5.1 PPE Selection, Chemical Resistance & Maintenance

5.1 PPE Selection, Chemical Resistance & Maintenance

Personal Protective Equipment (PPE) represents the applicator's final barrier against chemical exposure. While engineering controls—such as closed mixing systems, tractor cabs with carbon filtration, and drift-reducing spray nozzles—serve as the primary defenses against chemical contact, PPE is universally required across agricultural, commercial, and ornamental pesticide operations. In New Mexico, pesticide handling operations are governed by both federal standards under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) and state administrative rules under 21.17.50 NMAC.

---

The Legal Status of PPE Under FIFRA and 21.17.50 NMAC

A foundational principle of pesticide law tested on every licensing examination is that the label is the law. Under FIFRA Section 12(a)(2)(G), it is a federal violation to use any registered pesticide in a manner inconsistent with its labeling. The "Personal Protective Equipment" section of the pesticide label specifies the legally mandated minimum apparel and gear required for handlers, mixers, loaders, applicators, and early-entry agricultural workers.

The Legal Minimum Baseline

1. Enforceable Mandate: Failure to wear every piece of PPE specified on the product label during mixing, loading, application, or equipment maintenance constitutes a direct violation of both FIFRA and the New Mexico Pesticide Control Act (NMSA 1978, § 76-4-1 et seq.).
2. More Is Allowed, Less Is Prohibited: An applicator may legally choose to wear more protective equipment than specified on the label (e.g., wearing a full-face shield and chemical apron when only safety glasses and long sleeves are listed). However, an applicator can never wear less protection than the label specifies.
3. Task-Specific Variation: Pesticide labels frequently delineate distinct PPE requirements depending on the operational task. Mixing and loading chemical concentrates routinely demands heavier PPE (such as chemical-resistant aprons and face shields) than applying diluted mixtures from an enclosed tractor cab.

+-------------------------------------------------------------------------+
|                        PPE LEGAL REQUIREMENT RULE                       |
+------------------------------------+------------------------------------+
                                     |                                    
            +------------------------+------------------------+           
            |                                                 |           
+-----------v-------------------------+   +-------------------v-----------------+
|        LABEL SPECIFICATIONS         |   |        APPLICATOR DISCRETION        |
+-------------------------------------+   +-------------------------------------+
| * Legally binding minimum standard  |   | * May exceed label requirements     |
| * Mandatory under FIFRA & NMAC      |   | * Upgrading gear is fully legal     |
| * Omitting any item is illegal      |   | * Downgrading gear is a violation   |
+-------------------------------------+   +-------------------------------------+

---

Chemical Resistance: Materials and Degradation Dynamics

The term chemical-resistant means that no measurable movement of pesticide through the material occurs during the period of use. No single material protects against all chemicals. When choosing personal protective equipment, handlers must understand how chemical formulations interact with various protective polymers.

Mechanisms of Chemical Failure

• Permeation: The molecular diffusion of a chemical through a protective barrier without visible damage. Liquid dissolves into the outer surface, migrates through the material, and desorbs on the inner surface directly onto the skin.
• Breakthrough Time: The elapsed time between initial contact of the chemical on the outside surface of the material and its subsequent detection on the inside surface.
• Degradation: A physical change in the protective material caused by chemical contact. Signs of degradation include softening, swelling, stiffening, cracking, bubbling, dissolving, or color changes. Once degradation begins, breakthrough occurs rapidly.

Common Chemical-Resistant Polymer Types

---

EPA Chemical Resistance Category Selection Chart

The Environmental Protection Agency assigns pesticide formulations to Chemical Resistance Categories (A through H) based on the carrier solvents and emulsifiers used in the formulation. When a pesticide label states, "Chemical-resistant gloves such as barrier laminate, butyl rubber, or nitrile rubber (Category A)," handlers must cross-reference the EPA chart to select an approved material.

+---------------------------------------------------------------------------------------------------+
|                    EPA CHEMICAL RESISTANCE CATEGORY SELECTION CHART SUMMARY                      |
+----------+------------------------------------+---------------------------------------------------+
| Category | Solvent Carrier Type               | Acceptable Polymer Materials (High Resistance)    |
+----------+------------------------------------+---------------------------------------------------+
| A        | Water-based formulations           | Barrier Laminate, Butyl, Nitrile, Neoprene,       |
|          | (Dry, granules, wettable powders)  | Natural Rubber, Polyethylene, PVC, Viton          |
| B        | Ketones (e.g., acetone, MEK)       | Barrier Laminate, Butyl Rubber                    |
| C        | Aromatic hydrocarbons              | Barrier Laminate, Nitrile Rubber, Neoprene, Viton |
|          | (e.g., xylene, heavy aromatics)    | (Natural rubber and PVC strictly prohibited)      |
| D        | Aliphatic hydrocarbons (kerosene)  | Barrier Laminate, Butyl Rubber, Viton             |
| E        | Alcohols, glycols, organic acids   | Barrier Laminate, Butyl, Nitrile, Neoprene        |
| F        | Petroleum distillates, light oils  | Barrier Laminate, Butyl, Nitrile, Viton           |
| G        | Chlorinated hydrocarbons           | Barrier Laminate, Viton                           |
| H        | Highly volatile organic esters     | Barrier Laminate, Viton, Butyl Rubber             |
+----------+------------------------------------+---------------------------------------------------+

Solvent Carrier Warning

Notice that Category A formulations (water-based) allow virtually any chemical-resistant glove, including inexpensive natural rubber or PVC. However, once the formulation contains aromatic hydrocarbons (such as xylene carriers in Category C emulsifiable concentrates), natural rubber, polyethylene, and PVC dissolve or degrade within minutes. Handlers must verify the category code directly from the pesticide label.

---

Strict Prohibition Against Leather, Canvas, and Cotton

One of the most dangerous and strictly prohibited practices in pesticide handling is wearing leather work boots, canvas tennis shoes, or cotton/fabric gloves.

The Chemical Reservoir Effect

1. Porous Absorption: Leather, canvas, and woven cotton are highly porous matrices of biological or vegetable fibers. Rather than shedding chemical liquids, they act like sponges, absorbing concentrates and spray mixtures deep into their internal structure.
2. Irreversible Binding: Once absorbed, chemical active ingredients and petroleum solvents bind chemically to the tanning oils and proteins of leather. It is physically and chemically impossible to wash, decontaminate, or clean pesticide residues out of leather boots or gloves.
3. Continuous Dermal Dosing: A handler who wears contaminated leather work boots or cotton gloves experiences continuous dermal absorption through the skin. Perspiration and skin warmth accelerate chemical extraction from the leather directly into the capillary blood vessels of the hands and feet.
4. Exam Rule: If leather boots or fabric shoes become contaminated with concentrated liquid pesticide, they must be condemned, removed, and disposed of as hazardous waste.

---

Body, Foot, and Eye Protective Equipment

Body Protection

• Work Clothing: The universal minimum required for handling any pesticide is a long-sleeved shirt, long pants, socks, and chemical-resistant shoes. Fabric must be tightly woven.
• Coveralls: Woven fabric coveralls worn over regular work clothes provide an extra layer of protection against dilute spray drifts. Non-woven spunbonded polyethylene suits (e.g., Tyvek) provide liquid barrier protection.
• Chemical-Resistant Aprons: Labels frequently require a chemical-resistant apron made of rubber, PVC, or barrier laminate during mixing and loading. The apron shields the chest, abdomen, groin, and upper thighs from splashes, spills, and drips during container pouring and hose coupling operations.

Footwear Configuration: The Pant-Leg Rule

Chemical-resistant boots must be made of rubber, neoprene, or heavy PVC, without laces or cloth linings.

CRITICAL APPLICATION RULE: Handlers must always wear pant legs OUTSIDE of the boots, never tucked inside. If pant legs are tucked inside the boots, any chemical spray, splash, or container spill running down the outside of the trousers will drain directly down the inside of the boot, collecting around the handler's socks and ankles.

   CORRECT CONFIGURATION                INCORRECT CONFIGURATION
      (Pant Outside)                       (Pant Inside)

         |   |                                |   |
     ====|===|====  <- Pant Leg           ====|===|====  <- Pant Leg
     |   |   |   |                        |   | | |   |
     |   +---+   |                        |   | | |   |
     |     |     |                        |   +-|-+   |
     |  +-----+  |  <- Runoff drips       |  +--|--+  |  <- Runoff channels
     |  |BOOT |  |     harmlessly         |  |B |O |T |     INTO BOOT
     +--+-----+--+     to ground          +--+--|--+--+     onto skin!
        +-----+                              +--+--+

Eye and Face Protection

The eyes are among the most vulnerable and permeable tissues in the human body. Corneas rapidly absorb toxic chemicals and are easily scarred by caustic solvents.

• Safety Glasses with Side Shields: Protect against front and lateral physical impacts and incidental large spray droplets. They provide insufficient protection against fine chemical mists, splashing concentrates, or pressurized line leaks.
• Chemical Splash Goggles: Feature indirect venting (hooded air baffles that allow air circulation while preventing liquid splashes from entering). Standard direct-vent shop goggles are prohibited because liquids pass straight through open vents.
• Full-Face Shields: Made of clear polycarbonate or acetate; worn clamped over chemical splash goggles to provide complete coverage of the face, neck, and throat during high-risk mixing and pouring operations.
• Contact Lens Warning: Soft contact lenses absorb organic solvent vapors and trap chemical mists against the cornea, causing severe ocular ulceration. Handlers must avoid soft lenses or wear non-vented chemical goggles.

---

Inspection, Donning, and Doffing Protocols

Pre-Use Inspection

Before every single pesticide application, handlers must inspect all PPE:

1. Glove Air-Inflation Check: Fill gloves with air by rolling the cuff downward toward the fingers, or submerge the inflated glove in clean water. Squeeze gently to detect pinholes, air leaks, or seam failures.
2. Flexibility Check: Bend and stretch rubber garments; discard any item exhibiting brittleness, surface crazing, cracking, or discoloration.
3. Seam Integrity: Inspect tape seals on chemical suits and verify elastic cuffs are intact.

Step-by-Step Doffing Sequence

The most frequent cause of self-contamination occurs during the removal (doffing) of contaminated PPE. Handlers must follow a strict, disciplined sequence:

1. Wash Gloved Hands First: Before touching any other gear, thoroughly wash chemical-resistant gloves with warm water and heavy-duty soap while they are still on your hands. This removes surface residues.
2. Remove Apron and Exterior Suit: Unfasten and peel the chemical-resistant apron and outer protective suit off, folding the contaminated exterior inward.
3. Remove Boots: Slide boots off using hands or a boot-jack without touching the interior lining or socks.
4. Remove Eye Protection and Respirator: Wash gloved hands again. Carefully remove goggles and respirator by grasping the rear head-straps, pulling forward and off without touching the contaminated front surfaces.
5. Peel Gloves Off Inside-Out: Grasp the cuff of one glove, peel it downward toward the fingers so it turns inside out, and slip it off. Use the clean interior of the removed glove to grasp the opposite glove cuff, peeling it off inside out.
6. Immediate Personal Hygiene: Wash hands, wrists, and face immediately with clean water and soap. Shower thoroughly at the end of the shift.

---

Laundering and Disposal of Contaminated Work Clothing

Routine Work Garments (Dilute Spray Contact)

Garments contaminated with routine, dilute field spray drifts must be laundered under strict protocols:

• Daily Washing: Wash contaminated garments at the end of every working day. Never wear contaminated clothes for consecutive days.
• Segregation: Always wash pesticide-contaminated clothing completely separate from family laundry. Never mix with children's or household clothing.
• Pre-Rinse / Pre-Soak: Hose off garments outdoors or run an initial pre-rinse cycle in the washing machine.
• Wash Cycle Parameters: Use the hottest water setting available on the washing machine, the highest water level, and a heavy-duty liquid detergent. Liquid detergents penetrate petroleum-based formulations and emulsifiers far more effectively than granular powders.
• Drying Protocol: Line-dry clothes outside in direct sunlight. Solar ultraviolet (UV) radiation accelerates the photodegradation of pesticide residues. Machine drying can bake residues into dryer drums, cross-contaminating future loads.
• Purge Cycle: After removing the laundered work clothing, run the washing machine through a complete, empty cycle with hot water and detergent before washing household items.

Catastrophic Drenching: The Disposal Rule

MANDATORY EXAM RULE: If clothing, coveralls, or footwear are drenched or heavily contaminated with concentrated pesticides carrying the signal word DANGER (Toxicity Category I) or WARNING (Toxicity Category II), they MUST NEVER BE LAUNDERED.

Laundering heavily drenched clothing fails to extract the concentrated chemical and contaminates the washing machine. Drenched garments must be immediately placed in a heavy-duty plastic garbage bag, sealed, and disposed of as solid hazardous waste in compliance with state and federal disposal guidelines.

---

Practical Scenario: Mix and Load Compliance in the Mesilla Valley

An agricultural applicator in the Mesilla Valley of southern New Mexico is preparing to mix an emulsifiable concentrate (EC) herbicide containing a heavy aromatic hydrocarbon solvent (EPA Chemical Resistance Category C). The product carries the signal word WARNING.

Proper Operational Protocol:

1. Glove Selection: Handlers must reject natural rubber, PVC, or polyethylene gloves. They select 14-mil nitrile or barrier laminate gloves rated for Category C solvents.
2. Apparel Configuration: The handler dons long pants, steel-toed rubber boots (pant legs pulled down over the boot shafts), a heavy-duty nitrile apron covering chest to knees, and indirect-vent chemical splash goggles.
3. Spill Handling: During pouring, a container hose ruptures, saturating the handler's denim work shirt with concentrated chemical.
4. Correct Emergency Action: The handler does not attempt to wash the shirt. The handler immediately removes the drenched shirt, washes skin thoroughly under the emergency shower for 15 minutes, and places the saturated shirt into a sealed hazardous waste drum for destruction.