New evidence in mouse study suggests current standards for arsenic aren't good for pregnant and lactating women and their babies. Many states have natural groundwater an order of magnitude worse.
Exposure to arsenic in drinking water at the level the U.S. Environmental Protection Agency (EPA) currently deems as safe in the United States (10 parts per billion) induces adverse health outcomes in pregnant and lactating mice and their offspring, concludes a study led by Joshua Hamilton of the Marine Biological Laboratory (MBL) and Courtney Kozul-Horvath at Geisel School of Medicine at Dartmouth.
Pregnant and/or breastfeeding mothers who consumed low levels (10 ppb) of arsenic in their drinking water... their offspring showed significant growth and development deficits during the postnatal period before weaning.
The U.S. EPA recently lowered the Maximum Contaminant Level for arsenic to 10 ppb in public water supplies -- a regulated level that is considered "safe" for a lifetime of exposure -- yet concentrations of 100 ppb and higher are commonly found in private, unregulated well water in regions where arsenic is geologically abundant, including upper New England (Massachusetts, New Hampshire, Maine), Florida, and large parts of the Upper Midwest, the Southwest, and the Rocky Mountains.
"If you are on a private water system, particularly in a region with high arsenic, have your water tested so that you know what you are drinking."[emphasis mine]
A Consumer Reports alert on arsenic in rice. They tested widely and found "moderate to high" levels of arsenic, not just trace amounts. The FDA did their own tests with the same results. Consumer Reports recommends not giving babies rice baby food more than once a week.