Risk factors for juvenile dermatomyositis: exposure to tobacco and air pollutants during pregnancy.

OBJECTIVE

To evaluate the influence of exposure to inhaled environmental factors during pregnancy on the diagnosis of juvenile dermatomyositis (DM).

METHODS

We performed a case–control study comprising 20 juvenile DM patients and 56 healthy controls matched by age and sex who were residents in the metropolitan region of a large city. A questionnaire assessed demographic data and environmental inhalation exposure during pregnancy (occupational exposure to demolition, chalk, construction and/or quarry dust, paints, varnish, gasoline vapor, and/or battery fluids; stationary sources of inhaled pollution near the mother's home; and maternal tobacco exposure). Daily concentrations of inhaled particulate matter, SO2, NO2, O3, and carbon monoxide (CO) were evaluated throughout the gestational period.

RESULTS

Maternal occupational exposure to school chalk dust/gasoline vapor in the juvenile DM group was significantly higher compared with controls (50% versus 4.6%; P = 0.001). Smoking mothers and secondhand smoke exposure at home during pregnancy were significantly higher in the juvenile DM group versus controls (smoking mothers: 20% versus 1.7%; P = 0.01, and secondhand smoke: 35% versus 19%; P = 0.07). In univariate logistic regression models, maternal smoking, occupational exposure to inhaled agents, and the highest tertile of tropospheric CO (3.2–5.4 parts per million) in the third trimester were significantly associated with juvenile DM (P ≤ 0.05). In the multivariate analysis, smoking mother (odds ratio [OR] 13.26 [95% confidence interval (95% CI) 1.21–144.29], P = 0.03), occupational exposure (OR 35.39 [95% CI 1.97–632.80], P = 0.01), and CO (third tertile) exposure in the third trimester of gestation (OR 12.21 [95% CI 1.28–115.96], P = 0.03) remained risk factors for juvenile DM.

CONCLUSIONS

Inhaled pollutants and tobacco smoking during fetal development may contribute to juvenile DM.