We used multivariate unconditional logistic regression models to estimate associations between each SNP and thyroid cancer risk, as well as to directly estimate the genotype-environment interaction between each SNP and ionizing radiation.<b>Results:</b> Three SNPs were associated with increased risk of thyroid cancer and with thyroid microcarcinoma: <i>HUS</i> rs2708896, <i>HUS</i> rs10951937, and <i>MGMT</i> rs12769288.