Here's a variant for handling poison. This replaces the "Perils of Using Poison" rules, if you choose to use it.

Each poison is assigned a handling DC along with its damage, save DC, etc. This value shows how dangerous it is to handle. A character attempting to poison his blade, smear it on a lock, or put it into food must make an alchemy check (this can be attempted untrained) to do so without risking harm to himself. Failure means that the user has potentially harmed himself with the poison and must make an immediate Fortitude save as described for the specific poison.

Behind the Curtain
One thing the handling poison rule will do is make it very unlikely that a low-level character can use a really powerful poison. This equates poison use to levels more closely than before (although price helps, too).

In general, this rule makes poison only more dangerous to handle than before, since most characters will have a greater than 5% chance of failure.

Note that ingested poisons are extremely safe, and inhalants are very dangerous (if a character is dealing with inhalants, grant a +2 circumstance bonus to her check if she has something covering her face and nose). Everything else falls in between.