Exposure to Herbicides
Conditions
Keywords
Dietary Intervention, Glyphosate, Herbicide, Pregnancy, Agricultural Communities, Organic food
Brief summary
The purpose of this research is to understand whether and how pregnant women may be exposed to glyphosate, the active ingredient in a common herbicide. The researchers aim to assess glyphosate exposure among pregnant women in Idaho, and to attribute that exposure to agricultural and dietary sources. Pregnant women who live either near or far from glyphosate-treated fields will be recruited for study inclusion, and exposure will be assessed via urinary biomonitoring on a weekly basis throughout pregnancy. Each participant will also take part in a two-week dietary intervention, during which they will receive one week of organic food and one week of conventional food, in a crossover design. Urinary biomonitoring will occur on a daily basis during the dietary intervention phase. The researchers hypothesize that women who live near agricultural fields treated with glyphosate will have higher exposures than those who live in non-agricultural regions, and that consumption of an organic diet will reduce exposures in both groups. All study components will be completed with no face-to-face interaction to eliminate all coronavirus (COVID-19) related risks.
Detailed description
This study focuses on human exposure to glyphosate, the single most commonly applied agricultural chemical in the world. Glyphosate is an herbicide, and is most commonly known as the active ingredient in Round Up. Glyphosate has been declared a probable human carcinogen by the International Agency for Research on Cancer and multiple toxicological studies have further suggested potential neurological and developmental effects of glyphosate exposure at environmentally-relevant levels. However, despite its extensive use, frequent presence in food and environmental media, and potential toxicity, current exposure levels in human populations are not well documented. This study aims to assess glyphosate exposure among a cohort of pregnant women and to quantify the relative contribution of agricultural and dietary sources of this exposure. A cohort of 40 pregnant women will be recruited from urban areas \>10 miles from the nearest glyphosate-treated field and agricultural areas \<1 mile from the nearest glyphosate-treated field. Weekly urine samples collected from these women throughout their pregnancies will be used to analyze glyphosate exposure. These same 40 participants will also take part in a two week-long randomized cross-over design dietary intervention, during which participants will receive one week of exclusively organic food (grown without the use of synthetic pesticides, including glyphosate) and one week of exclusively conventional food, in random order. During the intervention, the researchers will collect daily spot urine samples from each participant to analyze glyphosate exposure related to diet. The researchers hypothesize that during the time of year when glyphosate is actively applied, women living near glyphosate-treated fields will have higher exposures than those living further away. They also hypothesize that glyphosate exposure will be reduced among participants during randomization to the organic diet, but that this decrease will be larger among urban women than among those living near glyphosate-treated fields. The researchers have taken extra precautions to eliminate all COVID-specific risks. There will be no face-to-face contact between research staff and study participants throughout the entire study. Interactions between researchers and study participants will take place through videos, emails, texts, and/or phone calls. All urine samples will be left for researchers to pick up at a predetermined location and time, and all groceries will be delivered to participants' home and left at their front door.
Interventions
OTHEROrganic Diet
Participants receive one week of organic food. Organic food is certified through the USDA's National Organic Program as produced without the use of synthetic pesticides, including glyphosate.
OTHERConventional Diet
Participants receive one week of conventionally grown (non-organic) food.
Sponsors
National Institute of Environmental Health Sciences (NIEHS)
Boise State University
Study design
Allocation
RANDOMIZED
Intervention model
CROSSOVER
Primary purpose
BASIC_SCIENCE
Masking
NONE
Intervention model description
Study participants will take part in a two-week dietary intervention. All participants will receive one week of organic food and one week of conventional food, randomized to order.
Eligibility
Sex/Gender
FEMALE
Age
18 Years to 35 Years
Healthy volunteers
Yes
Inclusion criteria
* Be in the first trimester of pregnancy * No diagnosis of gestational diabetes or other high risk pregnancy factors * Consume an exclusively conventional diet with no intentions to switch to an organic diet * Agree to refrain from applying residential glyphosate (Round Up) during the study * Either live more than 10 miles or less than 1 mile from a glyphosate treated field
Exclusion criteria
\- Occupational exposure to glyphosate, or live in a household with an individual with occupational glyphosate exposure
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Specific Gravity-adjusted Urinary Glyphosate Concentrations During Conventional and Organic Diet | One week conventional diet and one week organic diet | We collected 531 daily first morning void urine samples. We aliquoted 0.6 mL of each participant's seven daily urine samples to form a composite sample intended to represent each participant's mean glyphosate exposure during each week of the dietary intervention For all 39 participants there was one weekly composite urine sample from the conventional diet period and one weekly composite urine sample from the organic diet period. These 78 composite urine samples were analyzed for glyphosate concentrations and adjusted for urine specific gravity. |
Countries
United States
Participant flow
Recruitment details
We recruited 40 pregnant women in their first trimester from Women, Infants, and Children (WIC) clinics in Idaho as part of a longitudinal study to examine urinary glyphosate concentrations during pregnancy. We enrolled participants between February 23 and June 3, 2021 and followed them until they gave birth between August 5 and December 28, 2021. Of the 58 individuals referred by WIC clinics, 53 (91%) were eligible; 40 (75%) of eligible individuals were enrolled in the study.
Pre-assignment details
As part of the longitudinal study, we conducted a two-week randomized crossover dietary intervention from June 16-June 30, 2021. 39 of the 40 participants took part in the dietary intervention (one participant was assigned to an arm but was out of town during the intervention). We randomly assigned participants to receive one week of either organic or conventional groceries, followed by one washout day, then one week of groceries of the opposite food type.
Participants by arm
| Arm | Count |
|---|---|
| Organic Diet, Then Conventional Diet: These participants first received an organic diet for one week, defined as food certified through the United States Department of Agriculture's National Organic Program as produced without the use of synthetic pesticides, including glyphosate. During that week, daily first morning void urine samples were collected. After a washout period of one day, these participants then received a conventional (non-organic) diet for one week. During that week, daily first morning void urine samples were collected.
For each week, participants ordered all food they anticipated eating that week (up to $150) from a unique account with a local grocery store in accordance with either the organic diet or conventional diet. Study staff verified all food items corresponded with the dietary intervention that week, and then ordered the groceries to be delivered to the participant's home, when possible. For participants living in areas in which delivery was not available (generally rural areas), study staff picked up the food at the grocery store and delivered it to the participant's home. | 20 |
| Conventional Diet, Then Organic Diet These participants first received a conventional (non-organic) diet for one week. During that week, daily first morning void urine samples were collected. After a washout period of one day, these participants then received an organic diet for one week, defined as food certified through the United States Department of Agriculture National Organic Program as produced without the use of synthetic pesticides, including glyphosate.. During that week, daily first morning void urine samples were collected.
For each week, participants ordered all food they anticipated eating that week (up to $150) from a unique account with a local grocery store in accordance with either the organic diet or conventional diet. Study staff verified all food items corresponded with the dietary intervention that week, and then ordered the groceries to be delivered to the participant's home, when possible. For participants living in areas in which delivery was not available (generally rural areas), study staff picked up the food at the grocery store and delivered it to the participant's home. | 19 |
| Total | 39 |
Withdrawals & dropouts
| Period | Reason | FG000 | FG001 |
|---|---|---|---|
| First Intervention (1 Week) | out of town during dietary intervention | 0 | 1 |
Baseline characteristics
| Characteristic | Total | Organic Diet, Then Conventional Diet: | Conventional Diet, Then Organic Diet |
|---|---|---|---|
| Age, Customized 18-22 years | 11 Participants | 6 Participants | 5 Participants |
| Age, Customized 23-27 years | 10 Participants | 4 Participants | 6 Participants |
| Age, Customized 28-32 years | 13 Participants | 6 Participants | 7 Participants |
| Age, Customized 33-37 years | 5 Participants | 4 Participants | 1 Participants |
| Highest Level of Education Bachelor's degree | 1 Participants | 1 Participants | 0 Participants |
| Highest Level of Education Graduated high school/earned General Educational Development | 14 Participants | 9 Participants | 5 Participants |
| Highest Level of Education Graduate school/advanced degree | 1 Participants | 0 Participants | 1 Participants |
| Highest Level of Education Less than high school | 5 Participants | 2 Participants | 3 Participants |
| Highest Level of Education Some college | 18 Participants | 8 Participants | 10 Participants |
| Household income in previous year < $10,000 - 19,999 | 9 Participants | 5 Participants | 4 Participants |
| Household income in previous year $20,000 - 29,999 | 10 Participants | 3 Participants | 7 Participants |
| Household income in previous year $30,000 - 30,999 | 8 Participants | 3 Participants | 5 Participants |
| Household income in previous year $40,000 - 59,999 | 5 Participants | 4 Participants | 1 Participants |
| Household income in previous year > $60,000 | 5 Participants | 3 Participants | 2 Participants |
| Household income in previous year Missing or prefer not to answer | 2 Participants | 2 Participants | 0 Participants |
| Number living in household 1-3 | 15 Participants | 9 Participants | 6 Participants |
| Number living in household 4-6 | 22 Participants | 10 Participants | 12 Participants |
| Number living in household 7-9 | 2 Participants | 1 Participants | 1 Participants |
| Personally used herbicides at residence in last year No | 39 Participants | 20 Participants | 19 Participants |
| Personally used herbicides at residence in last year Yes | 0 Participants | 0 Participants | 0 Participants |
| Race/Ethnicity, Customized African American or Black | 0 Participants | 0 Participants | 0 Participants |
| Race/Ethnicity, Customized American Indian or Alaskan Native | 1 Participants | 1 Participants | 0 Participants |
| Race/Ethnicity, Customized Asian | 1 Participants | 1 Participants | 0 Participants |
| Race/Ethnicity, Customized Caucasian or White | 20 Participants | 9 Participants | 11 Participants |
| Race/Ethnicity, Customized Hispanic or Latina | 19 Participants | 10 Participants | 9 Participants |
| Sex: Female, Male Female | 39 Participants | 20 Participants | 19 Participants |
| Sex: Female, Male Male | 0 Participants | 0 Participants | 0 Participants |
| Someone else used herbicides at residence in last year Don't Know | 3 Participants | 1 Participants | 2 Participants |
| Someone else used herbicides at residence in last year No | 28 Participants | 13 Participants | 15 Participants |
| Someone else used herbicides at residence in last year Yes | 8 Participants | 6 Participants | 2 Participants |
| Type of herbicides used at residence in last year Cheetah® (glufosinate ammonium) | 1 Participants | 1 Participants | 0 Participants |
| Type of herbicides used at residence in last year Don't know or unknown pesticides sprayed by pesticide control company | 5 Participants | 4 Participants | 1 Participants |
| Type of herbicides used at residence in last year Roundup® (glyphosate) | 1 Participants | 0 Participants | 1 Participants |
| Type of herbicides used at residence in last year Spectracide® (combination of non-glyphosate herbicides) | 1 Participants | 1 Participants | 0 Participants |
Adverse events
| Event type | EG000 affected / at risk | EG001 affected / at risk |
|---|---|---|
| deaths Total, all-cause mortality | 0 / 39 | 0 / 39 |
| other Total, other adverse events | 0 / 39 | 0 / 39 |
| serious Total, serious adverse events | 0 / 39 | 0 / 39 |
Outcome results
Primary
Specific Gravity-adjusted Urinary Glyphosate Concentrations During Conventional and Organic Diet
We collected 531 daily first morning void urine samples. We aliquoted 0.6 mL of each participant's seven daily urine samples to form a composite sample intended to represent each participant's mean glyphosate exposure during each week of the dietary intervention For all 39 participants there was one weekly composite urine sample from the conventional diet period and one weekly composite urine sample from the organic diet period. These 78 composite urine samples were analyzed for glyphosate concentrations and adjusted for urine specific gravity.
Time frame: One week conventional diet and one week organic diet
Population: We geocoded each participant's address and verified the existence and location of all fields within a 0.5 km radius of their home. We report specific-gravity adjusted urinary glyphosate concentrations during the conventional and organic weeks for all participants and stratified by agricultural proximity, i.e. for participants living farther than 0.5 km of an agricultural field (far-field) and living within 0.5 km of an agricultural field (near-field).
| Arm | Measure | Group | Value (GEOMETRIC_MEAN) |
|---|---|---|---|
| Conventional Diet | Specific Gravity-adjusted Urinary Glyphosate Concentrations During Conventional and Organic Diet | All Participants | 0.19 ug/L |
| Conventional Diet | Specific Gravity-adjusted Urinary Glyphosate Concentrations During Conventional and Organic Diet | Far-field Participants | 0.18 ug/L |
| Conventional Diet | Specific Gravity-adjusted Urinary Glyphosate Concentrations During Conventional and Organic Diet | Near-field Participants | 0.21 ug/L |
| Organic Diet | Specific Gravity-adjusted Urinary Glyphosate Concentrations During Conventional and Organic Diet | All Participants | 0.17 ug/L |
| Organic Diet | Specific Gravity-adjusted Urinary Glyphosate Concentrations During Conventional and Organic Diet | Far-field Participants | 0.14 ug/L |
| Organic Diet | Specific Gravity-adjusted Urinary Glyphosate Concentrations During Conventional and Organic Diet | Near-field Participants | 0.20 ug/L |
Comparison: Based on previous pesticide research, we calculated a sample size of 40 participants to provide a power of 0.80 at a 0.05 significance level in a two-sided test. We assumed a standard deviation of 0.5 µg/L.p-value: 0.17Wilcoxon signed rank test
p-value: 0.06Wilcoxon signed rank test
p-value: 0.83Wilcoxon (Mann-Whitney)