Systemic effects of nonylphenol on tadpoles of Lithobates catesbeianus: gonadal, genotoxic and color alterations

Endocrine disrupting chemicals (EDCs) are one of the most important factors contributing to worldwide amphibian decline, since they alter hormonal regulation and affects reproduction and development of organisms. The 4-nonylphenol (NP) is one of the mostly used strogenic agents. This substance is a product of the degradation of lubricants, antioxidants, detergents, paints, and pesticides such as insecticides and herbicides. Here, we tested the effects of NP on embryogenesis, blood cell abnormalities, and body color of Pre-metamorphic tadpoles of Lithobates catesbeianus. Animals were exposed during 14 days to two concentrations of NP. Even though most animals were females, with ovarian-like cavity, oocytes or oogonia, intersex tadpoles were observed in control and treated groups. We found atretic oocytes in animals exposed to NP, with nuclear picnosis, cytoplasmic retraction, and vacuolization. Nonylphenol seems to increase erythrocyte nuclear abnormalities, but differences between control and treated groups were not significant. Finally, NP exposure increased body darkness, developmental stage. Our results suggest that oogenesis in pre-metamorphic tadpoles of L. catesbeianus are altered by exposure to NP and that pigmentation can be used as biomarker for exposure to this compound.