Thank You Pesticides

I appreciate all the responses in my flea conflict. I had googled what to do before anyone had responded, and it talked of soap and water. So I washed Lexi, letting the water get up to her neck, to drown all the fleas, I found 6 fleas in the bath water. I combed and blow dried her. I still had to quarantined her to the bath tub, because I still found live fleas on her after all that. She was not a happy dog not getting to go for rides in the car when ever we left, or play with her girls, or sleep with them at night. It was a hard time for her and us listening to her whelp. Max called the vet and they suggested Front line, to just pick up at the pet store. Max went and they were all out of Front line, but he picked up "Spot On"(a cheaper competitor) It is a chemical pesticide that is placed on the neck. I guess it worked because by the time I got home from work (because I don't work for the government and most people don't get Veterans day off), Max said he couldn't find any fleas on her. I had washed all the bedding and vacuumed all the areas she lays. So she is out of the quarantined bath tub, on her clean pillow, and we will see if there is a re infestation. I hope not. Only time will tell... approx 2 weeks. I wonder how safe these pesticides are for my family? If you have read my blog, or know me at all, you would know I hate bugs...not just fleas, not just spiders, any kind of bug. My question is will this chemical cause cancer in my children later on? I wonder if it is this like burning down the house to get rid of fleas, sure it does the job, but I wonder what I am left with? Just wondering.... in the mean time the girls are all back together.