Antibacterial products are found in hospitals, personal products and at home. However, recent studies say They may do more harm than good

Antimicrobial chemicals found in common household products could be wreaking havoc with people’s guts, according to a research paper out this week in the journal Science.

Triclosan is an antibacterial compound used in soaps, detergent and toothpaste, as well as toys and plastics. It was originally only used in hospitals, but it found its way into homes as Americans became more germ-phobic. (However, recent studies have found it no more effective at killing bacteria than plain soap.)

Now, there are growing concerns about the possible negative effects of the chemical on human health and the environment. According to the US Food and Drug Administration (FDA), animal studies have shown that the chemical can act as a hormone disruptor. A 2008 study found traces of triclosan in the urine of 75% of the participants – some as young as six. The chemical has also been found in more than half of freshwater streams in the US.

The latest research paper, written by academics from the University of Chicago, focused on the lesser-known effects of triclosan exposure on the bacteria in people’s guts.

Disturbing the human microbiome has been “linked to a wide array of diseases and metabolic disorders, including obesity, inflammatory bowel disease (IBD), irritable bowel syndrome (IBS) and behavioral and metabolic disorders,” wrote the paper’s authors, Alyson L Yee and Jack A Gilbert.

Yee and Gilbert examined conflicting research on just how the chemical impacts gut microbiomes. Studies using zebrafish and fathead minnows found that triclosan changed gut bacteria, but that the microbiomes recovered once exposure to the chemical was stopped. However, another study on biofilms in rivers found that the gut remained altered even after triclosan was removed.

To test the chemical’s effect in humans, researchers from Stanford and Cornell universities gave seven volunteers triclosan-containing products, such as toothpaste and liquid soap, to use for four months. After that period, the same volunteers were switched to products without triclosan. The volunteers were compared with a second group who first used the non-triclosan products, then changed to those containing triclosan.

The results showed that more triclosan was found in the urine of all the participants during the periods when they were using triclosan-containing products.

Yee and Gilbert also suggested that exposure to triclosan could be even more detrimental to the health of developing fetuses and newborns than to adults. A 2014 New York University study found that gut disruptions in early infancy could have lasting negative effects on immune and brain development.

The authors suggest that further studies are needed to understand the chemical’s effects on the human body.

Triclosan could also be contributing to antibiotic resistance, which scientists believe is caused by the overuse of antimicrobials in humans and animals. There are partial bans of the chemical in the European Union and in Minnesota, and the FDA says it will continue reviewing the chemical for its safety.

“Future research should explore the role of dose, timing, and route of triclosan exposure,” the paper’s authors wrote. “Humans are exposed to triclosan transiently and in small doses, but the presence of triclosan in surface, ground and drinking water indicates its potential to persist and accumulate in the environment.”

Alison Moodie

Sat 30 Jul 2016 07.00 BSTLast modified on Wed 20 Sep 2017 19.21 BST