Association of environmental volatile organic compounds with depression in adults: NHANES 2013-2018

•Benzene and ethylbenzene were found to be positively associated with depression after adjusting for the behavioral effects of smoking.•Participants claimed clear indoor second-hand smoke exposure. In indoor subgroup, m-/p-xylene showed significant association with depression in addition to benzene and ethylbenzene.•Benzene and ethylbenzene were identified as key chemicals of VOCs under the weighted quantile sum (WQS) model in both main and indoor subgroup. Volatile organic compounds (VOCs) exposure has been found to be associated with neurological dysfunction, with depression often being one of the classic symptoms of the disease, and indoor environments are more likely to be enriched with concentrations of VOCs. This cross-sectional study measured VOCs levels in whole blood, and estimated level of depression with the Patient Health Questionnaire in adults from NHANES 2013–2018. We found benzene (β = 0.40, 95%CI: 0.19, 0.61) and ethylbenzene (β = 0.22, 95%CI: 0.05, 0.39) were associated with depression adjusted for covariates in general linear regression models (GLM), and remained the consistent trend in quantile regression models. In indoor subgroup with higher VOCs level, benzene (β = 0.71, 95%CI: 0.21, 1.22), ethylbenzene (β = 0.47, 95%CI: 0.15, 0.78), and m-/p-xylene (β = 0.41, 95%CI: 0.15, 0.68) showed significant association with depression adjusted for covariates including cotinine in GLMs. Weighted quantile sum (WQS) model was used to assess the contribution of each VOC in mixed exposure. Results from WQS analyses revealed significantly positive associations between the mixed exposure and depression (β = 1.70, 95%CI: 1.18, 2.47), in which, benzene and ethylbenzene contributed 56% and 26%. We found statistically association between mixed exposure and depression before cotinine adjustment (β = 3.53, 95%CI: 2.78, 4.47). Our founding indicated a positive association between benzene and ethylbenzene exposure and depression, also with the most important effect in the mixture. Additionally, indoor VOCs sources of environmental pollution still cannot be ignored given the higher exposure level and health risk. [Display omitted]