Iowa Code § 321.444: Safety glass.

1. No person shall sell any new motor vehicle nor shall any motor vehicle, manufactured since July 1, 1935, be registered, or operated unless such vehicle is equipped with safety glass wherever glass is used in doors, windows, and windshields. Replacements of glass in doors, windows, or windshields shall be of safety glass.

2. “Safety glass” means any product composed of glass, so manufactured, fabricated, or treated as substantially to prevent shattering and flying of the glass when struck or broken. Safety glass and glazing materials shall comply with federal motor vehicle safety standard number 205 as published in 49 C.F.R. §571.205.