Pesticide exposure, risk factors, and neurobehavioral performance among vulnerable populations

Pesticides are toxic by nature and they pose a serious threat to populations in agricultural communities, particularly to children, and farmers in low-income countries. Children living in agricultural communities may face a higher risk from pesticide exposure in the home environment than children in the general population. Farmers in low-income countries may also have higher risks from increased pesticide exposure due to the use of highly toxic pesticides that are banned in other countries and to unsafe practices and behaviors while handling pesticides. There is a growing body of literature that suggests pesticides, specifically organophosphorus pesticides (OPs), cause neurobehavioral impairment in children and adults.

In a fruit orchard community in the U.S. Pacific Northwest, dust was collected from households and analyzed for four types of OPs. Various factors such as housing characteristics and resident behaviors were evaluated to examine their relationships with the OP concentrations in the home dust. School-aged children completed a battery of neurobehavioral tests at two time points, one year apart. The relationship between pesticide exposure, measured with parents’ occupations and a summary OP concentration, and neurobehavioral performance was examined.

A cross-sectional study was carried out in The Gambia to identify rural residents’ knowledge about pesticide hazards and practices while handling pesticides. Relationships between participants’ knowledge, characteristics, and practices were examined. Occupational exposure scores were developed to quantify participants’ chronic pesticide exposures using the study’s questionnaire. In addition, participants provided information on neurological symptoms associated with pesticide use and a neurobehavioral test battery was administered to assess cognitive function. The relationships between occupational exposure scores and neurological symptoms and neurobehavioral performance were examined.

In the orchard community, OP detection frequencies and concentrations were higher in agricultural households compared to non-agricultural households. Significant associations were found between higher OP concentrations in dust and the following: (1) homes with a parent working in an agricultural field and/or orchard, (2) homes with ≥ 2 agricultural workers living in the home, and (3) homes located in close proximity to an agricultural field or orchard. Having air conditioning in the home had a protective effect on OP concentrations. Results suggested that deficits in learning, or less improvement, on the neurobehavioral tests from the first visit to the second visit were found in agricultural children compared to non-agricultural children.

In The Gambia, the majority of participants reported risky practices while handling pesticides such as: not wearing any protective clothing or equipment; mixing with bare hands; applying with their bare hands, plastic bags, or leaves; storing pesticides in the home; inadequately disposing of empty pesticide containers; and wearing shoes into the home after working with pesticides. They also reported having concerns about the adverse effects of pesticides on their health. Participants having had farm or pesticide safety training reported having less risky pesticide handling practices and behaviors. Participants with high occupational exposure scores experienced more symptoms and had worse performance on several of the neurobehavioral tests, including tests of motor function and dexterity, compared to participants with low exposure scores.

Results from these studies suggest neurobehavioral impairments were found in participants with higher pesticide exposures compared to participants with lower exposures in the two populations. Further research is needed to identify successful strategies for reducing pesticide exposure in the home environment and while handling pesticides.