A team of scientists at the University of California in Riverside is hard at work analyzing samples collected from farm workers and strawberries in Santa Maria to better answer two important questions: How much pesticide are workers exposed to during the typical workday, and how is the chemical residue processed by the body?
For three weeks from July to mid-August, 19 workers at DB Specialty Farms—producers of Daren’s Berries—voluntarily took part in an extensive study conducted by the university. With researchers looking on, the workers picked strawberries, and the latex gloves they wore were collected and frozen. Additionally, the workers collected their own urine 24 hours after exposure to test for chemical metabolites. Scientists also obtained samples of the harvested fruit and leaves.
Robert Krieger, UC Riverside’s Department of Entomology specialist and expert toxicologist, headed the study. By measuring and comparing the samples of urine, gloves, and strawberries, Krieger said, scientists will be able to discover improved methods of measuring pesticide in the field.
“We will have a much more complete understanding of the fate of pesticides, both in and on the strawberry plants, as well as a better understanding of how those residues affect harvester exposure,” Krieger said.
Krieger’s study is focused on two common strawberry pesticides; malathion and fenpropathrin, which his team has researched for the past five years. After applying the chemicals, workers are given a three-day interval before returning to harvest the crop. From there, the monitoring begins.
According to Krieger, past research has indicated farm workers absorb minute amounts of pesticide residue—primarily through the plant’s foliage—and quickly excrete the chemicals in their urine. Most importantly, Krieger said the breakdown products formed in the fruit are the same ones formed in the workers, a discovery helping science understand the process.
“This is not an unusual situation to have chemical exposures at low levels and have your body deal with them,” he said. “That’s what we’re finding. The plants deal with it, the workers deal with it, and the evidence that we have is these compounds come out rapidly in the urine at very low levels.”
Once a fruit is packed, shipped, and arrives at a consumer’s home, the levels of pesticide residue are virtually nonexistent, Krieger said.
“The levels of exposure that you get from food are trivial compared to the exposures you get in the workplace, and in the workplace we’ve shown those levels are safe,” he explained. “If the food [pesticide] residue question is propelling you to buy organic, you’re wasting your money.”
Krieger and his team have tested workers at DB Specialty Farms since 1996. Previous studies focused on glove collection, but over time, the analysis has grown to account for a variety of environmental factors.
The most recent study is an extension of fieldwork done last year that also included workers at Santa Maria’s Safari Farms. A new approach this time, Krieger said, is the collection of urine samples from the farmworkers’ spouses or roommates, who share the same living space and diet.
“It’s much more detailed,” Krieger said. “It’s interesting, and it also made it a very difficult study to do, but we had great cooperation from the workers.”
For volunteering, farmworkers were paid $25 for each urine collection—taken over two days on five separate occasions—and were compensated with a $100 bonus for completing all 10 collections.
DB Specialty Farms’ assistant manager Joe Coelho said the expanded study will allow for a more precise look at workers’ exposure levels than ever before, and gives his farm a leg up on those who claim conventionally grown fruit is dangerous to eat or harvest.
“It basically just reinforces that our ag practices—and most people’s ag practices—are extremely safe,” Coelho said. “The people that participate in the study get to share in the results … and they’re happy to know they’re safe from pesticides.”
The California Strawberry Commission co-sponsored the study. The commission’s spokeswoman Carolyn O’Donnell said her group has worked with Krieger on similar studies in the past, but hopes the current research, as it develops, will provide a clearer picture of the effects of pesticide on harvesters.
“Certainly we are concerned about worker safety and their exposure to pesticides or any other things they may encounter in the field,” O’Donnell said. “We want to measure not only their exposure, but ways that are effective in reducing their exposure.”
At this point, O’Donnell said, farm workers aren’t required to wear latex gloves while picking strawberries. Safety precautions are left up to the individual growers, but that might change.
“We haven’t really seen any science one way or another, and maybe this study will help inform us further,” O’Donnell said. “That’s the great thing about science. In time, there are better methods and new ways of analysis that allow us to refine what previous science might have told us.”
Part of the chemical analysis is being performed by PrimusLabs in Santa Maria, which has also provided storage facilities for the samples. UC Riverside’s Personal Chemical Exposure Program co-sponsored the program; the Institutional Review Board of UC Riverside and the California Environmental Protection Agency approved the study.
The researchers’ findings are expected to filter out over the next six months.
“The results of this study are going to be highly significant with respect to harvester exposure,” Krieger explained. “They’re going to justify the time and effort that has gone into the study, on the part of our cooperators, the harvesters, and our study group.”
Contact Staff Writer Jeremy Thomas at jthomas@santamariasun.com.
This article appears in Sep 6-13, 2012.