Chlorpyrifos exposures in Egyptian cotton field workers

Abstract

Neurobehavioral deficits have been reported in Egyptian pesticide application teams using organophosphorus (OP) pesticides, but whether these effects are related to OP pesticide exposures has yet to be established. In preparation for a comprehensive study of the relationship between OP pesticide dose and neurobehavioral deficits, we assessed exposure within this population. We conducted occupational surveys and workplace observations, and collected air, dermal patch and biological samples from applicators, technicians and engineers involved in chlorpyrifos applications during cotton production to test the hypotheses that: (1) dermal exposure was an important contributor to internal dose and varied across body regions; and (2) substantial differences would be seen across the three job categories. Applicators were substantially younger and had shorter exposure histories than did technicians and engineers. Applicators and technicians were observed to have relatively high levels of skin or clothing contact with pesticide-treated foliage as they walked through the fields. Both dermal patch loadings of chlorpyrifos and measurements of a chlorpyrifos-specific metabolite (TCPy) in urine confirmed substantial exposure to and skin absorption of chlorpyrifos that varied according to job category; and dermal patch loading was significantly higher on the thighs than on the forearms. These findings support our hypotheses and support the need for research to examine neurobehavioral performance and exposures in this population. More importantly, the exposures reported here are sufficiently high to recommend urgent changes in work practices amongst these workers.

Figure 1

Pesticide application team consisting of a technician (left) who directs the applicators in the field, an applicator (center), and an engineer (right) who is instructing the applicator on how to hold the tube through which the pesticides are applied.

Figure 2

Pesticide mixing and loading. The pesticide formulation is mixed with water in the 40-liter blue barrel. The mixture is then transferred to the tank of the backpack sprayer. The sprayer is covered with plastic to protect the engine. Note that none of the workers are using gloves or other personal protection.

Figure 3

Applicators walk through the fields in a staggered pattern to avoid spraying each other. A technician can be seen leading the applicators, while another technician is just in front of the lead applicator on the left. Other technicians who are not in the picture are following the applicators. Note that the applicators are spraying in front of their bodies and walking into the spray.

Figure 4

Footwear worn by engineers, technicians, and applicators during workplace observations of chlorpyrifos applications in cotton.

Figure 5

Estimates of exposure / internal dose were made by analysis of urinary TCPy (µg/g creatinine), a chlorpyrifos-specific metabolite, in applicators, technicians, engineers and controls before and after the chlorpyrifos application (data presented as the mean ± SD, n=9 for controls and n=3 for occupational groups, note log scale). While there were no significant differences in pre- and post-application levels within a job category, there were significant differences between applicators, technicians, engineers, and controls.