test Browse by Author Names Browse by Titles of Works Browse by Subjects of Works Browse by Issue Dates of Works

Advanced Search
& Collections
Issue Date   
Sign on to:   
Receive email
My Account
authorized users
Edit Profile   
About T-Space   

T-Space at The University of Toronto Libraries >
School of Graduate Studies - Theses >
Doctoral >

Please use this identifier to cite or link to this item: http://hdl.handle.net/1807/32779

Title: Paternal Exposure to Ionizing Radiation in Ontario Uranium Miners and Risk of Congenital Anomaly in Offspring: A Record Linkage Case-control Study
Authors: Nahm, Sang-Myong
Advisor: Marrett, Loraine
Department: Dalla Lana School of Public Health
Keywords: Ionizing radiation
uranium miners
gamma ray
radiation measurement
radiation effects
occupational exposure
occupational health and safety
environmental exposure
paternal exposure
paternal exposure delayed effects
male reproduction
transgenerational effect
pregnancy outcome
congenital anomaly
birth defect
live birth
record linkage
case control study
Issue Date: 30-Aug-2012
Abstract: Objective: To determine if paternal preconception exposure to ionizing radiation through uranium mining increases the risk of congenital anomaly (CA) in offspring. Methods: A population-based matched case-control study was conducted. Cases were infants with CAs recorded in the Canadian Congenital Anomalies Surveillance System and born alive in Ontario 1979-86 (ICD-9 codes 740-759); controls were liveborn infants without CAs identified from Ontario birth certificates and individually matched to cases (case-control file {CCF}). Exposed fathers were identified through the linkage of the CCF to the Mining Master File or the National Dose Registry file, which include those who worked in Ontario uranium mines 1952-1986. For men who linked with a case or control child, radon, gamma and total gonadal doses were estimated for three preconception periods: entire, 3-months and 6-months. Odds ratios were estimated using conditional logistic regression. Results: Linkage of 28,991 uranium miners and 40,482 case-control pairs of fathers and offspring in the CCF identified 431 discordant pairs. There was no evidence of increased risk of a child having a CA if the father was ever a uranium miner before conception of the child (OR=0.89, 95% CI=0.74–1.08). Since gamma radiation (especially during the 6-month preconception period) is more biologically relevant to gonads than radon, further analyses were performed on 117 discordant pairs where data on gamma exposures were available. When ever/never miner, exposed to gamma (yes/no), and gamma dose-response variables were all in the model, there was no ever/never miner effect (OR=1.20, 95% CI=0.85–1.69, p-value=0.30), an inverse association for exposure to gamma (OR=0.42, 95% CI=0.25–0.71, p-value=0.001), but most importantly, there was no statistically significant dose-response relationship between gamma dose during the 6-month preconception period and all CAs (OR=1.15 per loge {mSv+0.01}, 95% CI=0.83–1.59, p-value=0.40). Similarly, no dose-response relationship was observed for exposure to gamma radiation in the 3-month preconception period, or for radon or total gonadal radiation in the 3- or 6-month preconception periods. Conclusion: There was no increased risk of a CA among liveborn children of Ontario uranium miners who were exposed to radon, gamma or total radiation during the 3- or 6-month periods before conception.
URI: http://hdl.handle.net/1807/32779
Appears in Collections:Doctoral

Files in This Item:

File Description SizeFormat
Nahm_Sang_M_201206_PhD_Thesis.pdf5.58 MBAdobe PDF

Items in T-Space are protected by copyright, with all rights reserved, unless otherwise indicated.