This is the time of year when you want your grass to look great, and there's a strong chance you're using a weed killer called 2,4-D to do so.
This herbicide is commonly found in "weed and feed" type lawn fertilizers, because it kills "broad leaf" weeds like clover and dandelion, while preserving grass.
Although the EPA considers this chemical safe enough for use both in households and on farm crops, many environmental groups beg to differ—they point out that 2,4-D was one of the chemicals in the notorious Agent Orange which poisoned so many soldiers in Vietnam, and that studies have linked its used to Non-Hodgkins Lymphoma in farm workers and lymphoma in pet dogs.
So, should you use this, or any other chemical herbicides, on your grass? There's no evidence that it poses a risk to adults using it domestically, but I choose not to use it anyway. Instead I'm opting for what my gardener calls a "meadow look" on our lawn, with patches of clover and similer little weeds mixed in the grass. If you want the flawless "green carpet" look you might consider the new fake grass, which really does look and feel great (some friends of mine recently installed it) and has the added advantage of requiring no water.
Interesting factoid: Until the invention of herbicides like 2,4-D, a lawn filled with clover was considered healthy and beautiful (clover is good for soil, because it adds nitrogen) but those little three-leafed plants were redefined as "weeds" once we had herbicides that easily killed them (this tidbit courtesy of a fascinating New Yorker article on the history of lawns).
Do you think a perfect lawn is worth any potential health risks, or are you also going for the "meadow look"?