Dennis Plank, age 12, of Williamsport, Pa., for his question:
Why is there no iodine around the Great Lakes?
Iodine is one of the 90 or so elements from which the world is made. It is a very rare element, yet it is vital to the human body. It is plentiful in almost all sea creatures, and traces of it occur in the air above the oceans. Yet, strange to say, we do not find it in sea water. On the other hand, it can be extracted from certain brine deposits. The cost of preparing this vital element is so high that the price of iodine is still one fourth that of silver.
On certain spots of the earth, the plants yield a plenteous supply of iodine and so do the meat animals which feed upon them. There seems to be iodine in the soil or, perhaps, in the air. Other regions are deficient in iodine and this deficiency is felt by animals and human beings.
Iodine is vital to the thyroid gland which controls the metabolism or burning processes of the body. A starved thyroid gland produces the throat swelling known as goiter. Regions short of iodine are sometimes called goiter belts. The Swiss Alps of Europe and the Great Lakes of North America are two such regions.
At various times in the earth’s long history, the sea has flooded and receded from most land areas. As it receded, it left piles of debris‑shells, decaying plant and animal life. This debris ultimately became soil. Perhaps the decaying sea life mingled its iodine content with this soil. However, both the Alps anal the region of the Great Lakes have been under sea water.
The central part of North America was submerged in the Carboniferous Period, some 200 to 250 million years ago. Perhaps this invasion of the sea did. leave its quota of iodine. Much later, in the past million years, both the Great Lakes region and the Alps felt the icy grip of the Ice Age glaciers. This is only a guess, iodine is a fragile element, always ready to combine with other elements and hide itself. Its freezing point is around 113 degrees and its boiling point 184‑degrees Centigrade.
If there were ever iodine in the soil of the Great Lakes region, perhaps the melting glaciers leached it away or caused it to combine with other elements. At best, this is only a guess, with no proof at all.
People who live near the sea get plenty of iodine from the air they breathe. They also tend to eat more iodine‑rich seafood. Farmers in iodine‑poor regions are urged to use fishfood fertilizers. The crops pick up iodine from this fish food and hand it on to the animals.
People who live in iodine‑poor regions are urged to eat iodized salt. This is salt with about one per cent iodine added ‑‑ which is enough to prevent all the goiters in a goiter belt.