A57-18 Body Mass Index Mediates the Association Between World Trade Center Dust Exposure and Pulmonary Function in Survivors

Rationale

World Trade Center (WTC) dust-cloud exposure is linked to long-term respiratory morbidity. Obesity is prevalent among WTC Survivors and generally adversely affects lung function. We examined whether body mass index (BMI) mediates the relationship between the WTC exposure and pulmonary function.

Methods

We analyzed 4,450 WTC Survivors enrolled between 2005 and 2022. Exposure was defined as being caught in the WTC dust-cloud (yes/no). BMI at enrollment was evaluated as a mediator. Outcomes included pre- and post-bronchodilator spirometry (FEV1, FVC, FEV1/FVC) and impulse oscillometry (R5, R20, R5-20, AX; log-transformed) at initial visit. Models adjusted for race/ethnicity, age, gender, income, education, smoking, and enrollment periods. The mediation effect was assessed using causal mediation analysis and structural equation modeling (SEM) with latent spirometry and oscillometry constructs. Subgroup analyses were conducted by race/ethnicity, gender, and age groups.

Results

Exposed participants had slightly higher BMI, higher oscillometric measures, and lower spirometry volumes. BMI showed marginal mediation of exposure effects on spirometry and oscillometry, with BMI accounting for approximately 18-30% of the total effect in causal mediation analysis. Mediation was strongest in non-Hispanic White participants, for whom BMI significantly mediated exposure effects across spirometry (Average Causal Mediation Effect (ACME): FEV1= -0.007; FVC= -0.013; Ratio= 0.083; proportion mediated 21-27%) and oscillometry (ACME: R5= 0.013; R20=0.008; R5-20=0.015; AX = 0.033; proportion mediated 28-40%). In the oldest group (initial visit age ≥65 years), BMI mediation was significant for FVC (ACME= -0.019; proportion mediated 58-67%) and oscillometry (ACME: R5= 0.021; R20=0.014; R5-20= 0.024; AX = 0.048; proportion mediated 31-54%). SEM results corroborated the causal mediation findings.

Conclusions

Among WTC Survivors, BMI partially mediates the association between dust-cloud exposure and impaired lung mechanics, particularly in non-Hispanic White and older individuals, indicating that adiposity explains a meaningful but incomplete portion of exposure-related respiratory dysfunction. While direct effects of WTC exposure remain predominant, these findings suggest that excess adiposity represents a potentially modifiable factor that may be relevant for risk stratification and supportive clinical management in exposed populations.

This abstract is funded by: NIH