Northern Leopard Frog (Lithobates pipiens) suffering from deformities. © US Fish and Wildlife Service

The twentieth century was an era full of scientific and engineering accomplishments, revealing unprecedented pathways of growth in many facets of life. Advancements in medicine, engineering, and science pushed boundaries and brought us to the forefront of our time. Despite these advancements, however, the emergence of a chemical era in which the effects of powerful synthetic chemicals on humans and the environment were not properly understood before their distribution—the most famous of which include DDT and the ozone-destroying CFCs—have challenged not only our perceptions on the safety of chemical exposure for both human and environmental health, but also how we must approach the conservation and valuation of sensitive species.

Arguably the most directly present and harmful chemical to both environmental and human health in the United States today is the herbicide atrazine, produced by the global agrochemical powerhouse, Syngenta1. The second best selling herbicide and the top polluter of surface and ground water in the world, atrazine is an endocrine disruptor that poses an immediate and severe threat to aquatic populations near agricultural centers and has potential deleterious effects on human health1,2. Amphibians are particularly vulnerable to pollutants such as atrazine due to their readily permeable skin and direct exposure to contaminated waters, which has put them at the forefront of atrazine research2,3. Atrazine continues to be used heavily in the US—almost 80 million pounds annually—despite health risks, contamination of drinking water, and damaging effects on the surrounding wildlife1,5. The European Union (EU), recognizing the potential for harm in humans and the tendency of atrazine to heavily and readily contaminate water supplies, banned atrazine in 20034. In the interest of preserving valuable amphibian wildlife, natural ecosystems, and human health, the US should follow the lead of the EU in order to ensure the continued existence of important amphibian species, cleaner water, and an exit out of the current gamble on human health.

A cloud of controversy has surrounded atrazine since the early 2000s when ecologists began to realize the detrimental effects of atrazine on frogs living in areas affected by agricultural runoff. As an endocrine disruptor, reproductive failures due to atrazine’s ability to interact negatively with hormonal production and developmental anomalies that arise because of immunodeficiency syndromes have been confirmed in recent scientific literature in amphibians, and evidence is accumulating showing similar effects in mammals1,11. Syngenta, however, the main producer of Atrazine, is playing a strong game of doubt generation in the US, one that is even affecting the ability of the US Environmental Protection Agency (EPA) to find reason to ban atrazine in the US4,5. A company that can be likened to the infamous Monsanto, Syngenta has continually refuted all claims that atrazine is harmful to wildlife or to humans5.

It is difficult, amongst this evidence, to see why atrazine is still prevalent in the US, but atrazine is, arguably, economically advantageous in that it is a cheap herbicide that is a generalist and can treat many kinds of weeds10. The simple fact that it is a generalist raises flags to its deleterious nature, however: as a generalist weed killer, it is also a generalist in that it can attack the systems of many different organisms, including humans1. Additionally, some scientific literature acknowledges some degree of uncertainty in the concrete effects of atrazine on humans as a carcinogen6.

The atrazine debate sphere is particularly concerned with the effects of atrazine on amphibians, for good reason. The amphibian connection is not just about the loss of amphibian diversity and their livable habitat, but also about consequences humans will face as a result of perpetuating this harmful chemical. The destruction of already at-risk amphibian populations through chemical contamination is an unwanted and dangerous product of our constant desire for more things, faster. Humans should consider themselves responsible for the restoration of wildlife and their surrounding environment to benefit both their health and the wildlife, particularly of areas whose destruction can be pinpointed to specific human choices, such as atrazine use. We must look at amphibians as the indicator species that they are, as premonitions for dangers ahead for those much less vulnerable than themselves, such as our own health and safety. Atrazine in amphibians converts testosterone to estrogen, and changes gene expression to make tadpoles more susceptible to deformity-causing parasites1,7. The discovery of this led to clear questions about how applicable this kind of damage is to human health, resulting in detailed studies in mammals that suggest atrazine could have carcinogenic and hormonal effects8,9.

The conservation of amphibians via routes that support the banning of atrazine in the US will greatly improve chances of amphibian survival in the United States, and will reduce the atrazine contamination in drinking water supplies. This “bottom up” conservation approach is important for human health and safety: conserving indicator species first allows less vulnerable organisms such as ourselves to never see the disastrous effects. Choosing prevention over remediation will save lives, wildlife species, and money. The benefits of discontinuing the use of atrazine in the US far outweigh the costs benefits and the lack of concrete knowledge on how it specifically harms humans. The logical route in proceeding from where we are today comes in recognizing that this chemical has dangerous health implications for humans, pollutes water supplies, and destroys valuable populations of amphibians and other wildlife. With our infamous history of pollutants in the US, taking another risk on our own health by continuing to use atrazine is irresponsible and not worth the possibility of a loss of natural systems and detriments in human health.

This opinion piece is the result of a class on Pollution, Environment, and Health at UC San Diego/Scripps Institute of Oceanography taught by Dr. Amro Hamdoun.

References:

  1. Gilbert, Scott F., and David Epel. Ecological Developmental Biology: Integrating Epigenetics, Medicine, and Evolution. Sunderland, MA: Sinauer Associates, 2009.
  2. Ji, Yuefei, et.al. “Heat-activated Persulfate Oxidation of Atrazine: Implications for Remediation of Groundwater Contaminated by Herbicides.” Chemical Engineering Journal 263 (2014): 45-54.
  3. Hayes, T. B. “Hermaphroditic, Demasculinized Frogs after Exposure to the Herbicide Atrazine at Low Ecologically Relevant Doses.” Proceedings of the National Academy of Sciences 8 (2002): 5476-480.
  4. Bethsass, Jennifer, and Aaron Colangelo. “European Union Bans Atrazine, While the United States Negotiates Continued Use.” International Journal of Occupational and Environmental Health 3 (2006): 260-67.
  5. “Atrazine Updates.” EPA. Environmental Protection Agency, Jan. 2013. <http://www.epa.gov/pesticides/reregistration/atrazine/atrazine_update.htm#post-red>.
  6. Gammon, Derek W., Charles N. Aldous, Wesley C. Carr, James R. Sanborn, and Keith F. Pfeifer. “A Risk Assessment of Atrazine Use in California: Human Health and Ecological Aspects.” Pest Management Science 4 (2005): 331-55.
  7. Koprivnikar, Janet, Mark R. Forbes, and Robert L. Baker. “Contaminant Effects On Host–Parasite Interactions: Atrazine, Frogs, And Trematodes.” Environmental Toxicology and Chemistry 10 (2007): 2166.
  8. Fan, WiQiang. “Atrazine-lnduced Aromatase Expression Is SF-1 Dependent: Implications for Endocrine Disruption in Wildlife and Reproductive Cancers in Humans.” The National Institute of Environmental Health Sciences (2007).
  9. “Economic Analysis of Atrazine.” Synapse Energy. <http://www.synapse-energy.com/project/economic-analysis-atrazine>.
  10. Forson, Diane, and Andrew Storfer. “Atrazine Increases Ranavirus Susceptibility in the Tiger Salamander, Ambystoma tigrinum.” Ecological Applications 6 (2006): 2325-332. Web.
  11. Tyrone B. Hayes, Vicky Khoury, Anne Narayan, Mariam Nazir, Andrew Park, Travis Brown, Lillian Adame, Elton Chan, Daniel Buchholz, Theresa Stueve, and Sherrie Gallipeau. Atrazine induces complete feminization and chemical castration in male African clawed frogs (Xenopus laevis). PNAS, March 1, 2010.

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944278_10200288777836246_1409213356_nMary Jade Farruggia, a lifelong amphibian lover, is on the path to a career in herpetology research and conservation. She is a senior undergraduate student in Ecology, Behavior, and Evolution at the University of California, San Diego with a minor in music. After studying abroad in Costa Rica as a sophomore, where she studied Cane Toad behavior, tropical biology, and jungle exploring, she left her heart in the rainforest and solidified her passion for amphibians. From sharing her love for outdoor ecology as a science program leader for the Girl Scouts, to exploring decades of collections as a herpetology intern at the San Diego Natural History Museum, Mary Jade seeks to share her excitement for amphibian conservation through many avenues, including the ASA!