I used to sit my cellphone in my babies car seat and turn on white noise to help him sleep. Now I worry I exposed him to too much radiation! True?

Don't know yet... Some studies suggest that there is an increased risk of brain tumors with excessive use of cell phones, while other studies do not agree. I think the jury is still out on whether this type of exposure can lead to any health problems. However, even if there is an increased risk, the overall risk of a problem because of this is still very low.
Doubt it. However, a simple radio at a distance dialed to a talk station (turned down) will do the same thing. .