He implied it was just natural. I was just amazed, though, for the topic to have been brought up casually in a Science
class out in the Ozarks. It has to be higher than the norm if it comes up in a Science
class more than 300 miles away!
I know the neighborhood I grew up in (age 6-18) never had any industry or such. I lived near the state line, and before the house was built, I was told it was just fields there. It was maybe 20 years old when we moved in. The area is still residential, lower upper class/upper middle class, so "prissy". The house we lived in was a real fixer-upper when we got it. I think mom and dad bought it for $40k, and wound up selling it for $60k (they never were able to afford to fix it up), but it's now worth over $350k. So definitely never had human introduced toxins beyond the every day car fumes, lawn pesticides, etc. And mom and dad didn't chemically treat the lawn (wasn't by choice, but because of budget).
Whether bromine or bromide was around there, there was definitely something in the area causing the mutation of the clover, and my sister and I definitely have unexplainable health issues. The ones in the family who are healthier didn't play out in the dirt like we did. There was nothing more fun than digging "caveman condos" in the dirt, living in them with Fisher Price Little People, running rivers of water down the side of the driveway, and driving on our dirt roads with Hot Wheels, not to mention running around with an occasional bodiless Barbie head by the hair like it was a voodoo shrunken head (when you forget where you temporarily bury the limbs, it doesn't leave much to play with).
One way or the other, it's interesting the topic came up. Especially since the Science
teacher doesn't regularly visit KC, didn't grow up in Missouri, so KC wasn't just on his mind. The bromine has to be "remarkable" for it to have been remarked on.