Thank you for the clarification!! However, that still does not address a potential cumulative effect. And, I have not seen stats that suggest that a cumulative effect is not possible.I meant to suggest that, if somebody has a cat that has had seizures, treating the cat at the vet might be a sensible option.
This whole issue with flea treatments having to become more potent in order to serve their purpose is rather frightening. But, I guess, what other choice is there?