Neurodevelopmental Delay Diagnosis Rates Are Increased in a Region with Aerial Pesticide Application

Abstract

A number of studies have implicated pesticides in childhood developmental delay (DD) and autism spectrum disorder (ASD). The influence of the route of pesticide exposure on neurodevelopmental delay is not well defined. To study this factor, we examined ASD/DD diagnoses rates in an area near our regional medical center that employs yearly aerial pyrethroid pesticide applications to combat mosquito-borne encephalitis. The aim of this study was to determine if areas with aerial pesticide exposure had higher rates of ASD/DD diagnoses. This regional study identified higher rates of ASD/DD diagnoses in an area with aerial pesticides application. Zip codes with aerial pyrethroid exposure were 37% more likely to have higher rates of ASD/DD (adjusted RR = 1.37, 95% CI = 1.06-1.78, p = 0.02). A Poisson regression model controlling for regional characteristics (poverty, pesticide use, population density, and distance to medical center), subject characteristics (race and sex), and local birth characteristics (prematurity, low birthweight, and birth rates) identified a significant relationship between aerial pesticide use and ASD/DD rates. The relationship between pesticide application and human neurodevelopment deserves additional study to develop safe and effective methods of mosquito prevention, particularly as communities develop plans for Zika virus control.

Keywords: autism spectrum disorder; environment; neurodevelopmental disorder; pesticide; pyrethroid.

Figure 1

Regional pesticide exposure. Mean yearly pesticide exposure for each zip code is shown in kilograms. These levels were determined using the most recently available data from the New York State Department of Environmental Conservation Mandated Reporting Database. Total pesticide exposure includes pyrethroids, organophosphates, and other pesticide families regardless of class or application method employed. Aerial-exposed zip codes are numbered 1–8 in white, and control zip codes are numbered 9–24 in black. Note that there was no statistical difference between mean concentration of pesticide exposure between aerial-exposed zip codes (49 kg/km²) and control zip codes (9 kg/km²).

Figure 2

Regional rates of autism spectrum disorder (ASD) and developmental delay (DD) diagnoses. Total numbers of children diagnosed with ASD/DD in each zip code were identified with a retrospective review of records at the State University of New York (SUNY) Upstate Regional Medical Center, and prevalence rates were calculated using publicly available American Community Survey data for each zip code. Zip codes exposed to aerial pyrethroid pesticides had a higher prevalence of ASD/DD than control zip codes with standard pesticide application methods.