Prevention of pesticide toxicity and poisoning

Pesticide Poisoning

Accidental exposure or overexposure to pesticides can have serious implications. The potential for pesticide accidents is real. Although most of these pesticides can be used with relatively little risk (as long as label directions are followed), some are extremely toxic and require special precautions. Wearing protective clothing and equipment when handling or applying pesticides reduces the hazards or risk of pesticide poisoning. The hazard of pesticide poisoning is reduced because the chance of exposure is reduced.
When considering the hazard of using a pesticide, you need to consider both the toxicity of the pesticide and the exposure (where did you get it on yourself, and how long did you leave it?). Understanding the toxicity of a product and the potential for personal exposure allows the hazard to be lowered. No matter how toxic a pesticide is, if the amount of exposure is kept low, the hazard can be held at an acceptably low level. The toxicity of a pesticide cannot be changed, but the applicator can manage the exposure.
Signal Words
Nearly all pesticides are toxic. They differ only in the degree of toxicity. Because of this, pesticides are potentially dangerous to people if exposure is excessive. A pesticide product label has one of three signal words that clearly indicate the degree of toxicity associated with that product (Table 1). The safest products no longer have a signal word. The signal words indicate the degree of potential risk to a user, not the effectiveness of the product.

Table 1 Signal words indicating toxicity level in pesticide products
Signal word	Toxicity	Oral lethal dosea (Human, 150 lb)
Dangerb	Highly toxic	Few drops to 1 teaspoonb
Warning	Moderately toxic	1 teaspoon to 1 tablespoon
Caution	Low toxicity	1 ounce to more than a pint
[none]	Very low toxicity	More than a pint
aLess for a child or person under 150 lb. bThe skull-and-crossbones symbol and the word "Poison" is often printed with the "Danger" signal word.

Along with the signal words, pesticide labels also include statements about route of entry and specific actions that must be taken to avoid exposure. Route-of-entry statements indicate the outcome that can be expected from exposure. For example, a pesticide label might read: "Poisonous if swallowed, inhaled, or absorbed through the skin. Rapidly absorbed through the skin and eyes." This indicates that the pesticide is a potential hazard through all three routes of entry, and that skin and eye contact are particularly hazardous. Specific action statements normally follow the route-of-entry statement and indicate what must be done to prevent poisoning accidents. In the case of the pesticide discussed above, the statement might read: "Do not get in eyes, on skin, or on clothing. Do not breathe spray mist."
Routes of Exposure
Pesticides can enter the human body three ways: (1) by absorption through the skin or eyes (dermally), (2) through the mouth (orally), and (3) by breathing into the lungs (inhalation).
Dermal exposure results in absorption immediately after a pesticide contacts skin or eyes. Absorption continues as long as the pesticide remains in contact with the skin. The rate at which dermal absorption occurs is different for each part of the body. The relative absorption rates are determined by comparing each respective absorption rate with the forearm absorption rate.
Relative absorption rates, compared to the forearm with an absorption rate of 1.0. It is easy to transfer pesticide residues from one part of the body to another. When this occurs, the applicator increases the potential for pesticide poisoning. For example, residues can be inadvertently moved from a hand to a sweaty forehead (4.2) or to the genital area (11.8). At this very high rate, the absorption of a pesticide is more dangerous than if it were swallowed! The speed of which it enters the body can be likened to that of direct injection by hypodermic needle into a vein.
Oral exposure may result in serious illness, severe injury, or even death if a pesticide is swallowed. Pesticides can be ingested by accident, through carelessness, or intentionally.
The most common accidental oral exposures occur when pesticides have been removed from their original containers and placed into an unlabeled bottle, jar, or food container. Children under 10 are victims of at least one-half of the accidental pesticide deaths in the United States. If pesticides were managed properly, children would never touch them.
Follow these guidelines:
�� Always store pesticides in their original labeled containers.
�� Never use the mouth to clear a spray hose or nozzle, or to begin siphoning a pesticide.
�� Never eat, drink, or use tobacco until after leaving the work area and washing thoroughly.
Respiratory exposure is particularly hazardous because pesticide particles can be rapidly absorbed by the lungs into the bloodstream. Pesticides can cause serious damage to nose, throat, and lung tissue if inhaled in sufficient amounts. Vapors and very small particles pose the most serious risks.
Lungs can be exposed to pesticides by inhalation of powders, airborne droplets, or vapors. Handling concentrated wettable powders can pose a hazard if they are inhaled during mixing. The hazard from inhaling pesticide spray droplets is fairly low when dilute sprays are applied with low-pressure application equipment. This is because most droplets are too large to remain airborne long enough to be inhaled.
However, when high-pressure, ultra-low-volume (ULV), or fogging equipment is used, the potential for respiratory exposure is increased. The droplets produced during these operations are in the mist- or fog-size range and can be carried on air currents for a considerable distance.