After receiving over 44,000 complaints from side-effects from chemical flea preventatives ranging from mild to death, the EPA has issued a warning. Evidently there is also a class-action lawsuit in the works.
I can say that personally, I had a pug puppy who was old enough to safely use Frontline per the instructions, and at half the recommended dose, the puppy exhibited a negative neurological response, losing control of normal motor skills. I immediately washed off the chemicals and he immediately improved with no apparent permanent ill effects. This was not reported to the EPA - how many others are there out there that have never been reported?
After a friend lost her cat to a flea treatment last night, I felt compelled to research things a bit more and to share the information. Here is a page that addresses the EPA's warning along with some alternative solutions to chemical flea preventatives.
We primarily use garlic internally to repel, along with diatomaceous earth and essential oils externally. Based on a high quality diet, with these preventative, there are few situations in which a chemical alternative is necessary.
P.S. - A common natural solution for grubs and fleas is the use of nematodes in the lawn. Although this is definitely a viable alternative for fleas, it also negatively affects beetles. And in areas with fireflies, that means them, too. So if you would like to preserve the beetles and fireflies, please be judiscious regarding the areas on which you choose to use nematodes!