I've found drastic inconsistencies with this. One airport will allow you to pass and others will not let you through. I stated the hand check policy and was told by a TSA agent, " I'm not sticking my hand in there. I don't know what you could have in it." I had to stay behind in Newark to go to the nearest FedEx station and have all of our negative sent that way. Most TSA security X-rays state that anything below 800ASA is safe, but as with all other TSA statements I'd take it with a grain of salt. Bottom line is, as others have suggested, be prepared to have it sent out of country prior to your departure.
good luck!