Potential Adsorption Affinity of Estrogens on LDPE and PET Microplastics Exposed to Wastewater Treatment Plant Effluents

Microplastics (MPs) are among the most common pollutants in the environment. Because of their small size, availability, and similarity to natural foods, they are commonly ingested by marine organisms. They can cause health problems in living organisms due to their bioaccumulation potential. It is, therefore, unknown whether endocrine-disrupting chemicals (EDCs), in particular estrogens, are capable of adhering to the diverse types of MPs found in water. Two MP polymers (low-density polyethylene (LDPE) and polyethene terephthalate (PET)) that could pose a threat to fish were tested for estrogen adsorption. The adsorption capacity of MP pellets was studied for 30 days in the effluent and influent of a wastewater treatment-plant. A laboratory simulation was conducted to validate the field and laboratory findings. We found that the concentrations of five types of estrogen ((diethylstilbestrol (DES), estrone (E1), 17β-estradiol (E2), estriol (E3), 17α-ethinyl estradiol (EE2)) were higher in the influent than the effluent streams. LDPE and PET MPs exposed to influent water in the laboratory had higher estrogen levels than wastewater treatment plants (WWTP) pellets. The PET pellets showed the highest adsorption affinity to EE2, while the LDPE pellets showed the highest affinity to E2. As a result, this study provided baseline data to investigate the estrogen adsorption capacity in MPs.