U.S. Senators Dick Durbin (D-IL) and Richard Blumenthal (D-CT) are calling on the Food and Drug Administration (FDA) to investigate manufacturers of dietary supplements containing "acacia rigidula" which is often used on dietary supplement labels to mask the inclusion of BMPEA - a potentially dangerous synthetic stimulant - in their products. Today's letter follows the release of a study last week in which researchers found BMPEA, in 11 of 21 over-the-counter dietary supplements.

The Senators also criticized the FDA for remaining silent on this issue while the percentage of brands of "acacia rigidula" labelled supplements that contain BMPEA have increased from 42.9% in 2012 to 52.4% in 2014.

"For too long, dietary supplement manufacturers have either failed to list BMPEA on product labels or have listed the stimulant as a 'natural botanical,' which the Food and Drug Administration's own scientists have disproved," wrote the Senators. "Other countries and entities have already taken note of A. rigidula and BMPEA's potential danger...We are very troubled by FDA's inaction on this issue."

The European Food Standards Agency and the Danish Veterinary and Food Administration have both cautioned against the consumption of A. rigidula products, while Canadian health authorities have called BMPEA "a serious health risk" and pulled supplements that contain it from store shelves. Furthermore, the chemical is classified as a doping agent by the World Anti-Doping Agency.