Trial Information

A Case-Control Study of Pesticides and Childhood Leukemia

Childhood leukemia is the most common type of childhood cancer and its etiology is largely
unknown. Most case-control studies of childhood leukemia have reported elevated risks among
children whose parents were occupationally exposed to pesticides or who used pesticides in
the home or garden. Investigators at the University of California at Berkeley (UCB)
conducted a case-control study of childhood leukemia in 35 counties in the San Francisco Bay
area and the agricultural Central Valley of California. A major focus of the UCB study was
to evaluate whether household or occupational exposure to pesticides increases the risk of
childhood leukemia. Our collaboration provided additional funding to collect carpet dust
samples for the measurement of pesticides and other chemicals. For 470 participants, we
attempted to collect carpet dust using a special high volume small surface sampler (HVS3)
vacuum and by taking dust from participants vacuum cleaner. As of July 2006, dust samples
were collected only from participant's vacuum cleaner. Samples were collected at a home
visit approximately 3-6 months after the first in-person interview. We also provided support
for mapping of the crops (i.e., determining crop field boundaries and crop species) within
1200 meters (3/4 mile) of residences so that the residential proximity to agricultural
fields treated with pesticides can be determined. We will conduct the epidemiologic analysis
of pesticide and other chemical levels in carpet dust and risk of childhood leukemia. We
will also evaluate whether residential proximity to agricultural pesticide use is associated
with risk of leukemia. Further, we will conduct an Exposure Pilot Study that will include a
subset of the study population. Two components of the Pilot Study will evaluate how well a
used vacuum bag and a window sill wipe predict pesticide and other chemical concentrations
in carpet dust samples collected with the more complicated HVS3 vacuum method. The third
component will compare pesticides detected in carpet dust with pesticides predicted by
geographic proximity to agriculture.