Phenolphthalein is a chemical that is commonly used as a colorimetric pH indicator. The compound has been observed to turn orange at pH <0, clear between pH 0-8.2, fuchsia between pH 8.2-12, and clear again at a pH above 12. It has been postulated that the mutagenic effects of Phenolphthalein at high doses can be attributed the enhancement intracellular free oxygen radicals. The compound has also been observed to induce mitotic abnormalities and micronuclei with kinetochores in vitro. In Syrian hamster embryos treated with 10-40 μM of Phenolpthalein a significant number of chromosomal aberrations occurred at the hprt locus. On human breast cancer cells Phenolphthalein has been observed to have weak estrogenic effects.
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