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"Silent Spring" Reality Check: Agricultural Insecticides Imperil Waterways Throughout the World in Spite of Regulation, New Study Shows

By Martha L. Crouch, Ph.D.

May 14, 2015
Center for Food Safety

At about the same time that the Beatles released their first LP, Americans were starting to question the safety of increasingly used pesticides, largely as a result of Rachel Carson’s groundbreaking book “Silent Spring.”[1] Back then I was much more interested in “Twist and Shout” than DDT. Who cared about real beetles?

But now, more than 50 years later, as a biologist I am alarmed at the continued, intensifying use of pesticides worldwide.[2] Although Carson’s warnings fostered the political will to create pesticide regulations in the US and elsewhere, tragically the resulting safeguards aren’t really protecting our environment.

This point was convincingly driven home by a new study published in the Proceedings of the National Academy of Sciences.[3] The authors, Drs. Stehle and Schulz of the Institute for Environmental Science of the University of Koblenz-Landau in Germany, analyzed more than 800 studies of 28 different agriculturally-applied insecticides in samples gathered from lakes, rivers, and streams around the world between 1962 – the year of “Silent Spring” – and 2012. They wanted to know how often these potent insecticides were found in surface waters and sediments at levels above thresholds set by regulatory agencies such as the US Environmental Protection Agency (EPA).

The answer is dismaying. Worldwide, roughly half of samples where insecticides were detected had levels that exceeded limits set to keep organisms in those waters safe. Even in the United States and European Union, where pesticide regulations have been in place for years, 54.2% of the insecticide-contaminated samples taken in the last 15 years exceeded levels known to decrease biodiversity. Fish, mussels, crabs, frogs, birds, dragonflies, and yes, beetles, are just a few types of animals at risk in such insecticide-impaired aquatic ecosystems.[4]

Are the culprits just older insecticides, developed before regulatory agencies supposedly got tough? According to this study, no.

In real-world monitoring, the most widely used newer insecticides - for example, synthetic pyrethroids that were developed to replace insecticides such as DDT – are even more likely to exceed regulatory thresholds for water, and are very poisonous to aquatic organisms. Although synthetic pyrethroids are less acutely toxic to people and many other animals than the insecticides they've in part displaced, this benefit of the swap may be illusory as serious chronic toxicity becomes apparent.[5] For example, just this year a study has linked pyrethroid exposure to a devastating neurological disorder, Parkinson’s disease, for the first time.[6]

Research also shows alarming harm to insects, birds, and other animals as another heavily used[7] new class of insecticides, neonicotinoids, move from farm fields into surrounding areas, including water bodies.[8] Again, lower acute toxicity to people may be a devil’s bargain as the whole food chain is affected. Aquatic invertebrates are impacted on a very wide scale[9], and new studies from the Netherlands have documented that bird populations that depend on those invertebrates are declining at alarming annual rates.[10] Similar bird declines in Europe, Canada and the United States point to the same smoking insecticide gun as a major factor. [11] On land, pollinators, such as honeybees and wild bees that are required for so many of our fruits and vegetables are particularly vulnerable to neonicotinoids that get into pollen and nectar.[12] Beneficial predator insects are being poisoned as they consume neonictotinoid-contaminated prey lower in the food chain.[13] Just one irresistible seed coated with neonicotinoids can disrupt a songbird’s reproduction, or even cause death.11

So, while we might have expected more protection of the environment after “Silent Spring,” and indeed there have been some notable improvements as a result[14], some of these newer insecticides are shaping up to be as bad as the older ones they are meant to replace. 

On balance then, according to this comprehensive study, throughout the world and over the years risk assessment procedures for insecticides have failed to protect aquatic environments in far too many cases. Why this failure has occurred no doubt involves a variety of factors[15], from meddling in regulation by pesticide makers and users[16] to the regulatory challenges of designing rules that work in the real world and then enforcing them. These same factors affect herbicides, fungicides, and all the other biocides too. I would therefore not be surprised to learn of similar regulatory failures wherever pesticides are used.

We can’t wait another 50 years for pesticide regulation to live up to its promise of protecting nature. There are gaping holes in the U.S. regulatory process that must be fixed as a first step. But even fixing them will not suffice. We need to slow, and eventually stop the pesticide treadmill – where new pesticides replace or supplement old ones when the latter become less effective due to evolution of pest resistance, even as the overall extent and intensity of pesticide use continues to climb.

If the latest “crop protection” innovations from agrichemical giants Monsanto and Dow AgroSciences are any indication, our besieged ecosystems are in for more pesticide treadmill action, not less.

Since their introduction in 1996, Monsanto’s genetically engineered (GE) herbicide-resistant crops have led to hugely increased use of the weed killer glyphosate[17], the active ingredient in Roundup®. As a result weeds have developed resistance to glyphosate right and left.[18] In response, Monsanto and Dow are poised to introduce new lines of GE crops resistant not only to glyphosate, but also to the older herbicides dicamba[19] and 2,4-D[20], respectively.

It doesn’t take a genius to foresee that dicamba and 2,4-D use will skyrocket, leading to more resistant weeds.[21]  And it’s already clear that agrichemical companies will genetically engineer crops for resistance to yet more herbicides – the transgenic treadmill – that will accelerate the treadmill of pesticide use. The expected big increases in the use of these herbicides over a large swath of the US will surely cause even more harm to the already stressed animals and plants in our pesticide-laden environment.[22] [23]

Where is the Environmental Protection Agency, charged with safeguarding the birds and the bees, and all living things (including us!) from rampant pesticide contamination? So far, EPA has been facilitating this pesticide-GE crop treadmill[24] when it should be working to stop the madness. Alternatives exist – sophisticated, sustainable, non-chemical ways to manage pests.[25]  Our regulatory agencies should lead a concerted effort to promote such ecological farming techniques, which will not only benefit the environment, but also improve the health and economic welfare of America’s farmers.


[1] Griswold, E. (2012). How ‘Silent Spring’ Ignited the Environmental Movement. New York Times, September 21, 2012.

[2] Epstein, L. (2014). Fifty years since silent spring. Annual Review of Phytopathology, 52, 377-402.

[3] Stehle, S. and R. Schulz (2015). Agricultural insecticides threaten surface waters at the global scale. PNAS; published ahead of print April 13, 2015, doi:10.1073/pnas.1500232112. Available at:

[4]Isenring, R. (2010). Pesticides and the loss of biodiversity. Pesticide Action Network Europe.

[5] Jabr, F. (2010). Derived from flowers, but not benign: Pyrethroids raise new concerns. Environmental Health News, February 26, 2010.

[6] Woodruff Health Sciences Center (2015). Immune gene variant magnifies Parkinson's risk from insecticide exposure, April 27, 2015.

[7] Douglas, M., & Tooker, J. F. (2015). Large-scale deployment of seed treatments has driven rapid increase in use of neonicotinoid insecticides and preemptive pest management in US field crops. Environmental Science & Technology.

[8] Worldwide Integrated Assessment of The Impacts of Systemic Pesticides on Biodiversity and Ecosystems (2015).

[9] Morrissey, C. A., Mineau, P., Devries, J. H., Sanchez-Bayo, F., Liess, M., Cavallaro, M. C., & Liber, K. (2015). Neonicotinoid contamination of global surface waters and associated risk to aquatic invertebrates: A review. Environment International, 74, 291-303.

[10] Hallmann, C. A., Foppen, R. P., van Turnhout, C. A., de Kroon, H., & Jongejans, E. (2014). Declines in insectivorous birds are associated with high neonicotinoid concentrations. Nature doi:10.1038/nature13531.

[11] Mineau P, and C. Palmer (2013). The Impact of the Nation’s Most Widely Used Insecticides on Birds. American Bird Conservancy.

[12] Krupke, C.H., G.J. Hunt, B.D. Eitzer, G. Andino, and K. Given (2012). Multiple Routes of Pesticide Exposure for Honey Bees Living Near Agricultural Fields. PLoS ONE 7: e29268. doi: 10.1371/journal.pone.0029268.

[13] Douglas, M. R., Rohr, J. R., & Tooker, J. F. (2015). Neonicotinoid insecticide travels through a soil food chain, disrupting biological control of non"target pests and decreasing soya bean yield. Journal of Applied Ecology, 52(1), 250-260., Press release:

[14] Epstein, L. (2014). Fifty years since silent spring. Annual Review of Phytopathology, 52, 377-402.

[15] Marcoux, C., & Urpelainen, J. (2011). Special interests, regulatory quality, and the pesticides overload. Review of Policy Research, 28(6), 585-612.;jsessionid=4ABD05733AA30FD4A5D5CD01721495E0.f02t01?deniedAccessCustomisedMessage=&userIsAuthenticated=false

[16] McDaniel, P. A., Solomon, G., & Malone, R. E. (2005). The tobacco industry and pesticide regulations: case studies from tobacco industry archives. Environmental health perspectives, 1659-1665.

[17] Benbrook, C. M. (2012). Impacts of genetically engineered crops on pesticide use in the US – the first sixteen years. Environmental Sciences Europe, 24(1), 1-13.

[18] Gurian-Sherman, D. and M. Mellon (2013). Union of Concerned Scientists, Policy Brief, 2013: The Rise of Superweeds - and What to Do About It.

[19] Summary of Center for Food Safety’s Science Comments to EPA on Monsanto’s Request to Register Dicamba Herbicide for Use on Monsanto’s Dicamba-Resistant MON 87708 Soybean, Submitted September 21, 2012.

[20] Freese, B., and M.L. Crouch (2012). Comments by Center for Food Safety to USDA APHIS on draft environmental assessment and draft plant risk assessment for Dow Agrosciences petition (09-349-01p) for determination of nonregulated status of event DAS-68416-4; 2,4-D-and glufosinate-resistant soybean.

[21] Mortensen, D. A., Egan, J. F., Maxwell, B. D., Ryan, M. R., & Smith, R. G. (2012). Navigating a critical juncture for sustainable weed management. BioScience, 62(1), 75-84.

[22] Center for Food Safety (2014). Coalition of Farmers and Environmental Groups to Challenge EPA Over Herbicide Approval, October 22nd, 2014.

[23] Freese, B. and M.L. Crouch (2015). Monarchs in Peril: Herbicide-Resistant Crops and the Decline of Monarch Butterflies in North America, Center for Food Safety Report.

[24] EPA (2015) Registration of Enlist Duo.

[25] Tomich, T. P., Brodt, S., Ferris, H., Galt, R., Horwath, W. R., Kebreab, E., ... & Yang, L. (2011). Agroecology: a review from a global-change perspective. Annual Review of Environment and Resources, 36, 193-222.

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