UV light does not just create repairable dimers in DNA bases, it can and does rip DNA apart. Enough exposure would cause more than enough irreparable damage to kill the cell and 99% of the cell being destroyed is certainly not salvageable.
The Delta flight is cheaper. But check a bag at a cost of $25 for the first checked bag each way on Delta, and your total fare climbs to $256 -- more than the cost of the Southwest flight, which includes free first and second checked bags. Add a second checked bag for $35 each way on the Delta flight, and you'll pay a whopping $326.
When flying with Delta Airlines you will face fees for checked bags, as of Spring of 2011, of $23 for the first bag and $32 for the second bag. International flights to Latin America and Europe typically allow one checked bag for free while charging around $20 for a second checked bag.