2009 Pesticide Residues in Fresh Produce


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About California’s Pesticide Regulatory Program

California has the nation’s most comprehensive program to regulate pesticide use. Under this program:

  • A pesticide’s safety and efficacy is evaluated before it is allowed to be used.
  • All agricultural pesticide use must be reported.
  • Pesticide specialists and environmental scientists enforce restrictions intended to ensure the proper and safe use of pesticides.
  • Domestic and imported produce are sampled and tested for pesticide residues via the California Pesticide Residue Monitoring Program (previously known as the Marketplace Surveillance Program).

Residue Monitoring via the California Pesticide Residue Monitoring Program

The Department of Pesticide Regulation’s (DPR) California Pesticide Residue Monitoring Program is the most extensive state residue-monitoring program in the nation. It is the final check in an integrated network of programs designed to protect human health and the environment. The Residue Monitoring Program is designed to meet the following goals:

  1. Monitor pesticide residues in fresh produce throughout the California food supply. DPR samples commonly consumed commodities, giving special emphasis to commodities consumed by infants and children, and pesticides listed as causing cancer or reproductive toxicity.

    In addition, in accordance with DPR’s commitment to environmental justice, we select commodities and sampling locations to reflect differences in consumption patterns among ethnic and socioeconomic groups.

  2. Identify specific commodities that have a higher incidence of illegal residues. DPR usually increases sampling of commodities that have a history of higher incidence of illegal residues, to better understand the extent of the problem.

  3. Generate data requested by DPR’s Medical Toxicology Branch while they conduct risk assessments of particular pesticides.

  4. Help keep produce with illegal residues out of the marketplace. When illegal residues are detected, DPR reacts immediately by removing the illegal produce from sale. Further, DPR traces the distribution of the produce to determine its source. When possible, DPR contacts the source of the illegal produce to educate them about the problem. DPR can, if appropriate, take enforcement action to ensure compliance.

The findings of the Residue Monitoring Program have been consistent over the years: the majority of produce samples have had no pesticide residues detected, and residues detected in produce are generally well below the allowable tolerances. A "tolerance " is the highest residue level of a particular pesticide that is legally allowed on a particular commodity. Tolerances for a pesticide are set by the U.S. Environmental Protection Agency (U.S. EPA) based on the potential risks to human health posed by that pesticide.

California Pesticide Residue Monitoring Program results from 2009

In 2009, DPR collected 3,429 samples of more than 180 kinds of commodities. All sampled commodities were derived from plants (no animal products) and were raw (not processed). Sampling of processed foods is the responsibility of the federal Food and Drug Administration (FDA) and U.S. Department of Agriculture (USDA).

Samples were collected throughout the channels of trade, including wholesale and retail outlets, distribution centers, and farmers markets. Both domestic and imported produce were monitored. Of the total samples, 57.4 % were domestic (1,969 of 3,429 samples), 41.6 % were imported (1,426 of 3,429 samples), and 1.0 % were of undetermined origin (34 of 3,429 samples).

All samples were tested in analytical laboratories using multiresidue screens capable of detecting more than 200 pesticides and breakdown products. The results:

  • 73.4 % of samples had no pesticide residues detected (2,517 of 3,429 samples).
  • 24.2 % of samples had residues that were within the legal tolerance levels (831 of 3,429 samples).
  • 2.4 % of samples had illegal residues (81 of 3,429 samples). A produce item with an illegal residue level does not necessarily indicate a health hazard.

Residues within tolerance were found in 24.2% of the samples (831 of 3,429 samples). As in recent years, the majority of these samples had residues at less than 10 percent of the tolerance level. Illegal residues were found in only 2.4 % of samples (81 of 3,429 samples). Of these, 12.3% (10 of 81 illegal samples) had residues that were over the tolerance level, and 87.7 % (71 of 81 illegal samples) had residues of a pesticide not authorized for use on the commodity (no tolerance established). Please note: Percentages may not add up to 100 % due to rounding.

In 2009, as in several recent years, certain commodities produced in certain locations had a higher proportion of samples with illegal residues:

Commodity and origin % of samples with illegal residues
(2008 and 2009 `combined)
Tomatillo produced in Mexico 8.2 % (4 of 49 samples)
Taro root produced in China 6.3 % (3 of 48 samples)
Chili peppers produced in Mexico 4.4 % (10 of 226 samples)
Papayas produced in Mexico 4.4 % (6 of 137 samples)
Snowpeas produced in Guatemala 4.3 % (2 of 47 samples)
Limes produced in Mexico 4.2 % (3 of 71 samples)
Bitter gourd produced in Mexico 4.0 % (4 of 99 samples)
Ginger produced in China 3.8% (6 of 160 samples)

Although illegal, most of these residues were at very low levels (a fraction of a part per million). Nonetheless, when illegal residues are found, DPR reacts immediately by removing the illegal produce from sale, then verifies that the produce is either destroyed or returned to its source. In addition, if the owner of the produce has similar produce from the same source, DPR quarantines that produce until the laboratory verifies that it is free from illegal residues. Further, DPR traces the distribution of the illegal produce by contacting distributors throughout California, imposing additional quarantines and conducting additional sampling as needed. In addition, DPR is actively working with partners including the federal Food and Drug Administration (FDA) and federal Immigration and Customs Enforcement (ICE) to identify and eliminate sources of illegal residues.

We also collaborate with trade organizations and farmer-training projects, encouraging them to educate producers about pesticide residues in their commodities. For example, as a result of a series of illegal residues in snow peas from Guatemala, DPR contacted the Guatemalan exporters’ association and United Nations officials to share our findings and request action. DPR’s 2009 monitoring indicates a substantial reduction in the proportion of Guatemalan snowpeas with illegal residues. Last year, the two-year combined data showed 21.7% of Guatemalan snowpeas with illegal residues. This year, that has dropped to only 4.3%. A portion of that decline was likely due to DPR’s outreach.

Significance of the Results

The validity of any sampling program lies in its design and in its ability to replicate the results. Over the past decade, even as the number of samples varied, the findings have been consistent from year to year. The majority of produce samples have no detectable pesticide residues. Residues that are found are usually at levels that are measured at a fraction of a part per million (ppm). In most years, approximately one percent of total samples have residues over the tolerance levels. Certain commodities produced in certain locations have a history of higher proportions of illegal residues.

While the goal of DPR’s regulatory program is to ensure that all food is in compliance with pesticide safety standards, a produce item with an illegal residue level does not necessarily indicate a health hazard. Each such incident, however, is evaluated for possible health concerns. The results from years of DPR residue monitoring document the overall safety of produce grown and consumed in California.

The data collected in 2009 are available for downloading on DPR’s Web site www.cdpr.ca.gov. Click on "A-Z Index" and then go to "Residue Monitoring Program."

DPR is working to improve our monitoring

In addition to the multiresidue screens that have been in use for decades, DPR is preparing to add a newer analytical technique called LCMS (liquid chromatography mass spectrometry). The advantage of LCMS is that it can detect residues of recently-registered pesticides. These newer pesticides have chemistries that are difficult to detect with the multiresidue screens.

In August 2009, DPR began a pilot project to test the new LCMS methodology. During 2009, we analyzed three commodities using LCMS: leaf lettuce, oranges, and table grapes. Those commodities were selected because some of the newer pesticides are used to produce them. So far, the pilot project has been very successful, as shown by the high detection rates with the LCMS screen:

  Screen used to detect residues
“Old” multiresidue screens
(averages from 2007 and 2008)
“New” LCMS screen
(2009 only)
Leaf lettuce 57.3% (176 of 307 samples) 55.6% (60 of 108 samples)
Oranges 34.4% (121 of 352 samples) 86.0% (43 of 50 samples)
Table grapes 29.3% (53 of 181 samples) 80.6% (29 of 36 samples)

Indeed, the LCMS screen successfully detected one low-level illegal fungicide residue on a sample of leaf lettuce. That fungicide residue would not have been detectable if we had used only the old multiresidue screen. DPR contacted the distributor to ensure the lot of contaminated lettuce was removed from sale. All other samples analyzed by LCMS either had residues that were within legal tolerances, or had no detectable residues.

The pilot project will continue with table grapes and additional commodities in 2010. DPR looks forward to expanding our use of LCMS to further strengthen our ability to detect the widest possible range of pesticides.