The Study: Gennet, S., J. Howard, J. Langholz, K. Andrews, M. D. Reynolds, and S. A. Morrison. 2013. Farm practices for food safety: an emerging threat to floodplain and riparian ecosystems. Frontiers in Ecology and the Environment 11:236-242.
The Big Question(s): Admit it: Did the 2006 bagged spinach E. coli outbreak, which caused 3 deaths and 276 illnesses, give you an excuse to avoid eating your greens? You’re not alone — the outbreak led to a $350 million loss in profit for the leafy greens industry.
The source of the contaminated spinach was traced to a farm in California’s Salinas Valley, where 70% of the United States’ leafy greens are grown. The Salinas Valley also happens to be home to several endangered species and provides critical stopover habitat for migratory birds traveling the Pacific Flyway.
After the 2006 E. coli outbreak, produce farmers in Salinas Valley implemented a number of practices aimed at reducing risk of contamination by wildlife feces, such as: removal of non-crop vegetation that might attract deer and other wildlife; treatment of irrigation reservoirs with chemicals; installation of fencing to prevent wildlife from entering fields; and use of poison to control rodent populations.
But Nature Conservancy scientist Sasha Gennet and her colleagues wanted to know: How might these new food-safety farming practices affect nature and wildlife?
Study Nuts and Bolts: To answer these questions, Gennet et al. measured changes in habitat in the Salinas Valley from 2005 (pre-E. coli outbreak) to 2009 (3 years after first implementation of food safety practices). They focused on wetlands and riparian habitat along the Salinas River and wildlife corridors between the river and adjacent foothills. They then modeled what kind of habitat impact these new farm practices could have if implemented across the state.
The Findings: Over the 5 years of the study period, 13% of the wetlands and riparian habitats in the Salinas Valley were converted to bare ground or cropland. And 75% of the identified wildlife corridors in the valley were at least partially fenced during this time period.
While the researchers couldn’t establish a direct cause-effect link to food safety practices, these habitat changes happened during a time of “aggressive implementation of on-farm food safety practices” such as removal of non-crop vegetation — and could impact wildlife both on land and in streams (such as Chinook salmon). Farmers paid the price too, with new farm safety practices costing an average of $21,000.
Looking into the future, the researchers projected an additional loss of 200,000 hectares of California’s grasslands, riparian areas, wetlands and other important habitat if these food-safety farm practices were to be implemented state-wide. For some counties, this could equal a loss as high as 40% of remaining riparian areas and wetlands.
What It All Means: Food-borne illnesses are a growing health concern and efforts to improve food safety are rightly focused on reducing the consumer’s risk. But the researchers found no scientific evidence that wildlife are a major source of food-borne pathogens — in fact, studies have shown that having non-crop vegetation in and around fields can actually reduce the survival and movement of pathogens.
So if new practices designed to reduce wildlife exposure aren’t likely to improve food safety — and actually are harmful to nature, as found by Gennet et al. — shouldn’t they be re-evaluated? Considering that agriculture is one of the top causes of land conversion and habitat loss in the United States, new food safety protocols add insult to injury by increasing agriculture-related habitat loss without producing measurable benefits for the consumer.
The authors highlighted the opportunity for California to lead the way in adopting a more integrated, science-based risk management approach to food safety protocols on farms.
Opinions expressed on Cool Green Science and in any corresponding comments are the personal opinions of the original authors and do not necessarily reflect the views of The Nature Conservancy.