Lead concentrations spiked in many children living in the nation's capital after the local water authority altered the treatment used to disinfect drinking water. About seven-and-a-half years ago, the District of Columbia’s water authority switched from chlorination to an alternative water-disinfection technology: chloramination. The goal had been to reduce the potentially carcinogenic by-products of chlorination that developed in drinking water. And the substitution worked. However, an unintended consequence of this improved disinfection technique was the sudden release of copious amounts of lead into the drinking water that serves the nation’s capital. Until then, notes Marc Edwards of Virginia Tech, no...