1.   Atrazine, part of a chemical family called triazines, is ranked among the most commonly used weed killers, particularly in Midwestern corn and soybean fields.

2.   By altering the seeds, Monsanto enables plants to withstand the widely used weed killer Roundup, which Monsanto also manufactures.

3.   The group focused on the most commonly used weed killers, atrazine and cyanazine.

4.   The review also will focus on two of its chemical cousins, also widely used weed killers.