Evidence of toxins were traced in the body of women who applied popularly branded nail polish. The study by researchers from Duke University and the Environmental Working Group, which targeted to uncover triphenyl phosphate (TPHP) content in personal care products, did indeed find TPHP in the study subjects after only 10 to 14 hours of putting on nail varnish.

TPHP is a chemical that has been suspected as an endocrine disruptor and has been linked to hormonal level changes. Previous research with animals determined a link between TPHP and developmental and reproductive problems. Endocrine disruptors have been considered to increase the risk of cancer and obesity.

Study co-author Kate Hoffman of the Nicholas School of the Environment relates that the study's findings were based on two phases of observation of 17 participants.  

The initial phase observed urine samples of the participants for traces of diphenyl phosphate (DPHP), which is a chemical that forms in the body after TPHP is metabolised.  The participants were subsequently required to apply nail varnish and then provide a second urine sample each. The DPHP levels among the women were determined to be six or seven times higher in comparison.

The uncertainty from the initial phase stemmed from the lack of clarity as to whether the chemical absorption came from the actual painting of nails or from inhalation of nail varnish fumes.

The researchers then required the participants to wear synthetic gloves which had fake nails attached.  These were painted with nail varnish as in the first phase. The urine test from this phase did not yield the same levels of DPHP that the first phase did.

Findings further showed that a few brands are not transparent about this content in their ingredients list.

Kate Hoffman says, "If someone was concerned [about the presence of TPHP], it could be hard to avoid because they don't know what's in the nail polish that they're applying," she said.

Knowing of the presence of TPHP in nail varnish, a market survey result indicating that 97 percent of American girls use nail products, including nail varnish, as early as the ages of 12 to 14 is more than reason for concern.  Nail varnish is also found to be used by 14 percent of teens and tweens on a daily basis.