Indoor air pollutants and blood pressure in toddlers: data from the Japan environment and children’s study

Abstract Background Hypertension in childhood has been recognized as an early marker of future cardiovascular risk, and blood pressure trajectories are known to track from early life into adulthood. Environmental exposures during early childhood, particularly indoor air pollutants such as particulate matter (PM) and volatile organic compounds (VOCs), may influence blood pressure regulation; however, evidence in very young children remains limited. Identifying early-life environmental factors associated with blood pressure may help improve risk assessment and prevention strategies later in life. Methods This study used secondary data from children who participated in a national birth cohort study in Japan, the Japan Environment and Children's Study. We measured the indoor concentrations of PM and VOCs at the ages of 1.5 and three years, and blood pressure (BP) at the ages of two and four years. To investigate the correlation between PM and VOCs and BP, scatter plots were created to visually assess the presence of a correlation, and the correlation coefficients were calculated. We investigated the correlation between PM and VOCs at 1.5 years of age and BP at two years of age. Similarly, we examined the correlation between PM and VOCs at three years of age and BP at four years of age. Results The total number of participants in this study was 4,854. There were no clear correlations between any of the PM, VOCs, and BP across all sexes and years. The absolute values of the correlation coefficients were all less than 0.2, indicating no significant correlation between any of the variables. Multiple regression analyses also showed that m,p-xylene at 1.5 years was associated with higher BP at age two, whereas PM2.5 was associated with lower BP. P-dichlorobenzene and toluene were associated with lower BP, respectively, and benzene at age three was associated with lower BP at age four; however, all effect sizes were small. Conclusion Exposure to PM and VOCs at levels sufficient to affect BP in early childhood is unlikely to occur during normal household life. However, this does not eliminate the long-term risks of hypertension or the potential for other diseases.