UC Davis Agricultural and Resource Economics

Imported vs. domestically produced fruits and vegetables, is there a difference in food safety?

The following summary is based upon a recent Economic Research Service article addressing the questions of produce safety. The summary was prepared by Dr. Chris Bruhn of the Center for Consumer Research at UC Davis, with some revisions by Dr. Roberta Cook.

Nutrition advice encourages the consumption of fruits and vegetables with U.S. dietary guidelines suggesting five to nine servings a day. Consumers are responding to this message. Annual per capita consumption of fresh produce was 311.3 pounds in 1996, compared to 266.1 in 1986.* Consumption has increased for both fresh and processed fruits and vegetables, but fresh grew at an average annual rate of 1.1% over the 1976 to 1996 period, compared to .5% for processed.

Although epidemiological evidence clearly indicates the benefits of eating produce, some express uncertainty about the long-term health risks from low-level intake of pesticides. Additionally, an increasing (although small) number of foodborne disease outbreaks have been traced to consumption of fresh produce. In October 1997 President Clinton proposed legislation to both permit FDA inspection of foreign food-safety practices and to halt imports of fruits and vegetables form countries that do not meet U.S. standards. The ERS article examines the statistical evidence of differences in risks between imported and domestically produced products.

Imports of fruits and vegetables have increased. Total imports accounted for 16.4% of all fresh and processed fruits and vegetables in 1996. There are substantial differences among products. Less than one percent of iceberg lettuce, 34% of fresh tomatoes, and 99.5% of bananas are imported.

Scientists and regulatory personnel consider contamination by bacteria and naturally occurring toxins as the greatest foodborne dangers to health. The Center for Disease Control and Prevention indicates that microbial pathogens caused 79% of the 2,423 reported foodborne disease outbreaks and 90% of the 77,373 cases of associated illness in the U.S. between 1988 and 1992. Fresh fruits and vegetables were the vehicle of transmission for 6% of the 1,072 outbreaks for which a specific food was identified. The food source was unknown for over half of the reported outbreaks. Five percent of the illnesses and 22% of the deaths were linked with fruits and vegetables.

Although relatively few outbreaks are traced to fresh produce, the number is increasing, perhaps because the causative bacteria is an emerging pathogen or because an association with produce was not made in the past. E. coli O157:H7 for example, was shown to survive in low acid products when unpasteurized apple juice was identified as the vehicle for an outbreak. Cyclospora believed to be transmitted by imported Guatemalan raspberries was responsible for outbreaks in 1995 and 1996.

Imported vs. Domestically Grown

CDC investigations of foodborne outbreaks have identified both imported and domestically grown produce as the vehicle for microbial pathogens. Whereas Guatemala was the source of raspberries with Cyclospora, foodborne disease was also linked with domestically grown products: apple cider, canteloupe, tomatoes, strawberries, orange juice, and leaf lettuce.

The fact that the point of contamination can not always be determined complicates comparing the safety of imported and domestically produced products. In the case involving frozen strawberries, the raw product was grown in Mexico, but the berries were processed in the United States. It has not been determined whether contamination occurred before the berries entered the United States or whether it occurred during processing or handling in this country.Interestingly, the confirmed cases centered around a Michigan school district.

Contamination of fresh produce can occur anywhere in the production and marketing chain, during irrigation, harvesting, packing, or washing. Foodborne illnesses are frequently due to food handling and preparation practices, such as improper holding temperature, inadequate cooking, contaminated equipment. The CDC reports several outbreaks of illness associated with cross-contamination when they were sliced on unsanitized surfaces following meat and poultry preparation.

Pesticide Concerns

Data on pesticide residues does not provide a clean answer to the question of differences in safety of imported and domestically grown produce. FDA's regulatory monitoring program has shown that imported produce violates tolerance limits more frequently than domestically grown produce. However, both for imports and domestic produce, the violation rates are very low. Further, a greater frequency of violations in and of itself does not indicate that there are differences in the level of health risks. To answer the health questions, it is necessary to know the amount of the specific pesticide ingested and the pesticide's toxicity. To distinguish health risks of domestic and imported produce, the critical question is the level of exposure to each chemical from each source.

Results from pesticide residue testing programs finds some pesticides are detected only in domestic produce, some only in imported produce, and some found in both, sometimes at clearly different levels. Because different chemicals have different health effects, there is no way to compare the safety of imported and domestic produce. We do know that consumer exposure to pesticide residues (from all sources) is very low and that scientists tell us they pose a neglible health risk.

In conclusion, there is no clear evidence that health risk due to pesticide residues or microbial bacterial contamination is greater with imported produce than with domestically grown.

Food Safety And Fresh Fruits And Vegetables : Is There A Difference Between Imported And Domestically Produced Products? L. Zepp, F. Kuchler, and G. Lucier, Vegetables and Specialties/VGS-274/April 1998, page 23-28.

Christine M. Bruhn, Ph.D.
Director, Center for Consumer Research

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e-mail cmbruhn@ucdavis.edu

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