Environmental Exposure to Traffic Pollution and Motor Function in Adolescence

Abstract

BACKGROUND AND AIM: Evidence supports the neurotoxic effects of air pollution on cognitive deficits, mental health, and behavioral outcomes in children. While heavy metal exposure has been associated with poor motor function, it is unclear whether traffic-related air pollution (TRAP) has a similar relationship. METHODS: Participants (n=332) were part of the Cincinnati Childhood Allergy and Air Pollution Study (CCAAPS). Elemental carbon attributable to traffic (ECAT), a marker of TRAP, was estimated at birth, age 12 years (current), and average exposure throughout childhood, using a validated land use regression model. Motor function was assessed with the Grooved Pegboard (GPB) test including time required to complete the task for dominant and non-dominant hand and number of dropped pegs. Associations between TRAP exposure and motor outcomes were estimated using linear (i.e., seconds to completion) and logistic (i.e, drops) regression; sex-specific effects were examined. Primary models controlled for child’s IQ, neighborhood deprivation, and total household income; secondary models included blood metals (i.e., lead, cadmium, mercury) collected at the age 12 visit. RESULTS:Children exposed to elevated current ECAT levels took on average 18 seconds longer to complete the GPB task with their non-dominant hand (95% CI 4.77, 31.14, p=0.008); ECAT was not associated with dominant hand completion. We did not observe a main effect of ECAT at any time point on probability of dropped pegs; however, girls exposed to higher childhood ECAT levels were more likely to drop pegs with their dominant hand during the GPB task (Psex*childhood ECAT = 0.03). Additionally controlling for heavy metal exposure did not alter the results. CONCLUSIONS:Higher TRAP exposure was associated with poorer motor function, and girls may be at increased risk for adverse outcomes. These findings, as well as others, suggest that air pollution is quickly becoming one of the leading threats to a child’s neurodevelopment. KEYWORDS: Children's environmental health, Neurodevelopmental outcomes, Traffic-related, Air pollution