Progestins as emerging contaminants in soil: An investigation on their pollution characteristics and ecological risks

Progestins (PGs) have become the most important pharmaceuticals of concerns after estrogens because the potent endocrine disrupting effects. Their occurrences and behaviors in the aquatic environment were widely explored, yet little was known about concentrations and risks of multiple PGs in the soil. This investigation explored the concentrations, distribution, potential drivers, and environmental risks of 55 natural and synthetic PGs in soil in Shandong Province, China. Thirty-four compounds were detected in soil, and concentrations ranged from not detected (ND) to 49 ng/g. The previously neglected natural PGs were identified as the dominant compounds with higher total concentrations (0.68-196 ng/g) and detection frequencies (most of which exceed 70 %) than synthetic PGs. Correlation analysis demonstrated that the number of year-end stocked cattle, pig, poultry, and human population might be important parameters affecting the occurrences and distribution of PGs in soil. The profiles of progestagenic activity exhibited differences with the concentration profiles, and three synthetic PGs (gestodene [GES], progesterone [P], and 19-norethindrone [NET]) were found to make significant contributions (36 %-100 %) to the progestagenic activity. A screening-level risk assessment based on limited data showed that terrestrial organisms might be under moderate or high risks posed by PGs in soil. The results can reveal the pollution profiles of PGs and provide basic data for the optimization of fertilization method to control PGs pollution in farmland system.