Alifia Merchant: Determining Pesticide Exposure with Antibodies and 96 Tiny Wells

Alifia croppedBy Alifia Merchant

Agriculture and landscape workers apply pesticides as part of their work. Pesticides benefit us by protecting plants from harmful insects, but they can be poisonous if used carelessly.

Workers need to know how to safely use pesticides, such as by wearing gloves and long pants and washing their hands immediately afterwards. In California, many agriculture and landscape workers have a limited understanding of English and may not be able to read the instructions on how to apply pesticides safely. On the other hand, they may not have formal training through their employment, especially if their business is freelance. Even with trained workers, mistakes can be made.

My goal as a graduate student in the Agricultural and Environmental Chemistry Graduate Group at UC Davis is to help better protect agriculture and landscape workers from harmful pesticide exposure. I am working with Drs. Debbie Bennett and Bruce Hammock, Western Center for Agricultural Health and Safety (WCAHS) investigators, to develop quick and easy methods to determine if a worker has been exposed to pesticides.

Alifia blog photo copyI will interview agriculture and landscape workers to gain information about their jobs and possible pesticide exposure. Then, I will collect urine samples on days that they have sprayed or otherwise been exposed to pesticides.

Why am I collecting urine? When chemicals enter the body they can be metabolized, meaning that their chemical structure changes. After metabolism, the chemical can leave the body through urine. Different chemicals remain in the body for varying amounts of time, but the pesticides that I am studying are present in urine within several hours after exposure.

I will determine pesticide exposure using a method called enzyme-linked immunosorbent assay or ELISA for short. Each ELISA test involves a plate with 96 tiny wells with specific antibodies added to the wells. Each antibody detects a specific pesticide.

Urine will be added to the wells. If a well contains urine with pesticiELISAde metabolites, the well turns light yellow or clear. If the urine does not contain pesticide metabolites, the well turns a bright yellow color. Thus, the color of the well allows us to know if a person has been exposed to a pesticide and to what degree.

In the future, we see using the ELISA to quickly know if someone has been unsafely exposed to a pesticide and needs medical help. It could also be used to train workers; if the ELISA shows that a worker was unsafely exposed to pesticides after applying them, the worker would be informed about their results and receive recommendations about how to better protect themselves while doing their job.

For information on how to safely use pesticides at work and home, check out The Pesticide Safety Project website and videos in both English and Spanish, produced by WCAHS in collaboration with the California Poison Control System, and the California Department of Pesticide Regulation.



From Scorpions to Asthma: An interview with Alex Castañeda, WCAHS Seed Grant Award Winner

DSCN0277Alex Castañeda is a 4th year UC Davis graduate student. He was awarded a 2013-2014 WCAHS Seed Grant to help him study air pollution and asthma. Below, he talks about what led him to love science and work to improve agricultural health and safety.

Favorite high school subject: “Biology. My high school biology teacher was passionate about making students learn the material, not just memorize it.”

Family: “My parents are originally from Mexico. They encouraged me to go to college and are proud of me. They both were well educated in Mexico – my dad as an electrical technician and my mom as a nurse. While my mom became a full time homemaker with 3 kids in the U.S., she shared her love of science with me and the importance of helping people.”

Scorpions: “After getting a bachelor’s degree at UC Irvine, I went to CSU Bakersfield for a master’s degree. My project was to understand how scorpions are affected by their environment and human activity. Things like building roads and homes can isolate scorpions from each other and their populations can disappear. Depending on your view, this could be good or bad!”

Air Pollution and Asthma: “While working on the scorpions project, I learned about molecular biology and how the environment can really affect us. I decided to use the same scientific techniques to study lung disease at UC Davis. The WCAHS Seed Grant has helped me study how air pollution, especially the tiny particulate matter in the air, causes asthma.”

“Asthma is a major health problem in many agricultural areas of California, especially near Fresno and Bakersfield. We want to understand why this happening and if there are certain parts of air pollution that are worse than others. To do this, we collaborate with Dr. Keith Bein, an air quality researcher. He uses sophisticated equipment to capture air samples and separate out the different components for testing. Many of the different components are pollutants from regular activities, like driving and home cooking, and some agricultural practices, like pesticide application and plowing.”

“Our goal is to better protect people, especially those working in dusty agricultural environments, by understanding exactly which components pose the greatest risk to health. We have found that mice exposed to certain types of particulate matter are more likely to get asthma when they are exposed to something allergic.”

Advice to young students: “Volunteer. Doing activities through my church (soup kitchen) and high school student council (organizing events) opened my eyes to what I liked best – helping people. It feels great to know that what I am doing in the lab could be used to improve the health of people.”

Future plans: “I will graduate next year and plan to do an academic post-doc in a lab looking at lung disease. Staying in California would be great, but I’m open to other possibilities.”

WCAHS Seed Grants support graduate student education and training, assist in connecting students to agricultural health and safety careers, and are open to student researchers in the WCAHS four-state region: AZ, CA, HI, and NV.

For more information, contact WCAHS Manager, Cindy Valencia,