Box 1. Literature searches carried out, and key words used to identify ALL risk exposures and potential exposure associated changes in DNA methylation.

Literature search	Key words
1. Identification of ALL risk exposures	Leukemia, acute lymphoblastic, leukaemia
2. Identification of evidence supporting an association between ALL and an exposure	Leukemia, acute lymphoblastic, leukaemia, radiation, smoking, alcohol, folate, folic acid, iron, coffee, caffeine, herbicides, pesticides, household chemicals, chemicals, household paints, paints, child care, day care, breast feeding, birth weight, infection history, infection, virus, and bacterial
3. Identification of relationships between ALL risk exposures and changes in DNA methylation	DNA methylation, and exposures identified in literature search 2.