Risk of childhood leukemia after in utero exposure to radiation compared to other risk groups

Group	Approximate risk	Increase in risk above baseline
Identical twin of leukemic twin	1/3	1000
Irradiation-treated polycythemia	1/6	500
Bloom syndrome	1/8	375
Hiroshima survivors who were within 1000 meters of the hypocenter	1/60	50
Down's syndrome	1/95	30
Irradiation-treated ankylosing spondylitis	1/270	10
Siblings of leukemic children	1/720	4
Children exposed to in-utero pelvimetry	1/2000	1.5
US White children <15 years old	1/2800	1

Data from: Miller RW. Epidemiologic conclusions from radiation toxicity studies. In: Late Effects of Radiation, Fry, RJM,Grahn, D, Griem, ML, et al (Eds). Taylor and Francis, London, 1970.

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