As recently as last year, paraben paranoia was getting a little wild, leading lots of fake-natural companies to swap it out of their formulas. It seems to have died down a little—replaced by worry over BPA and phthalates—but I think we can expect that to heat up again, thanks to a new CDC study that says they found methylparaben and propylparaben in 99.1% and 92.7%, respectively, of the 2,500 urine samples they studied.

Ew! But hold on. Why is is bad if we all have parabens in our pee? A big problem with parabens is that most of us don’t have a clue what they are, or how worried we should be about them. Soooo let’s discuss.

Briefly: They are a category of chemical preservative used in literally every beauty product category, from your shampoo all the way down to your foot scrub. There are a few different kinds, and some are thought to be worse than others.

One particularly troubling study found parabens can mimic estrogen in the body. Then there’s another, from 2004—a hotly debated on, we might add—that found parabens in 18 of 20 breast cancer tumors examined. Now before we get all freaked out, it’s worth noting that there is zero proof that the presence of the parabens caused the tumors.

But if you extrapolate on parabens’ estrogenic quality, and the fact that excess estrogen may be linked to breast cancer, it adds up to something that sure sounds like it has the potential to be bad. But the fact is, we just don’t know yet. So as with many other chemicals used in cosmetics (and food, and drugs, and, and, and)—we advise caution. Finding products without parabens is worth it, and it’s easy!

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