Paper straws are made from paper. So you must care about how long paper straws last for. Properly speaking, paper straws break down more quickly than plastic straws. At first you should know where you put paper straws in.
Differences of beverages can influence the lifetime of paper straws. For all I know, paper straws can last for 2 hours at least in beverages at normal temperature. The drink is hotter, the time is shorter.
At last, rubbish may be buried in the soil or thrown into the ocean. Under the circumstances, they degrade in just 30 days. There are too many microbes in the sea and in the soil.