UC Berkeley

BackgroundChildren who reside in agricultural settings are potentially exposed to higher levels of organophosphate (OP) pesticides, endotoxin, and allergens than their urban counterparts. Endotoxin and allergens stimulate maturation of the immune response in early childhood, but little is known about the effect of exposures to OPs or to the three combined.ObjectivesIn this study, we investigated the relationships between these exposures and Thelper 1 (Th1) and Thelper 2 (Th2) cytokines, biomarkers of allergic asthma, in the subjects of CHAMACOS (Center for the Health Assessment of Mothers and Children of Salinas), a longitudinal birth cohort in Salinas Valley, California. Exposures were ascertained by intervieweradministered questionnaires and by home visits, and clinical diagnoses were abstracted from medical records. Blood samples were collected at 12 and 24 months of age and analyzed for Th1/Th2 status by flow cytometric detection of intracellular interferongamma/interleukin4 cytokine expression.FindingsMean Th2 levels were significantly higher in children with doctordiagnosed asthma and children with wheezing at 2 years of age. In a multiple linear regression model, exclusive breastfeeding at 1 month and pet ownership were associated with 35.3% (p < 0.01) and 34.5% (p = 0.01) increases in Th1, respectively. Maternal agricultural work and presence of gas stove in the home were associated with a 25.9% increase (p = 0.04) and 46.5% increase (p < 0.01) in Th2, respectively.ConclusionsAsthma and wheeze outcomes in children at 24 months of age are associated with elevated Th2 status in children at an early age. Our data further suggest that early exposures to an agricultural environment, breastfeeding, pets, and gas stoves affect the development of children's Th1/Th2 immune response.