# Plaaben Compounds--Part I: An Overview of Their Characteristics, Detection, and Impacts
## 3 Paraben Potential Impacts
### Impacts in Animals
Additionally, the decrease in corpora lutea, increase in the number of cystic follicles, and thinning of the follicular epithelium was also revealed. Concentrations of estradiol and thyroxine also decrease for MP, EP, PP, iso-PP and iso-BuP. The author concluded that a long exposition of parabens can produce suppressive effects of hormonal responsiveness and can disrupt the morphology of reproductive target tissues. [PERSON] and [PERSON] [97] concluded that a mixture of MP and EP or MP and PP can cause a decrease in the permeation flux of the transdermal permeation in pig ear skin (except for EP). The authors think that this happens due to a higher retention of these mixtures in the pig epidermis and dermis. [PERSON] et al. [98] tested the effect of MP in zebrafish embryos, concluding that an increase in MP concentration of 200 uM or above decreased the heart rate of 2 days postfertilization embryos, in which the control group presented 42 beats in 20 s, while the values treated with 200, 400 or 800 uM had heart rate values of 36, 33 and 22 beats per 20 s. Additionally, abnormalities such as pericardial edema, bent spine and blood cell accumulation were observed, and these effects increased for higher concentrations of MP, achieving accumulation of blood cells of 5%, 25% and 75% for 100, 200 and 400 uM of MP, while pericardial edema was detected in 30% and 90% of embryos treated with MP concentrations of 200 and 400 uM, and the bent spine abnormality was observed in 90% of embryos treated with 400 uM of MP; 100% lethality was observed in embryos exposed to MP values of 1000 uM in 48 h after fertilization. The results obtained by [PERSON] et al. [98] showed that other aquatic organisms can suffer different problems due to the presence of parabens. [PERSON] et al. [99] tested the exposure to MP in _Daphnia magna_, and the acute toxicity EC\({}_{50}\) in 48 h for \(D\). _magna_ was 36.73 and 5.70 mg/L for indoor tests using UV radiation and outdoor tests using solar radiation, respectively. The authors also concluded that after 21 days of MP exposition, the survival of \(D\). _magna_ decreased as the MP concentration increased (lower survival rate was observed at 10 mg/L) and the number of young per female, number of young per brood and \(D\). _magna_ growth also decreased for concentrations of 3.2 mg/L of MP. The authors reports that the observed reduction in these parameters can affect aquatic ecosystems since invertebrates presents an important source of food for small fish in these ecosystems. Additionally, the study reported by [PERSON] et al. [100] concludes that MP, EP and PP are toxic to aquatic organisms, achieving EC\({}_{50}\) (in 48 h) values between 11 and 50 mg/L for _D. magna_ and EC\({}_{50}\) (in 72 h) values ranged from 15 to 91 mg/L for _Pseudokirchneriella subcapitata_ (a green algae). [PERSON] et al. [100] evaluated the acute toxicity for _D. magna_ and _V. fischeri_, reaching EC\({}_{50}\) values of 62, 32, 23, 30, 9.2, 9.8 and 6.6 mg/L for MP, EP, PP, iso-PP, BuP, iso-BuP and BeP, respectively, for _D. magna_ and 5.9, 4.6, 0.26, 0.62, 1.2, 3.5 and 0.0038 mg/L for the same parabens regarding _V. fischeri_. The authors point out that these results indicate that, in general, regarding _D. magna_, the most tested parabens were toxic to aquatic organisms (EC\({}_{50}\): 1-10 mg/L), but other obtained results can be classified as harmful to organisms (EC\({}_{50}\): 10-100 mg/L). For _V. fischeri_, values can be classified as toxic (EC\({}_{50}\): 1-10 mg/L) and very toxic to organisms (EC\({}_{50}\): \(<\)1 mg/L). The results also show that the most toxic compounds were dichloromethane benzylparaben for _D. magna_ and benzylparaben for _V. fischeri_. Additionally, [PERSON] et al. [101] tested the effect of parabens in Japanese medaka fish _O. latipes, daphnia magna_ and the green algae _P. subcapitata_. The EC\({}_{50}\) results were 80, 52, 36, 48, 9.5, 4.0 and 1.2 mg/L for the algae, about 34, 7.4, 2.0, 3.5, 1.9, 3.3 and 2.1 mg/L for _D.