A 2015 report from American Bird Conservancy finds that more than 90 percent of food samples taken from Congressional cafeterias contain neonicotinoid insecticides, a widely used class of chemicals that is highly toxic to birds and other wildlife.

To learn more, we caught up with Cynthia Palmer, Director of Pesticides Sciences and Regulation for ABC and the report's author.

ABC: How did you decide to do this report?

Cynthia Palmer: Neonicotinoid insecticides are harming the little creatures – birds, bees, beetles – that form the basis for vast food webs and crop production networks. These small but indispensable organisms are largely invisible in our daily lives, particularly in cities like Washington. We wanted to bring their plight to the attention of Congress, because ultimately we all depend on them to control our pests and to pollinate our apples, peaches, berries, nuts, and other crops.

Neonics are lethal to birds, such as this Horned Lark, as well as to the insects on which these birds feed. Photo: David Spates/Shutterstock

ABC: Why did you focus on cafeterias in Congress?

CP: Neonics are both persistent and systemic, meaning they penetrate the entire plant so you can't wash or peel them off. Given their widespread use, we knew we had a good chance of finding them in food. And what better fruits and vegetables to test than those eaten by our members of Congress? After all, these are the people who can restrict use of the chemicals, develop incentives for more targeted pest management approaches, and help transform the agricultural marketplace so that farmers have access to neonicotinoid-free seeds.

ABC: How did you gather the food samples? Did you focus on a particular type of food?

CP: We took field trips to the congressional cafeterias, where we took samples of a cross section of cold and hot foods. Each ABC team member was assigned to fill separate containers with specific items. For example, one colleague might be in charge of honeydew melon, grilled zucchini, and cherry tomatoes.

There were self-conscious moments when we met the gaze of fellow customers who seemed to wonder about our dietary preferences. We followed careful protocols to prepare the samples and to cold-ship them to the laboratory at the Harvard T.H. Chan School of Public Health.

ABC: What kind of analysis or testing did you do on the samples once you had them?

CP: Testing took place at Harvard T.H. Chan School of Public Health under the direction of Dr. Chensheng Lu and Dr. Lin Tao. They analyzed all food samples for seven distinct neonicotinoid insecticides. (You can read details on the testing procedures here.)

ABC staff collected 66 samples of hot and cold food served at Congressional cafeterias. Scientists at the Harvard T.H. Chan School of Public Health later analyzed the samples. Photo: Aditi Desai

ABC: Were there any surprises?

CP: We were surprised by the high numbers of neonicotinoids. We had not expected to find them in 91 percent of the items tested, with as many as five different neonicotinoids in samples of fresh-squeezed orange juice and green bell pepper. We were also surprised to find no trace of the chemicals in the corn samples, since an estimated 95 to 99 percent of the U.S. corn crop is treated with neonicotinoids. We learned about the distinction between field corn and sweet corn: Most of what is grown in this country is genetically engineered field corn, which is used for ethanol, livestock feed, and processed food ingredients like corn syrup. Virtually all field corn seeds are treated with neonicotinoids. The corn we eat, sweet corn, constitutes less than 1 percent of the corn crop. We have very little information on the proportion of sweet corn grown from neonicotinoid-coated seeds.

ABC: Which foods had the highest levels of neonics and why? 

CP: Cherry tomatoes, yellow squash, and honeydew melons stood out as the samples with highest levels of neonicotinoid residues. This is consistent with the USDA Pesticide Data Program findings. There are various possible reasons for the elevated levels. In particular, these crops are attractive to pests, so growers may use extra applications in hopes of warding off the pests. And these types of plants might be better than others at absorbing pesticide into the fruit.

Cherry tomatoes, yellow squash, and honeydew melons had the highest levels of neonicotinoid residues. Photo: Aditi Desai

ABC: You discovered that the levels of all the pesticides detected in the food samples were below the harmful thresholds for humans as identified by the Environmental Protection Agency. Does your report suggest that the system is working, and no one is in danger?

CP: Scientists are studying the effects on human health. There is enough evidence to suggest this research needs more attention.But I think the main threats to human health are indirect. The chemicals are threatening our food security. By harming pollinators such as bees and butterflies, and natural pest-control agents like birds and beneficial insects, neonicotinoids are sabotaging the very organisms on which farmers depend.

What's more, a growing body of research suggests agricultural lands that are biologically depleted from widespread use of neonicotinoids actually become more vulnerable to pest pressures, requiring large amounts of acutely toxic pesticides later in the growing cycle. So it's not as if we've replaced the “bad old pesticides” with the neonicotinoids – we are using both.

ABC: What do you want people to understand about neonics?

CP: These insecticides have transformed the way pest control is done in this country. Instead of the carefully targeted prevention, surveillance, and treatment that are the hallmark of Integrated Pest Management, we are indiscriminately covering our agricultural fields in chemicals. In doing so, we contaminate our watersheds and poison the birds, bees, butterflies, and other organisms that farmers rely on for pollination and pest control.

ABC: What can people do to help?

CP: Take action to tell Congress and EPA that we need to take neonics seriously. Use ABC's easy system to send a letter to your legislators. And, of course, another easy way to help is to avoid using neonicotinoids in your own home and garden!