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Publication #BUL331

A Descriptive and Comparative Analysis of Pesticide Residues Found in Florida Tomatoes and Strawberries, 1990-19931

Thomas J. Stevens III and Richard L. Kilmer2

Acknowledgments

Funding for this research was provided by the United States Department of Agriculture (USDA) Economic Research Service (ERS) and Agricultural Marketing Service (AMS) as well as the UF/IFAS Food and Resource Economics Department. Numerous individuals in industry and government provided information and advice that were essential to the completion of this study. Some of those who were frequently called upon for this purpose included: Biing-Hwan Lin with the USDA-ERS; John Schaub of the USDA-AMS; George Fong, Gail Parker, and Sheryl Spencer of the Florida Department of Agriculture and Consumer Services; Mack Willhite, Aubrey Bordelon, and Robert Freie of the Florida Agricultural Statistics Service. Individuals from various departments within the University of Florida Institute of Food and Agricultural Sciences included: Michel Roy, Scott Smith, and Ron Muraro with UF/IFAS Food and Resource Economics; Jeff Brecht, Phyllis Gilreath, George Hochmuth, Steve Sargent, Bill Stall and Robert Stall of UF/IFAS Horticultural Sciences; Dick Matthews and Norman Nesheim from UF/IFAS Food Science and Human Nutrition; and Karl Butts and Ben Castro of the UF/IFAS Extension. Other agencies or associations which provided input included: the South-East Agricultural Weather Service Center, the Florida Tomato Committee, the Florida Strawberry Growers Association, the Florida Fruit and Vegetable Association, and the National Association of State Departments of Agriculture. Finally, special thanks are due to the hundreds of Florida growers, packers, and distributors of strawberries and tomatoes who made this study possible by voluntarily providing detailed information on their individual cultural or handling practices.

Abstract

The purpose of this study was to demonstrate how the types and levels of pesticide residues can differ between two fresh commodities grown in Florida and how these difference may be associated with production and handling characteristics of each industry. The findings from this analysis can lead to a better understanding of some of the unique pesticide problems associated with a particular commodity. This could be useful for industry and government decision-makers and advisors. Data on the levels of 19 different pesticide residues found in Florida tomatoes and strawberries are matched to firm and decision-maker attributes as well as fundamental production practices. Descriptive statistics on these residues and the socio-demographic characteristics of the growers, packers, and distributors sampled by this study are presented. Descriptive statistics for strawberries and tomatoes at different market stages are also tested for significant differences. Fundamental differences in production and handling practices for each commodity are discussed and associated with residues. Topical as well as methodological recommendations are provided for future research, extension, and policy directives.

Key Words: pesticide residues, strawberries, tomatoes, Florida, industry characteristics, grower attributes.

Introduction

Problem Setting and Objectives

During the last two decades there have been growing societal concerns over issues related to public health, environmental quality, and food safety. One of the major controversies inciting these concerns involves the production and consumption of fresh fruits and vegetables. Research has shown that diets with greater proportions of fruits and vegetables can prevent or delay a number of debilitating and life threatening diseases. At the same time, public acceptance and adoption of these findings is being discouraged by ongoing re-evaluations of the possible health risks associated with minute amounts of pesticide residues sometimes found in or on these foods.

The objective of the study is to describe and evaluate differences in the levels and types of pesticide residues found in fresh tomatoes compared to fresh strawberries at the grower, packer, and distributor market stages. Various socio-economic characteristics of growers and handlers are also compared and associated with pesticide residues. The findings from this analysis will give industry and government decision-makers a better understanding of the basic relationships and differences between commodity production and distribution systems and pesticide residues.

Scope of Research

The scope of this investigation was limited to fresh tomatoes and strawberries grown in the state of Florida from October 1990, to June 1993. Data on pesticide residues and cultural and handling practices, as well as firm and decision-maker attributes, were collected and evaluated for the grower, packer, and distribution stages of each market channel. Together, nineteen different pesticide residues were detected in these two commodities. These included insecticides, miticides, fungicides, and herbicides.

Organization of Report

This report is organized into four sections including this one. The second section is entitled "Data and Procedures". It provides some background on the data sources and collection process; and reviews the procedures used to achieve the previously stated research objectives. A descriptive examination of the data is provided in the third section entitled, "Pesticide Residues in Florida Strawberries and Tomatoes and Characteristics of the Industries". From these findings, implications, conclusions, and recommendations are derived and presented in the last section entitled, "Conclusions and Recommendations". An assessment of the overall success of the project is included in this section with suggestions for possible future methodological improvements.

Data and Procedures

The data used for this analysis were acquired from both primary and secondary sources. Data on pesticide residues found in strawberries and tomatoes were obtained from the Florida Department of Agricultural and Consumer Services (FDACS), Division of Chemistry, Chemical Residue Laboratory (CRL). Data on producer and handler attributes or characteristics were obtained through personal interviews.

The CRL is responsible for the chemical analysis of poisonous or deleterious chemical residues remaining in or on human food and animal feed that is produced or marketed in Florida. Field agents for CRL collect samples of fresh and processed agricultural products from around the state at various stages of the marketing channel. These are rushed to CRL laboratories where they are checked for chlorinated hydrocarbon, organophosphate, and carbamate types of pesticide residues using multi-residue screening procedures. If any of these types of pesticide residues are detected by the screenings, then appropriate quantitative chemical assays are performed. Chemical analysis of most samples is completed within 48 hours after collection. In order to maximize the effectiveness of its monitoring effort, CRL sample collection is weighted more heavily toward those commodities and growing seasons which have a greater potential for accumulated residues. Consequently, the sampling procedures used by the CRL and the samples used in this analysis cannot be said to be randomly selected.

The residue analysis results of 307 tomato and 113 strawberry samples were acquired from CRL and converted to a micro-computer database format. These samples provided a list of potential interviewees from whom corresponding socio-economic and other data could be collected through a survey. Enumeration of this survey was conducted by the Florida Agricultural Statistics Service (FASS) under contractual arrangement. A total of 338, or 80 percent, of a possible 420 interviews were successfully completed. Results from the survey indicated that pesticides were only being applied to tomatoes and strawberries at the grower level. Since there was generally no coordination or trace-back of residue testing by CRL between market stages, it was impossible to determine which types of and how much residues were in or on tested samples before they arrived at the packing or distribution stages.

The data collected from CRL and the survey were evaluated and compared using standard descriptive statistics. Comparisons of residues for the different commodities at different market stages were presented in table and graphical formats. Next, producer/handler characteristics were likewise described and compared. From this analysis, implications and conclusions were developed. Recommendations were made for risk assessment and pesticide regulation policy. Finally, recommendations for future methodological improvements were suggested. A number of related problems which could be opportunities for further research were also mentioned.

Pesticide Residues in Florida Strawberries and Tomatoes and Characteristics of the Industries

The types and quantities of pesticides found in Florida strawberries and tomatoes as well as some of the socio-demographic characteristics of producers and handlers for each commodity are reviewed in this section. Important differences exist between the two commodities in both areas. Such knowledge is useful for understanding each industry's issues with regard to production, residues, and food safety.

Pesticide Residues in Florida Strawberries and Tomatoes

While there are literally hundreds of different pesticide products and product formulations labeled for use on strawberries and tomatoes, many are of little or no concern with respect to food safety. Many pesticides do not leave residues because they are not applied directly to the plant or fruit, or they are so volatile that they break down or dissipate long before harvest and consumption. The residues detected in the samples used for this analysis were confined to essentially 19 different pesticides for both commodities, or 13 each for strawberries and tomatoes individually. A listing of these pesticides, including their EPA tolerance levels, is provided in Table 1.

As shown in Table 1, the vast majority of pesticide residues detected in Florida tomatoes and strawberries are insecticides, miticides, and fungicides. Overall, there were 13 different insecticide or miticide compounds detected and five different fungicides. One type of herbicide residue was found in just two of the 338 samples for which interviews were conducted. No nematocides or bacteriacides were detected. EPA tolerances for pesticides vary between strawberries and tomatoes. In several instances, a particular pesticide has no tolerance level for one commodity but is approved for use on the other. This variation between commodities is often due to allocations made by EPA based on estimates of total dietary intake or quantitative risk assessments of a given pesticide residue from the consumption of many different foods over an average lifetime. Such allocations are sometimes based on the relative importance or average level of consumption of each commodity. In some cases the importance or benefit of a particular pesticide in protecting a given commodity from pest infestations may be considered. The variation in tolerance levels between different pesticides is in large part due to differences in their toxicologic, oncogenic, and mutagenic properties.

Descriptive statistics on residues found in strawberry and tomato samples for which interviews were successfully completed are shown in Table 2, Table 3, Table 4, Table 5, Table 6, Table 7 and Figure 1, Figure 2, Figure 3, Figure 4, and Figure 5. Separate tables are provided for each commodity at each market stage: grower, packer, and distributor. Generally, there is no coordination between produce sampled at different market stages. Occasionally, if a problem is first discovered at the packer or distributor stage, it may be traced back up the market channel to the producer. When samples are found to have residues at levels above EPA tolerances, harvesting is suspended or the lot is held in storage until confirmatory sampling can be done within three to five days. Confirmatory sampling results by FDACS were not used to calculate descriptive statistics for residues. In discussing these results it should be kept in mind that the sample used in this study should not be considered random and in fact is probably weighted toward higher levels of residues than would be found if such produce were sampled in a purely random fashion.

Statistics provided for each type of pesticide include: the proportion of samples found to have no detectable residues, the proportion found to have a residue level exceeding its EPA tolerance, the maximum parts per million found for each residue, the mean, and its standard error. Numbers for aggregate fungicides, insecticides-miticides, and all pesticides are shown in the last three rows of each table, 2 through 7. It should be noted that relatively small sample sizes for strawberries at the packer and distribution market stages resulted in large standard errors for the means as shown in the appropriate columns of Tables 4 and 6.

By examining the tables and figures referenced, some inferences about the nature of pesticide residues and pesticide use in strawberries and tomatoes can be deduced. Looking at Tables 2, 4, and 6, and Figures 1 and 2 it can be seen that fungicides are the dominant type of pesticide residue found in Florida strawberries. At the grower stage (Table 2) less than five percent of the samples contained no detectable residues of fungicide, with a mean level of 4.92 parts per million (ppm). Captan is far and away the biggest component of these fungicide residues (Figure 2). By comparing the mean level of Captan to those for aggregated fungicides and pesticides it can seen that Captan represents over 93 percent (4.6189 ÷ 4.9203) of all fungicide residues and more than 83 percent (4.6189 ÷ 5.5483) of all pesticide residues detected in grower stage strawberry samples. Roughly similar statistics for fungicide residues are found for strawberries at the other two stages (Table 4 and Table 6) although the sample sizes for these were not large enough to consider these statistics very meaningful. Although Captan residues are found in the vast majority of strawberry samples, none occurred at levels exceeding the EPA tolerance level of 25 ppm. Only two of the 47 samples reviewed contained any type of residues over EPA tolerances. In one instance, residues of the fungicide Chlorothalonil, which has a zero EPA tolerance in strawberries, were detected. In the other, Methomyl was detected at 3.07 ppm when its EPA tolerance level is 2.0 ppm. Methomyl, Endosulfan, and Mevinphos are the most frequently detected insecticide residues in strawberries (Figure 2). In comparison to fungicides, insecticide residues were found in approximately 38 percent of strawberry samples from the grower stage at an average level of 0.2388 ppm.

Descriptive statistics for the pesticide residues found in tomatoes are shown in Tables 3, 5, and 7, and Figures 1, 4 and 5. In contrast to strawberries, the predominant type of residues found in tomatoes are insecticides and miticides. The most frequently occurring insecticide residues include Acephate, Methamidophos, and Endosulfan. Methamidophos residues had the highest mean residue levels of all other individual pesticides at every stage of the market channel. Acephate was the only pesticide/insecticide which occurred at levels above EPA tolerances, which is zero ppm in this case. This incident occurred with a single grower during one season. Chlorothalonil and Maneb were the only fungicide residues detected in tomatoes. Maneb residues occurred at a lower frequency but at higher levels than Chlorothalonil in grower stage samples. At the packer stage Maneb residues were detected more frequently and at higher levels. Chlorothalonil was the only fungicide found in distribution stage samples.

Table 8 shows the results of T-tests for differences in the mean level of pesticide residues found in strawberries and tomatoes at different market stages. Although the number of observations for strawberries at the packer and distributor market stages is small, pesticide residues, particularly fungicides, were found to occur at significantly higher levels at these downstream stages. Since most strawberries are packed into retail containers at harvest and subsequently refrigerated at temperatures slightly above freezing, there is apparently little opportunity for residues to be removed or breakdown in this fruit between harvest and retail merchandising. Survey results found no packers or distributors applying pesticides to strawberries or tomatoes. While it is not impossible that residues could concentrate in strawberries during packing and distribution, it is strongly suspected that if tests were conducted using larger more randomly chosen samples, then this relationship would disappear.

The statistics for aggregate residues found in tomatoes at three market stages (Tables 3, 5, 7, 8 and Figure 1) show that both fungicide and insecticide/miticide residues diminish as the product moves through the market channel. The average level of fungicides found in tomatoes at the distributor stage are less than a tenth of those from the grower stage. Insecticide residues at the distributor stage are reduced to almost one fourth the levels found at the grower stage. A complimentary trend, though not as strong, is apparent for the frequency of occurrence of tomatoes found with no detectable residues. T-tests in Table 8 confirm these inferences, with highly significant differences found between average residues at the grower and packer stages, and grower and distributor stages. The reduction in residues at the packing stage is most likely due to the washing and rinsing processes that are customary at this stage. The fact that tomatoes are optimally stored at relatively higher temperatures than strawberries (near 60°F compare to slightly above freezing) could account for the continued decline in residue levels through the distribution stage.

In comparing the aggregate statistics in the tables, it is clear that strawberries carry a considerably higher load of pesticide residues than do tomatoes. This may be due to a variety of cultural and botanical characteristics. The susceptibility of strawberries and tomatoes to particular types and levels of disease and insect pressure are very likely due to some of their inherent physical or physiological characteristics. For instance, strawberries are a cooler season crop compared to tomatoes which thrive under warmer conditions. From a purely economic standpoint, strawberries are a higher value crop, thus the marginal return to individual pesticide applications is probably higher than comparable applications to tomatoes. This will result in a greater utilization of this input in strawberries.

Characteristics of Strawberry and Tomato Industries

In this section, various socio-demographic characteristics of decision-makers and firms involved in producing, processing, and distributing strawberries and tomatoes in Florida are presented and discussed. An unweighted or per capita representation of the sample set of decision-makers and their firms was used. Consequently, multiple observations for the same decision-maker or firms were eliminated. Specific results for these characteristics are discussed below.

Growers

Tables 9, 10, and 11 provide general descriptive statistics on various attributes of growers and their firms based on this sample. Separate tables are provided for strawberries and tomatoes. The sample set for tomatoes included ten greenhouse operations. Descriptive statistics for tomatoes are presented with and without greenhouses in Tables 10 and 11. Greenhouse size was translated into acres on the basis of plant populations. Each table includes the minimum, maximum, sample size, mean, and standard error of the mean, median, standard deviation of the sample, and coefficient of variation for seven characteristics of decision-makers or operations. These include age, education, experience, total acres in production, proportion of those acres that are owned, gross revenue of the operation, and whether the operation is affiliated with any down-stream market stages such as packing or distribution. Age and experience are measured in years. Education and gross revenue are classified according to a scheme described in the footnotes of Table 9. Percent owned represents the ratio of acres owned over total acres owned and rented. Affiliation is a yes-no question so that the mean represents the proportion of the sample that was affiliated with downstream market stages.

Looking at Tables 9, 10, and 11, strawberry growers tend to be slightly older, less educated, more experienced, smaller, and less frequently affiliated with down stream market stages than tomato growers (with and without greenhouses). The most prominent difference between firms of the two industries exist with respect to physical size or acres. The acreage size for tomato growers is at least ten times larger than that for strawberries, 14 times if tomato greenhouse operations are not counted. Since strawberries are a higher value crop, the difference between strawberry and tomato grower's gross revenue is not nearly as great. Substantially more tomato growers are affiliated with down-stream market stages. This is probably due to the fact that most strawberries are packed in the field. This precludes the necessity of having to coordinate harvesting and packing activities between different business entities. Experience appears to be the dominate attribute of strawberry growers with respect to workplace qualifications, while education holds this distinction for tomato growers. Possibly the larger size of tomato operations demands a more general education from its decision-makers.

Tables 10 and 11 can be compared to infer the characteristics of greenhouse populations relative to field grown tomato operations. Greenhouses are substantially smaller than field grown tomato operations even when measured by the total number of plants grown. The tables show that greenhouse decision-makers are older, but less experienced and educated. This tends to confirm anecdotal evidence that many greenhouse operations are developed as a source of secondary or retirement income for individuals with less dedicated backgrounds in tomato production.

Packers

Tables 12 and 13 provide general descriptive statistics on various attributes of packing firms and their decision-makers. Separate tables are provided for strawberries and tomatoes. Tables for the packing stage are identically formatted as those for growers but do not include any measures of size based on acreage. Education and Gross Revenue are represented by the same classification scheme described in the footnotes to Table 9. It should be kept in mind that the sample size for strawberry packers was relatively small. This is reflected in the larger standard errors in Table 12.

There are more similarities between tomato and strawberry packers than was the case at the grower stage. In contrast to the differences between growers, strawberry packers on average were more educated and larger, in terms of gross revenue, than tomato packers. The proportion of affiliated packers for each commodity is nearly equal and very close to that found for tomato growers. Comparing packers to growers, both strawberry and tomato packers are substantially larger in terms of gross revenue than their grower counterparts. Growers and packers had similar levels of experience within their respective commodities, but strawberry packers possessed substantially more formal education than strawberry growers. Like their grower counterparts, strawberry packers had on average more years of experience than tomato packers.

Distributors

Tables 14 and 15 provide general descriptive statistics on various attributes of distribution firms and their decision-makers. Again, separate tables are provided for strawberries and tomatoes and Education and Gross Revenue are represented by the same classification scheme described in the footnotes to Table 9. As was the case for strawberry packers, the sample size for strawberry distributors is relatively small.

Distributors interviewed for the survey were on average younger than decision-makers at the other market stages. Levels of education for strawberry and tomato distributors were similar to those found for their grower stage counterparts with tomato growers on average having some college education. The mean years of experience of strawberry distributors was the highest among all other categories of decision-makers. Tomato distributor's experience was on par with their upstream market stage counterparts. Tomato distributors had the largest average gross revenue of any other category of decision-makers, exceeding ten million dollars. The average for strawberry distributors was less than 2.5 million. One of the most significant contrasts in firm attributes occurs for affiliation at the distribution stage. Only 28 percent of the tomato distributors interviewed were affiliated with other market stages while over eighty percent of the strawberry distributors were affiliated. It appears likely that the strawberry sample included some observations representing road side stands or produce markets. In contrast, the sample set for tomato distributors appears to be represented for the most part by large grocery chains.

Conclusions and Recommendations

Conclusions

Significant differences exist in the occurrence of pesticide residues between strawberries and tomatoes and along marketing channels for each commodity. Some of these differences are due to EPA regulatory guidelines which permit the use of some pesticides on one commodity but not the other. In large part though, it is believed that most of the differences are due to cultural and handling differences used to produce and distribute them. These in turn are probably the result of each commodity's inherent botanical/cultural characteristics and the institutionalized operating procedures that have evolved around these differences and the particular characteristics of the markets these commodities serve.

The average level of residues in the strawberries and tomatoes sampled in this study were generally quite low when compared to EPA tolerances. Only two of the 321 samples in the study contained residues above EPA tolerances when those tolerances were greater than zero. Thirty-three of the 247 tomato samples contained the insecticide Acephate, which has a zero tolerance for this commodity. All of these above tolerance tomato samples originated from a single large grower during a single season. The overall level of residues found in the strawberry and tomato samples used for this study may be biased upward due to the non-random sampling techniques used by FDACS-CRL. This bias should not affect implications concerning the relative differences in types and levels of residues found in the two commodities. In general, the findings of this study indicate that the levels of pesticides found in fresh strawberries and tomatoes grown in Florida are quite low, and should be considered safe.

Overall, strawberries carry a higher pesticide residue load than tomatoes.This difference may be a function of physiological, cultural and economic characteristics of strawberries and their production. Strawberries are highly perishable, often due to fungus growth. As a result, growers may apply fungicides up to the point of harvest, presuming that fungicide residues left on the fruit after harvest will increase its shelf life downstream in the market channel. Also, strawberry production has a significantly higher dollar value per acre than do tomatoes. Consequently pesticide applications on strawberries will likely have a higher marginal value product and thus be used more frequently. The dramatically higher level of Captan residues in strawberries is only partly a result of this economics. Captan has a relatively high EPA tolerance level (25 ppm) in strawberries compared to other pesticides. Fungicides like Captan are typically applied on a preventative basis. That is, it is not usually effective to wait until a fungus infestation has developed to apply these fungicides.

The difference in overall residue levels between strawberries and tomatoes increases going from the grower to the packing and distribution stages. While the levels of pesticide residues in tomatoes declines rather dramatically as they move down the market channel, residues levels in strawberries tend to increase (Figure 1). This may be the result of the differences in the typical processing and storage practices used for each commodity. All tomatoes are sent through packing operations before shipment which involves washing and rinsing. Tomatoes are then stored at temperatures approximately 20 degrees higher (Fahrenheit) than those for strawberries. Most strawberries are packed directly in consumer marketable containers during harvest in the field. Consequently there is little opportunity for residues present on strawberries at harvest to be physically removed or break down as they move toward consumption.

Residues from pesticides in tomatoes were dominated by insecticides and miticides. Methamidophos was the predominant insecticide residue on tomatoes at all market stages. Maneb was the predominate fungicide found in tomatoes at the grower stage, but at the distributor stage, Chlorothalonil was the only fungicide detected. Since tomatoes are a warmer season crop than strawberries, it is not unreasonable to speculate that insects would present a greater pest threat or control problem than fungus or disease.

There may be some influence on residue levels between commodities due to the socio-demographic differences between strawberry and tomato growers. Tomato growers appear to possess and rely more on education and less on experience than strawberry growers. Thus tomato growers may be inclined to use more modern pest control strategies such as integrated pest management, thereby possibly reducing their use of pesticides and the residues left behind. A comparison of the relative size of strawberry and tomato growers based on acreage and gross revenue shows that strawberry production is much more capital intensive than tomato production. Again, this can encourage higher use of pesticide inputs in strawberries from an economic stand point.

Socio-economic differences between strawberry and tomato packers were minor compared to difference at the grower and distributor stages. Difference between strawberry and tomato distributors were similar to those between growers except in terms of affiliation with other market stages. At this stage 83 percent of strawberry distributors were affiliated compared to 28 percent for tomatoes, the reverse of the situation at the growers stage. It is suspected that a significant proportion of strawberry distributors sampled in the survey were road-side stands that were directly affiliated with growing enterprises.

Recommendations

Clearly the type and level of pesticide residues found on a particular commodity are highly determined by their inherent physiological and agronomic characteristics as well as the typical procedures or practices used in their production and handling down through the market channel. In the case of Florida strawberries verses tomatoes, the dietary risk from the consumption of residues on tomatoes should be significantly lower than that which would be estimated based on random samples collected in the harvest field since most tomatoes are washed prior to distribution and consumption. On the other hand, since most strawberries are packed directly into consumer containers in the field during harvest and not washed prior to shipment, then dietary intake estimates and tolerance settings based on harvest fields levels may be appropriate. Consequently, it is recommended that government agencies involved in the determination of safe residue tolerances and/or the monitoring of residue levels in foods consider these differences in production and handling practices when carrying out their mandates.

The differences in the types of pesticides found on tomatoes and strawberries in this study leads to the recommendation that research on control strategies to reduce the use and reliance on chemical pesticides should be individually tailored to each commodity. The physiological characteristics of each commodity in combination with the climatelogical conditions under which they are produced and stored determine a unique set of pest control problems and thus control treatments and strategies.

Bibliography

EPA, FDA USDA., Joint Release on Food Safety/Pesticides by EPA, FDA, USDA. September 21, 1993. Release No. 0815.93 "Clinton Administration Proposes Strengthening the Nation's Pesticide and Food Safety Laws."

Hubbell, Bryan J. and Gerald A. Carlson., "Fruit and Vegetable Pesticide Characteristics.", 1993, Draft.

Figures and Equations

Figure 1. 

Percent of Strawberry and Tomato samples with no detectable residues of different types of pesticides at the grower, packer, and distributor market stages, collected between October, 1990 and June, 1993.


[Click thumbnail to enlarge.]

Figure 2. 

Percent of specific types of fungicide residues found in Florida strawberries at different market stages, collected between October, 1990 and June, 1993.


[Click thumbnail to enlarge.]

Figure 3. 

Percent of specific types of insecticide residues found in Florida strawberries at different market stages, collected between October, 1990 and June, 1993.


[Click thumbnail to enlarge.]

Figure 4. 

Percentage of specific types of fungicide residues found in Florida tomatoes at different market stages collected between October, 1990 and June, 1993.


[Click thumbnail to enlarge.]

Figure 5. 

Percentage of specific types of insecticide residues found in Florida tomatoes at different market stages, collected between October, 1990 and June, 1993.


[Click thumbnail to enlarge.]

Equation 1. 

Equation 2. 

Tables

Table 1. 

EPA Tolerances for pesticide residues found in tomato and strawberry samples collected by FDACS Chemical Residue Laboratory between October, 1990 and June, 1993.

EPA Name

EPA Title 40 Article No. 1

Trade Name

Pest Type2

Found in3

Strawberry tolerance ppm.

Tomato tolerance ppm.

Acephate

180-108

Orthene

I

T

0.00

0.00

Captan

180-103

Captan

F

S

25.00

25.00

Carbaryl

180-169

Sevin

I

S

10.00

10.00

Chlorothalonil

180-275

Bravo / Daconil

F

S&T

0.00

5.00

Chlorpyrifos

180-342

Lorsban

I

T

0.50

0.50

DCPA

180-185

Dacthal

H

S&T

2.00

1.00

Diazinon

180-153

Diazinon

I

S&T

0.50

0.75

Dicofol

180-163

Kelthane

M

S

5.00

5.00

Endosulfan

180-182

Thiodan

I/M

S&T

2.00

2.00

Ethion

180-173

Ethion

I/M

T

2.00

2.00

Iprodione

180-399

Rovral

F

S

15.00

0.00

Malathion

180-111

Cythion

I

S

8.00

8.00

Maneb

180-110

Manzate/Dithane

F

T

0.00

5.00

Methamidophos

180-315

Monitor

I/M

T

0.00

1.00

Methomyl

180-253

Lannate

I

S&T

2.00

1.00

Mevinphos

180-157

Phosdrin

I/M

S

1.00

0.20

Parathion

180-121

Parathion

I/M

T

1.00

1.00

Permethrin (B)

180-378

Ambush/Pounce

I

S&T

0.00

2.00

Vinclozolin

180-380

Ronilan

F

S&T

10.00

3.00

1Code of Federal Regulations, Title 40, "Protection of Environment." Chapter 1, Subchapter E, Part 180. Office of the Federal Register, Washington, D.C.

2 M = Miticide, F = Fungicide, H = Herbicide, I = Insecticide.

3 S = Strawberries, T = Tomatoes.

Table 2. 

Descriptive statistics of pesticide residues found in 47 grower samples of Florida strawberries, collected between October, 1990 and June, 1993.

 

Type1 of Pesticide

Tolerance in ppm.2

Number of samples with no residue detected

Proportion of samples with no residue detected

Proportion of samples with residue > tolerance

Max. ppm.

Mean ppm.3

Standard Error

Captan

F

25

4

8.51%

0.00%

21.00

4.6189

0.8011

Chlorothalonil

F

0

46

97.87%

2.13%

1.47

0.0313

0.0313

Iprodione

F

15

40

85.11%

0.00%

2.21

0.1196

0.0648

Vinclozolin

F

10

37

78.72%

0.00%

2.03

0.1505

0.0688

Malathion

I

8

45

95.74%

0.00%

2.66

0.0602

0.0566

Methomyl

I

2

41

87.23%

2.13%

3.07

0.1027

0.0700

Mevinphos

I/M

1

43

91.49%

0.00%

0.67

0.0319

0.0183

Diazinon

I

0.5

45

95.74%

0.00%

0.04

0.0013

0.0009

Endosulfan

I/M

2

40

85.11%

0.00%

0.78

0.0428

0.0238

DCPA

H

2

45

95.74%

0.00%

0.41

0.0126

0.0095

Fungicides

all F

 

2

4.26%

2.13%

21.00

4.9203

0.8080

Insecticides

all I/M

 

29

61.70%

2.13%

3.10

0.2388

0.0915

Pesticides

all F & I/M

 

1

2.13%

4.26%

21.00

5.5483

0.8653

1 For type of pesticide: F = fungicide, H = herbicide, I = Insecticide, and M = miticide.

2 Pesticide tolerances are in parts per million and obtained from the Code of Federal Regulations, title 40, "Protection of Environment." Chapter 1, Subchapter E, Part 180. Office of the Federal Register, Washington D.C.

3 The mean residue level of individual pesticide j is computed as (equation 1) , with k = 1 ... n observations or samples.The mean of aggregate residues of pesticide type i are computed as (equation 2) , with k = 1 ... n observations or samples and j = 1 ... m individual pesticides of type i. The mean of all pesticide residues is similarly calculated.

Table 3. 

Descriptive statistics of pesticide residues found in 87 grower samples of Florida tomatoes, collected between October, 1990 and June 1993.

 

Type of Pesticide1

Tolerance in ppm. 2

Number of samples no residue detected

Proportion of samples with no residue detected

Proportion of samples with residue > tolerance

Max. ppm.

Mean ppm.3

Standard Error

Chlorothalonil

F

5

67

77.01%

0.00%

0.23

0.0107

0.0042

Maneb

F

5

78

89.66%

0.00%

1.10

0.0395

0.0186

Chlorpyrifos

I

0.5

66

75.86%

0.00%

0.07

0.0020

0.0008

Endosulfan

I/M

2

44

50.57%

0.00%

0.96

0.0422

0.0137

Methamidophos

I/M

1

42

48.28%

0.00%

0.56

0.0747

0.0127

Methomyl

I

1

86

98.85%

0.00%

0.02

0.0002

0.0002

Parathion

I/M

1

84

96.55%

0.00%

0.01

0.0002

0.0001

Permethrin

I

2

87

100.00%

0.00%

0.00

0.0000

0.0000

Acephate

I

0

63

72.41%

27.59%

4

0.41

0.0684

0.0128

Fungicides

all F

 

58

66.67%

0.00%

1.10

0.0502

0.0188

Insecticides

all I/M

 

27

31.03%

27.59%

1.01

0.1877

0.0221

Pesticides

all F & I/M

 

13

14.94%

27.59%

1.24

0.2379

0.0271

1, 2, 3 See notes from Table 2.

4 Samples containing residues of Acephate came from a single large grower.

Table 4. 

Descriptive statistics of pesticide residues found in 19 packer samples of Florida strawberries, collected between October, 1990 and June 1993.

 

Type of Pesticide1

Tolerance in ppm. 2

Number of samples no residue detected

Proportion of samples with no residue detected

Proportion of samples with residue > tolerance

Max. ppm.

Mean ppm.3

Standard Error

Captan

F

25

2

10.53%

0.00%

13.72

3.3616

0.9271

Chlorothalonil

F

0

19

100.00%

0.00%

0.00

0.0000

0.0000

Iprodione, parent

F

15

17

89.47%

0.00%

0.41

0.0342

0.0244

Vinclozolin

F

10

17

89.47%

0.00%

0.22

0.0118

0.0116

Malathion

I

8

19

100.00%

0.00%

0.00

0.0000

0.0000

Methomyl

I

2

17

89.47%

0.00%

0.43

0.0384

0.0269

Mevinphos

I/M

1

16

84.21%

0.00%

0.49

0.0489

0.0320

Diazinon

I

0.5

19

100.00%

0.00%

0.00

0.0000

0.0000

Endosulfan

I/M

2

16

84.21%

0.00%

0.64

0.0674

0.0394

DCPA

H

2

19

100.00%

0.00%

0.00

0.0000

0.0000

Fungicides

all F

 

2

10.53%

0.00%

13.72

3.4318

0.9277

Insecticides

all I/M

 

12

63.16%

0.00%

5.15

0.4758

0.2704

Pesticides

all F & I/M

 

2

10.53%

0.00%

14.67

3.9076

1.0345

1, 2, 3 See notes from Table 2.

Table 5. 

Descriptive statistics of pesticide residues found in 122 packer samples of Florida tomatoes, collected between October, 1990 and June 1993.

 

Type of Pesticide1

Tolerance in ppm. 2

Number of samples no residue detected

Proportion of samples with no residue detected

Proportion of samples with residue > tolerance

Max. ppm.

Mean ppm.3

Standard Error

Chlorothalonil

F

5

112

91.80%

0.00%

0.67

0.0089

0.0057

Maneb

F

5

109

89.34%

0.00%

0.42

0.0118

0.0050

Chlorpyrifos

I

0.5

116

95.08%

0.00%

0.03

0.0007

0.0004

Endosulfan

I/M

2

93

76.23%

0.00%

0.20

0.0090

0.0027

Methamidophos

I/M

1

85

69.67%

0.00%

0.87

0.0499

0.0121

Methomyl

I

1

122

100.00%

0.00%

0.00

0.0000

0.0000

Parathion

I/M

1

121

99.18%

0.00%

0.01

0.0000

0.0000

Permethrin

I

2

121

99.18%

0.00%

0.26

0.0021

0.0021

Acephate

I

0

115

94.26%

5.74%

4

0.47

0.0196

0.0074

Fungicides

all F

 

99

81.15%

0.00%

0.67

0.0207

0.0075

Insecticides

all I/M

 

64

52.46%

5.74%

1.00

0.0813

0.0160

Pesticides

all F & I/M

 

43

35.25%

5.74%

1.00

0.1021

0.0170

1, 2, 3 See notes from Table 2.

4 Samples containing residues of Acephate came from a single large grower.

Table 6. 

Descriptive statistics of pesticide residues found in 7 distributor samples of Florida strawberries, collected between October, 1990 and June 1993.

 

Type of Pesticide1

Tolerance in ppm. 2

Number of samples no residue detected

Proportion of samples with no residue detected

Proportion of samples with residue > tolerance

Max. ppm.

Mean ppm.3

Standard Error

Captan

F

25

1

14.29%

0.00%

17.81

8.9636

3.0437

Chlorothalonil

F

0

7

100.00%

0.00%

0.00

0.0000

0.0000

Iprodione, parent

F

15

7

100.00%

0.00%

0.00

0.0000

0.0000

Vinclozolin

F

10

4

57.14%

0.00%

0.46

0.0764

0.0647

Malathion

I

8

7

100.00%

0.00%

0.00

0.0000

0.0000

Methomyl

I

2

6

85.71%

0.00%

0.54

0.0771

0.0771

Mevinphos

I/M

1

6

85.71%

0.00%

0.16

0.0229

0.0229

Diazinon

I

0.5

7

100.00%

0.00%

0.00

0.0000

0.0000

Endosulfan

I/M

2

6

85.71%

0.00%

0.12

0.0171

0.0171

DCPA

H

2

6

85.71%

0.00%

0.10

0.0143

0.0143

Fungicides

all F

 

0

0.00%

0.00%

17.81

9.0400

3.0154

Insecticides

all I/M

 

5

71.43%

0.00%

0.54

0.1171

0.0808

Pesticides

all F & I/M

 

0

0.00%

0.00%

17.81

10.6371

2.6743

1, 2, 3 See notes from Table 2.

Table 7. 

Descriptive statistics of pesticide residues found in 39 distributor samples of Florida tomatoes, collected between October, 1990 and June 1993.

 

Type of Pesticide1

Tolerance in ppm. 2

Number of samples no residue detected

Proportion of samples with no residue detected

Proportion of samples with residue > tolerance

Max. ppm.

Mean ppm.3

Standard Error

Chlorothalonil

F

5

36

92.31%

0.00%

0.12

0.0033

0.0031

Maneb

F

5

39

100.00%

0.00%

0.00

0.0000

0.0000

Chlorpyrifos

I

0.5

38

97.44%

0.00%

0.01

0.0001

0.0001

Endosulfan

I/M

2

29

74.36%

0.00%

0.28

0.0226

0.0103

Methamidophos

I/M

1

30

76.92%

0.00%

0.37

0.0292

0.0141

Methomyl

I

1

39

100.00%

0.00%

0.00

0.0000

0.0000

Parathion

I/M

1

39

100.00%

0.00%

0.00

0.0000

0.0000

Permethrin

I

2

39

100.00%

0.00%

0.00

0.0000

0.0000

Acephate

I

0

38

97.44%

2.56%

4

0.01

0.0001

0.0001

Fungicides

all F

 

36

92.31%

0.00%

0.12

0.0033

0.0031

Insecticides

all I/M

 

25

64.10%

2.56%

0.64

0.0521

0.0208

Pesticides

all F & I/M

 

23

58.97%

2.56%

0.64

0.0554

0.0209

1, 2, 3 See notes from Table 2.

4 Samples containing residues of Acephate came from a single large grower.

Table 8. 

T-tests and P-values for statistical differences in average pesticide residue levels between market stages for Florida strawberries and tomatoes (2 failed tests).1

 

Strawberries

Tomatoes

 

Fungicide residues

Insecticide residues

Pesticide residues

Fungicide residues

Insecticide residues

Pesticide residues

Packer-

t-Test

-1.0605

1.0622

-1.0836

-1.6282

-4.0049

-4.4537

Grower

P-value

0.2940

0.2938

0.2836

0.1072

0.0001

0.0000

Distributor

t-Test

2.3896

-0.7904

2.8884

-1.2981

-0.9541

-1.4464

-Packer

P-value

0.0268

0.4402

0.0088

0.1967

0.3419

0.1507

Distributor

t-Test

1.7315

-0.5054

2.0675

-1.6659

-3.7776

-4.2520

-Grower

P-value

0.0895

0.6158

0.0438

0.0994

0.0003

0.0001

1 A negative test value indicates that the average downstream market stage pesticide residue level was less than the upstream market stage, i.e., t=packer average residue levels - grower average residue levels.

Table 9. 

Descriptive statistics for Florida strawberry growers/decision-makers.

 

Age

Education 1

Experience

Total acres

% acres owned

Gross rev. 2

Affiliation

Minimum

29

1

4

1

0

1

0 = No

Maximum

75

5

58

420

100

6

1 = Yes

Count

40

41

41

40

40

38

41

Mean

49.93

2.59

20.78

50.03

51

2.58

0.44

Standard error

1.93

0.22

2.18

11.73

7

0.19

0.08

Median

47

2

17

35.5

59

2

0

Standard deviation

12.34

1.43

13.96

75.11

44

1.22

0.50

Coeff. of variation

0.25

0.55

0.67

1.50

85

0.47

1.14

1 Education was divided into eight categories so that: 1 was less than high school; 2 was completion of high school; 3 was vocational training after high school; 4 was some college; 5 was completion of college; 6 was some or completion of graduate school.

2Gross Revenue was also divided into eight categories so that: 1 ranged from $1.00 to $50,000; 2 ranged from $50,001 to $200,000; 3 ranged from $200,001 to $500,000; 4 ranged from $500,001 to $1,000,000; 5 ranged from $1,000,001 to $2,500,000; 6 ranged from 2,500,001 to $10,000,000; 7 ranged from $10,000,001 to $25,000,000 and; 8 was greater than $25,000,000.

Table 10. 

Descriptive statistics for Florida tomato growers/decision-makers and their operations (including green houses).

 

Age

Education 1

Experience

Total acres

% acres owned

Gross rev. 2

Affiliation

Minimum

26

1

2

0.82

0

1

0 = No

Maximum

73

6

38

6200

100

8

1 = Yes

Count

35

35

35

34

34

32

35

Mean

48.94

3.46

12.63

503.01

67

3.13

0.74

Standard error

1.98

0.25

1.22

250.44

7

0.37

0.07

Median

46

4

12

30

100

2.5

1

Standard deviation

11.69

1.48

7.24

1481.64

43

2.18

0.44

Coeff. of variation

0.24

0.43

0.57

2.95

0.64

0.70

0.60

1,2 See footnotes from Table 9.

Table 11. 

Descriptive statistics for Florida tomato growers/decision-makers and their operations (excluding green houses).

 

Age

Education 1

Experience

Total acres

% acres owned

Gross rev. 2

Affiliation

Minimum

26

1

2

6

0

1

0 = No

Maximum

65

6

38

6200

100

8

1 = Yes

Count

25

25

25

24

24

22

25

Mean

47.84

3.56

14.84

711.83

53

4.00

0.72

Standard error

1.76

0.27

1.24

292.53

8

0.35

0.08

Median

46

4

14

67.5

7

3.5

1

Standard deviation

10.39

1.58

7.34

1730.61

45

2.09

0.46

Coeff. of variation

0.22

0.44

0.49

2.43

84

0.52

0.64

1, 2 See footnotes from Table 9.

Table 12. 

Descriptive statistics for Florida strawberry packer decision-makers and operations.

 

Age

Education 1

Experience

Gross Rev. 2

Affiliation

Minimum

35

2

4

4

0 = No

Maximum

66

6

35

8

1 = Yes

Count

10

10

10

10

10

Mean

47.30

3.90

19.60

6.40

0.70

Standard Error

14.96

1.23

6.20

2.02

0.22

Median

40.5

4

16.5

6.5

1

Standard Deviation

12.38

1.45

11.06

1.43

0.48

Coeff. of Variation

0.26

0.37

0.56

0.22

0.69

1, 2 See footnotes from Table 9.

Table 13. 

Descriptive statistics for Florida tomato packer decision-makers and operations.

 

Age

Education 1

Experience

Gross Rev. 2

Affiliation

Minimum

20

1

4

1

0 = No

Maximum

68

6

40

8

1 = Yes

Count

34

35

35

28

35

Mean

44.91

3.57

16.31

6.04

0.71

Standard Error

7.70

0.60

2.76

1.14

0.12

Median

45

4

14

6

1

Standard Deviation

10.47

1.38

9.48

1.79

0.46

Coeff. of Variation

0.23

0.39

0.58

0.30

0.64

1 , 2 See footnotes from Table 9.

Table 14. 

Descriptive statistics for Florida strawberry distributor decision-makers and operations.

 

Age

Education 1

Experience

Gross Rev. 2

Affiliation

Minimum

30

1

4

2

0 = No

Maximum

66

5

45

8

1 = Yes

Count

6

6

6

5

6

Mean

45.50

2.83

24.17

4.60

0.83

Standard Error

12.07

1.16

9.87

2.06

0.34

Median

39.50

2.50

19.00

4.00

1.00

Standard Deviation

14.46

1.47

17.06

2.41

0.41

Coeff. of Variation

0.71

0.52

0.71

0.52

0.49

1, 2 See footnotes from Table 9.

Table 15. 

Descriptive statistics for Florida tomato distributor decision-makers and operations.

 

Age

Education 1

Experience

Gross Rev. 2

Affiliation

Minimum

27

1

1

1

0 = No

Maximum

63

6

50

8

1 = Yes

Count

18

18

18

17

18

Mean

42.28

3.39

14.33

6.76

0.28

Standard Error

6.65

0.80

3.38

1.64

0.07

Median

42.00

3.50

13.50

8.00

0.00

Standard Deviation

9.57

1.69

11.85

2.41

0.46

Coeff. of Variation

0.50

0.50

0.83

0.36

1.66

1 , 2 See footnotes from Table 9.

Footnotes

1.

This document is BUL331, one of a series of the Food and Resource Economics Department, UF/IFAS Extension. Original publication date December 1999. Reviewed June 2015. Visit the EDIS website at http://edis.ifas.ufl.edu.

2.

Thomas J. Stevens III, post-doctoral associate; and Richard L. Kilmer, professor, Food and Resource Economics Department, UF/IFAS Extension, Gainesville, FL 32611.


The Institute of Food and Agricultural Sciences (IFAS) is an Equal Opportunity Institution authorized to provide research, educational information and other services only to individuals and institutions that function with non-discrimination with respect to race, creed, color, religion, age, disability, sex, sexual orientation, marital status, national origin, political opinions or affiliations. For more information on obtaining other UF/IFAS Extension publications, contact your county's UF/IFAS Extension office.

U.S. Department of Agriculture, UF/IFAS Extension Service, University of Florida, IFAS, Florida A & M University Cooperative Extension Program, and Boards of County Commissioners Cooperating. Nick T. Place, dean for UF/IFAS Extension.