Hello James & All,
James wrote:
 Given that coal tar products can be used as insecticides, and that
 coal tar creosote is what is used as a wood preservative, I'd be
 *very* apprehensive about using creosote in an apiary operation.  Coal
 tar creosote may have insecticidal properties.

Thanks James for the input. I should have added the beekeeper also had his
four way pallets treated. I was offered the pallets & bottom boards for sale
after his death but like you were apprehensive so I declined. I have seen
beekeeping sales with a small number of creosote dipped bottom boards.
I started beekeeping in rural Florida years ago and remember beekeepers
using creosote bottom boards. The use was not widespread.
Bob

for more information
http://www.atsdr.cdc.gov/tfacts85.html