you must be right : could be iode instead of oxygen ...

I was (incorrectly ...) remembering the words of a medical professor, explaining why people living in the Vosges area (medium montains range in the north-east of France) were more subject to cretinism : it was due to a lack of something (iode ?) ... in the water...
Other population known (end of 19th century) for a higher percentage of cretinism are people in the Alps area.

These old sayings seem no longer true with modern nutrition.