## 2 Endocrine Disrupting Compounds (EDCs) in the Environment and Associated Risks
Negative effects on development, sex differentiation, reproduction of different animal species and production of vittilogenin have been documented [3; 4; 7; 11; 12]. Intersexual disorders in fish in Europe, and a negative impact on the sexual behaviour of frogs in suburban areas in the United States have been observed [12]. In addition, it has been shown that 17\(\beta\)-estradiol, at concentrations of 0.1-1 ng/L, causes reproductive disorders in aquatic animals. Disrupting in the development, spawning and fertility of Japanese medaka (_Oryzaias latipes_) was showed at low estrogen concentrations [20]. An increase in osteoblast activity was also detected in fish such as goldfish and wrasse, which resulted in the \begin{table}
\begin{tabular}{c c c c c} \hline
**EDCs** & **Concentration** & **Occurrence** & **Sampling Period** & **References** \\ \hline
17\(\alpha\)-Ethynyl-estradiol & 17–501 ng/L & Atibaia River, Brazil & Dry winter period & [18] \\
17\(\beta\)-Estradiol & 464–6806 ng/L & Atibaia River, Brazil & High rainy periods & [18] \\
17\(\beta\)-Estradiol & 106–2273 ng/L & Atibaia River, Brazil & Dry winter period & [18] \\ Estrone & 16 ng/L & Atibaia River, Brazil & High rainy periods & [18] \\ Progesterone & 20 ng/L & Atibaia River, Brazil & High rainy periods & [18] \\ Progesterone & 20–195 ng/L & Atibaia River, Brazil & Dry winter period & [18] \\ Levonorgestrel & 19 ng/L & Atibaia River, Brazil & High rainy periods & [18] \\ Levonorgestrel & 19–663 ng/L & Atibaia River, Brazil & Dry winter period & [18] \\
4-Octylphenol & 21 ng/L & Atibaia River, Brazil & High rainy periods & [18] \\
4-Nonylphenol & 18 ng/L & Atibaia River, Brazil & High rainy periods & [18] \\ Testosterone & 1.9–2.7 ng/L & Lower Jordan River & May & [19] \\ Testosterone & 1.0–3.8 ng/L & Lower Jordan River & October & [19] \\ Estrogen & 0.6–2.2 ng/L & Lower Jordan River & May & [19] \\ Estrogen & 1.2–3.4 ng/L & Lower Jordan River & October & [19] \\ Estriol & 0.9–1.8 ng/L & Lower Jordan River & May & [19] \\ Estriol & 0.9–2.9 ng/L & Lower Jordan River & October & [19] \\ \hline \end{tabular}
\end{table} 
Table 1: _Cont._- mobilization and mineralization of fish scales [22]. The presence of this compound in the environment may cause disturbances in the secretion of endogenous gonadal sex hormone in humans and reduce sperm production, as well as increase the incidence of cancer [6]. In addition, it has been observed that often the response to estrogens is dependent on the age of the organisms. For instance, adults of common roach showed a slight response to the presence of estrogens, while exposure to hormonal compounds during the embryonic period caused 100% feminization in fish. In toxicological studies at various developmental stages, Atlantic salmon showed a higher level of vittogenin mRNA in the presence of EDCs in all stages, except in embryos. In addition, embryos were only sensitive to the highest levels of 17\(\alpha\)-ethynylestradiol while the remaining stages responded to the intermediate and highest doses not only of 17\(\alpha\)-ethynylestradiol, but also 17\(\beta\)-estradiol, and nonylphenol. Moreover, fry have been shown to be the most sensitive of the salmon life stage on EDCs [23]. [PERSON] et al. [24] showed a dose-dependent effect of estrogens on the growth of cyanobacteria _Microcystis aeruginosa_. Concentrations below 1 mg/L did not affect the growth of cyanobacteria, whereas concentrations of hormones above 10 mg/L inhibited their growth. This is due to the phenomenon of hormesis. Low hormone concentrations activate the repair functions of cyanobacteria and induce the activity of proteins involved in them. Higher concentrations damage the maintenance and repair functions of cells. It was also observed that the effect of chronic toxicity depended on the hormone used and it decreased according to the series: 17-\(\alpha\)-ethynylestradiol \(>\) progesterone \(>\) 17\(\beta\)-estradiol \(>\) 5-pregnen-3\(\beta\)-ol-20-one \(>\) testosterone \(>\) estrone\(>\) levonorgestrel \(>\) estriol.