Among a pile of other chemicals it probable has Phenol in it from the pine which it toxic.
See thread on
http://www.ssnakess.com/forums/elaph...-shavings.html
A little rinse is probably fine. (Water / bleach...then just water)
I like a little overkill sometimes so I would likely put the garden hose in the tank and let it just run and rinse itself for 15 minutes in the back yard.
He should be fine if it was just a few hrs or something similar.
Good luck on that one.