## 3 Endocrine-Disrupting Compounds EDCs
### Estrogen Degradation
Based on the available data, it is assumed that adverse effects due to the presence of E2 in water occur for concentrations above 0.03 nM [40]. In one of the first studies concerning the use of \(\gamma\) radiation to decompose trace amounts of 17 \(\beta\)-estradiol (E2) in water, it was shown that the dose of 10 kGy is sufficient for the complete degradation of 1.8 nM, while the estrogenic activity decreased to an acceptable level only after the application of the dose of 30 kGy [41]. By mineralization we mean the chemical decomposition of organic matter into simple inorganic substances including water, carbon dioxide, nitrogen, chlorine, phosphorus, sulfur, etc. However, decomposition and degradation are very often used as synonyms. If an attempt is made to determine the difference, decomposition can be regarded as a process that leads to other, new organic compounds while degradation leads to the formation of similar structures with smaller masses (degradation of perfluorinated acids also leads to the formation of acids, but with shorter chains [6]). The rate constant for the reaction of E2 with the \({}^{\bullet}\)OH radical was also estimated to be 1.6 \(\times\) 10\({}^{10}\) M\({}^{-1}\) s\({}^{-1}\). Removal of estrogenic activity has also been tested for various effluents containing 17\(\beta\)-estradiol (E2), estrone (E1), and 17\(\alpha\)-ethynylestradiol (EE2) [42]. The greatest activity was shown by livestock effluents due to higher concentrations of E2, E1, and EE2, which did not decompose completely after the application of the 10 kGy dose, so that estrogenic activity remained at a higher level compared to domestic and industrial wastewater. The degradation of 17\(\beta\)-estradiol (E2) in aqueous solutions was also studied using electron beam (EB) [43]. Experiments carried out using acetonitrile/water and ethanol/water solutions showed that the role of \({}^{\bullet}\)OH is dominant in the degradation of E2, and the reducing individuals have a minor participation in its degradation. Acidic or alkaline conditions are more favorable for E2 removal than neutral conditions. At pH values 9.1 and 4.9, the E2 degradation efficiency at a dose of 10 kGy was 88.3% and 79.4%, respectively, whereas only a 53.4% reduction was obtained at the same dose at pH 6.8. The addition of an appropriate amount of H\({}_{2}\)O\({}_{2}\) also promoted the degradation of E2. Synthetic estrogens such as dienestrol (DS), notethindrone (NET), and quinestrol (QS) are separate groups of compounds. These estrogens are used on a large scale, mainly in hormone replacement therapy and in the treatment of breast cancer, osteoporosis, and prostate cancer. They are designed to be resistant to structural changes to increase their persistence in the body, which simultaneously makes them more stable than natural estrogens in the environment [44; 45]. For DS, NET, and QS with initial concentrations of 2 mg dm\({}^{-3}\), it was observed that estrogen concentrations decreased when increasing the absorbed dose; at a dose of 6 kGy, the degradation efficiency was 100%. The highest efficiency of TOC reduction was obtained for oxygenated solutions; above 3 kGy, there was a rapid reduction in TOC, and in parallel with the decrease in the TOC value, a decrease in toxicity to rotifers was observed [46].