Can a dryer exhaust through PVC in a slab?
The duct is supposed to be smooth walled metal 4&quot; in diameter, unless otherwise specified by the manufacturer. So, you should probably not be using PVC.

International Residential Code 2012
Chapter 15 Exhaust Systems
Section M1502 Clothes Dryer Exhaust
M1502.1 General. Clothes dryers shall be exhausted in accordance with the manufacturer’s instructions.
M1502.4 Dryer exhaust ducts. Dryer exhaust ducts shall conform to the requirements of Sections M1502.4.1 through M1502.4.6.
M1502.4.1 Material and size. Exhaust ducts shall have a smooth interior finish and be constructed of metal having a minimum thickness of 0.0157 inches (0.3950 mm) (No. 28 gage). The duct shall be 4 inches (102 mm) nominal in diameter.

NOTE: I'm not familiar with California building code, or local amendments that may exist. IRC is a common building code, and lots of other building codes use similar standards.