Same risks.  Pick your poison, so to speak.  Lyme 
  disease can be caught & treated.  Cancers are another order of 
  problem. 
              I just sent a 
  more lengthy post to ridecamp with questions (for vets) about pyrethrins---but 
  "cancer" caught my eye---is there real evidence now that pyrethrins are linked 
  to cancer?   
   
   Personally I think I'd rather just move to Lyme disease tick free 
  area!  
              Is there such an 
  area??
   
  Actually, I was not even thinking about Lyme disease when I posted for 
  help with getting rid of the ticks--I was thinking about the misery the horse 
  was in at the moment with big ticks hanging in their ears and the sores the 
  ticks were making--and how ear-shy the horse was getting from my trying to do 
  something about the ticks.   I think I'll risk the possibility of 
  cancer down the road since they are not going to have more than "two packs of 
  tobacco" before they come home (where there are no ticks, apparently thanks to 
  the goats---so "legend" has it--grin).   Claudia