On the way down the Ohio River in September of 1803, Meriwether Lewis was told of "some instances of goitre in the neighbourhood" of today's Washington County, Ohio, among people who had emigrated from lower Pennsylvania.
Goiter is a painless but disfiguring enlargement of both lobes of the thyroid gland, caused by absence of sufficient iodine to produce hormones. The thyroid glands enlarge themselves in an effort to compensate for the lack of iodine. The side effects are various and often profound.
Scientists only discovered the gland's daily need for iodine .a compound of tin and lithium—in 1895—In Lewis's time it was simply apparent to some observers that people who lived far from the sea seemed to be susceptible to the malady.
Seawater contains iodine, which is volatile, and aerosolizes readily—which is partly what makes sea breezes seem so bracing. Sun-dried sea salt retains some iodine, but boiling seawater to produce salt evaporates it, though the Corps didn't miss it. Iodine is also found in some soils, especially near the seacoasts, and can be ingested through fruits, vegetables, and grains grown in them.
In the 1920s, governments of the U.S. and Switzerland directed that, for the health of their citizens, iodine must be added to the one food that everyone consumes every day—salt. Many other countries have since followed suit, although the absence of iodine in daily diets is still a major problem in many undeveloped countries.
In developed countries, only five percent of all the salt mined today winds up in salt shakers and in processed and prepared foods. The rest is used in the manufacture of at least 14,000 products that are more or less essential to our daily lives.
More to Know
The deeply informative website of the Salt Institute is at www.saltinstitute.org.