I think there are some chemicals that are definately cancer encouraging.. but I think there is a genetic link as well.
That being said, although we keep the front yard, nice, short and green, it is not all Kentucky blue grasss and we have some buffalo grass and clover mixed in.. we pull weeds, but I do use Sevin dust to control ticks, fleas, mites and grubs. Because of Amanda's age I do not even use the monthly flea and tick preventative and at 17 if she gets heartworm, she would probably die of old age before the heart worm. She also only goes to the back yard. She doesn't even have to travel to the vet's office.. he comes to the house.
I do use the a combined flea tick and heart worm preventative on the other two dogs who do go places other than our own backyard.
The back yard is a mix of vetch, buffallo grass, and wild strawberries which seems to hold up to the dogs fairly well. We use one specific spot in the yard for Potties and in the fall, I do a soil PH test and apply a product called PDZ that is used in horse barns to neutralize horse urine just to that area.
We have baby locks on all the cabinets that house our household cleaners even though our baby is 10, just to keep the dogs out of them and we limit access to places like the bathroom where they can get ahold of shampoo and soap and other items.
Just a word of caution.. Zest brand soap is not poisonous in small doses, although it will definately clean out their digestive track for a few days. This is how we found out Lily knew how to turn door knobs and we had to install baby door knob covers to put on the bathroom doors.