Childhood Cancer

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Pesticides and Childhood Central Nervous System Tumors

University of California, Los Angeles
Shiraya Thompson
Grant Type: 
POST Program Grants
Year Awarded: 
Type of Childhood Cancer: 
Brain Tumors
Project Description: 

Mentor: Dr. Julia Heck

Exposure to pesticides has been listed as a probable human carcinogen (Group 2A) by the International Agency for Research on Cancer (IARC), and IARC has implicated several specific pesticides in cancer risk. Multiple pesticides are established mutagens in experimental animals, and specific pesticides and pesticide classes have been linked to tumor induction and promotion and chromosomal aberrations in vitro. Improving our understanding of the impact of pesticides on cancers can inform public policy on pesticide regulation and can spur research on therapeutic and preventive strategies.

Pesticides and astrocytoma: literature review. Studies based upon parental recall found associations with parental occupational exposures or home pesticide use. In contrast, a study of paternal employment, as listed on birth certificates, found a negative association. Other case-control and an ecologic study found no associations.

Prior research on medulloblastoma/PNET is difficult to interpret due to changes in cancer subtype classifications.

In the proposed project we will conduct updated analyses of cancer-pesticide links analyzed earlier by our group (in the proposed project, we will use births to 2017 and cancer diagnoses to 2019), allowing for greater statistical power and ability to stratify by CNS cancer subtype. Pesticide exposures will be assigned by our GIS-based GRAPES program, which utilizes California’s unique Pesticide Use Reports; these are completed by California farmers and pesticide applicators for every commercial pesticide application. The GRAPES program overlays these against land-use maps to precisely estimate time-specific pesticide exposures, and links exposures to home addresses. Home addresses are taken from the child’s birth certificate. In addition to birth certificate address, we have recently ascertained full residential histories for most of our sample.

The proposed study is designed to complement and advance the knowledge gained in previous studies by utilizing a design in which exposure assessment is objective and precise with regards to time periods of exposure and specific pesticides used. We expect to advance the field in our proposed pilot data linkage study by examining hypotheses of the carcinogenicity of specific pesticides and pesticide classes, identified by EPA and IARC as likely or suggested human carcinogens, in relation to CNS tumor subtypes.