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Publication #PI-178

Farm Family Exposure to Glyphosate1

Frederick M. Fishel2

Introduction

This publication describes the Farm Family Exposure Study, conducted in 2000 to determine farm-family exposure to the commonly applied herbicide, glyphosate. The purpose of the study was to quantify real-world pesticide exposures immediately before, during, and after a pesticide application and to identify significant factors that influence exposure. The study was funded through a research contract with the University of Minnesota and sponsored by Bayer, Dow, DuPont, FMC, Monsanto, Syngenta, and the American Chemistry Council.

Methods

Farm families were recruited by randomly drawing licensed pesticide applicators from state listings in South Carolina and Minnesota. Criteria for participation in the study included the following:

  • The farmer, spouse, and at least one child -- 4 to 18 years of age -- had to live on the farm.

  • The farmer had to farm at least 10 acres within 1 mile of the family residence.

  • The farmer must plan to apply one of or a combination of the following: glyphosate, 2,4-D, or chlorpyrifos. (Only glyphosate results are described in this publication).

  • Family members had to be willing to collect all urine voids for five consecutive days -- the day before the pesticide application, the day of the application, and for three days after the application.

  • The farmer and spouse had to be willing to fill out pre- and post-study questionnaires that detailed family activities for the week before the study and the week of the study.

  • The farmer and spouse had to agree to have their on-study pesticide application observed by trained field staff.

Participating families were given a cash incentive of $300 and reimbursed for the pesticide used during the on-study application to a maximum of $1,000. Laboratory analyses were used to determine urinary glyphosate concentrations.

Results

Table 1 details characteristics of participating farmers and their spouses based on their questionnaire responses. Of the 48 farmers, 10 reported never wearing gloves when working with pesticides, 14 had applied glyphosate within a week before their scheduled on-study application, and the same number had made another application within three days of their on-study application. Most of the farmers reported having tractors with enclosed cabs.

On the day of the on-study glyphosate application, a trained observer was present at each farm, documenting practices and conditions that can influence exposure potential (Table 2). Of the 48 farmers, 14 were not wearing gloves during the application. According to the product label for the glyphosate used in this study, gloves were not required to be worn. However, use of rubber gloves when handling pesticides reduces dermal contact and absorption. All the farmers used tractors and boom sprayers, and most applied the Roundup Ultra® formulation over glyphosate-tolerant crops early in the growing season. Skin contact with glyphosate was observed for 15 of the farmers and approximately 15 percent of farmers were observed to have had spills during mixing or application. Thirteen repaired their equipment at some time during the application.

Urine concentrations of glyphosate for farmers ranged from less than 1 ppb to 233 ppb (Table 3). Some farmers did not have detectable glyphosate in their urine samples despite applications in excess of 100 acres. Overall, 29 farmers participating in the study had detectable values on the application day, declining to 13 farmers by the third day following the glyphosate application. The average concentration for farmers was 3.2 ppb on the application day, and the concentration declined thereafter. Findings differed between South Carolina and Minnesota. On the application day, 87 percent of the South Carolina farmers had detectable values, compared with 36 percent of the Minnesota farmers. Mean values were 7.9 ppb in South Carolina and 1.4 ppb in Minnesota (Table 4).

Of the farmers spouses, two had detectable concentrations on the day of application. No spouse participated in the glyphosate application. Nine of 78 children who provided samples had a detectable value on the day of application. Of these nine children, all but one were reported by their parents to have been present for or assisted with mixing or application activities.

Among the farmers who participated in the study, urinary concentrations were lower for those who were observed to wear rubber gloves when mixing and loading glyphosate (Table 4). The concentration for those wearing rubber gloves was 1.5 ppb, versus 9.7 ppb for other farmers. Use of rubber gloves was much more common in Minnesota than in South Carolina. The number of acres treated was not related with urinary glyphosate concentration, but there was a trend between concentration and the number of times farmers mixed and loaded the concentrated herbicide. Other factors positively associated with urinary concentration were using an open cab tractor, observed skin contact with the glyphosate concentrate, and repairing equipment during the application.

Use of rubber gloves was a major influence on glyphosate urinary concentrations (Table 5). For farmers who did not wear rubber gloves, the number of acres treated, the number of mixing operations, observed spills, and repairing equipment were associated with large differences in urinary concentrations.

According to the EPA, the lowest no-effect level from glyphosate toxicology studies is considered to be 175 ppm. The reference dose, an estimate of the daily oral exposure to the human population, including children, that is not likely to cause harmful effects during a lifetime, is 2 ppm per day. The urinary glyphosate concentrations presented in the study were exponentially lower than these values in all instances.

In all of these pesticide-handling activities, rubber glove use minimized urinary concentrations of glyphosate. Most pesticide product labels specify some type of protective gloves during handling activities. The study provides emphasis for the importance of protective glove use.

Several limitations should be considered when interpreting the results of the study:

  • There was only one application per family, so the results would not reflect the variation in exposure over a season or over years of applications.

  • All applications were made using a tractor and boom sprayer, so the results may not be representative of other applications methods.

  • Participation in the study may have influenced application practices because of being observed with the study's field staff.

Additional Information

Acquavella, J.et.al. 2004. Glyphosate Biomonitoring for Farmer-Applicators and Their Families: Results from the Farm Family Exposure Study. Environ. Health Perspect:112:321-326. http://ehp03.niehs.nih.gov/article/fetchArticle.action?articleURI=info%3Adoi%2F10.1289%2Fehp.6667 (accessed April, 2009).

Fishel, F.M. 2006. Glove Selection for Working with Pesticides. EDIS Publication PI-120, http://edis.ifas.ufl.edu/document_pi157 (accessed April, 2009). Department of Agronomy, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL.

U.S. EPA. 1993. Re-registration Eligibility Decision (RED) Glyphosate. EPA-738-R-93-014. Washington, D.C.: U.S. Environmental Protection Agency, Office of Pesticide Programs and Toxic Substances.

Tables

Table 1. 

Characteristics reported by farmers and spouses.

Characteristic

Number

of farmers

Number

of spouses

Total in study

Minnesota

South Carolina

48

25

23

48

25

23

Average age (years)

45.0

42.2

Average years lived on farm

40.8

26.4

Average years applied pesticides

23.9

---

Additional job

Yes

No

--

20

28

--

35

13

Currently smoke cigarettes

Yes

No

No answer

--

7

40

1

--

7

41

Schooling

High school or less

Vocational school

Some college

College or graduate degree

Other

No answer

--

19

12

4

12

1

--

20

6

7

13

2

Applied glyphosate in last seven days before study

Yes

No

--

14

34

 

Applied glyphosate within three days after on-study application

Yes

No

--

14

34

 

Enclosed cab

Yes

No

--

29

19

 

Glove changes

Do not wear

Change 1 – 4 times per season

Change when worn out

Change each time

Change once a month

Other

--

10

13

12

5

5

3

 

Spouse mixed any pesticides in week prior to study

Yes

No

 

--

2

46

Table 2. 

Field observers' characterization of farmers on the day of application.

Observation

Number

of farmers

Rubber glove use when mixing/loading

Yes

No

--

34

14

Acres treated

10 – 44

45 – 124

125 – 439

--

16

16

16

Number of loads

1 – 2

3

4 – 6

7 – 12

--

12

15

12

9

Tractor with closed cab

Yes

No

--

29

19

Pesticide spills during mixing

Yes

No

--

7

41

Spills during application

Yes

No

--

8

40

Skin contact with pesticide

Yes

No

--

15

33

Repaired equipment during application

Yes

No

--

13

35

Table 3. 

Average urinary glyphosate concentration values for study participants.

Study participant

Number

of samples

Concentration

(ppb)

Range (ppb)

Farmer – applicator

Preapplication

Application day

Postapplication day 1

Postapplication day 2

Postapplication day 3

--

47

48

48

48

48

--

7

29

23

16

13

--

< 1 – 15

< 1 – 233

< 1 – 126

< 1 – 81

< 1 - 68

Spouses

Preapplication

Application day

Postapplication day 1

Postapplication day 2

Postapplication day 3

--

47

48

48

48

48

--

1

2

0

1

1

--

< 1 – 3

< 1 – 2

All < 1

< 1 – 1

< 1 - 1

Children

Preapplication

Application day

Postapplication day 1

Postapplication day 2

Postapplication day 3

--

76

78

78

79

75

--

5

9

7

5

4

--

< 1 – 17

< 1 – 29

< 1 – 24

< 1 – 12

< 1 - 6

Table 4. 

Average urinary glyphosate concentration values on the day of application according to field observers' observations.

Observation

Number

of farmers

Concentration

(ppb)

Range

(ppb)

State

Minnesota

South Carolina

--

25

23

--

1.4

7.9

--

< 1 – 66

< 1 - 233

Rubber glove use when mixing

No

Yes

--

14

34

--

9.7

1.5

--

< 1 – 233

< 1 - 66

Acres treated

10 – 44

45 – 124

125 – 439

--

16

16

16

--

2.9

2.9

3.8

--

< 1 – 34

< 1 – 233

< 1 – 101

Number of loads

1 – 2

3

4 – 6

7 – 12

--

12

15

12

9

--

1.2

2.9

3.8

10.7

-

< 1 – 19

< 1 – 233

< 1 – 34

< 1 – 101

Closed cab

No

Yes

--

19

29

--

6.5

2.0

--

< 1 – 233

< 1 – 101

Spills during mixing

No

Yes

--

41

7

--

2.7

7.3

--

< 1 – 101

< 1 – 233

Spills during application

No

Yes

--

40

8

--

2.5

9.2

--

< 1 – 66

< 1 – 233

Skin contact with pesticide

No

Yes

--

33

15

--

2.0

9.0

--

< 1 – 51

< 1 – 233

Repair equipment during application

No

Yes

--

35

13

--

2.3

7.2

--

< 1 – 66

< 1 – 233

Table 5. 

Average urinary glyphosate concentration values on the day of application according to use of rubber gloves and field observers' observations.

Observation

Use of rubber gloves

Yes

No

Number

of farmers

Concentration (ppb)

Number

of farmers

Concentration (ppb)

State

Minnesota

South Carolina

--

24

10

--

1.4

4.5

--

1

13

--

---

12.2

Acres treated

10 – 44

45 – 124

125 – 439

--

10

11

13

--

3.4

0.9

2.5

--

6

5

3

--

2.1

33.7

25.1

Number of loads

1 – 2

3

4 – 6

7 – 12

--

8

11

9

6

--

0.8

1.8

2.6

5.1

--

4

4

3

3

--

2.5

10.6

11.4

45.8

Closed cab

No

Yes

--

12

22

--

4.7

1.2

--

7

7

--

11.2

8.4

Spills during mixing

No

Yes

--

28

6

--

1.7

4.1

--

13

1

--

7.6

232.7

Spills during application

No

Yes

--

28

6

--

1.7

3.6

--

12

2

--

6.1

153.6

Skin contact with pesticide

No

Yes

--

27

7

--

1.5

6.2

--

6

8

--

6.8

12.6

Repair equipment during application

No

Yes

--

27

7

--

1.9

2.4

--

8

6

--

4.6

26.0

Footnotes

1.

This document is PI-178, one of a series of the Agronomy Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Original publication date April 2009. Revised April 2009. Reviewed June 2012. Visit the EDIS website at http://edis.ifas.ufl.edu.

2.

Frederick M. Fishel, associate professor, Department of Agronomy, and director, Pesticide Information Office, Institute of Food and Agricultural Sciences, University of Florida, 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.