Open Access

Chronic dietary exposure to pesticide residues in the United States

International Journal of Food Contamination20152:11

https://doi.org/10.1186/s40550-015-0018-y

Received: 17 April 2015

Accepted: 27 June 2015

Published: 10 July 2015

Abstract

Background

Discussions as to the extent of pesticide residue contamination in the food supply often rely on results of government residue monitoring programs focusing primarily upon the percentages of samples containing pesticide residues and the number of violative residues identified. Such an approach does not adequately convey the likelihood of pesticide residues posing consumer risks since residue regulatory limits are not safety standards and violative pesticide residues rarely constitute residues of health concern. It is more appropriate to develop estimates of actual dietary exposure to pesticides and to compare such estimates to established toxicological criteria such as the Chronic Reference Dose (RfD). The U.S. Food and Drug Administration’s (FDA) Total Diet Study (TDS) previously provided such information but last published its findings in 1995 to estimate dietary exposure to pesticides detected between 1986 and 1991. This paper provides updated estimates of dietary exposure to pesticides in the United States using the most recent TDS findings on pesticide residues.

Results

A total of 77 specific pesticides were detected from market basket samples of 2240 TDS food items analyzed by FDA in 2004 and 2005. All estimated exposures to the 77 pesticides for the General US population were well below chronic RfD levels. Only 3 of the 77 pesticides showed exposures greater than 1 % of chronic RfDs, while 14 showed exposures between 0.1 and 1 % of chronic RfDs and 19 had exposures between 0.01 and 0.1 % of chronic RfDs. The remaining 41 pesticides had exposures below 0.01 % of chronic RfDs.

Compared with 1986–1991 findings, dietary exposure to six environmentally persistent chlorinated hydrocarbon insecticides were reduced by factors of 47 to 96 % in 2004–2005. Exposures to 15 different population subgroups were estimated and indicated that children, particularly two year-olds, frequently receive higher exposures to pesticide residues in their diets than do adults.

Conclusions

Chronic dietary exposure to pesticides in the diet, according to results of the FDA’s 2004–2005 TDS, continue to be at levels far below those of health concern. Consumers should be encouraged to eat fruits, vegetables, and grains and should not fear the low levels of pesticide residues found in such foods.

Keywords

Pesticides Food safety Risk assessment Exposure assessment Total diet study Reference dose

Background

Residues of pesticide chemicals are frequently detected on the edible portions of foods and consumers are routinely exposed to pesticide residues in their diets. The extent of pesticide contamination in the food supply is often discussed in terms of the results of regulatory monitoring conducted by bodies such as the U.S. Food and Drug Administration (FDA) and the European Food Safety Authority (EFSA). In 2012, FDA monitoring results of 1,158 domestic samples showed that 57 % had no detectable residues while 2.8 % contained violative pesticide residues (FDA 2015). Among the 4,365 imported food samples analyzed, 66 % had no detectable residues while violations were detected on 11.1 % of the samples. EFSA reported on the analysis of 80,967 food samples collected in 2013 and concluded that 54.6 % of the samples had no detectable residues while 2.6 % of the samples resulted in violations (EFSA 2015).

Such findings may be confusing to consumers since the majority of samples contained no detectable residues of pesticides although pesticide residue violations also frequently occurred. Unfortunately, while counterintuitive, the recitation of findings from regulatory monitoring programs is of little value in terms of assessing the potential health risks posed by pesticide residues in foods. This is primarily due to the fact that the allowable levels are not indicators of safety but rather reflect enforcement tools to assess whether Good Agricultural Practices have been followed (Winter, 1992). As such, residue violations often indicate breaches of Good Agricultural Practices but only in very rare circumstances represent cases of health concern. To clarify the differences between allowable pesticide residue levels and levels of health significance, a companion system to establish levels of safety concerns for specific pesticides on specific food items has been proposed (Winter and Jara, 2015).

The potential health risks posed by pesticide residues in foods can best be assessed by developing estimates of dietary exposure to pesticides and comparing exposure estimates to toxicological indicators of health concern such as the Chronic Reference Dose (RfD) or the analogous Acceptable Daily Intake (ADI). An accurate estimation of dietary pesticide exposure requires data on specific levels of pesticide residues detected (not just whether the residues were legal or violative) as well as estimations of consumption amounts of all foods for which residues are detected.

The FDA has conducted the Total Diet Study (TDS) annually since 1961 (Gunderson 1995). The TDS uses a market basket approach in which FDA inspectors purchase market baskets of 280 food items from retail locations in various regions of the country. The food items are prepared for consumption and then analyzed for potential food contaminants such as radionuclides and pesticide residues as well as for metals and selected nutrients. Food consumption estimates for the TDS diets are derived from national food consumption databases. By multiplying the levels of pesticide residues found on the food items by food consumption estimates, it is possible to obtain an estimate of chronic dietary exposure to pesticide residues in foods.

Historically, FDA released its estimates of chronic dietary exposure to pesticides obtained from TDS findings and compared exposure estimates to ADI levels. Unfortunately, the last public report of such findings was made in 1995 and estimated dietary exposure to pesticides from TDS market baskets collected between 1986 and 1991 (Gunderson 1995). Thus, while FDA continues to analyze TDS samples for pesticide residues, it has not made its findings of TDS consumer exposure to pesticides available for two decades.

At the same time, FDA does release the analytical data resulting from subsequent TDS market baskets as well as food consumption estimates for each of the TDS foods. It is therefore possible to estimate dietary exposure to pesticides from TDS data and to compare exposure levels to chronic RfD or ADI levels.

This paper provides estimates of dietary exposure to pesticides based upon the most recent two years (2004 and 2005) for which TDS pesticide residue data are available. Exposure estimates are compared with chronic RfD values to determine the potential risks associated with the exposures. In addition, comparisons between exposures from the 2004–2005 and the 1986–1991 market baskets are made to identify longer-term trends in dietary exposure to pesticides.

Methods

Pesticide residue levels on the 280 TDS foods were obtained from FDA’s summary of pesticide residue findings for Market Baskets 2004–1 through 2005–4 (FDA 2014). While analytical methods were capable of detection of more than 300 pesticides and/or pesticide metabolites or breakdown products, residues were detected for 77 specific pesticides. According to FDA guidelines, a value of 0 was assigned for residues below the analytical method’s limit of detection while trace findings were reported at the measured value.

Food consumption estimates for each of the 280 TDS foods were acquired by downloading FDA’s “TDS Diets, Version 3” (FDA 2013). Food consumption estimates were derived from the results of the United States Department of Agriculture’s 1994–96 and 1998 Continuing Survey of Food Intakes by Individuals. Consumption estimates were expressed in terms of grams of food per day and were separated into 15 population subgroups: Total US population, infants 6–11 months, children 2 years, children 6 years, children 6–10 years, males (14–16 years, 25–30 years, 40–45 years, 60–65 years, 70 years) and females (14–16 years, 25–30 years, 40–45 years, 60–65 years, 70 years).

To estimate dietary exposure to specific pesticides for each of the population subgroups, the mean residue level (expressed in mg/kg) found on a specific TDS food was multiplied by the food consumption estimate to yield an estimate of the daily exposure to the pesticide on that food. If, as was common, a pesticide was detected on more than one TDS food, contributing exposures from each food were combined to yield a daily exposure estimate to the pesticide.

To allow direct comparisons between chronic RfD values and exposure estimates, daily pesticide exposure levels were divided by body weight levels estimated for each population subgroup (EPA 2011). Final chronic dietary exposures to specific pesticides for each population subgroup were then expressed in terms of nanograms pesticide/kg body weight/day (ng/kg/day).

The methods used to estimate chronic dietary exposure to pesticides represent a simplistic deterministic approach in which residues are considered to be present at mean levels and food consumption estimates are chosen that represent the 50th percentile for each of the 280 foods considered. As such, the approach attempts to most accurately characterize typical chronic dietary exposure to pesticides. The use of higher percentiles of residue level or food consumption estimates would serve to artificially inflate exposure estimates. Deterministic methods using higher percentiles of residue levels and/or food consumption estimates are useful, and necessary, in assessing acute exposure to pesticides in foods but their use in a chronic exposure assessment is not warranted.

Chronic RfD values for specific pesticides were primarily obtained from the Integrated Risk Information System (IRIS) used by the United States Environmental Protection Agency (EPA). The chronic RfD represents an estimate of the amount of a chemical an individual could be exposed to daily throughout the individual’s lifetime that is likely to be without an appreciable risk of harm (Winter and Francis 1997). In some cases, chronic RfD values were not available through IRIS but could be identified through documents discussing EPA Pesticide Reregistration Eligibility Decisions for specific pesticides. Chronic RfD values were not obtained for the pesticides azinphos-methyl, chlorpyrifos-methyl, dicloran, dicofol, fenhexamid, omethoate, phenylphenol-ortho, quinoxyfen, tecnazene, thiabendazole, triadimefon, and trifloxystrobin; ADI values from the literature were chosen as chronic RfD surrogates for each of these pesticides.

Results and discussion

The FDA analyzed a total of 2240 food items (8 market baskets x 280 items per market basket) in its 2004 and 2005 TDS for residues of more than 300 pesticides and/or metabolites and breakdown products. Residues of 77 pesticides were detected.

The estimated chronic dietary exposures to the 77 pesticides for the General US population are compared with chronic RfD values in Table 1. Exposure levels to all 77 pesticides were below chronic RfD values. Exposures to 3 pesticides exceeded 1 % of the chronic RfD values while exposures between 0.1 and 1 % of chronic RfD values were noted for 14 pesticides. Another 19 pesticides demonstrated exposures between 0.01 and 0.1 % of the chronic RfD values, while exposures for the other 41 pesticides were below 0.01 % of the chronic RfD. The median exposure relative to the chronic RfD for the 77 pesticides was for the fungicide captan, with an exposure of 0.0074 % of the chronic RfD.
Table 1

Comparison of General US dietary exposure to pesticides with Chronic Reference Doses (RfDs)

Pesticide

General US

Chronic RfD

%RfD

 

Exposure

(ng/kg/day)

 
 

(ng/kg/day)

  

Acephate

18.4281

4000

0.4607

Atrazine

0.0072

35000

<0.0001

Azinphos-methyl

11.1229

5000

0.2225

Azoxystrobin

1.1496

180000

0.0006

Benomyl

9.2942

50000

0.0186

Bifenthrin

0.9997

15000

0.0067

Biphenyl

0.3963

500000

0.0001

Captan

9.6072

130000

0.0074

Carbaryl

10.2073

100000

0.0102

Carbofuran

0.3657

5000

0.0073

Chlordane (total)

0.0992

500

0.0198

 Chlordane, cis

0.0479

  

 Chlordane, trans

0.0125

  

 Nonachlor, trans

0.0367

  

 Octachlor epoxide

0.0020

  

Chloropropham

287.7204

200000

0.1439

Chlorothalonil

0.1205

15000

0.0008

Chlorpyrifos

2.3760

3000

0.0792

Chlorpyrifos-methyl

12.7964

10000

0.1280

Clopyralid

0.8296

150000

0.0006

Coumaphos

0.0068

700

0.0010

Cyfluthrin

0.2220

24000

0.0009

Cypermethrin

8.9699

10000

0.0897

Cyprodinil

12.9971

37500

0.0347

2,4-D

0.6738

10000

0.0067

DCPA

0.2398

10000

0.0024

DDT, total

6.6482

500

1.3296

 DDE, p, p’

5.9085

  

 DDT, o, p’

0.0120

  

 DDT, p, p’

0.1471

  

 TDE, o, p’

0.0258

  

 TDE, p, p’

0.5547

  

DEF

0.1086

100

0.1086

Diazinon

0.2394

200

0.1197

Dicamba

0.7488

30000

0.0025

Dichloran, total

2.9128

2500

0.1165

 Dichloran

2.8691

  

 2,4-Dichloro-6-nitrobenzeneamine

0.0437

  

Dicofol, total

0.3547

200000

0.0002

 Dicofol, o, p’

0.0345

  

 Dicofol, p, p’

0.3201

  

Dieldrin

0.9841

50

1.9683

Dimethoate

1.5595

200

0.7797

Diphenylamine

79.6903

25000

0.3188

Endosulfan, total

9.3737

6000

0.1562

 Endosulfan I

1.6268

  

 Endosulfan II

2.1831

  

 Endosulfan sulfate

5.5638

  

Endrin

0.0228

300

0.0076

Esfenvalerate

0.0281

1800

0.0016

Ethion, total

0.4912

500

0.0982

 Ethion

0.4869

  

 Ethion, oxygen analog

0.0043

  

Ethoxyquin

0.5940

20000

0.0030

Famoxadone

0.1185

1400

0.0085

Fenarimol

0.0196

65000

<0.0001

Fenhexamid

0.9919

200000

0.0005

Fenitrothion

0.0132

1500

0.0009

Fenoxaprop-ethyl

0.0002

15000

<0.0001

Fenpropathrin

3.3847

25000

0.0135

Fenvalerate

0.3790

25000

0.0015

Fludioxonil

21.1253

30000

0.0704

Heptachlor

0.0593

13

0.4563

Imazalil

0.5742

13000

0.0044

Iprodione, total

6.4931

40000

0.0162

 Iprodione

6.1491

  

 Iprodione metabolite

0.3441

  

Lambda-cyhalothrin

0.6892

5000

0.0138

Lindane

0.0693

300

0.0231

Linuron

0.2379

2000

0.0119

Malathion

29.6982

20000

0.1485

Metalaxyl

1.0858

60000

0.0018

Methamidophos

7.9984

50

15.9968

Methidathion

0.9529

1000

0.0953

Methomyl

1.9347

25000

0.0077

Methoxychlor, total

0.0428

5000

0.0009

 Methoxychlor, o, p’

0.0173

  

 Methoxychlor, p, p’

0.0255

  

Mirex

0.0020

200

0.0010

Omethoate

0.8798

300

0.2933

Oxamyl

0.0466

25000

0.0002

Permethrin, total

73.4122

50000

0.1468

 Permethrin, cis

35.4246

  

 Permethrin, trans

37.9876

  

Phenylphenol, ortho

11.3419

20000

0.0567

Phosalone

0.0491

2000

0.0025

Phosmet

4.7271

20000

0.0236

Piperonyl butoxide

0.0029

6300000

<0.0001

Pirimiphos-methyl

6.3524

10000

0.0635

Procymidone

0.0247

35000

0.0001

Propargite

11.6608

20000

0.0583

Propiconazole

0.0002

13000

<0.0001

Quinclorac

1.0475

380000

0.0003

Quinoxyfen

0.2185

200000

0.0001

Quintozene

0.0743

3000

0.0025

Tecnazene

0.0008

20000

<0.0001

Thiabendazole

77.7198

100000

0.0777

Triadimefon

0.0033

10000

<0.0001

Triclopyr

0.0398

50000

0.0001

Trifloxystrobin

0.3277

100000

0.0003

Vinclozolin

0.8230

25000

0.0033

The determination of chronic RfD values requires assessment of the No Observed Adverse Effect Level (NOAEL), which represents the highest continuous dose given to the most sensitive animal species that does not demonstrate any noticeable toxicity (Winter and Francis 1997). The NOAEL levels are typically reduced using uncertainty factors (100 or, in some cases 1000) to produce the chronic RfD level. In the case of dietary exposure to a pesticide that represents 0.01 % of the chronic RfD, the exposure level (assuming the use of a 100 fold uncertainty factor in deriving the RfD) is one million times lower than levels that do not cause any noticeable effects in animals dosed continuously with the pesticide throughout their lifetimes. Thus, findings from this study reinforce the notion that typical consumer exposure to pesticide residues is at levels far below those of health concern.

The highest exposure of a pesticide relative to the chronic RfD was for methamidophos, which showed an exposure to the General US population of 16 % of the chronic RfD. Methamidophos is an organophosphate insecticide that shares a common toxicological mechanism with several other common insecticides. The estimated exposure to methamidophos for the General US population, 8.0 ng/kg/day, is actually lower than estimated exposures to other organophosphate insecticides such as malathion (29.7 ng/kg/day), acephate (18.4 ng/kg/day), chlorpyrifos-methyl (12.8 ng/kg/day), and azinphos-methyl (11.1 ng/kg/day). The reason that methamidophos poses a much greater exposure relative to the chronic RfD than do the other organophosphate insecticides is that it has an extremely low chronic RfD of 50 ng/kg/day. This low RfD is derived partly from the use of a 1000 fold uncertainty factor (rather than the typical 100 fold) and also from a toxicologically suspect low NOAEL of 50 μg/kg/day. Comparisons of the LD50 values for methamidophos and some of the most acutely toxic organophosphate insecticides do not indicate such disparities in toxicity.

The only other pesticides showing dietary exposure greater than 1 % of the chronic RfD were dieldrin (2.0 % of chronic RfD) and DDT (1.3 % of chronic RfD). Both of these pesticides are chlorinated hydrocarbon insecticides that have been banned from use for decades; their presence in food results from low environmental degradation and uptake from contaminated soil by plants.

Several other chlorinated hydrocarbon insecticides were also detected in the 2004–2005 TDS. To indicate trends in exposure to chlorinated hydrocarbon insecticides over time, it is possible to compare these findings with those of prior years. Table 2 shows the reduction in dietary exposure levels for two year-olds (the population subgroup associated with the greatest dietary exposure to pesticides) from dietary estimates using the 1986–1991 TDS data (Gunderson 1995) to dietary estimates using the 2004–2005 TDS data. Dietary exposures were reduced by between 47 and 96 % from 1986–1991 to 2004–2005 for the six chlorinated hydrocarbon insecticides studied.
Table 2

Comparison of chlorinated hydrocarbon insecticide dietary exposure for two year-olds, 2004–05 vs. 1986–91 a

Pesticide

2004–05 (ng/kg/day)

1986–91 (ng/kg/day)

Percentage reduction

DDT

23.18

43.8

47

Dicofol

1.52

35.5

96

Dieldrin

2.7

7.2

63

Heptachlor

0.15

2.5

94

Lindane

0.26

3.2

92

Methoxychlor

0.1

0.9

89

a1986–91 data obtained from Gunderson (1995)

Chronic dietary exposure estimates to the 77 pesticides for each of the 15 population subgroups is shown in Table 3. While there is significant variation in the exposure estimates for specific pesticides among the population subgroups, all exposures to all population subgroups were below chronic RfD levels. Table 3 also indicates that the highest exposures are typically observed in the younger population subgroups, as is expected since younger members of the population consume more food relative to their body weights than do older members of the population. For 51 of the 77 pesticides, population subgroup exposure was highest for two year-olds, while another 13 pesticides showed highest exposure for 6–11 month infants. Exposure to six year-olds was highest for 6 pesticides and exposure to 60–65 year-old females was highest for 4 pesticides. Three other population subgroups (10 year-olds, 14–16 year-old males, 70 year-old males) showed the highest dietary exposure to one pesticide each.
Table 3

Dietary pesticide exposure estimates for specific population subgroups (ng/kg/day) a

Pesticide

US General

6–11 month

M/F 2 years

M/F 6 years

M/F 10 year

F 14–16

Acephate

18.4281

17.2302

42.6352

29.8366

17.0595

8.5112

Atrazine

0.0072

0.0103

0.0203

0.0096

0.0052

0.0047

Azinphos-methyl

11.1229

32.5191

82.2131

47.7940

26.9670

9.1684

Azoxystrobin

1.1496

0.8092

4.6546

2.2937

2.1211

1.1600

Benomyl

9.2942

57.5515

70.8385

34.5814

17.4725

7.3732

Bifenthrin

0.9997

2.8008

2.1272

1.6090

0.6109

0.3124

Biphenyl

0.3963

0.8070

1.4732

1.1553

0.6452

0.4489

Captan

9.6072

7.0953

72.0200

34.5332

21.3902

9.9809

Carbaryl

10.2073

64.3193

83.9221

41.4619

18.4712

11.6797

Carbofuran

0.3657

0.2989

1.2256

1.3252

0.4160

0.1333

Chlordane (total)

0.0992

0.0698

0.1761

0.1504

0.1270

0.0739

Chlordane, cis

0.0479

0.0220

0.0914

0.0790

0.0598

0.0378

Chlordane, trans

0.0125

0.0146

0.0234

0.0172

0.0198

0.0086

Nonachlor, trans

0.0367

0.0296

0.0585

0.0511

0.0461

0.0267

Octachlor epoxide

0.0020

0.0036

0.0028

0.0032

0.0012

0.0007

Chloropropham

287.7204

242.2743

981.7293

785.8608

528.4143

351.6736

Chlorothalonil

0.1205

0.0000

0.2162

0.1754

0.1824

0.0259

Chlorpyrifos

2.3760

2.5690

9.8882

5.5129

3.8547

2.2513

Chlorpyrifos-methyl

12.7964

12.4004

40.6889

37.3143

23.2516

13.4883

Clopyralid

0.8296

2.3563

5.2877

3.2069

1.8738

0.6758

Coumaphos

0.0068

0.0025

0.0218

0.0109

0.0014

0.0028

Cyfluthrin

0.2220

0.0079

0.1208

0.1013

0.1664

0.0467

Cypermethrin

8.9699

8.1437

17.1238

10.4601

3.8659

6.0168

Cyprodinil

12.9971

11.9101

119.2924

47.1034

31.9188

14.6596

2,4-D

0.6738

0.5266

2.1795

1.8683

1.1665

0.5975

DCPA

0.2398

0.1450

0.5591

0.3654

0.2523

0.1717

DDT, total

6.6482

8.0532

23.1850

18.0708

11.8551

6.3338

DDE, p, p’

5.9085

7.3662

21.6413

16.9921

11.1399

5.7689

DDT, o, p’

0.0120

0.0062

0.0156

0.0098

0.0070

0.0100

DDT, p, p’

0.1471

0.3271

0.6385

0.3535

0.2306

0.1427

TDE, o, p’

0.0258

0.0530

0.0241

0.0231

0.0076

0.0122

TDE, p, p’

0.5547

0.3008

0.8654

0.6923

0.4700

0.4000

DEF

0.1086

0.0153

0.4647

0.3953

0.2353

0.1265

Diazinon

0.2394

0.0658

0.3905

0.3455

0.2217

0.2152

Dicamba

0.7488

2.2202

4.8366

3.0227

1.8074

0.6574

Dichloran, total

2.9128

6.4696

5.3965

3.9703

3.9514

1.6418

Dichloran

2.8691

6.4696

5.3180

3.9066

3.8853

1.6323

2,4-Dichloro-6-nitrobenzeneamine

0.0437

0.0000

0.0784

0.0636

0.0662

0.0094

Dicofol, total

0.3547

0.4972

1.5264

0.9061

0.6697

0.2927

Dicofol, o, p’

0.0345

0.0465

0.2390

0.1394

0.0934

0.0248

Dicofol, p, p’

0.3201

0.4508

1.2874

0.7667

0.5763

0.2679

Dieldrin

0.9841

1.5196

2.7181

2.1000

1.5493

0.7663

Dimethoate

1.5595

9.5053

6.1889

3.5457

1.8318

1.0376

Diphenylamine

79.6903

98.6515

606.5610

395.4847

180.9575

70.1601

Endosulfan, total

9.3737

11.0237

21.0158

16.0028

10.7486

6.8948

Endosulfan I

1.6268

1.8331

4.4537

3.0479

2.2759

1.4302

Endosulfan II

2.1831

2.4196

6.1116

4.1611

2.9966

1.8655

Endosulfan sulfate

5.5638

6.7710

10.4504

8.7938

5.4761

3.5992

Endrin

0.0228

0.0627

0.0158

0.0187

0.0025

0.0075

Esfenvalerate

0.0281

1.1880

0.1006

0.0843

0.0328

0.0416

Ethion, total

0.4912

0.1987

1.3184

1.3622

0.9313

0.6354

Ethion

0.4869

0.1979

1.3153

1.3588

0.9288

0.6332

Ethion, oxygen analog

0.0043

0.0008

0.0031

0.0035

0.0025

0.0022

Ethoxyquin

0.5940

0.0848

0.7868

1.6565

0.8585

1.0186

Famoxadone

0.1185

0.0042

0.0645

0.0541

0.0888

0.0249

Fenarimol

0.0196

0.0104

0.1187

0.0392

0.0066

0.0055

Fenhexamid

0.9919

0.8467

5.9062

2.5504

2.0440

1.0660

Fenitrothion

0.0132

0.0118

0.0191

0.0261

0.0146

0.0120

Fenoxaprop-ethyl

0.0002

0.1076

0.0002

0.0000

0.0000

0.0000

Fenpropathrin

3.3847

15.5940

25.9598

13.3071

7.3449

3.1080

Fenvalerate

0.3790

3.0032

1.0053

0.5161

0.2748

0.2500

Fludioxonil

21.1253

33.0302

66.5408

56.8803

13.5351

26.1458

Heptachlor

0.0593

0.0534

0.1478

0.1303

0.0978

0.0489

Imazalil

0.5742

0.1826

0.3263

0.1806

0.1094

0.0859

Iprodione, total

6.4931

11.0094

26.2975

18.0616

5.8599

7.8378

Iprodione

6.1491

10.3505

25.2904

17.2475

5.6553

7.4416

Iprodione metabolite

0.3441

0.6589

1.0071

0.8142

0.2046

0.3961

Lambda-cyhalothrin

0.6892

3.5221

1.2727

0.5294

0.2707

0.6808

Lindane

0.0693

0.0272

0.2586

0.2933

0.1840

0.0942

Linuron

0.2379

0.2362

0.5644

0.5572

0.3341

0.1655

Malathion

29.6982

24.4021

94.4458

89.6674

57.0931

29.6243

Metalaxyl

1.0858

0.7104

9.1932

3.6071

2.3705

1.1077

Methamidophos

7.9984

13.9201

15.9612

9.7545

7.1500

4.5228

Methidathion

0.9529

0.7878

5.6458

3.3187

2.2614

1.3605

Methomyl

1.9347

1.1424

6.5387

3.6508

3.0433

1.7831

Methoxychlor, total

0.0428

0.0244

0.1006

0.0846

0.0622

0.0199

Methoxychlor, o, p’

0.0173

0.0000

0.0000

0.0000

0.0000

0.0000

Methoxychlor, p, p’

0.0255

0.0244

0.1006

0.0846

0.0622

0.0198

Mirex

0.0020

0.0010

0.0040

0.0024

0.0042

0.0021

Omethoate

0.8798

3.6634

1.7655

1.0999

0.8271

0.5772

Oxamyl

0.0466

0.0024

0.0764

0.0775

0.0538

0.0211

Permethrin, total

73.4122

88.3346

101.6469

80.6081

28.9863

22.4073

Permethrin, cis

35.4246

42.4138

48.9996

38.7410

14.0356

11.0349

Permethrin, trans

37.9876

45.9208

52.6472

41.8671

14.9507

11.3723

Phenylphenol, ortho

11.3419

36.9188

22.7534

17.2762

13.4283

7.9713

Phosalone

0.0491

0.1417

0.0232

0.0477

0.0617

0.0561

Phosmet

4.7271

17.3239

19.7964

15.2866

4.9499

5.3718

Piperonyl butoxide

0.0029

1.5171

0.0307

0.0000

0.0000

0.0000

Pirimiphos-methyl

6.3524

2.0673

19.2953

19.6057

15.6757

4.3406

Procymidone

0.0247

0.0127

0.0508

0.0672

0.0407

0.0377

Propargite

11.6608

16.8366

55.0796

33.4737

6.9992

 

Propiconazole

0.0002

0.1076

0.0002

0.0000

0.0000

0.0000

Quinclorac

1.0475

2.4162

3.8001

2.5547

1.6717

0.9916

Quinoxyfen

0.2185

0.1696

2.1860

0.8194

0.5358

0.2512

Quintozene

0.0743

0.0952

0.2157

0.1604

0.1027

0.0518

Tecnazene

0.0008

0.0003

0.0009

0.0008

0.0010

0.0008

Thiabendazole

77.7198

297.9485

615.7219

346.4239

157.2699

67.4992

Triadimefon

0.0033

0.0090

0.0348

0.0024

0.0058

0.0052

Triclopyr

0.0398

0.1179

0.2211

0.1905

0.1436

0.0520

Trifloxystrobin

0.3277

0.2543

3.2789

1.2290

0.8038

0.3767

Vinclozolin

0.8230

0.9713

2.9116

1.5535

1.1562

0.7111

M 14–16

F 25–30

M 25–30

F 40–45

M 40–45

F 60–65

M 60–65

F 70

M 70

16.6332

16.2023

15.7001

21.6464

16.1272

18.6599

17.3764

20.7385

24.0702

0.0047

0.0051

0.0053

0.0066

0.0067

0.0068

0.0085

0.0117

0.0138

8.3018

6.9344

7.9611

9.1004

7.1628

6.4063

10.6951

10.3453

12.4859

0.9070

1.0642

0.3536

1.3359

0.6003

1.4125

1.0705

1.1712

1.1343

5.7494

8.0872

5.3303

7.9251

5.6981

15.7172

8.8867

11.2131

9.4220

1.0640

0.8047

0.8643

0.7484

0.6973

1.7146

1.0494

1.3084

0.9522

0.4603

0.2670

0.2977

0.3111

0.3271

0.2688

0.3726

0.4180

0.4281

5.6579

7.1469

4.0346

9.5369

5.7625

7.9005

8.7611

9.7644

9.2733

10.4841

8.4267

6.1624

7.8695

7.7365

9.6286

8.2916

10.5855

8.9616

0.6874

0.2739

0.0836

0.3614

0.2877

0.2016

0.2547

0.3386

0.4815

0.0870

0.0689

0.0728

0.0768

0.0817

0.1271

0.0962

0.1116

0.1194

0.0416

0.0325

0.0372

0.0370

0.0383

0.0589

0.0503

0.0539

0.0607

0.0125

0.0091

0.0084

0.0095

0.0113

0.0177

0.0094

0.0132

0.0120

0.0313

0.0256

0.0257

0.0287

0.0306

0.0464

0.0347

0.0418

0.0441

0.0016

0.0016

0.0015

0.0016

0.0015

0.0042

0.0018

0.0026

0.0026

525.9805

249.3211

375.2243

191.8389

269.2749

116.9667

224.2651

158.1203

195.8510

0.1221

0.1160

0.0956

0.1034

0.0905

0.3776

0.1823

0.1505

0.1970

2.3484

1.8354

1.9704

2.3210

2.0765

4.0656

2.2079

2.4321

2.1384

19.1060

9.3327

12.5135

10.0469

11.2686

9.4714

10.4018

10.5705

11.0058

1.0531

0.5116

0.6111

0.4960

0.6298

0.6130

0.7019

1.0500

1.0474

0.0059

0.0055

0.0048

0.0056

0.0029

0.0589

0.0034

0.0073

0.0102

0.1485

0.1835

0.3236

0.3696

0.2331

0.3776

0.1847

0.1690

0.2134

7.3911

5.9054

7.3996

7.4440

5.7677

16.1349

12.9267

13.8612

9.2338

4.4096

9.4482

3.2211

12.4248

8.1982

13.2693

11.2770

15.4098

12.2943

0.8322

0.5248

0.6807

0.5106

0.5936

0.2281

0.6328

0.6007

0.6054

0.1457

0.2279

0.1898

0.2575

0.1982

0.2792

0.2255

0.2900

0.2151

10.0929

5.3405

5.8316

4.8189

5.9851

5.9422

6.5278

5.2919

5.3867

9.2297

4.6048

5.4149

4.1668

5.2854

5.1620

5.5193

4.4752

4.6449

0.0122

0.0092

0.0099

0.0120

0.0098

0.0188

0.0136

0.0129

0.0123

0.2212

0.1143

0.1368

0.1157

0.1290

0.1260

0.1384

0.1317

0.1387

0.0166

0.0240

0.0127

0.0230

0.0196

0.0365

0.0280

0.0404

0.0352

0.6132

0.5882

0.2573

0.5015

0.5414

0.5990

0.8284

0.6318

0.5557

0.1867

0.0914

0.1604

0.0800

0.0989

0.1099

0.0761

0.0407

0.0376

0.1779

0.2044

0.1988

0.2714

0.2196

0.3073

0.2134

0.1736

0.2062

1.0057

0.4768

0.5371

0.4497

0.6017

0.5380

0.6243

0.8806

0.8722

3.5281

2.6613

2.5448

2.4112

2.4526

6.1333

3.5399

2.9938

3.5544

3.4838

2.6193

2.5101

2.3737

2.4197

5.9964

3.4738

2.9392

3.4830

0.0235

0.0245

0.0219

0.0210

0.0225

0.0755

0.0320

0.0532

0.0526

0.2921

0.2439

0.2535

0.2669

0.2621

0.4260

0.3315

0.4221

0.3968

1.2978

0.7177

0.8500

0.7267

0.8265

1.1578

0.8707

1.0342

0.9787

1.3173

1.3197

1.0581

1.6276

1.3318

2.3255

1.2750

1.3512

1.5124

65.1788

48.8023

64.6768

70.0400

50.1053

21.8490

78.2527

64.3824

81.6502

10.0291

7.2010

8.0732

8.6182

7.8821

11.6984

8.2978

9.3896

9.2824

1.8862

1.2782

1.4997

1.4701

1.4373

1.5188

1.3303

1.3647

1.3876

2.7102

1.7453

2.0406

2.0020

1.7985

2.3578

1.8384

1.8595

1.8490

5.4327

4.1775

4.5329

5.1461

4.6463

7.8219

5.1291

6.1655

6.0459

0.0108

0.0202

0.0118

0.0198

0.0153

0.0323

0.0191

0.0384

0.0349

0.0329

0.0152

0.0231

0.0183

0.0161

0.1703

0.0291

0.0398

0.0277

0.9142

0.4462

0.5556

0.4021

0.4089

0.5313

0.2811

0.2328

0.2838

0.9111

0.4409

0.5519

0.3982

0.4049

0.5255

0.2792

0.2307

0.2810

0.0031

0.0053

0.0037

0.0039

0.0040

0.0057

0.0019

0.0020

0.0028

0.7313

0.6021

0.7855

0.6930

0.6076

2.0313

0.3458

0.2589

0.3347

0.0793

0.0980

0.1728

0.1973

0.1244

0.2016

0.0986

0.0902

0.1139

0.0032

0.0145

0.0184

0.0167

0.0156

0.0521

0.0155

0.0212

0.0312

0.6234

0.8525

0.2541

1.0779

0.5421

1.1354

0.8992

1.0622

0.9554

0.0091

0.0111

0.0110

0.0176

0.0114

0.0307

0.0082

0.0065

0.0057

0.0000

0.0000

0.0000

0.0000

0.0000

0.0130

0.0000

0.0000

0.0004

2.0885

2.1623

2.1035

3.0221

2.2667

3.5484

3.2033

3.4172

3.5806

0.2464

0.2754

0.2897

0.3427

0.3419

0.6703

0.4263

0.6357

0.7162

13.5739

18.9030

7.6395

24.7306

19.2154

18.2427

20.6759

27.8568

17.7320

0.0816

0.0474

0.0569

0.0443

0.0543

0.0740

0.0428

0.0483

0.0468

0.4188

0.3255

0.2403

0.5650

0.4071

0.6250

0.7987

1.5949

1.7592

3.7946

5.6403

2.2778

7.4015

5.6484

6.2786

6.2383

8.3525

5.5698

3.5852

5.3320

2.1398

6.9979

5.3389

5.9016

5.8986

7.9255

5.2641

0.2094

0.3083

0.1380

0.4036

0.3095

0.3771

0.3397

0.4270

0.3057

0.2008

0.4422

0.4518

0.8299

0.4960

1.7703

0.9220

0.8178

0.7633

0.1176

0.0677

0.0548

0.0509

0.0754

0.1302

0.0425

0.0358

0.0397

0.1302

0.2156

0.1544

0.2746

0.2104

0.3906

0.2221

0.1815

0.2134

42.7260

21.6705

29.3563

22.6826

26.6826

18.7036

25.9992

24.2481

25.5719

0.3646

0.7334

0.4357

1.0752

0.7592

1.1266

0.9553

1.2109

1.0349

6.0969

6.0924

7.5724

8.8198

7.6102

8.5927

8.3945

9.4966

10.7210

1.5486

0.7018

0.9954

0.6535

0.6442

0.2578

0.7235

0.9699

0.7849

1.5201

1.6876

1.0198

2.2454

1.3298

1.9276

1.7928

1.9009

1.8352

0.0331

0.0443

0.0364

0.0434

0.0402

0.0474

0.0454

0.0268

0.0340

0.0005

0.0215

0.0150

0.0220

0.0194

0.0042

0.0214

0.0118

0.0162

0.0326

0.0228

0.0214

0.0214

0.0208

0.0432

0.0241

0.0150

0.0178

0.0012

0.0017

0.0014

0.0016

0.0016

0.0021

0.0022

0.0021

0.0019

0.6311

0.7045

0.7028

0.9551

0.7554

1.4615

0.8879

0.8878

0.8731

0.0387

0.0272

0.0453

0.0432

0.0400

0.0714

0.0536

0.0423

0.0630

80.2934

57.2709

66.1862

56.3328

48.4414

130.2292

82.2046

101.4862

72.1103

38.5280

27.6290

31.8599

27.3468

23.4409

62.8005

39.6630

48.7888

34.8039

41.7654

29.6419

34.3263

28.9859

25.0005

67.4286

42.5416

52.6974

37.3064

23.6654

7.2615

6.2418

10.2150

9.1555

27.4469

13.1577

17.8501

14.0892

0.0464

0.0734

0.0799

0.0449

0.0500

0.0703

0.0111

0.0071

0.0156

3.2591

3.8788

2.2576

5.1557

3.9565

4.5583

4.6251

5.6095

4.2228

0.0000

0.0000

0.0000

0.0000

0.0000

0.1823

0.0000

0.0000

0.0000

8.1045

5.2557

6.2427

5.4557

4.8230

8.8276

5.5365

3.4975

3.7984

0.0648

0.0205

0.0188

0.0278

0.0245

0.0266

0.0167

0.0188

0.0194

6.6315

9.0565

5.8634

12.0346

9.6961

19.5833

10.0678

15.6229

13.0497

0.0000

0.0000

0.0000

0.0000

0.0000

0.0130

0.0000

0.0000

0.0004

1.2727

1.1870

1.1458

0.9132

0.9463

0.4484

0.7726

0.5402

0.4990

0.0542

0.1524

0.0542

0.2101

0.1428

0.2083

0.1836

0.2548

0.1979

0.0740

0.0637

0.0553

0.0663

0.0544

0.0693

0.0682

0.0857

0.0783

0.0013

0.0006

0.0009

0.0007

0.0008

0.0005

0.0008

0.0008

0.0009

70.3642

49.8231

61.0063

63.9146

52.3844

42.6089

75.2598

78.1656

84.9818

0.0013

0.0032

0.0041

0.0019

0.0024

0.0052

0.0017

0.0018

0.0020

0.0901

0.0397

0.0396

0.0265

0.0275

0.0339

0.0194

0.0150

0.0138

0.0813

0.2287

0.0813

0.3152

0.2141

0.3125

0.2754

0.3822

0.2968

0.5821

0.7231

0.3974

0.8727

0.5666

0.9401

0.8155

0.9626

0.9968

aLevels in bold represent highest exposed population subgroup

This paper provides estimates of chronic exposure to pesticides based upon mean residue levels found in the TDS and reliance on average food consumption patterns for the General US population and for population subgroups. As such, efforts were not made to assess acute toxicity risks from pesticide residue exposure to determine the likelihood that a single person’s dietary exposure to a pesticide could exceed the acute RfD on a given day. More sophisticated risk assessment methods, using probabilistic models to study variability in pesticide residue levels and food consumption data, would be needed to achieve this task. Such approaches are commonly performed by the EPA, however, and pesticides are not allowed to be registered for use unless EPA concludes that the pesticides pose a “reasonable certainty of no harm” when considering potential increased susceptibility for specific population subgroups, aggregate exposure to pesticides (water, food, and residential exposure) and cumulative exposure to families of pesticides possessing common mechanisms of toxicological action such as the organophosphate insecticides. For acute pesticide exposure, a pesticide poses a “reasonable certainty of no harm” when it can be established that acute exposure for sensitive population subgroups has at least a 99.9 % chance of being below the acute RfD (EPA 2014).

Conclusions

The findings from analysis of TDS pesticide residue data confirm that while pesticide residues are frequently detected in a variety of food products, chronic dietary exposure to pesticides continues to be at levels far lower than levels considered to be of health concern. Consumer fears from pesticide residues provide the potential for consumers to reduce their consumption of fruits, vegetables, and grains, negating the positive health benefits attributed to consumption of large amounts of such foods in one’s diet. Findings from this study also indicate that the potential health benefits from further reducing one’s exposure to pesticide residues through purchase of organic foods may not provide any appreciable benefit given the very low level of pesticide residues consumers are typically exposed to from conventionally produced foods and the finding that organic foods commonly have been shown to contain pesticide residues as well, although at lower frequency than their conventional counterparts (Winter 2012).

While the findings from this paper represent the most recently released TDS data for pesticide residues, such findings are still at least ten years old and may not reflect pesticide residue levels that are encountered today. Food consumption data is similarly dated, representing results from dietary surveys conducted in 1994–96 and in 1998. Fortunately, the methodology to develop exposure estimates for pesticides can be easily adapted to more contemporary residue and food consumption data when such data become available. At the present time, however, the methodology used in this paper provides a convenient and comprehensive approach to estimate chronic dietary exposure to pesticides and to compare such exposures with chronic RfD levels. Unless significant changes in pesticide use patterns and food consumption behavior become evident, it is unlikely that the use of more contemporary data will alter the conclusion that chronic dietary exposure to pesticides is typically well below chronic RfD levels.

Declarations

Authors’ Affiliations

(1)
Department of Food Science and Technology, University of California

References

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© Winter. 2015

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