Influence of Corn Farming on the Immune System

This study has been completed.
Sponsor:
Information provided by:
National Institutes of Health Clinical Center (CC)
ClinicalTrials.gov Identifier:
NCT00342121
First received: June 19, 2006
Last updated: October 7, 2014
Last verified: September 2014
  Purpose

This study will look for links between corn farming practices and short-term changes in immune function in farmers throughout the growing season. It will examine biologic effects associated with specific pesticide exposures and general planting activities, such as tillage. Farmers have an increased risk of non-Hodgkin s lymphoma and certain other blood cancers such as multiple myeloma and leukemia, but the reasons for this increase have not been identified. Findings of this study may contribute to learning the causes of cancers such as non-Hodgkin s lymphoma.

Farmers enrolled in the Agricultural Health Study (a study of pesticide applicators and their spouses in Iowa and North Carolina) and a group of control subjects selected from agricultural extension workers in Iowa may participate in this study.

The study involves six home visits to farmers and four visits to farmers to individuals in the control group. All participants will complete the following tests and procedures:

  • Questionnaires and diaries During the first visit, all participants will have a medical history review, including questions about smoking and other health habits. Farmers will be asked about their farming practices, and controls will be asked about their occupations. Farmers will fill out daily diaries during short time periods of interest around certain pesticide applications to describe farming activities that day. At other times during the growing season before harvest, farmers will fill out weekly diaries describing farming activities; controls, meanwhile, will fill out weekly diaries describing their health and work activities. At home visits during the farmers growing season, all participants will fill out questionnaires about their health. Finally, farmers and controls will complete a more extensive questionnaire in the off-season, during the last home visit, to learn about their activities and exposures in the final part of the year (post-harvest for farmers).
  • Urine samples: At the time of each home visit, controls will provide a urine sample that the interviewer will take that day. Farmers, too, will provide urine samples at the time of home visits, but they will also collect urine samples for a period of 4 days each during short time periods of interest after certain pesticide applications. The interviewer will collect these samples immediately at the end of these periods.
  • Blood samples: At the time of each home visit, the interviewer will draw 50 ml (3.5 tablespoons) of blood.
  • Telephone calls: Farmers will be called frequently from once every 2 weeks to every other day to schedule visits at the times of interest. Control subjects will also be called frequently to schedule their visits closely to those of the farmers.

Condition
NHL

Study Type: Observational
Study Design: Time Perspective: Prospective
Official Title: Influence of Corn Farming on the Immune System

Resource links provided by NLM:


Further study details as provided by National Institutes of Health Clinical Center (CC):

Estimated Enrollment: 40
Study Start Date: May 2002
Detailed Description:

When compared to the general population, farmers have an increased risk of non-Hodgkin's lymphoma (NHL) and certain other hematopoeitic cancers (i.e., multiple myeloma, leukemia). Factors that contribute to this excess risk have not been discerned. While several epidemiologic studies have observed an increased risk of NHL among farmers who are exposed to certain pesticides (i.e., phenoxyacetic acids, organophosphates, organochlorines, and triazines), these studies have not been conclusive. In addition, a clear mechanistic association between farming or pesticide exposure and subsequent development of cancer has not been identified. Given that immunocompromised individuals are at increased risk for NHL, it has been hypothesized that altered immune function may be an indicator of increased potential for the development of immunologically based diseases such as NHL. Therefore, research into early immunologic effects of farming exposures holds some promise in discerning disease mechanisms and in identifying specific etiologic agents for lymphatic cancers such as NHL. Few such studies have been conducted.

This protocol outlines a study of immune effects among corn farmers within Agricultural Health Study (AHS) cohort. The main objective is to evaluate the changes in immune parameters in farmers throughout the growing season, as well as effects of specific pesticide exposures including atrazine and organophosphate (OP) insecticides. Farmers and control subjects were contacted just prior to planting (February-March) to be enrolled in the study. Biological sampling before and after planting and application of preemergent pesticides (likely to include atrazine and possibly Ops or carbamates) allowed examination of short-term biologic effects associated with specific pesticide exposures and general planting activities (e.g., tillage). The first post-emergent application of organophosphate insecticide will also be monitored, in order to evaluate short-term biologic effects associated with this OP exposture. Post-harvest and off-season samples also were collected to allow evaluation of overall immune effects of farming activities. Pesticide exposures (e.g., atrazine, OPs, and potentially 2,4-D or carbamates) are being assessed primarily by measurement of the parent compound or its metabolites in urine, and additional information on farming activities and work practices will be obtained by questionnaire. Farmers serve as their own self-controls, and a selected control group will provide a means for external comparison.

  Eligibility

Ages Eligible for Study:   18 Years and older
Genders Eligible for Study:   Male
Accepts Healthy Volunteers:   No
Criteria
  • INCLUSION CRITERIA:

Male corm farmers in the AHS who plan to apply specific pesticides.

Any ethnicity or race groups are included.

Limit the age criteria for inclusion to 40 to 60 years.

Only non-smokers are included in the study.

  Contacts and Locations
Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the Contacts provided below. For general information, see Learn About Clinical Studies.

Please refer to this study by its ClinicalTrials.gov identifier: NCT00342121

Locations
United States, Iowa
University of Iowa
Iowa City, Iowa, United States, 52242
Sponsors and Collaborators
Investigators
Principal Investigator: Laura Beane-Freeman National Cancer Institute (NCI)