Paraben

From CopperWiki

Parabens are synthetic preservatives used in cosmetics and personal care products and are which can give many people allergic reactions. These are some alternatives.

Parabens-- such as propylparaben, ethylparaben and butylparaben--are synthetic preservatives commonly used in cosmetics and personal care products like shampoos, skin creams and deodorants. They are suspected to be endocrine disruptors, and they have been found to mimic estrogen in laboratory experiments.