Prenatal exposure to air pollutants and the second to fourth digit ratio in adult women

The study aimed to analyse the association between the digit ratio in adult women and the degree of air pollution (suspended particulate matter, sulphur dioxide, nitric dioxide, benzene levels) in the place of residence of their mothers during pregnancy. The data was collected from female students in several Polish cities. Measurements were taken, and questionnaire data were collected. 2D:4D ratios were calculated for the left and the right hand. The ratio was analysed as a continuous variables. Air quality information was retrieved from reports by the Chief Inspectorate for Environmental Protection. Statistically significant differences both in right- and left-hand 2D:4D ratio were found for PM₁₀ and benzene. In addition, the right-hand 2D:4D differed significantly depending on PM_2.5. The association between digit ratio and the complex air pollution index was also found. Poor air quality was associated with higher values of the ratio. Our results indicate that a high airborne pollutant level, especially suspended particulate matter, is associated with a higher digit ratio.