Urinary arsenic and relative telomere length in 5–7 year old children in Bangladesh

•Early childhood is a critical period for telomere biology.•Prior studies of urinary As and telomere length in children have had mixed findings.•We examined urinary As and telomere length in 5–7 year old Bangladeshi children.•Urinary As was associated with significant decreases in relative telomere length.•Arsenic exposure may be related to telomere shortening in early to mid-childhood.