Geospatial determinants of urinary insecticide concentrations and internalizing disorders in Ecuadorian adolescents

Background: Depression and anxiety are top 5 contributors of increased disability-adjusted life years. Pesticide exposure has been linked to increased depression and anxiety; evidence in adolescents is limited. This study assesses clustering patterns of mental health symptoms and urinary pesticide metabolites, and their relationships with home proximity to floricultural crops in an Ecuadorean agricultural county. Methods: We assessed 514 adolescents (11-17 years) who lived in the 5 parishes of Pedro Moncayo County, Ecuador. We measured 8 urinary metabolites for neonicotinoid, pyrethroid and organophosphate pesticides, and assessed depression and anxiety symptoms using standardized questionnaires. Getis-Ord Gi* evaluated spatial clustering to identify hot and cold spots of pesticide metabolites, depression symptoms and anxiety symptoms. The association between home distance to floricultural greenhouses and anxiety/depression scores were tested using generalized estimating equations, adjusting for confounders. Results: The floricultural surface areas (% of total land) across parishes were: Tocachi: 0.12 km2 (0.001%), La Esperanza: 0.43 km2 (0.01%), Malchingui: 0.04 km2 (0.05%), Tupigachi: 5.36 km2 (12.5%), and Tabacundo: 9.36 km2 (13.2%). The average scores for anxiety (53.0 [SD=9.31]) and depression (58.8 [SD=9.61]) were in the anticipated range. We observed hotspots for anxiety and depression symptoms in Tupigachi (95-99%C [confidence]) and Tabacundo (90-95%C). There were hotpots for organophosphate and pyrethroid metabolites in Tupigachi, coinciding with anxiety and depression hotspots (malathion dicarboxylic acid [90%-99%C], para-nitrophenol [95%], 2-isopropyl-4-methyl-6-hydroxypyrimidine, trans-3-(2,2-Dichlorovinyl)-2,2-dimethylcyclopropane carboxylic acid [90%C], and 3-phenoxybenzoic acid [95%C]). Additionally, greater proximity to greenhouses was associated with greater depression (βper100m=0.94 [95%CI: 0.53, 1.36]) and anxiety (βper100m= 0.32 [95%CI: 0.11, 0.54]) scores. Conclusions: We observed hotspots in Tupigachi for both anxiety, depression, and multiple organophosphate/pyrethroid metabolites. Throughout the county, residential proximity to floricultural crops was associated with higher anxiety and depression symptoms. This suggests that off-target pesticide drift from crops may be a contributor to increased internalizing behaviors. Keywords: Pesticides