Seasonal variation of endocrine disrupting potentials of pollutant mixtures associated with various size-fractions of inhalable air particulate matter

Ambient air pollution, namely exposure to air particulate matter (PM), has been shown to be connected with a number of adverse health effects. At least part of the effects can be caused by organic pollutant mixtures associated with PM, which can elicit a wide range of specific toxic potentials. These potentials could be affected by seasonal variation of pollutant mixtures and PM size fraction. To examine this, six size subfractions of PM₁₀ were collected at rural and urban site in the Czech Republic in a year-long sampling campaign. The samples were assessed for aryl hydrocarbon (AhR)-mediated activity, estrogenicity and anti-androgenicity using mammalian cell models. The concentrations of detected toxic potentials differed among seasons. The greatest levels were observed in samples collected during winter when AhR-mediated effects and estrogenicity were at least 10-times greater than in summer. While the observed potentials were mostly less pronounced in samples from rural area, during winter, their AhR-mediated activity was twice as great as at the urban site. This was probably caused by the low-quality of fuel used for heating at the rural site. Assessed toxic potentials were associated mainly with PM size fractions with lesser aerodynamic diameters (<1 μm). Toxic potentials were compared with data from chemical analyses covering 102 chemicals from different pollutant groups to model their contribution to the observed effects. For AhR-mediated activity, chemical analyses explained on average 44% of the effect and the main identified effect-drivers were polycyclic aromatic hydrocarbons. For estrogenicity and anti-androgenicity, detected chemicals were able to explain on average less than 1.6% and 11% of the potentials, with their highest explicability reaching 13% and 57%, respectively. This was affected by the lack of data on specific toxic potency of some detected air pollutants, but also indicates a possible role of further not analyzed chemicals in these effects.