Methylparaben is listed by the Hazardous Substances Data Bank as a food preservative, as well as a preservative for cosmetics. It is a fungicide, which can preserve the life of a product. The HSDB states that methylparaben is quickly absorbed through the skin and the intestinal tract (when used as a food preservative). There is a great deal of controversy surrounding its use, with many reports of dangerous side effects.
Methylparaben is widely used as a preservative in women's cosmetics, such as skin creams and deodorants. One of the physical dangers associated with methylparaben is its connection with tumors in the breast. A report in the January-February 2004 issue of the Journal of Applied Toxicology states that when several breast tumors were examined by researchers, high levels of methylparaben were found in the tissues.
The October 3, 2006, issue of Toxicology published a study that shows when skin treated with creams that contain methylparaben was exposed to the sun's UVB rays, the skin cells died and there was considerable oxidative stress on the skin's tissue. Oxidative stress, according to the National Institute of Standards and Technology, is responsible for a number of disease processes, including cancer.
When used as a preservative in eye drops, methylparaben has been shown to cause ocular damage. Researchers at the Department of Opthamology at the Mount Sinai Medical Center in New York report that eye drops containing methylparaben, even in small amounts, can cause a degree of eye tissue damage. This study is published in the April 2009 issue of the Journal of Ocular Pharmacology and Therapeutics.
Parabens, including methylparaben, have estrogenic affects on the body, which means they can affect the reproductive glands. The January 2009 issue of Reproductive Toxicology reports that there is a probable interaction between parabens and the health and activity of cells in the testes, meaning a possible decrease in sperm production in males.