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Once part of the “goiter belt,” Michigan led salt iodization

black and white photo of female salt mine workers
Archives of Michigan
Women packing salt in hand labeled paper cans at Diamond Crystal Salt in St. Clair Shores, circa 1910

Iodized salt is a standard item on U.S. grocery store shelves today, but a century ago, iodine deficiency plagued Michigan. Iodine is essential for the thyroid to produce hormones that regulate metabolism. When the thyroid doesn’t get enough of the mineral, it can become enlarged, causing a neck swelling known as endemic goiter.

Endemic goiter is rare here today, but before 1925, Michiganders had a lot of goiters. In some parts of the state, nearly 60% of people suffered from them.

The problem was so widespread that much of the northern half of the country became known as “the goiter belt.” And Michigan was “smack dab in the middle” of it, said Rachel Clark, Education Specialist at the Michigan History Center.

“Michigan and what became the ‘goiter belt’ just simply did not have enough natural iodine in either plant or animal life to create high enough levels in people,” said Clark.

“Scientists and doctors knew what iodine was. They knew the benefits of iodine,” said Clark. The association with thyroid health had been identified in 1895. “But it wasn't until really the 1920s in Michigan that you start to see a change in policy.”

In 1923, the State Department of Public Health conducted a goiter survey to assess the problem, taking water samples and interviewing people.

Most people with goiters dealt primarily with discomfort, though “there were people who did suffer from breathing problems, and it could spread into lungs and other parts of your body and cause problems,” Clark said.

Iodine deficiency caused other serious problems. Historian Howard Markel has documented the case of a Houghton County draft board physician who rejected nearly 30% of potential army recruits to participate in the Great War in 1918 because of goiter and hypothyroidism. A 1924 survey found that half of schoolchildren statewide showed symptoms. Some suffered brain damage.

The widespread problem needed a sweeping solution, and fortified salt was determined to be the easiest way to increase the amount of iodine in Michiganders’ diets.

black and white photo of man standing next to salt piles
Archives of Michigan
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A man stands next to mounds of salt in a mine tunnel at the International Salt Company's Detroit Salt Mine. Now operated by the Detroit Salt Company, the mine remains active underneath the city today, primarily producing road salt.

"The state arranged with Michigan Salt Company, which is out of Marine City, and then later on with Martin Salt and I believe Detroit Salt as well, to make sure that iodized salt was sold across Michigan,” said Clark.

Much of that salt came from local mines.

“We have enormous salt mines even today in Michigan,” she added.

Those mines, coupled with Michigan’s goiter crisis, led the state to play a central role in normalizing iodized salt across the national market.

“Because of the percentages of people in Michigan that were suffering," Clark said, "we really did push it forward and sort of were at the forefront of that.”

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Elizabeth Harlow is an Assistant Producer for Stateside.
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