A proof of concept study demonstrating that environmental levels of carbamazepine impair early stages of chick embryonic development

• Published in: Environment international Vol. 129; pp. 583 - 594
• Main Authors: Kohl, Ayelet, Golan, Naama, Cinnamon, Yuval, Genin, Olga, Chefetz, Benny, Sela-Donenfeld, Dalit
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier Ltd 01.08.2019; Elsevier
• ISSN: 0160-4120; 1873-6750
• DOI: 10.1016/j.envint.2019.03.064

Carbamazepine (CBZ) is an anticonvulsant drug used for epilepsy and other disorders. Prescription of CBZ during pregnancy increases the risk for congenital malformations. CBZ is ubiquitous in effluents and persistent during wastewater treatment. Thus, it is re-introduced into agricultural ecosystems upon irrigation with reclaimed wastewater. People consuming produce irrigated with reclaimed wastewater were found to be exposed to CBZ. However, environmental concentrations of CBZ (μgL−1) are magnitudes lower than its therapeutic levels (μgml−1), raising the question of whether and how environmental levels of CBZ affect embryonic development. The chick embryo is a powerful and highly sensitive amniotic model system that enables to assess environmental contaminants in the living organism. Since the chick embryonic development is highly similar to mammalians, yet, it develops in an egg, toxic effects can be directly analyzed in a well-controlled system without maternal influences. This research utilized the chick embryo to test whether CBZ is embryo-toxic by using morphological, cellular, molecular and imaging strategies. Three key embryonic stages were monitored: after blastulation (st.1HH), gastrulation/neurulation (st.8HH) and organogenesis (st.15HH). Here we demonstrate that environmental relevant concentrations of CBZ impair morphogenesis in a dose- and stage- dependent manner. Effects on gastrulation, neural tube closure, differentiation and proliferation were exhibited in early stages by exposing embryos to CBZ dose as low as 0.1μgL−1. Quantification of developmental progression revealed a significant difference in the total score obtained by CBZ-treated embryos compared to controls (up to 5-fold difference, p<0.05). Yet, defects were unnoticed as embryos passed gastrulation/neurulation. This study provides the first evidence for teratogenic effect of environmental-relevant concentrations of CBZ in amniotic embryos that impair early but not late stages of development. These findings call for in-depth risk analysis to ensure that the environmental presence of CBZ and other drugs is not causing irreversible ecological and public-health damages. [Display omitted] •CBZ is detected in reclaimed wastewater and in agricultural ecosystems.•Environmental concentrations of CBZ are 103–105 fold lower than therapeutic dosages.•The chick embryo is a powerful model system to test environmental contaminants.•Environmental levels of CBZ impair specific stages of chick embryonic development.•Exposure to CBZ leads to neural tube defects and reduced cell division.