Next week I am moving across the country and am hauling all of my frozen breast milk with me. If it thaws during the flight, it has to be used right away, and I have about 200 ounces I am planning on bringing. The best way to ensure it doesn't thaw is by packing it in dry ice. How much dry ice can I pack it in and is that something that I should bring as a carryon or checked bag?
if that link does not work, research What can I bring? Breast milk on the TSA.gov website.
I suggest that you carry it on if all possible. Most airlines suggest that most perishables and critically important items (like medicines) be carried on. Allow extra time please for check-in screening.
I hope your travels go well and that all makes it safely.
Particularlly for breast milk that you are relying on having, the extremely small risk that it goes wayward as checked luggage may be too high which is what @CareforNOLA is getting at - anything critical like medicine or "priceless" items could have a small (but greater than zero) risk of going missing or taking an extended trip. If that risk is too great compared to the effort that will be needed to carry on the frozen milk, then it should be a carry on.
If it would be a burden to carry it through the airport and you can take a <1% risk about its loss, then checking it is also allowed subject to the quantity of dry ice guidelines, and labeling.
I hope this helps!
Home airport MDW, frequent visitor to MCO to see the mouse.
My relative, who works for TSA, suggests carrying on only what you need for the flight. Southwest only allows you to check 5.5 pounds of dry ice (in a ziplock, labeled), so if that is not enough ice, you may have to carry some of it on. The milk can't be slushy or thawed if you carry it all on, as you are carrying on way more than you need for the flight and anticipated delays. My relative says your security screening process will take a long time if you carry all 200 oz. on, so you will need to plan ahead.
I totally get your need to bring this milk with you, so I hope it all works out!