A study has found that dust on office surfaces can expose people to harmful chemicals from flame-retardants.

In a study of 31 Boston offices, polybrominated diphenyl ether (PBDE) flame-retardants, now banned internationally by the Stockholm Convention on Persistent Organic Pollutants, were detected in every office tested.

The research, links concentrations of PBDEs in office dust with levels of the chemicals on the hands of the offices’ occupants.

The study authors also found the amount of PBDEs on workers’ hands to be a good predictor of how much was measured in their blood. However, frequent hand washing appeared to reduce exposure to certain PBDEs.

This is the first peer-reviewed research to correlate levels of PBDEs on people’s hands to concentrations in their blood, says lead author Deborah Watkins, a Ph.D. candidate at the Boston University School of Public Health’s Department of Environmental Health.

Although scientists don’t know exactly how people accumulate high concentrations of PBDEs in their bodies, hand-to-mouth exposure is thought to play a significant role.

In this study, workers who reported washing their hands with soap and water four or more times per day tended to have lower levels of penta-PBDEs on their hands than those who washed their hands less often.