UBC Theses and Dissertations
Childhood cancer in the offspring of male sawmill workers occupationally exposed to chlorophenate fungicides Heacock, Helen Jane
The purpose of this study was to determine whether paternal occupational exposure to chlorophenol fungicides, namely tetra- and pentachlorophenate, and their dioxin contaminants is associated with childhood cancer in the offspring of sawmill workers. The study was conducted using data from 23,829 British Columbian sawmill workers employed for at least one continuous year between 1950-1985 in eleven chlorophenate-using sawmills and to live births born at least one year after the initiation of employment in the period 1952 - 1988. Probabilistic linkage of the sawmill worker cohort to the provincial Division of Vital Statistics' marriage and birth files produced an offspring cohort of 19,674 children. The offspring cohort was then linked to the British Columbia Cancer Registry. All malignant cases less than twenty years of age and appearing in the cancer registry between 1969 - 1993 were included. Forty cases of cancer were identified during 259,919 person-years of followup; twenty-two cases among the girls and eighteen among the boys. Childhood cancer trends were assessed using both external and internal analyses. Standardized incidence ratios (SIRs) were calculated using the British Columbia population as a reference. Among girls, the SIR for all cancers was 1.22, (95% CI 0.76 - 1.84), for leukemia 1.00, (95% CI 0.32 - 2.33) and for brain cancer 2.02, (95% CI 0.74 - 4.40). Among boys, the SIR for all cancers was 0.89, (95% CI 0.53 - 1.41), for leukemia 0.95, (95% CI 0.35 - 2.08) and for brain cancer 0.77, (95% CI 0.16 - 2.25). A nested case-control analysis assessed the effects of paternal cumulative exposure and windows of exposure on risk of developing cancer in the offspring. Although the results produced slightly elevated dose-response relationships, most noticeably with brain neoplasms, none were statistically significant. Even though the study power was limited, the analyses provide little evidence to support a relationship between risk of childhood cancer and paternal occupational exposure to chlorophenate fungicides in BC sawmills.
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