A molecular pump designed to transport iodine also concentrates the pollutant perchlorate in breast milk, scientists have shown. The result is higher levels of the chemical in breast milk than in other parts of the body, with implications for the amount of perchlorate that pregnant and lactating women can safely ingest.
For the past decade, scientists have debated the health effects of perchlorate, which leaches into groundwater around explosives manufacturing plants. The contaminant was found in some states' drinking water in the mid-1990s. Since then, perchlorate has also turned up in produce grown with contaminated water, and scientists and policy makers have reached no consensus on what levels of the chemical are safe in humans.