Inorganic arsenic (iAs), a toxic metalloid, affects millions of people worldwide, mainly from drinking contaminated water. Arsenic is a human carcinogen that targets skin, lung, bladder, and possibly other sites. iAs and its methylated metabolites readily cross the placenta and reach the fetus [National Research Council (NRC) 1999], producing effects ranging from developmental toxicity to cancer (NRC 1999; Waalkes et al. 2007). Thus, early-life As exposures are drawing escalating health concerns. (Editorial) March 2008