## 3 Ecotoxicology  
Often, studies do not evaluate the ecotoxicity of PPCPs metabolites or conjugate transformation products, which are sometimes suggested to be biologically damaging [345; 346] and often the resulting products can be more toxic [347; 348]. In addition, the effects of excipients of the drugs and the additives added to different PPCPs have been poorly studied [349]. NPX photo-transformation products have been suggested to be more toxic than the parent compounds for algae, rotifers and microc crustaceans [346]. When the toxicity of the abiotic degradation products of IBU and 4-acetylbenzoic acid using test organism (_Bacillus megaterium_, _Pseudoaltermones atlantica_, and algae of the _Chlorella_ genus) was evaluated, the toxicity was reduced in the case of IBU but the same did not occur with 4-acetylbenzoic acid [350]. Therefore, ecotoxicological evaluation should be a prerequisite for risk assessment of intermediate or non-degraded chemicals in the water and soil recovery processes [351]. Thus, ecotoxicological tests using biomarkers have brought to light important changes in the behavior of populations of aquatic invertebrates [352], stress oxidative in Zebra mussels [68], and delay in fish development and in frog's metamorphosis [353]. Table 1 contains a detailed review of the most commonly used biomarkers to determine the ecotoxicity of recovered water. For example, the global order of sensitivity of the species to 26 PPCPs considered in aquatic environments was: _Vibrio fischeri(15 min) \(>\) algae\(>\) crustaceanseans \(>\) fish \(>\) WWTP biomass [36]. Fewer biomarkers have been used in agricultural soils or terrestrial ecosystems, where some nematodes, anelids and only one species of arthropod (Table 2) stand out. The selection of the appropriate biomarkers to environmental pollution detection is important, both in aquatic and terrestrial environments. This selection will come determined by multiple factors, among others, the PPCPs mixture composition (Tables 1 and 2). In addition, the degree of sensitivity to pharmaceutical products does not depend on the complexity of the organizations [8]. The monogononta rotifers could be one of these organisms. They have high rates of population growth, what allows the study of multigenerational effects in short times. In addition, they are bioindicators sensitive to water changes are susceptible to a wide range of contaminants and reproduce in a parthenogenic way that allows for comparing genetically identical individuals [354]. A chronic exposure to PPCPs of the rotifer _Plationus patulus_ decreased egg production and increased egg detachment [65]. Algae are at the base of aquatic food webs and they play important roles in the transfer of energy and nutrients to species at higher trophic levels. The algae have a rapid reproduction rate and high sensitivity to contamination [67]. Microalgae have ecological relevance, they are easily cultivated in the laboratory and are sensitive [355; 356]. In many studies developed with microalgae, after the exposure to PPCPS, an inhibition of the growth has been observed [67; 69]. _Daphnia magma_, a planktonic crustacean of the order Cladocera and _Dreissena polymorpha_, a mollusc bivalve, are used in ecotoxicological bioassays for their low phenotypic variation and high sensitivity to toxic compounds. In one study signs of oxidative stress with high levels of lipid peroxidation in zebra mussels (_Dreissena polymorpha_) exposed to GFZ and DFC were proven [68]. Ethinylestradiol and fluoxetine generated changes at hormonal levels, decreasing fertility and fecundity and increased mortality, affecting growth rates in _Daphnia magma_[76]. Meanwhile, antibiotic contaminants that were commonly released in fisheries reduced the growth of green algae (_Scenedesmus vacuolatus_) and duckweed (_Lemma minor_), as well as the viability of the crustacean _Daphnia magma_[66].