Hi Nancy My initial reaction to your question is one of caution.
I would wonder what the manufacturer has used as a bonding agent to tie all the sawdust together? Let's face it, we're talking about saw mill scrap destined for an airtight stove, not organic gardening. You might check the wrapping on the logs to see the chemical content or look for warnings.
If you have a doubt...toss it out. Different vegetables absorb metals in different concentrations. It is not worth the risk in my books.
On a side note, given the demands on our environment, anything we can do to reduce our "footprint" can only protect the future for our children.
You might want to try wood splitting; besides being cheaper than your current product, it is a great stress reducer. You have no idea how many arguments you will win when you take an axe to a cord of wood (it's a Zen thing, trust me).
Take care, Duncan