XXIX. THE IODINE CONTENT OF SOME SOUTH CAROLINA PRODUCTS ROE E. R E M I N G ~SOUTH N, CAROLINA FOODRESEARCH C O ~ I S S I O NCXARLESTON, , Sown CAROLINA
The general assembly of the state of South Carolina at its 1928 session created a commission and provided funds for the purpose of making studies on the mineral elements contained in foods grown or produced in the state. The commission consists of six members: the president of the state university, the president of the state agricultural college, the dean of the medical college of the state, and the secretary of the state board of health, ex officio; Dr. William Weston, pediatrician and student of nutrition of Columbia, and Dr. R. R. Walker, a practicing physician of Laurens, the last two appointed by the governor. A laboratory was established in affiliation with the Medical College of the State of South Carolina a t Charleston. I t is the aim of this commission to accumulate information, on a more complete scale than has heretofore been attempted, as to the occurrence of the so-called mineral elements (mineral elements in the sense that they are usually separated and determined as inorganic salts) in the various substances used as food for man or domestic animals. Among these elements the most common are calcium, phosphorus, magnesium, chlorine, iron, and the alkali metals. Others, however, which have attracted recent interest are iodine, fluorine, manganese, copper, and zinc. W e the exact part which some of these latter elements may play in nutrition is as yet problematic, the r61e of iodine has been quite de6nitely established. Endemic thyroid enlargement, myxedema and cretinism are results of iodine deficiency. The studies of McClendon on surface waters and on vegetable foods have shown that there is very little iodine in the food and waters of that part of the United States in which simple goiter is a serious problem. In fact, no surface waters in the country contain sufficient iodine to provide entirely for the needs of nutrition. Goiter is not endemic in South Carolina: examination of over seventeen thousand high-school students in twenty counties by the State Board of Health having shown an incidence of 3.8 per cent, as compared with 70 per cent or more for the upper Mississippi Valley, 40 per cent for southern Ohio and Colorado, etc. I t appeared then, that South Carolina would be a desirable place to make an exhaustive study on the occurrence of iodine in human environment, and this project was accordingly taken up in the laboratory. 2396
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CHEMICAL PROGRESS IN THE SOUTH
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Careful analyses of a wide variety of vegetables show that iodine is extremely widely distributed throughout the products of the agriculture of the state in amounts ranging from 100 to 1000 or more parts per billion, these amounts being several times greater than have been previously reported from anywhere in the United States (Table I). TABLE I Iodine Content of Some South Carolina Vegetablesand Fruits (Parts per billion, dry basis) Alrnogc
Numb" of iodine mmplas content
Pruils
Asparagus Green beans Beet tops Cabbage Carrot tops Chinese cabbage Collards Cucumbers Egg plant Kale Lettuce Mustard Okra Onions Pimentos Rape Spinach Summer squash Turnip tops
26 14 3 17 6 1 3 2 3 2 13 2 3 6 1 3 19 7 7
285 210 657 263 433 300 232 530 187 278 912 224 223 222 150 300 692 625 376
Blueberries Dewberries Peaches Pears Strawberries Tomatoes Watermelon Roots Artichokes Beets Carrots Irish potatoes Rutabagas Sweet potatoes Turnips
2 1 3 1 5 8 1
1 9 16 76 5 70 13
Seeds
Cottonseed meal Peas Oats in hull Peanuts Rye in hull
1 3 1 1 1
TABLE I1 Iodine Content of Potatoes in Relation to Distance from the Sea Di~lonrrfrom sea
0- 50 miles 50-100 miles 100-150 miles 150-200miles 200miles
Number of som~lcs
19 16 15 15 4
Iodine conlcnl in ports per billion drv boris (noclose)
180 213 223 249 266
For the purpose of a systematic survey, samples of Irish potatoes were collected from all parts of the state and results show a slight but definite progressive increase in iodine as we go from the coast to the mountains (Table 11). This finding is not in agreement with the accepted theory
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that salt spray from the sea is the predominant source of iodine. The ratio of chlorine to iodine in sea water is a million to one, and some streams in upper South Carolina have been shown by Mitchell to contain onefourth as much iodine as does sea water, yet the streams are far from being salty. The most evident explanation lies in the theory that the source of iodine is in the disintegration of granitic rocks in the Blue Ridge, and Fellenberg has reported more iodine in granitic rocks than sedimentary rocks. In view of the ditference in the physical and chemical properties of the soil in the diierent parts of the state, soils of the Piedmont being more colloidal than coastal plain soils, and the fact that Chilean nitrate of soda (which carries a fraction of a per cent of iodine) has been used in South Carolina agriculture for more than fifty years, the exact source of the iodine may he questionable. Doubtless systematic surveys of iodine in the environment of dwellers in every locality will contribute materially to our knowledge of the endemic goiter problem. The South Carolina work is the fist attempt to do this on a thorough scale. Other states are following. Attempts are being made by the South Carolina Natural Resources Commission to capitalize this work in a commercial way in encouraging immigration into the state from goitrous regions, and in creating a demand for South Carolina vegetables in such regions.
