But atrazine often washes into water supplies and has become among the most common contaminants in American reservoirs and other sources of drinking water.
Now, new research suggests that atrazine may be dangerous at lower concentrations than previously thought.
Recent studies suggest that, even at concentrations meeting current federal standards, the chemical may be associated with birth defects, low birth weights and menstrual problems.
Laboratory experiments suggest that when animals are exposed to brief doses of atrazine before birth, they may become more vulnerable to cancer later.
TVNL Comment: Previously "thought" or previously "disclossed?"