2010 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 California Pesticide 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, DPR staff 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 to conduct risk assessments of particular pesticides.

  4. Help keep produce with illegal residues out of the marketplace. DPR directs its residue monitoring toward enforcement of U.S. Environmental Protection Agency (U.S. EPA) tolerances. A "tolerance" is the highest residue level of a particular pesticide that is legally allowed on a particular commodity. U.S. EPA sets tolerances based on the potential risks to human health posed by the pesticide.

    If illegal residues are detected, DPR immediately removes the illegal produce from sale. In addition, DPR traces the distribution of the illegal produce by contacting distributors throughout California, imposing quarantines and conducting extra sampling as needed. DPR levies fines on distributors for residue violations. If investigators find that California farmers used pesticides illegally, the farmers can also be fined.

The findings of the California Pesticide 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.

California Pesticide Residue Monitoring Program results from 2010

In 2010, DPR collected 3,020 samples of more than 170 kinds of commodities. All sampled commodities were derived from plants (no animal products) and were raw (not processed)1. DPR collected samples from 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, 59.1 % were domestic (1,784 of 3,020 samples), 40.1 % were imported (1,212 of 3,020 samples), and 0.8 % were of undetermined origin (24 of 3,020 samples).

All samples were tested in analytical laboratories using multiresidue screens that can detect more than 200 pesticides and pesticide breakdown products. The results:

California-grown produce continued its excellent safety record

In 2010, 98.6% of samples of produce grown in California were in compliance with U.S. EPA tolerances (1,118 of 1,134 samples). Sampling included more than 110 commodities grown in California.

For all sources of produce:
64.8 % of samples had no pesticide residues detected (1,957 of 3,020 samples).
32.8 % of samples had residues that were within the legal tolerance levels (991 of 3,020 samples).
2.4 % of samples had illegal residues (72 of 3,020 samples). A produce item with an illegal residue level does not necessarily indicate a health hazard.

Residues within tolerance were found in 32.8% of the samples (991 of 3,020 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 (72 of 3,020 samples). Of these, 12.5% (9 of 72 illegal samples) had residues that were over the tolerance level, and 87.5 % (63 of 72 illegal samples) had residues of a pesticide not approved for use on the commodity (no tolerance established). Please note: Percentages may not add up to 100 % due to rounding.

In 2010, as in 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
(2009 and 2010 combined)
Tomatillo produced in Mexico 10.2 % (6 of 59 samples)
Limes produced in Mexico 8.9 % (5 of 56 samples)
Spinach produced in California 6.3 % (4 of 63 samples)
Papaya produced in Mexico 4.9 % (8 of 162 samples)
Ginger produced in China 4.4 % (5 of 113 samples)
Chili peppers produced in Mexico 3.4 % (7 of 204 samples)
Bitter gourd produced in Mexico 3.4 % (4 of 119 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 (either above the tolerance level or with no tolerance for that combination of commodity and pesticide), DPR immediately removes the illegal produce from sale. Before releasing it from quarantine, DPR verifies the produce has been reconditioned to remove illegal residues. If that cannot be done, the produce must be destroyed. In addition, if the owner of the commodity has similar produce from the same source, DPR quarantines those lots until the laboratory verifies that the produce is free from illegal residues. Further, DPR traces the distribution of the illegal produce by contacting distributors throughout California, imposing quarantines and conducting extra sampling as needed.

If investigators find there was illegal pesticide use, violators can be fined. DPR also can levy fines for residue violations. For example, in 2010, DPR imposed a $10,000 civil penalty against a produce importer that had a history of recurring residue violations, mostly on produce imported from Mexico. In addition, DPR is actively working with partners including the federal Food and Drug Administration (FDA) to identify and eliminate sources of illegal residues. DPR also collaborates with trade organizations and farmer-training projects, encouraging them to educate producers about pesticide residues in their commodities.

Significance of the Results

DPR’s sampling program is designed primarily to meet the goal of preventing "public exposure to illegal pesticide residues" (California Food and Agricultural Code section 12532). For that reason, the data are not statistically representative of the residues typical for a particular pesticide, commodity, or place of origin. Some sampling bias may be incurred by intentionally concentrating on such factors as commodity, place of origin with a history of violations, or large volume of production or import. Nonetheless, over the past decade, the findings have been consistent from year to year, even as the number of samples varied. The majority of produce samples have no detectable pesticide residues. Residues that are found are usually at levels of a fraction of a part per million (ppm). In most years, approximately two 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. DPR scientists, however, evaluate each incident to determine if there are 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 2010 are available for downloading on DPR’s Web site at www.cdpr.ca.gov. Click on "A-Z Index" and then go to "Residue Monitoring Program."

DPR is working to improve monitoring

Besides the multiresidue screens that have been in use for decades, DPR has added a newer analytical technique called LC/MS (liquid chromatography / mass spectrometry) to analyze some samples. The advantage of LC/MS is that it can detect residues of recently registered pesticides. These newer pesticides have chemistries difficult to detect with the multiresidue screens.

During 2010, DPR concentrated the use of LC/MS on six commodities, selected because some newer pesticides are used to produce them. As expected, the LC/MS screen did increase the proportion of samples on which DPR was able to detect residues:

  Screens used to detect residues
"Old" multiresidue screens alone (averages from 2007 and 2008) "New" LC/MS screen together with multiresidue screens (2010)
Bok choy 50.0% (51 of 102 samples) 60.8% (48 of 79 samples)
Celery 87.9% (29 of 33 samples) 76.3% (45 of 59 samples)
Grapes, table 29.3% (53 of 181 samples) 90.2% (46 of 51 samples)
Kale 66.7% (2 of only 3 samples) 75.0% (27 of 36 samples)
Peaches 51.2% (108 of 211 samples) 95.7% (45 of 47 samples)
Spinach 60.0% (21 of 35 samples) 95.9% (47 of 49 samples)

Just as for the multiresidue screens, the vast majority (96.8%) of residues detected by LC/MS were within legal tolerance levels (271 of the 280 samples on which LC/MS detected residues). Illegal residues were found in only 3.2% of samples analyzed via LC/MS (9 of 280 samples). LC/MS did detect illegal residues of several pesticides that would not have been detectable using only the old multiresidue screens. As always, whenever illegal residues were detected, DPR immediately removed the illegal produce from sale.

The use of LC/MS will continue with more commodities in 2011. DPR looks forward to expanding the use of LCMS to further strengthen our department’s ability to detect the widest possible range of pesticides.

1Sampling of processed foods is the responsibility of the federal Food and Drug Administration (FDA), the U.S. Department of Agriculture (USDA), and the California Department of Public Health.