In your case, the lid of the kettle is effectively in contact with the water. It sits exposed to hot steam, the steam condenses at the lid, and drops fall back into the water you're boiling.

Since the article repeatedly made a point to talk about cooking spatulas and hot oil, our only hope is that those flame retardants don't dissolve well in water - but dissolve very well in oil.

But if they do dissolve in water, it's safe to assume you're boiling them out of your kettle lid every time that thing runs.