From the nursery to the salon, nail polish is popular with girls of all ages.
However, a joint study by Duke University and the Environmental Working Group finds chemicals in some polishes can get inside your body.
EWG's Tasha Stoiber says researchers tested women for signs of the common chemical flame retardant triphenyl phosphate or TPHP; and found every woman who had elevated levels had just painted their nails.
"Nail polish is the only personal care product that has this chemical listed as an ingredient," said Stoiber.
The EWG estimates about half of all nail polishes have TPHP which is also used as a flame retardant in some foam furniture like couches.
The group says more research is needed on the effects of TPHP in humans, but says animal studies indicate the chemical is linked to reproductive and developmental issues.
The Personal Care Products Council, the group that represents nail polish manufacturers, says the research, "speculative, misleading." They go on to say, "TPHP has been widely and safely used across many industries..." including to prevent "electrical, automobile and furniture fires."