9. Parabens
(methyl-, ethyl-, propyl-, butyl-, isobutyl-) Parabens, which have weak estrogenic effects, are common preservatives that appear in a wide array of toiletries. A study found that butyl paraben damaged sperm formation in the testes of mice, and a relative, sodium methylparaben, is banned in cosmetics by the E.U. Parabens break down in the body into p-hydroxybenzoic acid, which has estrogenic activity in human breast-cancer cell cultures.

10. Petroleum Distillates
Possible human carcinogens, petroleum distillates are prohibited or restricted for use in cosmetics in the E.U. but are found in several U.S. brands of mascara, foot-odor powder and other products. Look out for the terms "petroleum" or "liquid paraffin."

11. P-Phenylenediamine
Commonly found in hair dyes, this chemical can damage the nervous system, cause lung irritation and cause severe allergic reactions. It's also listed as 1,4-Benzenediamine; p-Phenyldiamine and 4-Phenylenediamine.