A review of phytoestrogens: Their occurrence and fate in the environment

Phytoestrogens are plant compounds with estrogenic activities. Many edible plants, some of which are common in the human diet, are rich in phytoestrogens. Almost all phytoestrogens eaten daily by people were reported partly recovered in urine or feces, which can be regarded as one of the main sources of their occurrence in municipal wastewaters. As they may act as one part of the endocrine disrupting compounds (EDCs) in water systems, some phytoestrogens have been monitored and detected in wastewater and other various environments. It is very difficult to monitor numerous unknown EDCs in complex wastewater samples, and it is helpful if some estimation of target EDCs can be done before monitoring. With this in mind, this review will: (1) summarize estrogenic activities or estrogenic potencies of phytoestrogens by different bioassays; (2) summarize daily urinary excretion rates of phytoestrogens by humans, and compare their urinary excretion rates to that of estrone, which suggests that most phytoestrogens may occur in municipal wastewaters; (3) collect and summarize published data on the occurrence and fate of phytoestrogens in various environments.