Household dust endotoxin: a mediator between poverty and all-cause mortality

Household dust carries indoor bacteria, fungi, and mites. Endotoxin, a component of the cell wall of gram-negative bacteria, is a known important indoor toxic pollutant. To our knowledge, the association between household dust endotoxin and all-cause mortality risk has not been studied. Using data from the National Health and Nutrition Examination Survey (NHANES) 2005-2006 with mortality follow-up through 31 December 2019, we evaluated this association while adjusting for relevant covariates and performing mediation analyses. Elevated household dust endotoxin levels showed a significant linear association with all-cause mortality (P-overall = 0.015), an effect significantly modified by the poverty-income ratio (PIR). Given the established links between poverty and poor living conditions, we hypothesized that household dust endotoxin mediates the relationship between poverty and increased mortality risk. Mediation analysis confirmed a significant indirect effect, with household dust endotoxin accounting for 6.1% of the total effect of PIR on mortality (P for indirect effect = 0.01), a finding that remained robust in sensitivity analyses. These results indicate that household dust endotoxin not only increases all-cause mortality risk but also serves as a significant mediator in the pathway linking poverty to elevated mortality.