Pet Flea and Tick Control Exposure During Pregnancy and Early Life Associated with Decreased Cognitive and Adaptive Behaviors in Children with Developmental Delay and Autism Spectrum Disorder

Approximately 18% of U.S. children experience cognitive and behavioral challenges, with both genetic and environmental contributors. We examined if household insecticides, particularly those used in and around the home and on pets, are associated with neurodevelopmental changes. Data were from children aged 24-60 months in the CHARGE study with the following classifications: autism spectrum disorder (ASD, <i>n</i> = 810), developmental delay (DD, <i>n</i> = 192), and typical development (TD, <i>n</i> = 531). Exposure to indoor, outdoor, and pet insecticides was reported for the period from three months pre-conception to the second birthday. Cognitive and adaptive functioning were assessed using the Mullen Scales of Early Learning and Vineland Adaptive Behavior Scales. Linear regression was used to evaluate associations by diagnostic group, adjusting for confounders. Flea/tick soaps, shampoos, and powders used during year two were significantly associated with lower cognitive and adaptive scores in children with ASD after FDR correction. Flea/tick skin treatments in early pregnancy were associated with reduced scores in the DD group, though not significant after correction, especially when used with high frequency. No associations were observed in TD children. These findings underscore the need to examine early-life exposure to non-agricultural insecticides as modifiable risk factors for neurodevelopment.