use than one of a much lower basic toxicity. For example, parathion, a nonstandard
organophosphate which is extremely toxic (LD50 13 mg/kg or less), often present less
hazard than DDT from the standpoint of residues in food crops. Dieldrin is extremely
hazardous when the skin is contaminated with dusts or sprays, although its oral toxicity
is similar to that of lindane, which is used next to the skin as a delousing powder. The
most toxic pesticide in a secured storeroom is less hazardous than the least toxic
pesticide on a kitchen shelf. The type of formulation used also may have a
considerable effect on the degree of hazard for the same chemical applied at the same
dosage. Oil solutions and emulsions, for example, are absorbed more readily by the
skin than are dusts and water suspensions.
HAZARDS IN THE USE OF PESTICIDES
a. Carelessness. Most of the accidents resulting from the use of pesticides
have been caused by a careless disregard of precautions printed on the label.
Pesticide manufacturers, to comply with Federal pesticide laws, are required to include
warning statements on the label concerning the precautions that should be taken when
using the pesticide, antidotes known to counteract the poison, first aid
recommendations, and a statement concerning the hazardous nature of the material.
When current recommendations of the manufacturer are followed, even the most
hazardous pesticide can be used with relative safety. When recommendations are not
followed, the safety hazard is increased even when using the least toxic materials.
b. Factors in Assessing Hazard. The most important factors to be
considered in estimating the hazard from a given pesticide are:
(1) Acute oral and inhalation toxicity.
(2) Degree of skin absorption and dermal toxicity.
(3) Cumulative effect on the body.
(4) Concentration of toxicant handled in mixing or applying the chemical.
(5) Amount of toxicant that must be applied to achieve control.
(7) Conditions under which the chemical is applied and the degree of
exposure to the residues.
(8) Physical and chemical properties of the toxicant.