest on one document: the pesticide label is the law.

Point Source vs. Non-Point Source Pollution

• Point source pollution comes from a discrete, identifiable origin-a spill at the mixing/loading site, tank rinsate dumped down a drain, or a back-siphoned well.
• Non-point source pollution is diffuse-pesticide carried off a whole field in runoff or on wind-blown sediment.

Concentration is measured in ppm (parts per million) and ppb (parts per billion); a residue tolerance is the legal maximum residue allowed on a harvested crop or in the soil for the current and a future rotational crop.

Spray Drift

Drift is the off-target movement of spray droplets (and vapor) during or after application. The CCA must manage the factors that drive drift:

• Wind speed: applications are safest at 3-10 mph, blowing away from sensitive areas; avoid calm conditions below 3 mph (possible temperature inversion) and high winds.
• Nozzle selection and boom height: coarse droplets drift less; a lower boom shortens the droplet travel distance.
• Temperature inversion: a warm air layer traps spray near the ground; never spray during a pronounced inversion (often at dawn or dusk).
• Carrier volume, pressure, ground speed, adjuvants, and evaporation all alter droplet behavior.

A site's vulnerability to soil- and water-quality contamination depends on the pesticide's solubility, persistence (half-life), and soil adsorption (Koc) (Section 10.3), combined with proximity to surface water, sinkholes, shallow aquifers, and endangered-species habitat. Endangered species may trigger label restrictions, buffer requirements, or product prohibitions via EPA's Bulletins Live! Two.

Reducing Pesticide Loss from the Field

• Maintain surface residue and buffer strips to intercept runoff.
• Use contour or strip farming to slow overland flow.
• Manage subsurface drainage timing and consider cover crops to scavenge residual pesticide.
• Always consult the label for set-backs from water and plant-back intervals.

Pesticide Modes of Entry into the Body

A pesticide can enter the body by four routes:

1. Dermal-absorption through the skin; the most common route for handlers. Wettable powders and emulsifiable concentrates are readily absorbed.
2. Inhalation-breathing spray mist or vapors.
3. Oral/Ingestion-swallowing, usually from eating, drinking, or smoking without washing.
4. Ocular-splashes to the eye, which absorb chemicals rapidly.

Acute vs. Chronic Poisoning

Acute poisoning results from a single exposure; symptoms appear within hours. Organophosphate and carbamate insecticides inhibit cholinesterase, producing the SLUDGE syndrome (Salivation, Lacrimation, Urination, Defecation, Gastrointestinal distress) plus muscle twitching, pinpoint pupils (miosis), and difficulty breathing. Chronic poisoning results from repeated small exposures over time; possible long-term effects include neurological, reproductive, and organ damage. Any suspected exposure requires immediate first aid per the label's Statement of Practical Treatment and a call to Poison Control.

Worker Protection Standard (WPS)

EPA's Worker Protection Standard (40 CFR Part 170) protects agricultural workers and pesticide handlers on farms, forests, nurseries, and greenhouses. Key elements:

• Restricted-Entry Interval (REI): the time after application during which workers may not enter the treated area without PPE; printed on the label.
• Personal Protective Equipment (PPE): the label-specified minimum (gloves, respirator, coveralls, eye protection) that handlers and early-entry workers must wear.
• Information exchange and notification: workers must be told about applications, REIs, and treated locations (oral and/or posted warning signs).
• Decontamination supplies: soap, water, and towels must be available for handlers and workers.
• Emergency assistance: the employer must provide transportation to a medical facility and supply label information.

Cleanup, Disposal, Storage, and Spills

• Equipment and PPE cleanup: rinse spray equipment and launder PPE separately from family clothing.
• Container disposal: triple-rinse (or pressure-rinse) empty containers, adding the rinsate to the spray tank, then puncture and dispose of or recycle per the label and state rules.
• Storage and transport: store pesticides in a locked, ventilated, signed facility away from water, feed, and children; secure containers during transport to prevent spills.
• Spill response: control the spill (wear PPE, use absorbent), contain it (dike to prevent spread to water), and clean it up per the label and state regulations; keep a spill kit on the rig.

A CCA who integrates label discipline, drift management, and WPS compliance keeps pesticides effective and people and water safe.