Study of Biomarkers of Exposure and Effects in Agriculture

Trial Information

Study of Biomarkers of Exposure and Effects in Agriculture

We propose to conduct a molecular epidemiology study with a subset of participants in the
Agricultural Health Study (AHS), a prospective cohort of 57,310 licensed pesticide
applicators in Iowa and North Carolina. Blood and urine samples will be collected from 1,600
cancer-free male AHS participants over the age of 50. These participants will also be asked
to complete a brief interview (approximately 20 minutes) regarding recent exposures and
other lifestyle and health characteristics, which will be conducted at the time of the
biospecimen collection. Participants in both Iowa and North Carolina will be enrolled and
home visits for interviews and sample collection will take place throughout the year between
2010-2014.

The proposed study has two primary objectives. First, we will determine the prevalence and
study the etiology of monoclonal gammopathy of undetermined significance (MGUS), which is a
precursor biomarker for multiple myeloma. We will compare the prevalence of MGUS in the AHS
cohort with the prevalence in two general population-based cohorts ( i.e., Olmsted County
and NHANES IID) with well-characterized MGUS prevalence levels. As a result of previous data
collection efforts in the AHS, comprehensive information on lifetime occupational exposures
and lifestyle factors will be available for the subjects included in this study. We will
examine the associations between MGUS and lifetime exposure to specific pesticides within
the AHS cohort. We will also evaluate several other biomarkers, including telomere length
and global DNA hypomethylation in peripheral blood lymphocytes, for associations with
specific pesticides and excess risk of MGUS.

The second objective is to establish a resource with the remaining blood and urine samples
collected from the participants in this study. These biospecimens will be used to evaluate
the biological plausibility and the mechanism-of-action of associations between pesticides
and cancers observed in earlier AHS studies. Many of these pesticides are non-genotoxic and
their mechanism of carcinogenesis has not been determined. One such future study involving
repository samples will be an investigation of monoclonal B-cell lymphocytosis (MBL), a
marker which has been shown to precede chronic lymphocytic leukemia in previous studies.
Several pesticides in current widespread use in the AHS have been linked to leukemia. We
will determine the prevalence of MBL in the AHS cohort and evaluate potential associations
with specific pesticides of interest to better explain the relation between pesticide
exposures and leukemia risk.