This fourth, final case illustrates the exposures that agricultural applicators can receive in a day, especially from handling pesticides in the field. The skin of these individuals can come into contact with the residues during mixing, loading, and applying the pesticide. If the chemical has a high vapor pressure, or is formulated as a powder, inhalation exposure during handling can become a significant component. In addition to inhalation and dermal exposures received onsite, offsite secondary sources of exposure include: dietary intake; drinking water; and indoor or outdoor ambient air away from the field.

For agricultural workers or other users, the exposures occur at the treatment site may or may not be significant, compared to those from the secondary sources. It actually depends on the application method, the personal protective equipment (PPE), and the clothing requirements specified on the product label that these workers must and would follow. Some product labels specify that a pesticide applicator must wear intensive PPE or clothing, including coveralls over normal work clothes (long pants, a long-sleeved shirt, shoes plus socks), goggles, and chemical-resistant gloves. In other cases, applicators may be required to wear an approved respirator during handling.

The discussion here on the label requirements suggests that with some pesticides, none of the exposure pathways or sources by itself is significant enough to induce the adverse health effect(s) of concern. Yet when combined, they could provide an aggregate daily dose (i.e., total absorbed daily dose) exceeding the critical or otherwise inducible level.