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Tyrone B. Hayes
Tyrone B. Hayes

(1967-07-29) July 29, 1967 (age 54)
CitizenshipUnited States
EducationPhD (1993, Berkeley), BA (1989, Harvard)
Known forExposing Syngenta's toxic agriculture chemicals
WebsiteAtrazine Lovers

Tyrone B. Hayes (born July 29, 1967) is an American Afrikan biologist and professor of Integrative Biology at University of California, Berkeley known for his research findings that the herbicide atrazine is an endocrine disruptor that demasculinizes and feminizes male frogs. He is also an advocate for critical review and regulation of pesticides and other chemicals that may cause adverse health effects. He has presented hundreds of papers, talks, and seminars on the role of environmental chemical contaminants in global amphibian declines and in the health disparities that occur in minority and low income populations. His work has been contested by Syngenta, the Swiss manufacturer of atrazine, and was used as the basis for the settlement of a multi-million dollar class-action lawsuit against them.

Early Life

Born in Columbia, South Carolina, Hayes spent his childhood studying frogs and lizards in his community. He would collect many specimens and expose them to different controlled environments to record the results. His father once remarked, while watching him conduct an experiment that "there is a fine line between a genius and a fool.[1] and won a state science fair with research that showed anole lizards had to be awake to change color.[2] In sixth grade, Hayes was accecpted into a program for 'gifted' children. After some time, in this program, he took note that the people in his community, began to treat him differently, accusing him of striving to 'act white'.

Education and Career

Hayes went on to highschool and did so well that he recieved a scholarship to Harvard. In 1985, he began what he called "the worst four years of his life"[3] He didn't do well at all in his time there. He went as far as to be placed on academic probation. This went on until he became close to a biology professor. He turned his academic career around after that, and met his soon to be wife, Katherine Kim, a Korean from Kansas. After graduating from Harvard University, Hayes was a technician and freelance consultant from 1990–1992 for Tiburon, California based Biosystems, Inc.[4] Hayes has held an academic appointment (professorship) at the University of California, Berkeley since completing his doctoral research there in 1992;[2] He was hired as a graduate student instructor in 1992, became an assistant professor in 1994, associate professor in 2000, and professor in 2003 in the Department of Integrative Biology, Molecular Toxicology, Group in Endocrinology, Museum of Vertebrate Zoology, Energy and Resources Group, University of California, Berkeley.[4]

Atrazine research

Xenopus laevis, the African Clawed frog

In 1997, the consulting firm EcoRisk, Inc.[upper-alpha 1] paid Hayes to join a panel of experts conducting studies for Novartis (later Syngenta) on the herbicide atrazine.[2][3] When Hayes' research found unexpected toxicities for atrazine, he reported them to the panel, however the panel and company were resistant to his findings. He wanted to repeat his work to validate it but Novartis refused funding for further research; he resigned from the panel and obtained other funding to repeat the experiments.[2][3]

In 2002 Hayes published findings that he says replicate what he found while he was working for EcoRisk,[2] that developing male African clawed frogs and leopard frogs exhibited female characteristics after exposure to atrazine, first in the Proceedings of the National Academy of Sciences (PNAS)[5] and then in Nature.[6][7]

In 2007, Hayes was a co-author on a paper that detailed atrazine inducing mammary and prostate cancer in laboratory rodents and highlighted atrazine as a potential cause of reproductive cancers in humans.[8] At a presentation to the U.S. National Institute of Environmental Health Sciences in 2007, Hayes presented results of his studies that showed chemical castration in frogs; individuals of both sexes had developed bisexual reproductive organs.[9]

In 2010, Hayes published research in PNAS[10] describing laboratory work showing how exposure to atrazine turned male tadpoles into females — albeit with impaired fertility.[3]

The US EPA conducted literature reviews of atrazine toxicity in 2007[11] and 2012 and disregarded Hayes' studies because they were deemed too restrictive, or did not meet the standards set by the agency.[3]


A map of pounds per square mile of atrazine application in the U.S. in 1997

Based on his research findings, Hayes has become an advocate for banning atrazine.[12]

According to Hayes, the link between atrazine and altered "aromatase and estrogen production has been demonstrated... in fish, frogs, alligators, birds, turtles, rats and human cells", and, "I believe that the preponderance of the evidence shows atrazine to be a risk to wildlife and humans. I would not want to be exposed to it, nor do I think it should be released into the environment."[12][13] He travels and lectures extensively, and uses the language of rap to convey his message to lay people: “I see a ruse / intentionally constructed to confuse the news / well, I’ve taken it upon myself to defuse the clues / so that you can choose / and to demonstrate the objectivity of the methods I use.”[3] He also has raised issues of environmental racism, "warning that the consequences of atrazine use were disproportionately felt by people of color. 'If you’re black or Hispanic, you’re more likely to live or work in areas where you’re exposed to crap,' he has said."[3]

Research published by Hayes and other scientists was used as evidence in a class action lawsuit against Syngenta by 15 water providers in Illinois that was settled for 105 million dollars in May 2012,[7][14][15] which reimbursed more than 1,000 water systems for the costs of filtering atrazine from drinking water, although the company denies any wrongdoing.[3][16]

Syngenta's responses to Hayes' research

In 2014, New Yorker writer Rachel Aviv reported that Syngenta might have been orchestrating an attack not only on Hayes' scientific credibility, but on other scientists as well whose studies have shown atrazine to have adverse effects on the environment and/or human and animal health.[3]

Aviv reported that Syngenta has criticized Hayes' science and conduct in press releases, letters to the editor, and through a formal ethics complaint filed at University of California-Berkeley.[3] Internal Syngenta documents from 2005 released by a class-action lawsuit in 2014 show ways that Syngenta considered to discredit Hayes, including attempting to get journals to retract his work, and investigating his funding and private life.[3][17][18]

In one of the 2005 e-mails obtained by class-action lawsuit plaintiffs, the company’s communications consultants had written about plans to track Hayes' speaking engagements and prepare audiences with Syngenta's counterpoints to Hayes's message on atrazine. Syngenta subsequently stated that many of the documents unsealed in the lawsuits refer to "ideas that were never implemented."[3]

Popular culture

Hayes' work was featured in the 2008 documentary film Flow: For Love of Water.[19] He appeared in the 2012 documentary film Last Call at the Oasis.[20][21]

Hayes is the subject of The Frog Hunter, a biographical book for children, first published in 2009.[22]

Hayes was a biologist on the Public Broadcasting Service, National Geographic program Strange Days, where he expressed his concerns for human health, particularly that of minority and low-paid workers exposure to agricultural chemicals.[23] He is a National Geographic Society Explorer.[24]

See also


  1. EcoRisk, Inc., for which Hayes worked, has ceased to exist as of 2014[2]


  2. 2.0 2.1 2.2 2.3 2.4 2.5 Slater, Dashka (January–February 2012). "The Frog of War". Mother Jones.
  3. 3.00 3.01 3.02 3.03 3.04 3.05 3.06 3.07 3.08 3.09 3.10 3.11 Aviv, Rachel (February 10, 2014). "A Valuable Reputation: After Tyrone Hayes said that a chemical was harmful, its maker pursued him". The New Yorker. Retrieved February 7, 2014.
  4. 4.0 4.1 "Tyrone Hayes Curriculum Vita". Atrazine Lovers Website. Retrieved August 23, 2013.
  5. Hayes TB, Collins A, Lee M; et al. (April 2002). "Hermaphroditic, demasculinized frogs after exposure to the herbicide atrazine at low ecologically relevant doses". Proc. Natl. Acad. Sci. U.S.A. 99 (8): 5476–80. doi:10.1073/pnas.082121499. PMC 122794. PMID 11960004. Explicit use of et al. in: |author= (help)CS1 maint: multiple names: authors list (link)
  6. Hayes T, Haston K, Tsui M, Hoang A, Haeffele C, Vonk A (October 2002). "Herbicides: feminization of male frogs in the wild". Nature. 419 (6910): 895–6. doi:10.1038/419895a. PMID 12410298.CS1 maint: multiple names: authors list (link)
  7. 7.0 7.1 Dalton R (August 2010). "E-mails spark ethics row". Nature. 466 (7309): 913. doi:10.1038/466913a. PMID 20725013.
  8. Lua error in ...ribunto/includes/engines/LuaCommon/lualib/mwInit.lua at line 17: bad argument #1 to 'old_pairs' (table expected, got nil).
  9. Ball, Eddy (April 2007). "Amphibian Specialist Challenges EPA and Pesticide Manufacturers". Environmental Factor NIEHS News. National Institute of Environmental Health Sciences. Retrieved February 7, 2014. I could take tap water that is regulated by the U.S. EPA," Hayes noted, "and I could chemically castrate frogs.
  10. Hayes TB, Khoury V, Narayan A; et al. (March 2010). "Atrazine induces complete feminization and chemical castration in male African clawed frogs (Xenopus laevis)". Proc. Natl. Acad. Sci. U.S.A. 107 (10): 4612–7. doi:10.1073/pnas.0909519107. PMC 2842049. PMID 20194757. Explicit use of et al. in: |author= (help)CS1 maint: multiple names: authors list (link)
  11. Staff (January 2013), Atrazine Updates: Amphibians Status Update, U.S. Environmental Protection Agency, retrieved August 23, 2013
  12. 12.0 12.1 "Hormone Disruptors Linked To Genital Changes and Sexual Preference", Living on Earth, National Public Radio, January 7, 2011, retrieved February 7, 2014
  13. Randall Amster (March 19, 2010). "Silent Spring Has Sprung". Truthout. Retrieved February 7, 2014.
  14. "City of Greenville v. Syngenta Crop Protection, Inc., and Syngenta AG Case No. 3:10-cv-00188-JPG-PMF". City of Greenville. Retrieved August 23, 2013.
  15. Staff (June 19, 2013). "Tillery planning to file new litigation involving atrazine". Madison County Record. Retrieved August 23, 2013.
  16. Berry, Ian (25 May 2012). "Syngenta Settles Weedkiller Lawsuit". The Wall Street Journal. Retrieved 9 February 2014.
  17. "Court-released documents: Exhibit 19, part1" (PDF). Source Watch. Center for Media and Democracy. Retrieved February 7, 2014.
  18. Howard, Clare (June 17, 2013). "Special Report: Syngenta's campaign to protect atrazine, discredit critics". Environmental Health News. Retrieved August 23, 2013.
  19. Collins, Cyn (July 31, 2008). "Film note: All dried up". Twin Cities Daily Planet. Retrieved August 23, 201. Check date values in: |accessdate= (help)
  20. "Tyrone Hayes". Retrieved 6/24/2014. Check date values in: |accessdate= (help)
  21. Scott, A.O. (May 3, 2012). "When There Really Is Not a Drop to Drink 'Last Call at the Oasis,' a Documentary About Water Supplies". New York Times. Retrieved February 7, 2014. Tyrone Hayes, a biologist, shows us mutant frogs, their endocrine systems scrambled by pesticide-borne chemicals.
  22. Pamela S. Turner (2009). The Frog Scientist. Houghton Mifflin Books for Children. ISBN 978-0-618-71716-3.
  23. "Tyrone Hayes, PhD". Strange Days, Biographies. Public Broadcasting System. 2013. Retrieved August 23, 2013. I am concerned about the adverse impacts of Atrazine on endangered species and on racial/ethnic minorities. Prostate and breast cancer are two of the top causes of death in Americans age 25-40, but in particular Black and Hispanic Americans are several times more likely to die from these diseases. Ethnic minorities and people of low income are also more likely to hold the "unskilled" laborer positions in agriculture and pesticide production that would put them at higher risk of exposure and are least likely to have access to the emerging science demonstrating the dangers of exposure. Thus, this environmental and public health issue is also a racial/social justice issue because minority and working class people are the primary targets of pesticide exposure.
  24. "Tyrone Hayes Biologist/Herpetologist". August 23, 2013. National Geographic.

External links

For additional reading

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