Dr. Cara Natterson: All of the things we use to beautify ourselves: shampoo and conditioner, make up, nail polish are considered cosmetics. Women are the primary consumers, but men (aftershave, cologne, sunscreen) and children (bubble bath, baby lotion, diaper cream) use them everyday, too.

Many people don't think of cosmetics as potentially harmful because they go on top of our skin or in our hair -- but various ingredients in cosmetics have found themselves on the receiving end of controversy over the past several years. Phthalates are "plasticizers" that add flexibility to products: they help nail polish avoid cracking, they help hair spray work without creating too much stiffness and maintain smell in perfumes and shampoos. They are also used in thousands of products in our lives, including vinyl flooring, toys, detergents, food packaging, and more.

• The most common phthalates used in cosmetics include dibutyl phthalate (DBP), diethyl phthalate (DEP) and dimethyl phthalate (DMP)
• A study in 2008 put phthalates in the spotlight because it showed that children absorb them from baby shampoos and lotions
• Phthalates seem to act as endocrine disruptors and affect reproductive system development and hormone levels in males
• The law requires that phthalates be disclosed on the ingredient list of retail cosmetic products but not in fragrances or in cosmetics used for professional use
• Parabens are preservatives -- they make it nearly impossible for microorganisms to live in and on our cosmetics, extending the shelf-lives of many of these products.
• On the label, you may see them listed as methylparaben, propylparaben, ethylparaben, butylparaben, benzyl paraben, and so on
• In 2003 a study was published showing that parabens are present in some breast tumors
• The American Cancer Society, the National Cancer Institute at the National Institutes of Health, the FDA, and others adamantly disagree that parabens cause cancer, but there are ongoing studies to address this concern

Ultimately, there are really dozens of chemicals in cosmetics -- above and beyond just phthalates and parabens -- that have been on the receiving end of bad press.

• Formaldehyde (a preservative) and tolouene (a solvent) are both thought to be allergens present in nail polish
• The preservatives quaternium 15 and bronopol, commonly used in baby products, break down to form formaldehyde
• Cosmetic-grade talc has been shown to be carcinogenic in lab animals
• Lanolin is of concern because it can be contaminated with DDT and other pesticides

What is the bottom line?
There is evidence that phthalates may act as endocrine disruptors -- and endocrine disruptors may affect the way hormones work in some bodies. There is also evidence that parabens are absorbed through the skin but there is no clear link causing disease. That's about all we know.

• Phthalates and parabens haven't been proven to be medical dangers, but they haven't been disproven either.
• Just because there is no clear evidence demonstrating that phthalates and parabens in cosmetics actually cause cancer doesn't mean that exposure is okay.
• I don't generally advocate "all natural" products, because you don't necessarily get something safe.
• And natural may imply healthy, but natural products aren't always well studied.

When it comes to cosmetics, though, if a plasticizer or a preservative can be left out and the product still accomplishes what you need it to, then that's likely the better choice. Is your child so much cleaner with the phthalate-containing soap or shampoo? Probably not. So it is reasonable to buy phthalate-free.

Remember though:

• Chemicals in the product aren't always listed in the ingredients
• We can pick on phthalates and parabens today, but there will inevitably just be another additive to pick on tomorrow -- there will always be another scare, another toxin to worry about, another poison threatening our children -- and we will have to wade through that hype and decide whether it is legitimate.
• And even though pesticide-free or organic products are not automatically free of phthalates, they are likely to have fewer of them; meanwhile, many companies have chosen to remove parabens from their products.