Triclosan – found in soaps, detergents, shampoos, toothpaste – can trigger liver cancer in mice

Despite other scientists calling for caution over findings, University of California researchers say chemical may cause similar changes in people

Triclosan, chemical ingredient of some cosmetics, soaps, detergents, shampoos and toothpaste has been found to trigger liver cancer in laboratory mice, raising concerns about how safe it is for humans. The commonly used anti-bacterial agent added to bathroom and kitchen products, promotes the growth of liver tumours in mice fed relatively large quantities of the substance, an Oct 2014 study found.

Abstract

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Despite other scientists calling for caution over findings, University of California researchers say chemical may cause similar changes in people.

Triclosan [5-chloro-2-(2,4-dichlorophenoxy)phenol; TCS] is a synthetic, broad-spectrum antibacterial chemical used in a wide range of consumer products including soaps, cosmetics, therapeutics, and plastics. The general population is exposed to TCS because of its prevalence in a variety of daily care products as well as through waterborne contamination. TCS is linked to a multitude of health and environmental effects, ranging from endocrine disruption and impaired muscle contraction to effects on aquatic ecosystems.

We discovered that TCS was capable of stimulating liver cell proliferation and fibrotic responses, accompanied by signs of oxidative stress. Through a reporter screening assay with an array of nuclear xenobiotic receptors (XenoRs), we found that TCS activates the nuclear receptor constitutive androstane receptor (CAR) and, contrary to previous reports, has no significant effect on mouse peroxisome proliferation activating receptor α (PPARα). Using the procarcinogen diethylnitrosamine (DEN) to initiate tumorigenesis in mice, we discovered that TCS substantially accelerates hepatocellular carcinoma (HCC) development, acting as a liver tumor promoter. TCS-treated mice exhibited a large increase in tumor multiplicity, size, and incidence compared with control mice. TCS-mediated liver regeneration and fibrosis preceded HCC development and may constitute the primary tumor-promoting mechanism through which TCS acts.

These findings strongly suggest there are adverse health effects in mice with long-term TCS exposure, especially on enhancing liver fibrogenesis and tumorigenesis, and the relevance of TCS liver toxicity to humans should be evaluated.

Sources and more information
  • The commonly used antimicrobial additive triclosan is a liver tumor promoter,
    PNAS, doi: 10.1073/pnas.1419119111, November 17, 2014.
  • Triclosan: Soap ingredient can trigger liver cancer in mice, warn scientists, The Independent, 17 November 2014.

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