Question about converting bigint field to int field

We made a poor decision a long time ago when designing our database
structure. We used bigint data types as the identity keys for many of
our base tables. For many reasons I would like to change these fields
to int at the largest. The largest data in these fields is around
200,000. I know that int can easily store this.

What should I be worried about when changing these fields from bigint
to int? If anything. Your help is appreciated. I did several
searches without much luck.

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