Urbanization-related changes over the last 20 years in occurrence, sources, and human health risks of soil PAHs in rural Tianjin, China

Polycyclic aromatic hydrocarbons (PAHs) are major pollutants in urban areas, and thus present a high risk to the resident health. However, studies on local PAH emissions and associated health risks related to urbanization are scarce. Here, the concentrations of PAHs were determined in 57 surface soil samples obtained from two rural districts in 2018 in Tianjin, China. The sources, risks, and the linkage between urbanization and PAH contamination of soils in 2018 were compared with PAH data in 2001 from a previous study to investigate the changes induced by urbanization. Results show an increase in PAH concentrations from 2001 to 2018, with in particular the predominance of anthracene and dibenz[a,h]anthracene. The major sources of soil PAHs changed from coal combustion 32.9%, petroleum sources 32.1%, and traffic sources 22.1% in 2001, to traffic sources 63.7%, and petroleum and biomass combustion 18.7% in 2018. The carcinogenic risk of soil PAHs to residents also increased from safe level to low level, and dermal contact was the prevailing pathway of PAH exposure. The increase in cancer risk is mainly due to the changes in PAH sources.

Automated summary

The study found that with the advancement of urbanization, the concentration of PAH in soil is increasing, and the main sources are also changing. Due to the changes in PAH emission sources, the cancer risk of residents exposed to soil PAHs has also increased.