Endocrine Disruption: In Vitro Determination of Transthyrethin (TTR) Binding using the TTR-TR-CALUX® Assay: Mn Metal Powder and MnCl2

This study evaluated the transthyretin (TTR) binding potential of two Mn-containing materials, manganese chloride (MnCl₂) and high-purity electrolytic manganese powder ((HPEMP) also known as Mn metal), using the TTR–thyroid receptor beta (TRβ) CALUX® assay in vitro.

A single valid TTR-binding experiment was conducted after a solubility assessment to determine suitable top concentrations. Milli-Q water was used as vehicle, and dimethyl sulfoxide was included to maintain constant concentrations.

Both materials were tested across nominal concentrations from 9.7 nM to 970 µM, noting that actual Mn exposure from Mn metal was lower due to very low water solubility. No cytotoxicity was observed after TRβ-CALUX® exposure.

Overall, MnCl₂ showed no TTR binding up to 970 µM, and Mn metal was also considered negative within the tested concentration range in this in vitro study.