Frontline Plus safety short and long term? How prevalent are dangerous counterfeits?

What are the long term health detriments to using frontline plus on dogs?
Where does one find the results of the clinical trial of this product?
http://www.epa.gov/opp00001/factsheets/r... described how to recognize counterfeit frontline plus. Does anyone have additional insights and knowledge about the problem?
Answers:
Here is a VERY good article about spot on type flea killers-- http://64.233.167.104/search?q=cache:pjo...

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While I don't think it's necessarily a great idea to put chemicals on my dogs each month the bottom line is this: they work.
Depending on where you live it can be impossible to manage fleas and ticks. My dog was infected with lyme disease 2 years ago and was very ill for some time. Deer ticks, that most common carrier of lyme are smaller than the tip of a pen. Almost impossible to detect, using Frontline (or other similar products) is the best way to prevent something like this. Even on Advantix my lab got lyme.
As far as counterfeits, I have been warned about this by my vet. This is why he will not write a prescription for use on sites like 1-800 pet meds or other mail order type places. I only buy Frontline from my vet or my very trustworthy small local pet store whom I know the owners of. My vet said selling expired flea and tick medication is actually more common than counterfeit. That most products from 1-800 pet meds are expired and sold at slashed prices. There is obviously no real data on using these expired products.
My solution has been to use frontline from May-October when these pests are most common and then manage by hand the rest of the year. I figure this gives my dogs the lowest possible exposure while still keeping them safe from pests.
Diatamaceous earth and nemotodes in the yard and garden are two great natural way to control fleas and ticks outside, but I found are most effective when you start pest free. They are not as effective as chemicals when trying to stop an infestation.
Thanks for the links to the articles, both very interesting.