If the ED college's financial aid package contains too much student loan [international student]

No - the way it typically goes is undergraduate degree (with research) → OPT during which you apply to a PHD → PHD → OPT or academic H1B (these are easier to find in Economics or STEM). Academic H1Bs are unrestricted. That being said, academic positions are more and more uncommon.
Also, for a PHD in Economics you nearly need a Math major.

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