Risk assessment of parabens in a transcriptomics-based in vitro test

Florian Seidel; Franziska Kappenberg; Susann Fayyaz; Andreas Scholtz-Illigens; Anna Cherianidou; Katharina Derksen; Patrick Nell; Rosemarie Marchan; Karolina Edlund; Marcel Leist; Agapios Sachinidis; Jörg Rahnenführer; Reinhard Kreiling; Jan G Hengstler

doi:10.1016/j.cbi.2023.110699

Risk assessment of parabens in a transcriptomics-based in vitro test

Chem Biol Interact. 2023 Oct 1:384:110699. doi: 10.1016/j.cbi.2023.110699. Epub 2023 Sep 9.

Affiliations

¹ Leibniz Research Centre for Working Environment and Human Factors at the Technical University of Dortmund (IfADo), Ardeystrasse 67, 44139, Dortmund, Germany. Electronic address: Seidelf@ifado.de.
² Department of Statistics, TU Dortmund University, Vogelpothsweg 87, 44227, Dortmund, Germany.
³ Clariant Produkte (Deutschland) GmbH, Brüningstrasse 50, 65929, Frankfurt am Main, Germany.
⁴ Leibniz Research Centre for Working Environment and Human Factors at the Technical University of Dortmund (IfADo), Ardeystrasse 67, 44139, Dortmund, Germany.
⁵ University of Cologne, Faculty of Medicine and University Hospital Cologne, Center for Physiology, Working Group Sachinidis, Robert-Koch-Str. 39, 50931, Cologne, Germany.
⁶ In Vitro Toxicology and Biomedicine, Department of Biology, University of Konstanz, Universitätsstr. 10, PO, Box M657, 78457, Konstanz, Germany.
⁷ University of Cologne, Faculty of Medicine and University Hospital Cologne, Center for Physiology, Working Group Sachinidis, Robert-Koch-Str. 39, 50931, Cologne, Germany; Center for Molecular Medicine Cologne (CMMC), University of Cologne, 50931, Cologne, Germany.
⁸ Leibniz Research Centre for Working Environment and Human Factors at the Technical University of Dortmund (IfADo), Ardeystrasse 67, 44139, Dortmund, Germany. Electronic address: Hengstler@ifado.de.

PMID: 37690743
DOI: 10.1016/j.cbi.2023.110699

Abstract

Parabens have been used for decades as preservatives in food, drugs and cosmetics. The majority however, were banned in 2009 and 2014 leaving only methyl-, ethyl-, propyl-, and butyl-derivates available for subsequent use. Methyl- and propylparaben have been extensively tested in vivo, with no resulting evidence for developmental and reproductive toxicity (DART). In contrast, ethylparaben has not yet been tested for DART in animal experiments, and it is currently debated if additional animal studies are warranted. In order to perform a comparison of the four currently approved parabens, we used a previously established in vitro test based on human induced pluripotent stem cells (iPSC) that are exposed to test substances during their differentiation to neuroectodermal cells. EC₅₀ values for cytotoxicity were 906 μM, 698 μM, 216 μM and 63 μM for methyl-, ethyl-, propyl- and butylparaben, respectively, demonstrating that cytotoxicity increases with increasing alkyl chain length. Genome-wide analysis demonstrated that FDR-adjusted significant gene expression changes occurred only at cytotoxic or close to cytotoxic concentrations, for example 1720 differentially expressed genes (DEG) at 1000 μM ethylparaben, 1 DEG at 316 μM, and no DEG at 100 μM or lower concentrations. The highest concentration of ethylparaben that did not induce any cytotoxicity nor DEG was 1670-fold above the highest concentration reported in biomonitoring studies (60 nM ethylparaben in cord blood). In conclusion, cytotoxicity and gene expression alterations of ethylparaben occurred at concentrations of approximately three orders of magnitude above human blood concentrations; moreover, the substance fitted well into a scenario where toxicity increases with the alkyl chain length, and gene expression changes only occur at cytotoxic or close to cytotoxic concentrations. Therefore, no evidence was obtained suggesting that in vivo DART with ethylparaben would lead to different results as the methyl- or propyl derivates.

Keywords: Alternative testing strategies; Developmental and reproductive toxicity; Gene expression; In vitro test; Induced pluripotent stem cells; Parabens; Toxicogenomics; Transcriptomics.