Fifteen years ago, China noticed pesticide in U.S. grain shipments.
That pesticide was grown by the GMO crop itself.
The U.S. response was, sorry, that GMO crop was meant for livestock feed only and somehow got in the human supply.
This became a bigger problem because grains all get mixed in storage elevators,
so non-GMO grain effectively became pesticide embedded GMO grain.
One can say GMO crops are usually healthful to eat, but grains can be GMO modified to actually kill people.
You don't want to allow anybody's GMO modification to be sold!
There is a "GMO" modification that presents no problem -- remove genes (rather than add genes).
Nature itself often removes genes.
CRISPR cas9 technology, arising from bacteria's defense against viruses, can selectively remove genes.
This was done with button mushrooms, removing a gene that created ethane, so those mushrooms don't get slimy and brown as quickly.