By Moe Clark
Photos by Tim Mossholder on Unsplash

When Nayamin Martinez emigrated from Mexico to California in 2001, agricultural practices were the last thing on her mind.

But when she found herself smack in the middle of the Central Valley – an agricultural oasis that produces 25% of the nation’s food – she couldn’t unsee the ways conventional agricultural practices were taking a toll on farmworkers’ health.

Now the executive director of the Central California Environmental Justice Network in Fresno, California, Martinez has teamed up with researchers at Colorado State University to calculate the hidden costs of agricultural abundance.

Scientists in the College of Veterinary Medicine and Biomedical Sciences are studying how exposures to pollutants are impacting farmworkers’ health and well-being in the Central Valley of California, the High Plains of Colorado, and the agricultural communities of Florida and Kansas. The goal? To improve conditions for farmworkers who face a disproportionate share of the health burdens that come with safeguarding the food supply of the United States.

“We have people, especially people who tend to be lower income and mostly Spanish-speaking immigrants, being disproportionately exposed to environmental chemicals and pollutants that most of us are protected from through workplace laws,” said Sheryl Magzamen, an associate professor of environmental health in the Department of Environmental and Radiological Health Sciences.

“There’s a lot of economic and environmental complexities that come with these agricultural workers and we, as researchers, can’t solve all of these,” she added. “But what we are trying to do is collect data to help organizations like CCEJN tell stories about what’s going on with the health and well-being in these communities.”

Agriculture’s “ground zero”

When Magzamen started planning a research study looking into how mixtures of pollutants impact farmworkers and surrounding agricultural communities in late 2018, the location was, unfortunately, a no-brainer.

The list of environmental concerns for farmworkers in California’s Central Valley is long: high levels of air pollution due to vehicle emissions, industrial practices, and wildfires; lack of drinking water due to groundwater pumping, drought, and pesticide contamination; and increasingly unsafe farm working conditions due to climate change and, more recently, COVID-19.

“What makes this situation really untenable for workers is these developments in climate change, but also the structure of their jobs from an economic framework,” Magzamen said. “Many of these workers are paid by piece, not by wage. And if they don’t work, then they don’t get paid.”

“So that means working during COVID. It means working during extreme heat days. It means working during wildfire season,” she added. “From a food systems perspective, I think that we have been ignoring this critical cog in our supply chain for produce.”


“Many of these workers are paid by piece, not by wage. And if they don’t work, then they don’t get paid. So, that means working during COVID. It means working during extreme heat days. It means working during wildfire season. From a food systems perspective, I think that we have been ignoring this critical cog in our supply chain for food.”


To study the impact of mixtures of pollutants on human health, Magzamen teamed up with Martinez’s environmental justice organization to find research participants who live within 200 feet – the equivalent of a 20-story building – of where pesticides are applied.

“Primarily, migrant workers and their families are living in these communities,” said Grace Kuiper, an epidemiologist and research associate with CSU who is working on the project. “And they’re smack in the center of a field. It’s kind of amazing to see because you’re just driving, and there’s fields, fields, fields, fields, and then, all of a sudden, this little community sprouts out.”

The team was specifically interested in Fresno for a couple reasons. First, it’s the No. 1 county in the U.S. for agricultural products sold – meaning it’s ground zero for pesticide use. It also has notoriously bad air quality.

“Because of the geography, a lot of pollutants get trapped,” Kuiper explained. “The area also has several main interstates that transect the valley. And all of that diesel, all of those icky pollutants from trucks and things like that, get trapped in the valley.”

Pesticides and pláticas

The research days were long, but rewarding. Each home visit took around an hour, with dozens of households on their docket each day. “It wasn’t uncommon for us to stop at In & Out Burger at 8 or 9 p.m. We’d be so excited for food,” said Kuiper, with a chuckle.

California and Washington are the only states with a pesticide use registry, which allows the researchers to track where – and when – specific pesticides are applied. But they want to better understand how that translates in terms of personal pesticide exposure, which can occur by ingesting the chemicals, absorbing them through the skin, or inhaling them.

The team visited nearly 40 homes in January 2019 to conduct household surveys, collect urine samples, and suck up household dust using fancy research vacuums. The goal is to follow each participant over time to better correlate pesticide exposure and pollution levels with health outcomes.

“We know that pesticides are harmful to health,” said Kuiper, who earned a master’s degree in public health from CSU in 2019. “They’re associated with things like cancer and impaired neurodevelopment in children, and also neurological diseases later in life such as Alzheimer’s disease and Parkinson’s disease. There is also evidence, of course, associated with respiratory health outcomes.”

At the height of the pandemic in 2020, the research team tried to continue their community outreach remotely by mailing participants sample instructions and talking to them on the phone. But it wasn’t the same.

The relationships that Martinez’s team had already established with community members became more important than ever.


“We are so resilient. And that’s just because we don’t have any other choice. But I think that with the pandemic, even our resiliency was challenged.”


“Our role is to be the boots on the ground, communicating with the participants, answering any questions that they have, and just building that trust,” Martinez said.

CCEJN began hosting Zoom meetings as part of their outreach efforts, but they quickly learned that many of the areas they were trying to reach were without internet. Instead, they started hosting over-the-phone pláticas – or lectures in English – to educate community members about COVID-19 and their pesticide and air quality outreach efforts. But still, their reach was limited.

“When you come from communities that have to endure so many things…. They’re so resilient. We are so resilient,” Martinez said. “And that’s just because we don’t have any other choice. But I think that with the pandemic, even our resiliency was challenged.”

The silver lining for Martinez was that the pandemic put a spotlight on the sacrifices made by agricultural workers in order to keep not only food on their own dinner tables, but also the rest of the country’s.

Kuiper agrees. “A lot of the things that are grown in that area are almonds, citrus, grapes, pistachios,” she said. “Fresno and Tulare counties are No. 1 and No. 2 in the country for agricultural products sold. There’s a pretty good chance if you go to your grocery store, there’s produce there from these communities.”


Bodies of evidence

Over the years, Martinez’s organization has helped push forward legislation surrounding clean drinking water and pesticide use, including helping pass a law in California that made the state the first in the country to legislatively recognize the human right to water. They were also involved in successfully pushing California’s Department of Pesticide Regulation to ban the pesticide chlorpyrifos in 2019.

Though there have been plenty of successes, change has been slow.

“There have been many moments in which I’m ready to give up and say, ‘I’m gonna go and work 8 to 5 and go home and sit down in front of the TV and forget about the world,’” Martinez said. “But that’s not me.”

“If we just gave up every time that a bill didn’t pass, we wouldn’t get anywhere,” she added.

Lately, she’s shifted her focus away from trying to ban individual pesticides. “It’s a losing battle,” she said. “There’s just too many of them.”

Instead, she’s exploring mitigation options. For example, the possibility of planting trees on the edge of agricultural fields to try to block the surrounding community from getting sprayed by pesticides.

Ultimately, Martinez would like to see California cut ties with pesticides all together.

“That obviously is not going to happen suddenly, but it has to happen,” Martinez said. “For climate change and for public health.”

The data provided by Magzamen’s team is critical to their fight, according to Martinez.

“It gives ammunition to community members to build their case,” she said. “It adds to the body of evidence.”

Moe Clark is a multimedia journalist based in Colorado. She reports on environmental and social justice issues.

Cows as canaries

Researchers at CSU are taking a novel approach to studying air pollution and respiratory health in humans by turning their focus toward a familiar mammal: the dairy cow.

Because dairy cows produce milk three times a day, every day of the year, it was easy for the researchers to measure changes in the milk depending on chemical exposures, pollution levels, and temperature change.

“Agricultural areas do not have strong on-ground monitoring the same as urban areas do,” said Sheryl Magzamen, an associate professor of environmental health in the Department of Environmental and Radiological Health Sciences. “And so we thought, ‘Can we use cows to assess what happens due to changes in pollution?’”

The researchers selected three dairy farms along Colorado’s Eastern Plains, making sure they were close enough to Environmental Protection Agency air quality monitors so they could look specifically at changes in two air pollutants: ground-level ozone, commonly called smog, and PM 2.5, fine particulate matter formed by incomplete combustion that penetrates deep in the lungs.

“The EPA monitors are designed to collect traffic and point source-related combustion, but not combustion from other sources, like wildfire smoke,” Magzamen said. “So, I think we have a problem because we can’t tell if an environmental exposure is harmful if we don’t measure it.”

The team found that when PM 2.5 is high, the cows produce less milk and they have more inflammatory markers in their milk, according to Magzamen. But, according to their research, the impact on milk production is dependent on where the PM 2.5 comes from. To understand how agricultural sources of PM 2.5 impacted the cows’ health, the researchers removed data from days that had high PM 2.5 that was likely due to wildfire smoke.

When they did that, they saw the negative health impacts for the cows increase. Meaning, breathing PM 2.5 from wildfires is likely not good, but breathing in pollutants from other agricultural sources might be even worse.

“So, there’s something about PM 2.5 on the Front Range,” Magzamen added. “And if it’s bad for cows, it can’t be good for people.”

While using human subjects would be ideal, the data is helping researchers better understand the physiological response that happens when a mammal is exposed to mixtures of pollution for extended periods of time.

“There’s so much more of this story to tell,” Magzamen said. “My biggest question is, how do we actually inch closer to telling stories about what’s happening in places that we don’t monitor or places that don’t have good tools to monitor? That’s what I’m interested in.”

Breathing bioaerosols

Joshua Schaeffer and Stephen Reynolds, researchers at CSU’s High Plains Intermountain Center for Agricultural Health and Safety, recently launched a study of Colorado’s dairy cattle workers. They are investigating workers’ exposures to bioaerosols – fine particles found in the air that can contain things such as bacteria, fungi, pollen, toxins, and viruses – and how those compounds impact lung function.

Schaeffer first started researching bioaerosols 10 years ago, after visiting a few farms and getting a wake-up call. “My allergies just went wild. Having that reaction made me wonder if other workers might be experiencing that,” he said. “I remember thinking, ‘Wow, I’m allergic to my research.’”
Schaeffer and Reynolds observed a noticeable decline in lung function after a single eight-hour workday. To help disrupt that, they are studying the use of a hypertonic saline solution (which has anti-inflammatory properties) to flush workers’ nasal passages before and after their shifts.

While evaluating nasal swabs from dairy workers, the research team stumbled upon a pathogen that raised some alarms. They found the presence of influenza D, a virus known to infect pigs and cattle, but not humans.

“It’s something we are definitely keeping a close eye on moving forward,” Schaeffer said. “There’s no need to panic yet, but given the state of things, it’s better to stay on top of it.”

Ultimately, they want to better understand what dairy workers are breathing in during their workdays and how it impacts lung function. Instead of isolating single pathogens or other organisms, they are trying to take a more holistic approach.

“We’re trying to get a better understanding of what bacterial and viral communities are present and how they may contribute to specific respiratory health outcomes,” Schaeffer said. “We know that specific microbial markers don’t fully explain the respiratory issues that we’re observing.”

Schaeffer’s research has also taken him to Guatemala where he’s looking at inhalation exposures among sugarcane workers. “We are trying to see what they’ve been exposed to as a potential link to a chronic kidney disease epidemic in the area,” he said.

Smoked out

When Sheryl Magzamen was an assistant professor at the University of Oklahoma, she was approached by a handful of organizations that were concerned about the health impacts of yearly agricultural burns.

“Folks from impacted communities in Kansas called me and said, ‘Look, there’s no guidance, and the prairies burn every year. There’s just no air quality monitoring, and we know there is smoke in our communities.’”

Magzamen wanted to help provide answers. “That’s really our job,” she said. “To conduct research and promote science for the public good.”

To do so, she joined forces with a group of atmospheric scientists at CSU to monitor air quality around agricultural burns in Florida and Kansas, using ground-based sensors and satellite data. The research is supported by a $218,000 grant from NASA.

Though both places burn agricultural land every year, the reasoning for each is different. In Kansas, the controlled burns are to minimize woody growth in the fields – a common farming practice that’s been utilized for thousands of years, according to Magzamen.

“There’s data to indicate that when the cattle graze on fresh grass, especially grass grown after a burn, that they are able to gain weight more efficiently,” she explained.

The story is different in Florida, where sugarcane farmers burn the fields to rid them of crop residue – the plant material left behind once the sugarcane is harvested. When there is fire, there is smoke. And when there is smoke, there is PM 2.5, which is harmful to the lungs and multiple organ systems, explained Magzamen.

“There hasn’t been a lot of conversation, especially from a health perspective to say, ‘All right, if these activities are beneficial for production for animals, if they’re beneficial for the land, are they beneficial for humans?’”

When the team initially submitted their grant proposal, Magzamen was unaware of how controversial the topic was.

“In Florida, there’s a very strong sugarcane lobby behind the practice that supports what they do,” Magzamen said. “And it’s a very contentious topic, even among the people that live in impacted communities as they’re largely dependent on the sugar industry for employment.”