Steroid hormones in wastewater: Sources, treatments, environmental risks, and regulations

Steroid hormones are micropollutants that contaminate the water worldwide and exhibit a significant threat to human health and the environment even at low concentrations. Steroid hormones are among the most common endocrine disruptors investigated due to their widespread use as active ingredients in hormonal treatments and natural secretions. Three main types of steroids that are critical for human development and multiorgan homeostasis are estrogens, progesterone, and androgens. The common sources of steroid hormones in environment are human and livestock excretion, veterinary medicines, agricultural runoff, and pharmaceuticals. When they reach environment, their effects on human health and the environment are detrimental. Therefore, this review discusses the sources, the efficiency of available wastewater treatment techniques to remove these hormones from wastewater, their potential environmental risks, and available international standards to regulate them. This review concludes that the different emerging hybrid treatment approaches show the best efficiencies in hormone removal from wastewater. Moreover, most studies have focused on estrogen, but equal attention in research should also be given to progesterone and androgen. The international and national standards need more detailed guidelines to encourage the development of more advanced treatment systems. Overall, many modern technologies are available for treatments, but there is still a research gap to make them sustainable, environmentally safe, and cost-efficient.