Lactation education

Environmental Factor – September 2022: Exposure to antibacterial chemicals via breastfeeding linked to liver damage in newborn mice

Researchers at the University of California (UC), San Diego found evidence that newborn mice can be exposed to triclosan while nursing, leading to a significant buildup of fat in their livers – an early sign of liver damage. The study was partially funded by the NIEHS Superfonds research program (SRP) and by a NIEHS Exploratory Research/Development Grant.

Triclosan is an antibacterial chemical associated with many health issues, including endocrine disruption, antimicrobial resistance, and non-alcoholic fatty liver disease (NAFLD). In 2016, the United States Food and Drug Administration banned triclosan from over-the-counter soaps, but the chemical continues to be found in medical-grade antibacterial soaps, toothpastes, and some cosmetics.

Triclosan and liver disease

The team, led by Robert Tukey, Ph.D., and Michael Karin, Ph.D., previously reported that triclosan exposure worsened NAFLD in mice fed a high-fat diet. NAFLD occurs when fat builds up in liver cells, impairing organ function and can lead to more advanced forms of liver disease and increase the risk of developing type 2 diabetes later in life.

“The increasing use of triclosan in consumer products poses a risk of human liver toxicity,” Tukey said in a 2021 press release. (Photo courtesy of Maskmedicare Shop/

Although liver disease typically occurs in adults, the prevalence of NAFLD in children is increasing in the United States

Breast milk chemistry

Triclosan has already been detected in humans breastmilkpotentially exposing infants to the chemical.

“Recent increases in pediatric NAFLD may be a consequence of mother-to-child transmission of environmental toxicants like triclosan,” Tukey said at a UC San Diego. Press release.

Left to right: Heather Henry, Ph.D., SRP Scientific Health Administrator;  Karin;  PRS Health Specialist Brittany Trottier;  SRP Health Scientific Administrator Michelle Heacock, Ph.D.;  and SRP Director William Suk, Ph.D. Karin and SRP staff after her 2018 NIEHS Distinguished Lecture. Left to right: Heather Henry, Ph.D., SRP Health Science Administrator; Karin; PRS Health Specialist Brittany Trottier; SRP Health Scientific Administrator Michelle Heacock, Ph.D.; and SRP Director William Suk, Ph.D. (Photo courtesy of NIEHS Superfund Research Program)

To test their hypothesis, the researchers exposed pregnant mice to triclosan in their diet and found that it was efficiently transferred via lactation to newborn mice. They observed that newborn mice exposed to triclosan through their mother’s milk had higher liver weights and accumulated more fat in the liver, among other common early signs of NAFLD.

Potential targets for treatment

In the new study, the scientists further revealed that triclosan altered the expression of two metabolic mechanisms involved in the development of NAFLD: transcription activating factor 4 (ATF4) and proliferator-activated receptor alpha. of peroxisomes (PPARα).

The team found that blocking these mechanisms reduced triclosan-induced fat accumulation in the liver and prevented the expression of genes associated with increased de novo lipogenesis, a key feature associated with NAFLD. De novo lipogenesis is a metabolic process that converts carbohydrates into fats.

These mechanisms play an important role in the progression of NAFLD and may provide a basis on which to develop potential therapies for toxicant-associated liver disease, the authors noted.

Quote: Weber AA, Yang X, Mennillo E, Ding J, Watrous JD, Jain M, Chen S, Karin M, Tukey RH. 2022. Lactational administration of Triclosan promotes non-alcoholic fatty liver disease in newborn mice. Common Nat 13(1):4346.

(Mali Velasco is a science writer for MDB Inc., a contractor to the NIEHS Superfund research program.)