Research ArticlePUBLIC HEALTH

A common antimicrobial additive increases colonic inflammation and colitis-associated colon tumorigenesis in mice

See allHide authors and affiliations

Science Translational Medicine  30 May 2018:
Vol. 10, Issue 443, eaan4116
DOI: 10.1126/scitranslmed.aan4116

eLetters is an online forum for ongoing peer review. Submission of eLetters are open to all. Please read our Terms of Service before submitting your own eLetter.

Compose eLetter

Plain text

  • Plain text
    No HTML tags allowed.
  • Web page addresses and e-mail addresses turn into links automatically.
  • Lines and paragraphs break automatically.
Author Information
First or given name, e.g. 'Peter'.
Your last, or family, name, e.g. 'MacMoody'.
Your email address, e.g. higgs-boson@gmail.com
Your role and/or occupation, e.g. 'Orthopedic Surgeon'.
Your organization or institution (if applicable), e.g. 'Royal Free Hospital'.
Statement of Competing Interests
CAPTCHA

This question is for testing whether or not you are a human visitor and to prevent automated spam submissions.

Image CAPTCHA
Enter the characters shown in the image.

Vertical Tabs

  • RE: Studies from us and other investigators support that there is an urgent need to reassess the potential health risk of triclosan on gut microbiota and gut health
    • Haixia Yang, Postdoctoral fellow, University of Massachusetts Amherst
    • Other Contributors:
      • Weicang Wang, PhD student, University of Massachusetts Amherst
      • Hang Xiao, Professor, University of Massachusetts Amherst
      • Federico Rey, Professor, University of Wisconsin-Madison
      • Guodong Zhang, Professor, University of Massachusetts Amherst
      • Katherine Z. Sanidad, PhD student, University of Massachusetts Amherst

    Dr. Slezak stated that “dosing levels in the tests was vastly greater than exposure from consumers exposed to consumer products containing TCS”. However, we believe that the dose regimen used in our study could mimic human exposure to TCS, and the details are discussed below:
    (1) Dr. Slezak has only considered human exposure to TCS from using TCS-containing toothpaste; however, beyond toothpaste, TCS is incorporated into many other consumer products (1). The average human intake levels of TCS from using a combination of various consumer products were estimated to be 0.047-0.073 mg/kg/day (2) (equivalent to ~0.56-0.88 mg/kg in mice, with the dose conversion from humans to mice calculated as described in Ref (3)). This dose range is comparable to the lower dose used in our animal experiment (10 ppm TCS in diet, administering TCS at a dose of ~1 mg/kg/day, based on a diet of 3 g daily chow).
    (2) The No-Observed-Adverse-Effect Level (NOAEL) of TCS was reported to be 25-40 mg/kg/day (4), which leads to a calculated Acceptable Daily Intake (ADI) of TCS = 0.25-0.4 mg/kg/day (5). The ADI dose is comparable to the lower dose (10 ppm in diet, ~ 1 mg/kg/day) used in our animal experiment.
    (3) Our LC-MS/MS analysis showed that after several weeks of exposure to 10-80 ppm TCS via diet, the plasma concentrations of total TCS (free-from TCS plus TCS-glucuronide) were comparable to those reported in human studies (6, 7). We acknowledge that there could be differences in...

    Show More
    Competing Interests: None declared.
  • RE: Mice are not Men: Differences in metabolism of triclosan mean Yang et al findings have limited relevance for human health.

    Abstract: In a recent paper (A common antimicrobial additive increases colonic inflammation and colitis-associated colon tumorigenesis in mice” by Yang et al appearing in Science Translational Medicine Volume 10, May 30, 2018) the authors state : “We report that brief exposure to TCS, at relatively low doses, causes low-grade colonic inflammation, increases colitis, and exacerbates colitis-associated colon cancer in mice.” However, the authors did not account for the differences in TCS metabolism between mouse and man when calculating doses. The doses used in this study are 240, 1900, and 3000 times higher than exposure to brushing from a TCS containing toothpaste, with the majority of the findings observed at levels 1,900 times higher than exposure from brushing. As a result, the study did not use doses that could be characterized as "relatively low" and has limited relevance for human health.

    The authors of Yang et al. reported that exposure to TCS at relatively low doses resulted in low grade inflammation, and increased colitis and exacerbated colitis-associated colon cancer in mice. Colgate-Palmolive recognizes the important benefit of investigative scientific studies in animal models, which are an important element in identification of potential hazards and/or mechanistic pathways of a chemical. However, in this case the authors did not account for the differences in TCS metabolism between mouse and man when calculating doses. The doses used in th...

    Show More
    Competing Interests: None declared.