Agriculture Reference
In-Depth Information
materials such as wax bars and wiper wicks. Each type of formulation may
require distinct strategies for protecting pesticide handlers with PPE.
Liquids may splash or slosh during mixing and loading, causing a poten-
tial exposure through ocular, dermal, and oral routes. Furthermore, until
sprays have dried, such formulations have the potential to soak through non-
chemical-resistant materials, creating dermal exposure. Due to perspiration,
they may penetrate even after drying.
Dry formulations often cause clouds or puffs of powdery pesticide to waft
upward during mixing and loading, causing potential exposure through ocular,
dermal, and inhalation routes (see Figure 6.4 ) . Persons exposed to dry formu-
lations may be unaware that pesticides have penetrated their clothing or
equipment, because they do not sense "wetting through."
Gas formulations have obvious exposure potential through the inhalation
route, but some also present an exposure risk through the dermal route. Expo-
sure may occur if the gases become trapped in clothing made of fabrics or ma-
terials having low air permeability.
2.
Toxicity
In general, the greater the pesticide toxicity, the greater the amount of pro-
tection needed by the worker. Toxicity categories ( Table 6.1 ) are based on the
LD 50 , a statistical estimate of a chemical dose which, when administered, will
kill 50 percent of the test animals within a stated period of observation.
Table 6.1 Toxicity Categories
Category
Toxicity
Signal word
I
Highly toxic
Danger
II
Moderately toxic
Warning
III
Slightly toxic
Caution
IV
Relatively nontoxic
Caution
Correlating PPE recommendations with the pesticide toxicity categories is
helpful for the pesticide user accustomed to reading signal words on the prod-
uct labels. One complication, however, is that a single pesticide may be
ranked as Category I for oral toxicity and as Category II for dermal toxicity. A
second complication is the duration of the exposure. Pesticide handlers may
mistakenly believe they do not need protective equipment because they are
using pesticides of low toxicity. In fact, long-term exposure to slightly toxic
pesticides can sometimes be as dangerous as a brief exposure to a highly toxic
pesticide.
 
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