Exposure to low doses of ionising radiation may result in the induction of cancer. In fact this and genetic damage are the only proven effects of very low doses of radiation. Note that it is believed by all International Regulatory Authorities that we should assume that there is a very small risk of contracting cancer no matter how low the dose of radiation. Hence:
LOW DOSE RADIATION may lead to CANCER
The average risk is approximately 5% per Sv (or 1 in 20,000 per mSv). It is less for older people and may be up to 10-15% per Sv for a foetus and young children, it is also slightly greater for women than for men.
NOTE that there is a 5-10 year delay before the cancer becomes detectable.