2014 DNA article by Thompson and Newmaster retracted

2014 DNA article by Thompson and Newmaster retracted

November 2021: Co-author known for controversial article on DNA analysis of herbal products

Published: Monday, November 22, 2021

An AHPA Science Alert distributed this morning is forwarded below, as it may be of interest to a broader readership than just the subscribers to that list.

The co-author of the recently retracted article was Steven Newmaster, a botany professor in the Department of Integrative Biology at the University of Guelph in Ontario Canada.

Dr. Newmaster was also the lead author a year earlier of an article that reported that the majority of 44 herbal products analyzed using DNA barcoding “contained species of plants not listed on the labels” and that many “also contained contaminants and or fillers not listed on the label.” (See Newmaster et al. DNA barcoding detects contamination and substitution in North American herbal products. BMC Medicine 2013, 11:222).

AHPA and others roundly criticized the 2013 paper when it was published. In a letter to the journal’s editor, AHPA’s president Michael McGuffin identified inaccuracies and communicated that the authors’ “blanket assertions about the accuracy of this novel analytical tool are premature.” (AHPA Update November 5, 2013: “AHPA criticizes inaccurate article on supplement contamination.”) An in-depth review prepared by the American Botanical Council went further, calling for the Newmaster et al. article to be retracted. (Gafner, S. et al. November 2013. “ABC Review and Critique of the Research Article ‘DNA Barcoding Detects Contamination and Substitution In North American Herbal Products’ by Newmaster et al.” HerbalEGram Number 11.)

The 2013 article also served as a primary basis for New York’s Attorney General to issue cease and desist orders in early 2015 to four large retailers of herbal products. These misdirected legal actions led to many news articles that challenged the quality and integrity of herbal products, and ultimately to the current state of affairs, where many retailers to this day require extra-regulatory compliance for dietary supplement companies.

The AHPA Science Alert is appended below in its entirety.

Editor's Note

Papers published in peer reviewed scientific journals are rarely retracted, at a rate estimated to be about four retractions for every 10,000 articles (Brainard and You 2018. Science: doi: 10.1126/science.aav8384). The retraction cited in this AHPA Science Alert is of an article published in 2014 that purported to show that the use of DNA barcoding is more effective and significantly less expensive than traditional morphology-based tools for plant species identification in vegetative surveys. As of the October 27 date of the retraction, however, the journal’s editor “no longer has confidence in the validity of the data reported in this article.”

This retraction was instigated “at the request of the corresponding author,” Ken Thompson, when he developed concerns with the data availability, and could not confirm validity of the data included in the article. The notice provides some specific details on these concerns, and states that the article’s claim “regarding the use of these data as a suitable barcode could be considered questionable.”

The retraction notice reports that Thompson agrees to this retraction, but that the article’s co-author, Steven Newmaster, “has not responded to any correspondence from the Editor or publisher about this retraction.”

Two articles have been published in the journal Science in the last several months that provide a thorough narrative of Thompson’s efforts. See M. Enserink. June 15, 2021. doi: 10.1126/science.abk0016 (“When his suspicions went unanswered, this biologist decided to disavow his own study”); and C. Piller. October 28, 2021. doi: 10.1126/science.acx9500 (“DNA barcoding paper retracted after its first author flags serious problems”).

27 October 2021
Biodiversity and Conservation
DOI: https://doi.org/10.1007/s10531-021-02316-2

Retraction Note to: Molecular taxonomic tools provide more accurate estimates of species richness at less cost than traditional morphology‑based taxonomic practices in a vegetation survey.

Ken A. Thompson · Steven G. Newmaster
Published online: 27 October 2021
© Springer Nature B.V. 2021
Retraction to: Biodiversity and Conservation 23:1411–1424 (2014):

The Editor-in-Chief has retracted this article at the request of the corresponding author. Concerns were raised regarding the data sources and reproducibility. Post-publication review of the article confirmed concerns with the data availability, and the validity of the data included in the article could not be confirmed, specifically:

  • The authors have been unable to present a list of species analyzed, locality details, voucher specimens and GenBank accession numbers of ITS and rbcl genes of more than 200 samples studied.
  • It appears that sequences were neither uploaded to Genbank nor to the BOLD system at the time of the study. It does appear that sequences related to this article have been uploaded to Genbank in September 2020, but as this happened six years after publication and no voucher information is presented in the article, post-publication review was unable to confirm whether these sequences were indeed derived from the research described in this article.
  • The article does not appear to provide barcoding gaps between inter-specific and intraspecific divergences among the studied material, thus the claim regarding the use of these data as a suitable barcode could be considered questionable.

These findings were in agreement with the corresponding author Dr. Ken A. Thompsons’s concerns. The Editor-in-Chief therefore no longer has confidence in the validity of the data reported in this article. Author Ken A. Thompson agrees to this retraction.

Author Steven G. Newmaster has not responded to any correspondence from the Editor or publisher about this retraction.


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