Effects of children exposed to pyrethroid pesticides on their neurodevelopment at age two: A cohort study in rural Western China

This study explored the association between infants' daily exposure to PYRs and their neurodevelopmental outcomes at age 2. Based on Yunnan cohort study, the children were followed up from age 1 until age 2. Using high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS), the levels of PYRs in urine were measured. Neurodevelopmental assessments were conducted using the Bayley Infant and Toddler Development Scale-3rd edition (Bayley-III) at both ages. At age 1, the detection rates of 3PBA, 4FPBA, DBCA were 87.54 %, 88.20 % and 38.36 %, respectively. At age 2, the detection rates were up to 93.77 %, 91.48 % and 72.46 %, respectively. The average scores of cognition, language, motor, social-emotional and adaptive behavior were 97.25 ± 15.57, 92.18 ± 13.97, 94.25 ± 14.91, 102.38 ± 18.39 and 88.24 ± 14.49 at age 1, respectively, and 95.99 ± 16.61, 93.70 ± 14.58, 95.51 ± 17.92, 104.30 ± 21.63 and 87.23 ± 12.12 at age 2, respectively. Compared with those with low levels of DBCA, 2-year-old children with high levels had higher risk of a decline in language development (OR = 2.259, 95 % CI = 1.185, 4.306), and in adaptive behavior development (OR = 2.032, 95 % CI = 1.090, 3.789). 2-year-old children with high levels of 3PBA had higher risk of a decline in motor development than those with low levels (OR = 1.900, 95 % CI = 1.001, 3.605). Rural children are widely exposed to PYRs daily. At age 2, children who are exposed to high levels of deltamethrin pesticides with DBCA as specific metabolites (DBCA ≥ 2.872 μg/g) may experience negative impacts on their language and adaptive behavior development. Additionally, children who are exposed to high levels of PYRs (3PBA ≥ 2.525 μg/g) may experience negative impacts on their motor development.