Association among persistent chemical pollutants and infectious encephalitis: a mixture exposure and mediation...

Most overlook the harmful effects on diseases, particularly the chronic neurotoxicity, which remains undetermined. This study aims to determine the impact of major environmental factors on infectious encephalitis.

Our study investigated the correlation between persistent chemical pollutants and reports and mortality cases of infectious encephalitis (Epidemic cerebrospinal meningitis and Encephalitis B). First, the quantile-based g computation (qgcomp) statistical method was used to analyze the correlation of different chemical pollutants. Bayesian Kernel Machine Regression-Causal Mediation Analysis (BKMR-CMA) method was applied to explore the mediating effect of greenhouse gases between persistent chemical pollution mixtures and incidence and mortality of infectious encephalitis. Finally, the Lasso regression method was used to assess the sensitivity of different age groups of encephalitis patients to the risks of different chemical pollutants.

For epidemic cerebrospinal meningitis report cases, N₂O mediates at the 10% and 90% levels, and PCB and OC exhibit a positive risk effect at all levels. For death cases, N₂O mediates at the 10% and 90% levels, and the direct effect risk of the controlled chemical pollution mixture shows a downward trend, with PCB and NMVOC exhibiting a positive risk effect at all levels. For encephalitis B reports and death cases, N₂O mediates at the 10% and 90% levels, and the direct effect risk of the controlled chemical pollution mixture shows a trend of first decreasing and then increasing, with CH₄ and HCB exhibiting a positive risk effect at all levels. The mediating effect of N₂O is concentrated in encephalitis B reports and deaths, where the control direct effects (CDE) of the CH₄, N₂O, and HCB chemical pollutant model were assessed at three different quantiles. The CDEs at the 10%, 50%, and 75% quantiles were 757.37 (95% CI: 85.36, 1580.16), 872.86 (95% CI: 215.66, 1706.86), and 894.98 (95% CI: 209.22, 1726.33), respectively. The death effects were 31.31 (95% CI: -0.05, 66.40), 36.76 (95% CI: 8.62, 71.13), and 38.06 (95% CI: 8.46, 75.09).

We found that most persistent chemical pollutants in the air increase the risk of neurotoxicity-related morbidity and mortality. Among them, epidemic cerebrospinal meningitis is primarily driven by PCB and OC, while encephalitis B is mainly driven by CH₄ and HCB. The greenhouse gas N₂O may play a mediating role between chemical pollutant exposure and the outcomes of infectious encephalitis. In the future, identifying the effects of chemical mixtures can better support the causal relationship between air pollution and neurotoxicity.