Photo of farmworker and Marc Schenker UC Davis epidemiologist Marc Schenker was one of the first public health professionals to focus on the occupational health of California's farmworkers.

UC Davis epidemiologists help policymakers by identifying, tracking farmworkers' health risks

When professor and epidemiologist Marc Schenker joined UC Davis in the 1980s, it didn't take him long to realize that hardly anyone was studying the occupational health of California's agricultural workers. It was a huge group — about a million farmworkers — in a huge industry. California was, and still is, the most productive agricultural region in the country.

Agriculture was also a highly hazardous industry. Year in and year out, agriculture typically lagged behind only the mining industry in terms of mortality and injury rates. Exposure to machinery, large farm animals and the need to work from heights, such as when picking fruit, combined to make farm work a risky business. "It was too obvious," says Schenker.

40 percent of the workers reported persistent pain in one or more body parts, including the back, neck and shoulders.
— The California Agricultural Workers Health Survey

"It was right there in front of everybody and yet it was an area very few people were working in."

Part of the reason was the existence of significant language and cultural barriers. About 90 percent of the workers were Hispanic, and many of them spoke only Spanish. They tended to be poorly paid, and as Schenker says, "poverty hardly favors giving up time from work to answer surveys."

Distrust of authorities was also widespread, as was the fear of losing jobs if workers cooperated with researchers. Moreover, the workforce was transitory, with laborers often working on a farm for a couple of weeks before moving on. The sheer number of farms — approximately 75,000 — was also a problem.

Shoe-leather investment

"A lot of people said, 'well, you can't do traditional epidemiology,'" Schenker recalls. "It required much more of a shoe-leather investment to study."

A turning point came in 1990 when a meeting convened at UC Davis to consider the issue of agricultural safety in California. The gathering, which included farmworkers and medical practitioners, led to the establishment, through a cooperative agreement with the National Institute for Occupational Safety and Health, of the UC Agricultural Health and Safety Center at Davis.

The research organization has a slightly different name today — the Western Center for Agricultural Health and Safety. However, its primary mission remains the same: to improve the health and safety of farmers, family members and farmworkers, not only in California, but also in Arizona, Nevada and Hawaii. It is one of nine such centers the Centers for Disease Control established in the U.S.

Research magnet

According to Stephen McCurdy, a UC Davis professor who works along side Schenker in the Department of Public Health Sciences and an authority on agricultural injury, the center has been a "magnet" for researchers. That's borne out by the center's Web site, which boasts "a team of 17 scientists from a variety of disciplines plus 22 affiliated scientists and numerous support staff" engaged mostly in "field-oriented research and interventions."

Don Villarejo, founder of the California Institute for Rural Studies, has participated in various center projects on a National Academy of Sciences committee reviewing the occupational safety and health institute's programs in agriculture, forestry and fisheries. He estimated that more than 100 scientific papers have been published as a result of investigations sponsored by the UC Davis center.

Clearly, the days when no one was paying attention to the workplace hazards faced by California farmworkers are long gone.

Real-world impact

Photo of McCurdy and farmworker family Professor Stephen McCurdy, an expert in agricultural injury,often meets with farmworker families, like Xehidia Moleas, Enedina Felix-Garcia and Jose Garcia and their son, to better understand and document the workplace hazards they face.

Schenker, director of the center, says that studies sponsored by the center have had real-world impacts. One, which found that the use of smaller buckets during the grape harvest substantially reduced back and musculoskeletal injuries, led to the adoption of the buckets as the industry standard. Another led to the standardization of a laboratory test monitoring pesticide exposure in farmworkers.

Schenker and McCurdy teamed up in the 1990s to look at the risk of respiratory disease among farmworkers.

The impetus was a seeming contradiction that Schenker had noticed in a previous study: Lung cancer incidence in farmworkers was less than the state average because of lower smoking rates, yet the incidence of death from obstructive lung disease was higher.

The explanation, it turned out, was dust.

Before Schenker and McCurdy's work, it was believed that specific exposures, whether they were allergenic or chemical, posed the greatest respiratory risk for farmworkers.

However, the duo, in a field study of 600 farmworkers that included physical exams and breathing tests,showed that chronic exposure tohigh dust levels could also impair lung function.

Stirring up dust

Schenker was the lead author of a major report by the American Thoracic Society on the subject that came out afterwards. But heightened awareness has so far not led to change out in the field in terms of requiring farmers to provide workers with protective masks.

"There's a culture in farming that dirt's just part of the job, that it's just a nuisance, something you wash off at the end of the day," says Schenker, a pulmonary and occupational-medicine specialist.

"We're trying to change that. We're saying that it actually has an adverse effect and that you need to protect yourself."

In their work, Schenker and McCurdy identified another easily preventable health hazard — dermatitis, a condition that workers who pick grapes with their bare hands frequently suffer.

More recently, McCurdy has focused on agricultural injuries, finding for example that the injury rate among female farmworkers quadrupled when they were paid by the piece instead of an hourly wage.

Payment by piecework is inherently riskier, McCurdy explains, because it rewards those who work fast rather than carefully.

Widespread ailments

In a paper slated for publication this year called "The California Agricultural Workers Health Survey," McCurdy and lead author Villarejo of the California Institute of Rural Studies, report the results of a long-term study of 970 hired farm laborers. They found that 40 percent of the workers reported persistent pain in one or more body parts, including the back, neck and shoulders; 12 percent of men and seven percent of women reported irritated eyes, clouded vision, skin irritations and headaches from pesticide exposure; and significant numbers reported diarrhea and stomach aches lasting three or more days from being required to taste unwashed grapes in vineyards for sweetness while picking.

"My role is to bring information to the table so people can make decisions based on facts instead of on suppositions and biases," McCurdy says.

As for Schenker, he is currently two years into a study of 900 individuals living in Mendota, a San Joaquin Valley farming community.

He has found an intriguing immigration shift: Fully one-third of the agricultural workers he's studying come from Central America, mostly El Salvador. In the past, California farmworkers have hailed almost exclusively from Mexico.

He also has documented what he termed "horrible housing conditions" that include a lack of indoor plumbing, poor sanitation and overcrowding. Workers and their families also are suffering from dental problems due to many factors, including a lack of access to fluoridated water, Schenker says.

Workers' champions

Mario Gutierrez of the California Endowment, a private philanthropic organization that has provided funding for the Mendota study, called Schenker "a real champion for seeking the evidence" of farming's impact on workers.

McCurdy, meanwhile, was praised by colleague, Lorann Stallones, an agricultural epidemiologist with Colorado State University, for his ability to overcome cultural and linguistic obstacles. Noting that McCurdy is fluent in Spanish, Stallones says "he has done a remarkable job of tracking and getting useful information from a population that's notoriously difficult to engage."

There's no indication that the pair are going to slow down anytime soon. So it's a good bet that UC Davis will continue to be a leader in what was once a neglected field of study — the occupational health and safety of California's farmworkers.

"It's an area of expertise that, right now, UC Davis can bring to the field of public health in great strength," says Schenker, who is part of the campus effort to establish a new school of public health at UC Davis. "Our proximity to the agricultural industry and our strengths in rural and environmental health issues, as well as disparities in health care, position us as a potential powerhouse program."