Many tend to think of their health mainly in terms of what they eat and drinkwhat goes into their body. I certainly take this approach: Buy the organic granola bars instead of the cheap, preservative-laden ones that I can afford, swap an apple for that second cookie, and drink lots of water. In the introductory piece of my chemicals in materials series, the focus was solely on food and water and how chemicals might cause contamination. But there are other and perhaps more important routes of potential exposure.

Skin is our first line of defense against dangers in the environment, bombarded daily by the sun’s UV rays and air pollution. Our noses are designed to help us sense our surroundings while filtering out the dangers of them, and mouths self-regulate to prevent infection and keep teeth strong so we actually can eat.

Our bodies work to keep us healthy, yet the Food and Drug Administrationcharged with “protecting and promoting your health”—doesn’t have authority over the countless personal care products we use daily. The very products we use to take care of ourselves and our bodies are free to use toxic substances.

Ironically enough, many of these harmful ingredients are included to keep the products safe. Antimicrobials, antifungals, and preservatives are what allow that tube of chapstick or jar of lotion to sit in your medicine cabinet until you’ve used it all up. Without compounds like parabens and triclosan, bacteria and other microorganisms would quickly render these products rotten.

Ironically enough, many of these harmful ingredients are included to keep the products safe.

Eye infections, even infamous staph and MRSA, can be prevented through the use of these agents. Deodorants, meanwhile, use them to kill bacteria that makes sweat smell, and triclosan in toothpaste is meant to fight gingivitis. B.O. and gum disease aren’t great, and infections even less so, but compare these to the potential health effects of the preservatives themselves.

Parabens and triclosan are both endocrine disruptors. Mimicking hormones like estrogen, these types of chemicals can cause cancer, birth defects, and developmental disorders. Sunscreens employing chemical filters are similarly well-intentioned but, as endocrine disruptors, pose a risk to reproductive systems and fetal development (mineral sunscreens, like those made with zinc, don’t pose the same risk). Phthalates used in fragrances, nail polish, and hair products fall into this category, as does the toluene that contributes to the harsh fumes of nail polish and hair dye.

B.O. and gum disease aren’t great, and infections even less so, but compare these to the potential health effects of the preservatives themselves.

Though there is a clear trend, the common chemicals in cosmetics don’t stop at interfering with hormones. Their impact extends even beyond the drug-resistant germs that triclosan promotes or the damage to nervous and immune systems that can come from toluene. There are two particularly large issues that distinguish personal care products in the world of chemicals.

First, because cosmetics are applied directly and are often designed specifically to be absorbed by the skinthink wrinkle creams and anti-perspiranttheir ingredients also penetrate the body and join the bloodstream, where they may cause unknown internal harm. This in combination with the daily use of at least several such products amounts to exceptional exposure.

Second, personal care products have a way of getting into the environment, particularly water supplies. Whether rinsed off in the sink, washed down the drain of your shower, or thrown out, the countless chemicals in cosmetics infiltrate the water supply. As water treatment plants are unequipped to remove them, over 100 chemicals from personal care products can be detected at low concentrations in our drinking water or in habitats.

While there exist strong bodies of evidence against many ingredients in personal care products, minimization of exposure, rather than complete elimination, is key.

This is certainly overwhelming. If you’re anything like me, maybe it’s crossed your mind that we should throw hygiene and the chemicals that come with it out the window.

In the spirit of this series, however, I’ll quote my Environmental Toxicology professor, Elsie Sunderland, who frequently quoted the first toxicologist Paracelsus: “the dose makes the poison.” That is, the danger of something, of anythingeven water—lies in the degree of exposure. While there exist strong bodies of evidence against many ingredients in personal care products, minimization of exposure, rather than complete elimination, is key.

Awareness of hazardous ingredients in your purchases and their safe alternatives can easily accomplish this. Brush up on the (many) names of the (many) chemicals used in cosmetics, read labels, and buy organic when possible.

While the FDA doesn’t regulate personal care products, the USDA certifies products that are 100%, 95%, and 70% organic. Replacing even a few of the products you use daily can cut exposure and protect your health, rather than harm.

The following sources can make informed purchasing even simplersee them for companies and products that don’t use toxic ingredients, or to find which do.