Alkylphenol ethoxylates (APEO) are the most commonly used non-ionic surfactants in the industry. They are mostly water-insoluble compounds, which are mainly used in form of solution, which, after use, are discharged into municipal and industrial waste water, from which they are subsequently transported to water-treatment plants. Biodegradation occurs during the purification process, resulting in short-chain APEOs and alkylphenols (APs). APs are the most important degradation products known to act as endocrine disruptors and which accumulate in the enviornment. In the aqueous enviornment, halogens are often present in various forms, in particular chlorine and bromine compounds, which can react APEOs and APs to form halogenated transformation products. Since products can enter the food chain, it is very important to know their fate in the enviornment. In the scope of this Master's thesis, we focused on two APs,their mono- and diethoxylated alkylphenols as well as their halogenated transformation products(mono- and dichlorinated and mono- and dibrominated). We used two different programs to study compounds in silico, Endocrine Disruptome and VegaNIC. They allow for the prediction of the environmental impact, acute toxicity and endocrine function of compounds. On the basis of literature survey and our findings, we have corroborated that logP has a significant effect on the fate of these compounds. Among other things, we were interested in the probability of biodegradation, resistance to biodegradation, and bioaccumulation factor (BCF). In predicting persistence, we found that non-ethoxylated APs are much more persistent than APEOs, which still transform to APs during purification processes and during retention in the aqueous environment. In addition, we also observed that the stability also increases with halogenation, especially via bromination, which means that the halogenated transformation products are likely to beeven more stable than their parent compounds. The least persistent compund was designated OP2EO, which has the lowest BCF value, and the most persistent is the NP with the highest BCF value. NP was the most acutely toxic compound, whereas the least toxic was NP2EO with the highest LC50 value. When comparing the LC50 values of the starting compounds with those of their halogenated derivates, we observed that halogenation increased the acute toxicity. When studying endocrine function, we predicted that APs and APEOs have the highest probabilities of binding to the androgen, mineralocorticoid and thyroid receptors (AR, MR, TRα and TRβ), with no significant change in the likelihood of halogen binding. On the basis of all obtained results, we concluded that the safest studied compound was NP2EO and the most toxic was NP. Although APs and APEOs occur in low concentrations in the environment, they have been shown to interfere with the functioning of the human endocrine system. Their usehas been restricted over the years, although they are still the most widely use non-ionic surfactants in the industry.
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