@GoldPeaPuffer @DetectiveHyde @thinkpad @solidsanek You spit out toothpaste, but even so if you wanted to be puritan about it and not use any fluoride the brushing does the vast majority of the job. The long-term exposure to trace amounts of it in all of the water you drink that is deliberately added in active concentrations is a whole different story.
Lead, mercury, arsenic, and so on can also be found in lakes and rivers but that doesn't mean that in elevated concentrations those substances aren't harmful.