The Problem with Pesticides: A Toxic Perspective

By Briana Bernstein, Summer Research Intern, Levin Lab

Despite being a Carolina undergrad, I entered “enemy territory” this summer to intern with Dr. Ed Levin’s lab at Duke. My passion for neuroscience pushed me past the fierce sports rivalry and into the world of toxicological research.

I began examining how prenatal exposure to diazinon, an organophosphate pesticide (OP), affects brain development in rodents and may alter behavior later in life. In humans, some areas of concern with this pesticide include lower IQ levels and developmental issues such as attention-deficit hyperactivity disorder (ADHD) and autism spectrum disorder (ASD). I have seen friends and family members suffer from some of these health issues, so if preventing exposure to diazinon and other pesticides limits the risk, it is worth investigating. 

Briana in the lab
Briana analyzing data

Traces of OPs such as diazinon can be found all around us, from carpets to home gardens to agricultural areas. In the real world, we are not exposed to individual contaminants; we are exposed to environmental mixtures of many different compounds like diazinon. But this makes it difficult to determine levels of hazardous exposures in humans. To better understand the health effects of specific contaminants, animal models can be used to control dosage, sensitive windows of exposure, and confounding variables including age and mixture effects of compounds.

My work in the Levin lab focused on a study where pregnant rats were exposed to diazinon, and their pups were then tested for psychological effects at both early and later stages of development. To study potential effects, I observed and collected data for the novel object recognition (NOR) task, which is used to assess attention and memory in a low-motivational setting. This means a rat will choose to explore an object without any external motivation or stimuli from something such as food.

Here’s how the test works. Randomized objects used for this task included ducks, baseballs, sippy cups, and other figures. After a habituation period to the new cages, I placed two of the same random objects in the cage, and let the rats explore for ten minutes. After an hour, the rats were placed back in the new cages with one previously seen object, and one novel object. I then calculated the time spent actively exploring each object to see if the rats recognized that a new object had been placed in the testing arena. A rat with a healthy brain is expected to spend more time investigating the new object. The Levin lab recently found that adolescent rats were less likely to remember a familiar object when exposed to diazinon, so testing them at an older age may provide different results. NOR is just one of the many behavioral tests used to study the effects of diazinon exposure in the Levin lab.

Researching OPs like diazinon has broadened my perspective on how the field of neuroscience can be advanced to understand health risks. This summer internship has also taught me to take a step back and consider how and why environmental exposures matter in development, and I hope reading this may help you reflect on that as well.

Learn more about the Novel Object Recognition Test (video 2:36)