Tamoxifen: Occurrence, Fate, Transformation Products, and Non-Conventional Treatment Technologies

Tamoxifen is a non-selective estrogen receptor modulator (SERM) used to treat breast cancer as well as a prophylactic agent in women with significant risk of developing the disease. After intake, it is partially metabolized in the liver and both tamoxifen and a series of metabolites are excreted. Hydroxylation plays a key role in the metabolism, and therefore hydroxylated metabolites such as 4-hydroxy-tamoxifen and endoxifen are excreted. After excretion, tamoxifen and metabolites enter the sewer system via hospital and domestic sewage, and since they are not totally removed in the conventional wastewater treatment plants (WWTPs), they are further discharged into natural water bodies. In fact, several studies have reported the presence of this compound in hospital and urban wastewater effluents as well as in surface waters at concentration levels of ng/L. The presence of this drug in the aquatic environment may be considered as a threat to organisms due to its known toxicity, endocrine disruption effects, and bioaccumulation potential. In this chapter, the occurrence of tamoxifen, and its metabolites, in water bodies is reviewed and its transformation in non-conventional wastewater treatments as well as its environmental risk is evaluated.