How many potentially toxic ingredients do you smear on your skin, hair or nails on a daily basis?

Ingredients linked to allergies, hormone disorders and cancer are found in everything from toothpaste to hair gel. In 2008, a study by the Environmental Working Group (EWG) found 16 chemicals from four chemical families – phthalates, triclosan, parabens and musks – in the blood and urine of 20 teen girls. Though many of these ingredients are banned in other countries, they are not strictly regulated in the U.S.

Here are five common chemicals of concern found in cosmetics and personal care products, how they affect our bodies and what you can do to avoid them.

Phthalates

This group of chemicals is often used as a softener in plastic products and an additive in cosmetics like nail polish, moisturizer and fragrance, including scents added to other products. Because companies aren't required to list the ingredients used to create 'fragrancem,' phthalates are often not listed on the label.

Health hazards: Phthalates are considered hazardous waste and are regulated as pollutants in air and water. Banned in Europe, chemicals in the phthalate family are known to be endocrine disruptors and carcinogens, and linked to a number of heath problems. Phthalate exposure is linked to a number of reproductive problems in both men and women including reproductive system birth defects, damage to sperm DNA and infertility.

How to avoid it: Choose products that don't list phthalates or fragrance among the ingredients, or specify that they are phthalate-free.

Triclosan

Triclosan, the main active ingredient in antibacterial soaps and hand sanitizer, is also found in toothpastes, deodorants, face and body washes and acne treatments. Numerous studies have detected triclosan in the breast milk, blood and urine of ordinary people; in fact, a 2008 CDC survey found that 75 percent of Americans have triclosan in their bodies.

Health hazards: Triclosan, which has been proven to accumulate in the bodies of people and animals over time, is linked to the disruption of thyroid function and other critical hormonal systems. A 2010 study found that triclosan exposure is linked to allergies and hay fever in young people. Both the U.S. Environmental Protection Agency (EPA) and the U.S. Food and Drug Administration (FDA) are currently evaluating the safety of triclosan use.

How to avoid it: In 2005, the FDA determined that soaps branded as “antibacterial,” including those containing triclosan, are no more effective than soap and hot water at killing germs or reducing the spread of infection, so choosing triclosan-free soaps is a safe way to go.

Parabens

Parabens are widely used as a preservative in all sorts of body care products and cosmetics to prevent the growth of bacteria and mold. On ingredient lists, they appear as methyl-, ethyl-, propyl-, isopropyl- and butylparaben.

Health hazards: The FDA concluded that very low levels of parabens are a safe additive in cosmetic products, but this determination does not account for the constant exposure that we receive through dozens of products on a daily basis. Laboratory studies show that parabens mimic the hormone estrogen in the body, and in one 2004 study, parabens were found in the breast cancer tumors of 19 of 20 women examined.

How to avoid it: Look for products that say “paraben-free” right on the label.

Nitro- and polycyclic musks

Another toxic ingredient hidden in the catch-all term 'fragrance' is musk, or specifically, nitro- and polycyclic musks. These chemicals are found in many products that list 'fragrance' among their ingredients and can be absorbed through the skin, inhaled and ingested.

Health hazards: Studies have shown that musks irritate the skin or cause allergic reactions, disrupt the hormone system and may be linked to cancer.

How to avoid it: Choose products with no added fragrance; products with naturally-derived fragrance will list the individual ingredients used for scent such as essential oils.

Formaldehyde

Eyelash glue, nail glue, nail polish and hair gel: these are just a few of the ways in which we are exposed to formaldehyde. Formaldehyde is used to prevent the growth of bacteria in personal care products and cosmetics.

Health hazards: Formaldehyde has been shown to cause allergic skin reactions and rashes in some people, and is considered a probable carcinogen.

How to avoid it: In Europe and Canada, products containing formaldehyde must carry a warning label, and in Japan and Sweden, it has been banned from use in cosmetics and toiletries altogether. In other countries such as the U.S., look for the following ingredients: formalin, methanal, urea, quatemium 15, oxymethyline, methylaldehyde, formic aldehyde, oxomethane formalin, 1,3-dioxetane, phenol formaldehyde and methylene oxide.

For more on chemicals in cosmetics, check out the following resources: