Minor? That depends..
urination and defecation put minor stress on the body
In my experience, the amount of stress can vary greatly. Not only does your intake matter, also the manner and timing/timeliness of expulsion can greatly contribute to stress levels. Even the very event may prove stressful. For instance, if it's explosive and unplanned I think stress levels may reach well beyond "minor", especially if there are no trouser clips handy.
These people need to travel a bit more :)