## 2 Endocrine Disrupting Compounds (EDCs) in the Environment and Associated Risks
Moreover, the hormone mixture caused a significant increase in toxicity compared to the same concentrations of individual hormones. The range of EC\({}_{50}\) values obtained for the mixture of hormones and individual hormones were 56.66-166.83 mg/L and 88.92-355.15 mg/L, respectively (according to the EU classification, pollutants with EC\({}_{50}\) values of 10-100 mg/L are harmful to aquatic organisms). The negative impact of hormones on cyanobacteria is connected with the rapid penetration of hormones into cells and the impact on photosynthetic activity by interfering with the flow of electrons through the photosystem II [24]. A significant increase in the toxicity of the mixture compared to individual substances may translate into more serious ecological effects. This observation is all the more important because of the environment where we usually deal with mixtures of hormones. Moreover, estrogens can accumulate in the food chain and the effects may appear in the next generation, threatening the health of the human population [4; 11; 24]. Also, the World Health Organization classified estrogens as group 1 carcinogens and some of their catechol metabolites such as 4-hydroxyestrone are also carcinogens [12; 25]. Another group of endocrine substances that can be found in the environment are androgens. Like estrogens they can interfere with the normal functioning of the endocrine system of non-target organisms in trace concentration and they have many sources from which they get into the water, and due to filtration they also get into underground water. One of the most commonly identified androgens in the environment is testosterone, its presence in the environment may cause a high percentage of males in the aquatic environment, appearance of male secondary sex characteristics in female fish, inhibition of vittellogenin induction, reduction of reproductive capacity and masculinization in mammals [26]. For example, defeminisation has been observed in fathead minnows that have been exposed to wastewater from cattle farms [27]. Moreover, it has been showed that male Atlantic salmon exhibit an odorant response to testosterone at extremely low concentration (0.003 ng/L) [28]. There are also substances in the environment that disturb the action of endogenous compounds due to the similarity of their structure to hormones (chemicals mimic hormones), such as bisphenol A, 4-nonylphenol, parabens and phthalate, as well as antibacterial triclosan [29; 30]. Moreover, some mycotoxins, such as zeaeralenone produced by several _Fusarium_ spp., have strong estrogenic activity [31]. These compounds are resistant to microbiological degradation and their duration in sediments can be up to 40 years and, similar to hormonal substances, sometimes they can be food contaminants and thus, they can cause reproductive and developmental disorders of aquatic animals and humans [29; 31]. [PERSON] et al. [31] showed that zeaeralenone significantly increased the uterus weight in a dose dependent manner and upregulated complement component 2, calbindin-3 expression,and decreased apelin and aquaporin 5 mRNA levels. This is due to the high affinity of zearalenone for estrogen receptors. Moreover, this compound and its metabolite \(\alpha\)-zearalenol stimulate the proliferation of MCF-7 human adenocarcinoma cells [31]. Nonylphenol may cause various disorders of the male reproductive system, such as a reduction of testicle size and decrease of sperm production in _Oncorhynchus mykiss_. This mimic hormone was also observed to induce the proliferation of the human breast cancer cell line [32]. Due to the prevalence of endocrine compounds and other pharmaceuticals in the environment and their possible negative effect on non-target organisms, more and more attention is being paid to the methods of their removal from the environment.