A widespread Cyclospora outbreak in the United States has heightened consumer concerns about fresh-produce safety. Although federal health officials have found no direct link between the outbreak and domestically grown crops, demand for fresh vegetables has fallen sharply, forcing some farms to destroy mature produce.

According to NielsenIQ, U.S. fresh lettuce sales declined 8.7% year over year during the four weeks ending July 18, representing a drop of more than 7.6 million pounds. Of the 37 vegetable categories tracked, 28—including carrots, cauliflower and spinach—recorded lower sales.

Coastline Family Farms, located in California’s Salinas Valley, said its sales had fallen between 20% and 30% as restaurant and retail customers reduced their orders. The farm was forced to plow approximately 300,000 pounds of mature lettuce back into the ground because harvesting and storage costs could not be justified. The downturn has also led to cuts in agricultural jobs.

An investigation by the U.S. Food and Drug Administration linked the outbreak to lettuce sourced by Taylor Farms from central Mexico. U.S.-grown produce has not been implicated. However, the announcement has done little to ease consumer concerns.

After health officials associated some illnesses with lettuce served by Taco Bell, the chain’s U.S. sales fell 25% and customer traffic declined 21% during the week ending July 25. Salad-focused restaurant chain Chopt also experienced a traffic decline of more than 12%.

Western Growers said uncertainty about food safety had prompted many consumers to avoid purchasing fresh produce. The International Fresh Produce Association warned that highly publicized food-safety incidents could have lasting effects across the industry.

Meanwhile, some consumers are turning to locally grown produce. Farmers markets in Washington, D.C., and surrounding areas have recently reported an approximately 30% increase in customer traffic.