The association of air pollution with new-onset epilepsy

Abstract

Objective: Air pollution has been associated with certain neurological disorders, but its association with epilepsy has been insufficiently explored. The study's objective was to estimate the association of long-term exposure to fine particulate matter (PM2.5), nitrogen dioxide (NO2), and ozone (O3) with the risk of new-onset epilepsy among adults in Ontario, Canada. Methods: We used a nested case–control study design and linked health and environmental databases, including Ontario residents ages 18 to 80 as of January 1, 2010, without prior diagnoses of seizures or epilepsy. We identified cases as those who developed epilepsy by December 31, 2016, and matched each with up to five controls on age and sex. We used individual- and multi-pollutant conditional logistic regression models to estimate the associations between interquartile range (IQR) increases in each pollutant and new-onset epilepsy. Results: We included 24 761 cases and 118 692 controls. The median (IQR) pollutant concentrations were 7.9 (1.3) μg/m3 for PM2.5, 9.6 (9.2) ppb for NO2, and 42.7 (5.4) ppb for O3. In the individual pollutant models, we observed significant associations with epilepsy for PM2.5 (incident rate ratio [IRR] = 1.055, 95% confidence interval [CI]: 1.034–1.076), NO2 (IRR = 0.938, 95% CI: 0.903–0.974), and O3 (IRR = 1.096, 95% CI: 1.074–1.119). In the multi-pollutant model, we observed significant associations with epilepsy for NO2 (IRR = 0.928, 95% CI: 0.891–0.965) and O3 (IRR = 1.090, 95% CI: 1.060–1.121). Although the association for NO2 was negative overall, the association was positive among individuals 65 and older. Significance: PM2.5 and O3 may be associated with an increased risk of new-onset epilepsy. We also observed a negative association for NO2. However, residual confounding may have occurred. Future research should continue exploring the associations between specific air pollutants and new-onset epilepsy.