What better way to start the week than to ponder what might be lurking in your water supply - and how it got there. New research is turning up evidence that arsenic used in chicken feed may be contaminating some groundwater and surface water sources.

Chicken droppings, like many other forms of animal excrement, are used as fertilizer because of their concentrations of nitrogen and phosphorous. (These elements can also make their way into water supplies.) According to the web site of the journal Environmental Science and Technology, many chickens raised to be roasted are fed a supplement called roxarsone - a form of arsenic that is relatively harmless but seems to be breaking down into a more harmful variety once it's in the soil.