A new study published Wednesday in Environmental Science & Technology suggests that the health impact of common antimicrobial ingredients may be more widespread than assumed. The new study comes on the heels of a recent announcement by the FDA banning antibacterial soaps.

Researchers collected dust samples from an indoor athletic and educational facility and tested them for the presence of both antimicrobial chemicals and genes known to provide antibiotic resistance in bacteria. They found at least six distinct associations between certain chemicals and resistance, such that higher concentrations of a chemical were found alongside a greater amount of specific genes. In particular, the chemical triclosan was associated with the presence of a gene that helps provide resistance to several antibiotics. Triclosan, a known endocrine disruptor, was also cited as dangerous in the FDA's recent ban of antibacterial soaps.

The current study is the first of its kind to show such an interaction in indoor dust, the authors wrote.

As Medical Daily has previously explained, triclosan is among the most common chemicals in our everyday household products. Until recently, it was also the primary antimicrobial ingredient found in antibacterial soaps. Triclosan, though not an antibiotic itself, kills bacteria in a similar way to many common drugs. When bacteria eventually learn to resist triclosan, researchers have found, they may also learn to better fight off these other conventional antibiotics.

Triclosan’s popularity had started to wane even prior to the FDA banning 19 such ingredients from being used in consumer soaps and washes earlier this September. While the largest reason for the banning was simply that antibacterial soaps weren’t shown to work any better at making hands germ-free than plain old soap and water, the FDA also cited research showing that the presence of triclosan in the environment (oftentimes ending up in sewage and wastewater) was linked to greater antibiotic resistance.

Although triclosan and other antimicrobials will be gone from our hand soaps in a year’s time, their universal presence in cleaning products and even toothpastes may still be a problem if they find their way into our indoor dust, the researchers wrote. At this point, though, it’s too early whether to say antimicrobial-laden dust promotes resistance that’s actively harmful for us. While many bacteria develop antibiotic resistance, most don’t cause human disease — the real danger comes when seemingly harmless bacteria pass on resistance genes to those that aren’t.

More research will need to be done to find out whether indoor dust can contribute to that mixing of genes.

Source: Hartmann E, Hickey R, Hsu T, et al. Antimicrobial Chemicals Are Associated with Elevated Antibiotic Resistance Genes in the Indoor Dust Microbiome. Environmental Science & Technology. 2016.