Exposure to cigarette smoke and harmful particles in the air during pregnancy and after birth were identified as potential risk factors for the development of juvenile idiopathic arthritis (JIA) in a study.
The study, “Risk Factors Associated with Juvenile Idiopathic Arthritis: Exposure to Cigarette Smoke and Air Pollution from Pregnancy to Disease Diagnosis” was published in The Journal of Rheumatology.
JIA is the main cause of chronic arthritis in children and adolescents. Previous studies have suggested that both outdoor and indoor environmental factors are associated with the disease.
Outdoor pollutants include sulfur dioxide, nitrogen dioxide, carbon monoxide, ozone, and particulate matter, which are mainly present in exhaust from vehicles and power plants. Indoor pollutants include cigarette smoke, domestic dust, and volatile compounds (mainly chemicals used for housecleaning).
Exposure to these pollutants is known to increase inflammation in both children and adults by triggering an increase in the body’s production of inflammatory proteins, such as interleukin-1 beta, interleukin-6, and tumor necrosis factor-alpha.
The purpose of the study was to evaluate the exposure to outdoor and indoor pollutants during pregnancy and after birth until JIA diagnosis in residents of São Paulo, a large city of Brazil.
Participants included 66 JIA patients and 124 healthy controls matched by age and sex. They all lived in the São Paulo metropolitan area until JIA diagnosis, and their mothers lived in the same region during pregnancy.
Air pollutant exposure was assessed through a questionnaire focusing on demographic data; gestational and perinatal-related factors; and exposure to inhalable environmental factors during pregnancy and after birth. Outdoor air pollutant levels were also measured.
Data showed that cigarette exposure and the mother’s occupational exposure to pollutants, including chalk powder, cleaning products, sewing dust, and volatile vapor, during pregnancy were significant risk factors for JIA development.
Maternal employment and ideal maternal weight gain during pregnancy were negatively associated with the risk of JIA, suggesting these two parameters seem to lower the risk of JIA development, although the team emphasized that these observations “should be interpreted with caution, and more studies will be necessary.”
Results also showed that secondhand smoke exposure from birth to JIA diagnosis and ozone exposure during the second year of life were also significant risk factors for the disease.
“In our study, cigarette smoke exposure (intrauterine and after birth), exposure to O3 [ozone] in the second year of life, and maternal occupational exposure were identified as potential risk factors for JIA,” the researchers concluded.
“Our results are sufficiently compelling to warrant future studies to investigate the potential role of maternal occupational and air pollutant exposure in the pathogenesis of JIA,” the team said.