Scientists at CAESAR, the Center of Advanced European Studies and Research, in Bonn, Germany, observed and documented direct action of endocrine disrupting chemicals (EDCs) on human sperm. The goal of their study was to systematically determine if 96 ubiquitous EDCs (ex: personal care products, surfactants, pharmaceuticals) affect human sperm adversely, in hopes that acquiring such knowledge can lead to more strict guidelines on the use of EDCs.

Since CatSper is the principle calcium channel that controls intracellular calcium levels, and consequently, overall sperm navigation and function, the scientists decided to closely monitor how CatSper was affected in the presence of each EDC. One way to detect that CatSper reacted to certain substances was to use a calcium indicator to measure calcium response of the sperm upon EDC treatment. The human sperm were loaded in the experiment with calcium dye Fluo-4 and pH indicator BCECF (since human CatSper is also sensitive to pH changes), while the mouse sperm used in the experiment were prepared with Cal-520^®. Following treatment of both these types of sperm with EDCs, the differing calcium responses between human and mouse sperm for certain EDCs indicated that CatSper-mediated calcium signals were species-specific. With these results, the scientists concluded that mouse CatSper was not a suitable model for human CatSper in the context of EDC testing.

In the materials and methods section of the study, the scientists demonstrated that Cal-520^® could be used at such a low concentration (5 µM) to load the mouse sperm adequately for calcium detection. Furthermore, the dye loading buffer did not require any additional reagents to prevent dye leakage, as other calcium dyes might. Cal-520^®'s sensitive signal and enhanced intracellular retention allows for its use without high concentrations and without additional reagents, both aspects which may affect calcium activity in prepared cells.