This is the second post in our series on harmful skin chemicals found in our everyday products.

1. Lead

At this point, nearly everyone knows about lead’s toxicity. You would probably steer clear of a house with lead paint and be concerned about contaminated water or soil, so you might be surprised to learn that some personal care products still contain quantities of lead.

Some hair dyes are known to contain lead acetate, and though the FDA has concluded that very little lead is absorbed by the body while using hair dye, scientists have countered that the frequency with which consumers apply the dye puts them at an increased risk for absorption than was previously assumed.

Lead is also found in some lipsticks. The FDA has a lengthy article about its testing process for lead in lipsticks, following a 2007 report about lead content in lipsticks that resulted in a public outcry for better testing methods and more transparency about cosmetic ingredients. The full report, if you’re interested, can be found here. It’s lengthy and, at times, confusing, but the essential conclusion is that while testing is done regularly and the FDA believes lipstick is safe “when used as intended,” there are still lipsticks on the market that contain lead and that come frighteningly close to ingestion. It’s a tricky issue to parse and avoid, primarily because lipstick tubes often don’t contain ingredient lists. Also, lipsticks in the same line might contain different amounts of lead or even completely different ingredients.

2. Formaldehyde

You may remember formaldehyde as the smelly liquid that was used to preserve frogs between dissections in biology class. It is also used in many building materials, household products, adhesives, insulation products, and disinfectants. In smaller quantities, it can be found in food products, cosmetics, and skincare products. Basically, formaldehyde is everywhere. But is it safe?

Formaldehyde has also been shown to cause cancer in laboratory animals, and has proven to be a human carcinogen in large quantities. The long-term effects of human exposure to small quantities of formaldehyde is unknown, but it’s wise to be wary of products that contain larger quantities of formaldehyde (e.g., chemical hair straighteners).

Formalin, the name for formaldehyde dissolved in water, is often found in nail polish and other nail products. A number of nail polish companies have recently started offering quality formalin-free nail products. Look for nail polishes that advertise themselves as “5-free,” meaning they are free of 5 toxic ingredients: formaldehyde, dibutyl phthalate (DBP), toluene, formaldehyde resin, and camphor. If you’re pregnant, it may be best to avoid nail polish of any kind.