LIBRARY. A 8: M COLLEGE. " i TEXAS AGRICULTURAL EXPERIMENT STATION A. B. CONNER, DIRECTOR, College Station, Texas BULLETIN NO. 595 NOVEMBER 1940 -___._._..~_ .. 2,“) IODIN E IN DRINKING WATERS, VEGETABLES, COTTONSEED MEAL, AND ROUGHAGES G. S. FRAPS and J. F. FUDGE Division of Chemistry r Agricultuzai ssiiszge niiexas fiaiisga WKBS AGRICULTURAL AND MECHANICAL COLLEGE OF TEXAS T. O. WALTON, President ' A96-1140-7M-L180 [Blank Page in Original Bulletin] Iodine was determined in nearly 500 samples of city and rural drinking waters, vegetables, cottonseed meals, roughages and grasses from various parts of Texas. Iodine was deficient in only a very few samples, and in most samples was high when compared with similar samples from areas where the iodine was sufliciently low to cause goiter. Iodine in 103 samples of city waters ranged from 4 to 312 parts per billion, with an average of 56. Iodine in three samples of cistern water averaged only 4 parts per billion. Iodine in city waters averaged lowest in the East Texas Timber Country (24 parts per billion) and highest in the High Plains (101 parts per billion). There was good agreement between the average iodine in waters and the average iodine content of soils of the same region. The iodine content varied directly with the quantities of sodium chloride in the waters. Iodine in 37 samples of vegetables ranged from 62 to 3502 parts per billion. Iodine in Texas vegetables was much higher than in corresponding vegetables from. goitrous areas, and as high as or higher than that in vegetables reported from other non- goitrous areas. Iodine in 235 samples of cottonseed meal ranged from 23 to 1420 parts per billion. The average iodine in samples from dif- ferent geographic divisions ranged from 92 parts per billion in the West Cross Timbers to 251 parts per billion in the Rio Grande Plain. There was good agreement between the average iodine in cottonseed meal and that in soils of the same region. Iodine in 56 samples of roughages and grasses ranged from 17 to 1125 parts per billion. There was a considerable range in the iodine content of different samples of the same type of forage and a wide range between average iodine contents of dif- ferent types of forage, but iodine was deficient in only a very few cases. The use of iodized table salt for human consumption in Texas is not advisable, except under the supervision of a competent physician. The use of iodized mineral mixtures for livestock in Texas is not recommended. TABLE OF CONTENTS PAGE Introduction . . . . . . . . l . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Method of analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 6 Iodine and salts in drinking waters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Iodine in vegetables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 Iodine in cottonseed meal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 15 Iodine in roughages and grasses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 18 Discussion of results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 19 The use of iodine in table salt and mineral mixtures . . . . . . . . . . . . . . . . . . 21 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 Literature cited . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 24 IODINE IN DRINKING WATERS, VEGETABLES, COTTON- SEED MEAL, AND ROUGHAGES IN TEXAS G. S. Fraps, Chief, and J. F. Fudge, Chemist, Division 0f Chemistry Iodine in minute quantities has long been recognized as necessary for the health of man and animals. Where very low quantities of iodine in foods, feeds, and waters occur, there may be a high incidence of simple goiter (43, 45, 46, 49, 50, 51, 59, 60, 63). Other disturbances of health may also be due in part to insufficient iodine intake. The quantity of iodine required daily is very small, 1 microgram of v iodine per pound of animal or man being considered sufiicient (48), (one microgram is about two one-billionths part of a pound). Continuous con- sumption of quantities of iodine considerably in excess of the quantities required may result in injury to health of animals and of man (5). Texas is not in an area in which deficiencies of iodine for man or animals are known to occur and give rise to goiter. No instance of an animal suffering from a disease due to deficiency of iodine has heretofore been found by the Division of Veterinary Science. Nevertheless, efforts are being made commercially to promote the use of iodine in animal feeds. Iodized salt is extensively distributed in Texas, and if sufiicient quantities of iodine are present in the food or water, the use of iodized salt is unnecessary and may even injure health. A survey of the possible needs for iodine in Texas is therefore important. The need for and importance of iodine surveys in different geographical regions, in order to determine whether or not the iodine supply is sufiicient for proper development and maintenance has been shown by the Work of Marine (43), McClendon (49), Weston (74), and others. Such a survey of the iodine content of soils, drinking waters, vegetables, cottonseed meal, and roughages from various sections of Texas was begun by the authors a number of years ago. Work already published has shown that very few of the soils of Texas are deficient in iodine, and that some of them are relatively quite high (20), and that the iodine content of vegetables and drinking waters from various sections of Texas is also relatively high (19). This bulletin presents in detail the results of a study of the iodine con- tent of vegetables, cottonseed meal, and a few roughages collected from various sections of Texas, together with the iodine and mineral content of drinking waters collected from a number of cities. Cottonseed meal was selected as an indicator of the iodine taken by plants from the soil. Irish potatoes and cabbage have been used by other investigators (50, 61, 64) for the same purpose. Cotton is widely grown, and meal from the cotton seed grown in various locations of the state can easily be secured, as representative of the different localities. 6 BULLETIN NO. 595, TEXAS AGRICULTURAL EXPERIMENT STATION Method of Analysis In case of water, an aliquot, usually 500 cc, was treated with a sligg excess of sodium, hydroxide and evaporated to about 30 cc. Iodine W then estimated by the method described elsewhere in detail (21). T, waters collected were also analyzed for mineral salts. a Vegetables and feeds were cut into small pieces and dried in an a. at about 45° C. The material was then ground in a Wiley mill and stor in tightly closed jars. Cottonseed meals were ground in a Quaker Ci mill. A portion of the sample, from 25 to 100 grams, was burned in current of oxygen in the apparatus described by von Kolnitz and Re f‘ ington (31). The combined absorbing solution and washings were th evaporated to about 30 cc and iodine estimated. The estimation of iodine was made by a colorimetric modification ~ the method described by Trevorrow and Fashena (16, 72) already scribed in detail (21). In this procedure, iodine and residual orga matter are oxidized by chromic acid, the iodates reduced by phosphorof acid, the iodine distilled in an all-glass apparatus, the iodine in the dl tillate oxidized to iodic acid by the addition of bromine, the bromine boil off, and the iodic acid reduced by potassium iodide. The liberated iod' is extracted from the aqueous solution with carbon tetrachloride, and -g color produced by the iodine compared with that produced by iod’ from a standard iodide solution treated in the same way. The distillati of the iodine was necessary to eliminate interfering substances. Iodine and Salts in Drinking Waters The quantities of iodine and mineral salts found in the drinking watt 1 from 103 cities in Texas are shown in Table 1. The numbers given in g fourth column of Table 1 refer to the geographic division of Texas sho in Figure 1. Iodine in these city waters ranged from 4 to 312 parts billion. The iodine content varied within a given division, and also betw different divisions. With a very few exceptions, however, all of the Te J samples had a high content of iodine in comparison with waters if goitrous areas shown in Table 2. The mean iodine content, as shown _ Table 3, was 56 parts per billion, with a standard deviation of 60 pa 1A per billion. Iodine was lowest in city waters from the East Texas Tim I Country and the West Cross Timbers; both of these areas are covered r sandy, noncalcareous soils low in iodine as compared with other Te l soil (20). Iodine was highest in city waters from the High Plains and Rio Grande Plain, both of which are covered, in the main, by heavier soil many of which are calcareous and high in iodine. However, waters c l taining relatively low quantities of iodine occur throughout the state, ‘ is shown by the minimum analyses (Table 3). In the opinion of Miss Mildred Horton, State Home Demonstrati Agent, and the District Home Demonstration Agents, goiter is of ve rare occurrence in all districts, with the possible exception of certa F i wwvwv..r,-_,....,-.._.,,.w_,k -... 8 NOLLVLS LNEIWIHEIJXEI TVHHJIIHOIHDV SVXELL ‘Q69 ‘ON NLLEYYIIIH Hebbronville . . . . . . Hempstcad . . . . . . . Henderson . . . . . . . . Hillsboro . . . . . . . . . Houston . . . . . . . . . . Huntsville . . . . . . . . Jacksonville . . . . . . Jasper . . . . . . . . . . . Jayton . . . . . . . . . . . Junction . . . . . . . . . Kingsville . . . . . . . . Lamesa . . . . . . . . . . Lampasas . . . . . . . . Laredo . . . . . . . . . . . Livingston . . . . . . . . Lockhart . . . . . . . . . Longview . . . . . . . . . Lubbock . . . . . . . . . Lufkin . . . . . . . . . Lufkin . . . . . . . . . . . Madisonville . . . . . . Marshall . . . . . . . . . Mexia . . . . . . . . . Mineola . . . . . . . . . . Mineral Wells. . . . . Midland . . . . . . . . . . Montague . . . . . . . . McAllen . . . . . . . . . . McCamey . . . . . . . . Nacogdoches . . . . . . Navasota . . . . . . . . . Odessa . . . . . . . . . . . Oakwood . . . . . . _ . . Paducah . . . . . . . . . Palacios . . . . . . , . . . Palestine . . . . . . . . . Paris . . . . . . . . . . . . . Plainview. . . . . . .. Raymondvillc. . . . . Refugio . . . . . . . . . . Rockdalc . . . . . . . . . Round Rock . . . . . . usk . . . . . . . . . . . . San Angelo . . . . . . . San Antonio . . . . . . Schulenburg . . . . . . Seymour . . . . . . . . . Spur . . . . . . . . . . . . . pd i-l l-l QUWHOJHHHI-‘Or—¢OJn—*\Ir>O\IOO¢.CP-‘IHI—NQ0HH\I i-l v-l flDtCwfiiCi-lifildflfiCfififiNfiDl-iCJil-‘OOQUT OLE "IVEIN (IEIHSNO-L-LOO ‘SEFIEIVLEIDEIA ‘SQIELLVAA ‘DNDINIHQ NI HNIGOI 6 . Table 1. Iodine (parts per billion) and salts (parts per million) in waters from cities in Texas~—Continued Ge0- _ Mag- Mag- Mag- _ Lab. _ (glraphic Calcium Calcium nesium nesium nesium Sodium Sodium Sodium N0. City (Iirvision Iodine carbonate sulphate carbonate sulphate chloride carbonate sulphate chloride ig. 1) 44518 Sulphur Springs. .. 3 62 35 10 . . . . . . . . . . 21 . . . . . . . . . . . . . . . . . . . . 18 28 48742 Sweetwater . . . . . . . 8 63 170 15 . . . . . . . . . . 36 28 . . . . . . . . . . . . . . . . . . . . 3 47276 Taylor . . . . . . . . . . . 3 171 43 . . . . . . . . . . 15 . . . . . . . . . . . . . . . . . . . . 307 580 361 46357 Teague . . . . . . . . . . . 1 43 39 . . . . . . . . . . 13 9 . . . . . . . . . . . . . . . . . . . . 27 54 48801 Temple. . . . . . . . .. 3 15 130 44 . . . . . . . . .. 17 28 . . . . . . . . . . . . . . . . . . .. 20 46145 'l‘errell . . . . . . . . . . . 3 37 55 27 . . . . . . . . . . 27 . . . . . . . . . . . . . . . . . . . . 11 25 44515 Texarkana . . . . . . . . 1 44 43 19 . . . . . . . . . . . . . . . . . . . . 33 . . . . . . . . . . . . . . . . . . . . 7 47275 Thorndalc . . . . . . . . 3 210 55 . . . . . . . . . . 13 18 . . . . . . . . . . . . . . . . . . . . 14 50 46354 Trinity . . . . . . . . . . . 1 127 29 . . . . . . . . . . 8 . . . . . . . . . . . . . . . . . . .-. 21 11 393 44514 Tyler . . . . . . . . .. 1 21 23 15 . . . . . . . . . . . . . . . . . . .. 26 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 46682 Uvalde . . . . . . . . . . . 7 15 202 . . . . . . . . . . 7 19 19 . . . . . . . . . . . . . . . . . . . . 15 49187 Vernon . . . . . . . . . . . 9 22 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44401 Victoria . . . . . . . . . . 2 102 79 . . . . . . . . . . 42 . . . . . . . . . . . . . . . . . . . . 154 23 162 46148 vVaco . . . . . . . . . . . . 3 52 130 32 . . . . . . . . . . 11 21 . . . . . . . . . . . . . . . . . . . . 31 46146 Waxahachie . . . . . . 3 51 12 . . . . . . . . . . 10 . . . . . . . . . . . . . . . . . . . . 406 160 480 44399 Wharton . . . . . . . . . 2 28 161 . . . . . . . . . . 20 23 7 . . . . . . . . . . . . . . . . . . . . 83 48710 Wichita Falls. . . . . 9 23 45 194 . . . . . . . . . . . . . . . . . . . . 71 . . . . . . . . . . . . . . . . . . . . 410 » . . m... NOLLVLS LNEINIHEIJXEI TVHILIFIIIOIHDV SVXIELL ‘Q69 "ON NLLEITIIIH IODINE IN DRINKING WATERS, VEGETABLES, COTTONSEED MEAL, ETC. 11 Table 2. Iodine (parts per billion) in some city waters from goitrous areas Iodine Region Reference Low High Average Illinois . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6, 7 .13 1.33 . . . . . . . . . . Maryland . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8, 53 .06 5.0 . . . . . . . . . . Massachussets . . . . . . . . . . . . . . . . . . . . . . . . . . .. 10, 11 O 6.3 2.14 Michigan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14, 59 O 8.7 . . . . . . . . . . Minnesota (Duluth) . . . . . . . . . . . . . . . . . . . . . . . 6 . . . . . . . . . . . . . . . . . . . . .014 Nebraska . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 .005 .30 . . . . . . . . . . North Dakota . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69 Too small to d etermine Utah . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 24 .18 2.16 . . . . . . . . .. Poland . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 32 1.1 12.4 . . . . . . . . .. England (Suffolk) . . . . . . . . . . . . . . . . . . . . . . . . . 6O . .‘ . . . . . . . . . . . . . . . . . . 8.2 England (Somerset) . . . . . . . . . . . . . . . . . . . . . . . 60 . . . . . . . . . . . . . . . . . . . . 2.9 Norway . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 4O 1.5 2.0 . . . . . . . . .. Germany (Westphalia) . . . . . . . . . . . . . . . . . . . . . 3, 4 .12 19.6 . . . . . . . . . . New Zealand . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68 .4 15.0 . . . . . . . . . . Average for Texas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 312 56 the water contained 5 parts per billion of iodine. In Poland, iodine in 56 waters (71) ranged from 46 parts per billion in northern Poland, where no goiter occurs, to .05 parts per billion in the southern mountainous region, where goiter frequently occurs. The lowest quantity of iodine in drinking waters required for good health is estimated difierently by different workers. Broll (8) recommends that iodine be added to the drinking water supply whenever the iodine content falls below .3 parts per billion. Little (36) states that the addition of 169 micrograms of sodium iodide to a gallon of water, equivalent to 44.6 parts per billion of iodine, for 2 weeks in the spring and 2 weeks in the fall, cured or prevented common goiter. This would average less than 4 parts per billion for the entire year. Rogers (66) states that when the iodine content of the water exceeds 2 parts per billion, goiter incidence is reduced; however, Lunde (40) reported 1.5 to 2 parts per billion of iodine in drinking water in Norway when the incidence of goiter was about 70 * per cent. McClendon (47) states that 10 parts per billion or over of iodine in water is sufiicient to prevent goiter, even though the diet is deficient in iodine. This seems to be a liberal allowance. Only 3 of the waters from Texas cities contained less than 10 parts per billion of iodine (Table 1); it may therefore be concluded that city waters in Texas usually contain suflicient quantities of iodine. The quantities of the mineral salts in the waters analyzed are given in Table 1. Excessive quantities of salts are not contained in any of these waters. The relation between the iodine and the other salts in drinking water is of interest. Throughout thei Middle West, where the incidence of goiter is much higher than it is in Texas (37), waters are in most cases high in calcium and low in sodium. Many Texas waters contain consid- erable quantities of sodium and in many, the quantity of sodium greatly exceeds the quantity of calcium (Table 1). The coefficient of correlation Table 3. Average iodine (parts per billion) in city waters in Texas ZI _Fre uency Number Iodine y groups Standard _ _ Geographic Division in Fig. l Total Mean deviation Minimum 0-25 25-50 51-75 76-100 101 + East Texas Timber Country . . . . . . . . . . . . . . . .. 1 33 19 14 0 0 0 24 l2 9 West Cross Timbers . . . . . . . .. 5 4 3 0 1 0 0 28 16 14 Rolling Plains . . . . . . . . . . . . . . . . . . . . . 8 l3 5 6 1 O 1 38 27 13 Grand Prairie . . . . . . . . . . . . . . . . . . . . . 4 1 0 1 0 0 0 43 . . . . . . . . . . 43 Basins and Mountains . . . . . . . . . . . . . 10 1 O 1 0 0 0 48 . . . . . . . . . . 48 Edwards Plateau . . . . . . . . . . . . . . . . . . 7 3 O 1 2 O O 55 11 49 Gulf Coast Prairie . . . . . . . . . . . . . . . .. 2 5 1 2 O 1 1 58 37 25 Blackland Prairies . . . . . . . . . . . . . . . . . 3 20 3 5 7 1 4 68 49 l5 Rio Grande Plain . . . . . . . . . . . . . . . . . . . . . . . . . .. 6 14 3 3 2 0 6 99 89 14 High Plains . . . . . . . . . . . . . . . . . : . . . . . . . . . . . . . . 9 9 2 1 1 1 4 114 101 4 All Divisions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103 36 34 14 3 16 56 60 4 .4I4¢~Ax._4 smaaaiil... NOLLVCLS JJQEINIHEIJXEI "IVHHJIIHOIHDV SVXELL ‘E69 'ON NILEPYIIIH IODINE IN DRINKING WATERS, VEGETABLES, COTTONSEED MEAL, ETC. 13 Table 4. Iodine (parts per billion) in waters from farms in Northwest Texas Depth of well _ Locality County feet Iodine Lamesa . . . . . . . . . . . . . . . . . . . . . . . . Dawson . . . . . . . . . . . . . . 80 213 Lamesa . . . . . . . . . . . . . . . _ . . . . . . . . Dawson . . . . . . . . . . . . . . 5O . 223 Lamesa . . . . . . . . . . . . . . . . . . . . . . . . Dawson . . . . . . . . . . . . . . Unknown 196 Lamesa . . . . . . . . . . . . . . . . . . . . . . . . Dawson . . . . . . . . . . . . . . Unknown 97 Spur . . . . . . . . . . _ . . . . . . . . . . . . . . . . Dickens . . . . . . . . . . . . . . Cistern 4 Dickens . . . . . . . . . . . . . . . . . . . . . . . . Dickens . . . . . . . . . . . . . . 5O 4O Dickens . . . . . . . . . . . . . . . . . . . . . . . . Dickens . . . . . . . . . . . . . . 55 42 Clairmont . . . . . . . . . . . . . . . . . . . . . . Kent . . . . . . . . . . . . . . . . . Cistern 3 Clairmont . . . . . . . . . . . . . . . . . . . . . . Kent . . . . . . . . . . . . . . . . Cistern Clairmont . . . . . . . . . . . . . . . . . . . . . . Kent . . . . . . . . . . . . . . . . . 200 31 Farwell . . . . . . . . . . . . . . . . . . . . . . . . Parmer . . . . . . . . . . . . . . 200 76 Farwell . . . . . . . . . . . . . . . . . . . . . . . . Parmer . . . . . . . . . . . . . . . 200 64 between iodine and calcium salts was + .0335, and is not significant, while that for iodine and sodium salts was + .4099, and is highly significant. The coefficient of correlation between iodine and calcium carbonate, the prin- cipal calcium salt, was + .1007, and is not significant; that between iodine and sodium chloride, the principal sodium salt, was + .8131, and is highly significant. The iodine is probably derived from the sea water contained in the deposits when they were laid down under the sea. Iodine in Vegetables Iodine was determined in a small number of vegetables secured from Weslaco in the Rio Grande Valley, Winter Haven in the western part of the Rio Grande Plain, Sugar Land and Prairie View in the Gulf Coast Prairie, and College Station in the East Texas Timber Country (Table 5). The limited number of vegetables analyzed is, of course, not sufiicient to represent all parts of the vast area of Texas, but the results secured indicate that the vegetables from all of the areas sampled are relatively high in iodine (Tables 5 and 6). While iodine in most of the vegetables was high, it varied considerably with the portion of the plant used as food, the variety, location, and soil. The effect of the season upon the iodine content of the vegetables was not determined. Leafy vegetables contained much more iodine than root or ' fruit vegetables. Greens from beets and turnips contained about 75 per cent more iodine than roots from the same plants. Copenhagen Market cabbage j from Weslaco contained over four times as much iodine as All Head cab- bage collected at the same time and place. A sample of Italian Green Sprouting broccoli grown on a Brennan fine sandy loam at Weslaco con- tained over eight times as much iodine as the same vegetable grown on a Duval fine sandy loam at Winter Haven. Other comparisons may be made from the data presented in Table 5. The vegetables analyzed contained quantities of iodine which are in most cases as high as, or higher than, amounts reported for similar vegetables from other states (Table 6). The averages for carrots, okra, and tomatoes Table 5. Iodine (parts per billion) in vegetables grown in Texas Vegetable Variety Location Soil Type Iodine Beans . . . . . . . . . . . . . . . Bountiful . . . . . . . . . . . . . . . . . . . . . . . . . . . Weslaco . . . . . . . . . . . . Victoria sandy loam . . . . . . . . . . . . . . . . . . . 955 Beets, leaves . . . . . . . . Unknown . . . . . . . . . . . . . . . . . . . . . . . . . . . Sugar Land . . . . . . . . Miller silt loam . . . . . . . . . . . . . . . . . . . . . . . 915 Beets, leaves . . . . . . . . . Unknown . . . . . . . . . . . . . . . . . . . . . . . . . . . Prairie View . . . . . . . . Hockley fine sandy loam . . . . . . . . . . . . . . . 702 Beets, leaves . . . . . . . . Unknown . . . . . . . . . . . . . . . . . . . . . . . . . . . College Station. . . . . Lufkin fine sandy loam . . . . . . . . . . . . . . . . . 369 Beets, leaves . . . . . . . . Dark Red Turnip . . . . . . . . . . . . . . . . . . . College Station . . . . . . Lufkin fine sandy loam . . . . . . . . . . . . . . . . . 1030 Beets, roots . . . . . . . . . Unknown . . . . . . . . . . . . . . . . . . . . . . . . . . . Sugar Land . . . . . . . . Miller silt loam . . . . . . . . . . . . . . . . . . . . . . . 588 Beets, roots . . . . . . . . . Unknown . . . . . . . . . . . . . . . . . . . . . . . . . . Prairie View . . . . . . . . Hockley fine sandy loam . . . . . . . . . . . . . . . 431 Beets, roots . . . . . . . . . Unknown . . . . . . . . . . . . . . . . . . . . . . . . . . . College Station. . . . . Lufkin fine sandy loam . . . . . . . . . . . . . . . . . 180 Beets, roots . . . . . . . . . Dark Red Turnip . . . . . . . . . . . . . . . . . . . College Station. . . . . Lufkin fine sandy loam . . . . . . . . . . . . . . . . . 308 Broccoli. . . . . . . . . . . . . Italian Green Sprouting . . . . . . . . . . . . . Winter Haven . . . . . . Duval fine sandy loam . . . . . . . . . . . . . . . . . 429 Broccoli . . . . . . . . . . . . . Italian Green Sprouting . . . . . . . . . . . . . Weslaco . . . . . . . . . . . . Brennan fine sandy loam . . . . . . . . . . . . . . . 3502 Broccoli . . . . . . . . . . . . . Glory of Calabria . . . . . . . . . . . . . . . . . . . . Weslaco . . . . . . . . . . . . Brennan fine sandy loam . . . . . . . . . . . . . . . 521 Brussels Sprouts. . . . . Long Island Improved . . . . . . . . . . . . . . . Winter Haven . . . . . . Duval fine sandy loam . . . . . . . . . . . . . . . . . 62 Cabbage . . . . . . . . . . . . Unknown . . . . . . . . . . . . . . . . . . . . . . . . . . . Sugar Land . . . . . . . . Miller silt loam . . . . . . . . . . . . . . . . . . . . . . . 1208 Cabbage . . . . . . . . . . . . Marion Market . . . . . . . . . . . . . . . . . . . . . Sugar Land . . . . . . . . Miller silt loam . . . . . . . . . . . . . . . . . . . . . . . 2163 Cabbage . . . . . . . . . . . . Enkhuizen . . . . . . . . . . . . . . . . . . . . . . . . . . Weslaco . . . . . . . . . . . . Victoria sandy loam . . . . . . . . . . . . . . . . . . . 370 Cabbage . . . . . . . . . . . . All Head . . . . . . . . . . . . . . . . . . . . . . . . . . . Weslaco . . . . . . . . . . . . Victoria fine sandy loam . . . . . . . . . . . . . . . . 153 Cabbage. ." . . . . . . . . . . Copenhagen Market . . . . . . . . . . . . . . . Weslaco . . . . _ . . . . . . . Victoria fine sandy loam . . . . . . . . . . . _ . . . . 667 Carrots . . . . . . . . . . . . . Danver’s . . . . . . . . . . . . . . . . . . . . . . . . . . . Weslaco . . . . . . . . . . . . Victoria fine sandy loam . . . . . . . . . . . . . . . . 233 Eggplant . . . . . . . . . . . . Imperial Black Beauty . . . . . . . . . . . . . . . Weslaco . . . . . . . . . . Webb fine sandy loam . . . . . . . . . . . . . . . . . 112 Endive . . . . . . . . . . . . . . Green Curled . . . . . . . . . . . . . . . . . . . . . . . Weslaco . . . . . . . . . . . . Brennan fine sandy loam . . . . . . . . . . . . . . . 559 Mustard . . . . . . . . . . . . Southern Giant Curled . . . . . . . . . . . . . . Weslaco . . . . . . . . . . . . Brennan fine sandy loam . . . . . . . . . . . . . . . 498 Mustard . . . . . . . . . . . . Tender green . . . . . . . . . . . . . . . . . . . . . . . Weslaco . . . . . . . . . . . . Webb fine sandy loam . . . . . . . . . . . . . . . . . 1071 Mustard . . . . . . . . . . . . Unknown. . ._ . . . . . . . . . . . . . . . . . . . . . . . . Sugar Land . . . . . . . . Miller silt loam . . . . . . . . . . . . . . . . . . . . . . . 510 Mustard . . . . . . . . . . . . Southern Giant Curled . . . . . . . . . . . . . . Weslaco . . . . . . . . . . . . Victoria fine sandy loam . . . . . . . . . . . . . . . 866 Mustard . . . . . . . . . . . . Southern Giant Curled . . . . . . . . . . . . . . . College Station . . . . . . Lufkin fine sandy loam . . . . . . . . . . . . . . . . . 1185 Okra . . . . . . . . . . . . . . . . White Velvet . . . . . . . . . . . . . . . . . . . . . . . Weslaco . . . . . . . . . . . . Webb fine sandy loam . . . . . . . . . . . . . . . . . 251 Pepper. . . . ._ . . . . . . . . . California Wonder . . . . . . . . . . . . . .'. . . . . Weslaco . . . . . . . . . . . . Webb fine sandy loam . . . . . . . . . . . . . . . . . 312 Potatoes, Iri_sh . . . . . . . Early Triumph . . . . . . . . . . . . . . . . . . . . . . Sugar Land . . . . . . . . . Miller silt loam . . . . . . . . . . . . . . . . . . . . . . . 220 Potatoes, Irish . . . . . . . Bliss Triumph . . . . . . . . . . . . . . . . . . . . . . Weslaco . . . . . . . . . . . . Victoria sandy loam . . . . . . . . . . . . . . . . . . . 347 Potatoes, Irish . . . . . . . Triuméih . . . . . . . . . . . . . . . . . . . . . . . . . . . Weslaco . . . . . . . . . . . . Victoria fine sandy loam . . . . . . . . . . . . . . . 162 Potatoes, Irish . . . . . . . Iri_sh obbler . . . . . . . . . . . . . . . . . . . . . . . Sugar Land . . . . . . . . Lake Charles clay loam . . . . . . . . . . . . . . . . 160 Potatoes, Irish . . . . . . . Triumph . . . . . . . . . . . . . . . . . . . . . . . . . . . Sugar Land . . . . . . . . Lake Charles clay loam . . . . . . . . . . . . . . . . 1045 Spinach . . . . . . . . . . . . . Unknown . . . . . . . . . . . . . . . . . . . . . . . _ . . Sugar Land . . . . . . . . Miller silt loam . . . . . . . . . . . . . . . . . . . . . . . 821 Spinach . . . . . . . . . . . . . Bloomsdale Savoy . . . . . . . . . . . . . . . . . . . Weslaco . . . . . . . . . . . . Brennan fine sandy loam . . . . . . . . . . . . . . . 679 Squash . . . . . . . . . . . . . . Giant Summer Straightener . . . . . . . . . . Weslaco . . . . . . . . . . . . Webb fine sand loam . . . . . . . . . . . . . . . . . 290 Swiss Chard . . . . . . . . . Giant Lucullus . . . . . . . . . . . . . . . . . . . . . . College Station. . . . . Lufkin fine san y loam . . . . . . . . . . . . . . . . . 2088 Tomato . . . . . . . . . . . . . Bonn Best . . . . . . . . . . . . . . . . . . . . . . . . Weslaco . . . . . . . . . . . . Webb fine sandy loam . . . . . . . . . . . . . . . . . 351 Tomato . . . . . . . . . . . . . Marg obe . . . . . . . . . . . . . . . . . . . . . . . . . . . Weslaco . . . . . . . . . . . . Brennan fine sandy loam . . . . . . . . . . . . . . . 339 Turnips, leaves . . . . . . . Shogoin . . . . . . . . . . . . . . . . . . . . . . . . . . . . Weslaco . . . . . . . . . . . . Webb fine sand loam . . . . . . . . . . . . . . . . . 723 Turnips, leaves . . . . . . . Purple Top White Globe . . . . . . . . . . . . . College Station . . . . . . Lufkin fine san y loam . . . . . . . . . . . . . . . . . 1525 Turnips, roots . . . . . . . Shogoin . . . . . . . . . . . . . . . . . . . . . . . . . . . . Weslaco . . . . . . . . . . . . Webb fine sandy loam . . . . . . . . . . . . . . . . . 460 Turnips, roots . . . . . . . Purple Top Globe . . . . . . . . . . . . . . . . . . . Weslaco . . . . . . . . . . . . Victoria fine sandy loam . . . . . . . . . . . . . . . . 705 Turnips, roots . . . . . . . Purple Top White Globe . . . . . . . . . . . . . College Station . . . . . . Lufkin fine sandy loam . . . . . . . . . . . . . . . . . 833 ‘VI NOLLVLS LNHWIEIEIJXEI "IVHIIJIIIIOIHDV SVXELL ‘Q69 'ON NLLEYYIHH IODINE IN DRINKING WATERS, VEGETABLES, COTTONSEED MEAL, ETC. 15 Table 6. A comparison of the iodine (parts per billion) in vegetables from difierent states _ South Texas Oklahoma* GeorgiaT Carolina}; Califl Beans . . . . . . . . . _ . . . . . . . . . . . . . . . 955 501 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Beets, roots . . . . . . . . . . . . . . . . . . . . 377 245 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Beets, leaves . . . . . . . . . . . . . . . . . . . 854 651 . . . . . . . . . . . . . . . . . . . . 8 Cabbage . . . . . . . . . . . . . . . . . . . . . . . 912 286 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Carrots . . . . . . . . . . . . . . . . . . . . . . . . 233 507 . . . . . . . . . . . . . . . . . . . . 8 Mustard . . . . . . . . . . . . . . . . . . . . . . . 826 561 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Okra . . . . . . . . . . . . . . . . . . . . . . . . . . 251 777 . . . . . . . . . . 412 . . . . . . . . . . Potatoes . . . . . . . . . . . . . . . . . . . . . . . 387 210 54 333 . . . . . . . . . . Spinach . . . . . . . . . . . . . . . . . . . . . . . . 750 483 567 . . . . . . . . . . 32 Tomato . . . . . . . . . . . . . . . . . . . . . . . . 345 379 . . . . . . . . . . . . . . . . . . . . 20 Turnip greens . . . . . . . . . . . . . . . . , . 1124 676 226 . . . . . . . . . . . . . . . . . . . . *See Literature cited, 25 TSee Literature cited, 27 ISee Literature cited, 52 are lower than the averages reported for Oklahoma (25), but for carrots and tomatoes are very much higher than those reported for California (52). Conner (12) states that vegetables grown in Florida contain about the same quantities of iodine as similar crops grown in South Carolina. Potatoes from Michigan contained 94 parts per billion of iodine (64), from Minnesota, 86 parts per billion (64), from Pennsylvania, '78 parts per billion (23), from the eastern section of Minnesota, 85 parts per billion (50), and from the western section of Minnesota, 226 parts per billion (50), while the average of 5 samples of potatoes grown in Texas was 387 parts per billion (Table 6). Cabbage from the east-northeast section of Minnesota contained 111 parts per billion of iodine, and from the southwest section of Minnesota, 174 parts per billion (51), while the average of the Texas samples (Table 6) was 912 parts per billion. Mc- Clendon and his associates are of the opinion that the lower occurrence in goiter in the western sections of Minnesota, as compared with the eastern section of the state, is largely attributable to the higher iodine content of the vegetables. Cabbage grown in Texas contained 912 parts per billion of iodine, compared with 174 parts per billion in the less goitrous part of Minnesota; potatoes grown in Texas contained 387 parts per billion of iodine, compared with 226 parts per billion in the less goitrous parts of Minnesota. If McClendon and his associates are correct, the comparatively high iodine content of Texas vegetables should be sufii- ' cient to preclude the probability of the development of goiter in Texas because of an insufficient supply of iodine in vegetables. The limited number of vegetables analyzed is of course not sufficient to represent all parts of the vast area of Texas. Iodine in Cottonseed Meal Cottonseed meal was analyzed for iodine in order to compare the quan- tities of iodine which could be taken up by the cotton plant from soils in different parts of the State. Since cottonseed meal could be readily secured and represents a single kind of plant grown on different soils 16 BULLETIN NO. 595, TEXAS AGRICULTURAL EXPERIMENT STATION Table 7. Iodine (parts per billion) in samples of cottonseed meal Primar Number County geograp ic o High Low Average d1YlSl0I1 samples (Fig. 1) Anderson . . . . . . . . . . . . . . . . . . . . . . 1 4 166 52 98 Bastrop . . . . . . . . . . . . . . . . . . . . . . . . 3, 1 5 218 60 109 ee . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 2 998 65 532 Bell . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 1 . . . . . . . . . . . . . . . . . . . . 253 Bexar . . . . . . . . . . . . . . . . . . . . . . . . . 7 3 140 65 108 Bosque . . . . . . . . . . . . . . . . . . . . . . . . 5 1 . . . . . . . . . . . . . . . . . . . . 27 Bowie . . . . . . . . . . . . . . . . . . . . . . . . . 1 3 201 102 150 Brazos . . . . . . . . . . . . . . . . . . . . . . . . . 1 1 . . . . . . . . . . . . . . . . . . . . 73 Brown . . . . . . . . . . . . . . . . . . . . . . . . . 5 2 144 67 106 Caldwell . . . . . . . . . . . . . . . . . . . . . . . 1, 3 4 203 92 156 Cam . . . . . . . . . . . . . . . . . . . . . . . . . 1 3 157 89 132 Chil ress . . . . . . . . . . . . . . . . . . . . .. 9 5 534 94 217 Coleman . . . . . . . . . . . . . . . . . . . . . . . 9 2 120 102 111 Collin . . . . . . . . . . . . . . . . . . . . . . . . . 3 3 121 77 99 Colorado . . . . . . . . . . . . . . . . . . . . . . . 3, 1 1 . . . . . . . . . . . . . . . . . . . . 104 Cooke . . . . . . . . . . . . . . . . . . . . . . . . . 5 1 . . . . . . . . . . . . . . . . . . . . 146 Coryell . . . . . . . . . . . . . . . . . . . . . . . . 5 1 . . . . . . . . . . . . . . . . . . . . 98 Crosby . . . . . . . . . . . . . . . . . . . . . . . . 10 1 . . . . . . . . . . . . . . . . . . . . 42 Dallas . . . . . . . . . . . . . . , . . . . . . . . . . 3 2 200 111 156 Delta . . . . . . . . . . . . . . . . . . . . . . . . . . 3 5 371 56 223 De Witt . . . . . . . . . . . . . . . . . . . . . . . 3, 1 4 513 46 212 Ellis . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 7 475 50 155 El Paso . . . . . . . . . . . . . . . . . . . . . . . . 11 4 441 153 241 Erath . . . . . . . . . . . . . . . . . . . . . . . . . 5 2 41 39 40 alls . . . . . . . . . . . . . . . . . . . . . . . . . . 3, 1 4 807 79 341 Fannm . . , . . . . . . . . . . . . . . . . . . . . . 3, 1 3 214 61 120 Fayette . . . . . . . . . . . . . . . . . . . . . . . . 3, 1 2 84 55 70 loyd . . . . . . . . . . . . . . . . . . . . . . . . . 10 2 372 138 255 Fort Bend . . . . . . . . . . . . . . . . . . . . . 2 2 93 40 67 Gonzales . . . . . . _ . . . . . . . . . . . . . . . . 3, 1 4 151 48 104 Grayson . . . . . . . . . . . . . . . . . . . . . . . 1, 3 5 346 95 197 Gregg . . . . . . . . . . . . . . . . . . . . . . . . . 1 1 . . . . . . . . . . . . . . . . . . . . 139 Grimes . . . . . . . . . . . . . . . . . . . . . . . . 1 1 . . . . . . . . . . . . . . . . . . . . 48 Guadalupe . . . . . . . . . . . . . . . . . . . . . 3, 1 3 132 48 98 Hale . . . . . . . . . . . . . . . . . . . . . . . . . . 10 2 78 44 61 Hamilton . . . . . . . . . . . . . . . . . . . . . . 5 2 207 56 132 Hardeman . . . . . . . . . . . . . . . . . . . . . 9 4 156 41 88 Harris . . . . . . . . . . . . . . . . . . . . . . . . . 2 2 210 176 193 Harrison . . . . . . . . . . . . . . . . . . . . . . . 1 1 . . . . . . . . . . . . . . . . . . . . 189 Haskell . . . . . . . . . . . . . . . . . . . . . . . . 9 2 145 125 135 Henderson . . . . . . . . . . . . . . . . . . . . . 1 4 184 42 119 Hill . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 7 194 65 151 Hopkins . . . . . . . . . . . . . . . . . . . . . . . 1, 3 5 576 81 222 Houston . . . . . . . . . . . . . . . . . . . . . . . 1 ‘ 1 . . . .. . . . . . . . . . .. 105 Hunt . . . . . . . . . . . . . . . . . . . . . . . . . . 3, 1 8 478 68 200 Jim Wells . . . . . . . . . . . . . . . . . . . . . . 7 2 216 91 154 Jones . . . . . . . . . . . . . . . . . . . . . . . . . . 9 3 140 42 91 Karnes . . . . . . . . . . . . . . . . . . . . . . . . 7 3 910 48 353 Kaufman . . . . . . . . . . . . . . . . . . . . . . 3, 1 7 230 23 77 Kent . . . . . . . . . . . . . . . . . . . . . . . . . . 9 2 163 56 110 Knox . . . . . . . . . . . . . . . . . . . . . . . . . . 9 2 76 67 72 Lamar . . . . . . . . . . . . . . . . . . . . . . . . . 3 1 . . . . . . . . . . . . . . . . . . . . 117 Lamb . . . . . . . . . . . . . . . . . . . . . . . . . 10 1 . . . . . . . . . . . . . . . . . . . . 249 Lavaca . . . . . . . . . . . . . . . . . . . . . . . . 3 2 899 708 804 Lubbock . . . . . . . . . . . . . . . . . . . . . . . 10 5 223 50 125 McCulloch . . . . . . . . . . . . . . . . . . . . . 9 3 265 132 199 McLennan . . . . . . . . . . . . . . . . . . . . . 3, 1 6 437 59 164 Maverick . . . . . . . . . . . . . . . . . . . . . . 7 2 110 82 96 Milam . . . . . . . . . . . . . . . . . . . . . . . . . 3, 1 3 587 77 282 Mitchell . . . . . . . . . . . . . . . . . . . . . . . 9 1 . . . . . . . . . . . . . . . . . . . . 131 Nacogdochcs . . . . . . . . . . . . . . . . . . . 1 2 504 232 368 . 3 5 255 59 125 9 2 "129 95 112 7 4 1420 29 465 10 1 . . . . . . . . . . . . . . . . . . . . 48 10 4 105 55 81 Red River . . . . . . . 1 2 83 64 74 Robertson . . . . . . . . 1, 3 1 . . . . . . . . . . . . . . . . . . . . 511 Runnels . . . . . . . . . . . . . . . . . . . . . . . 9 5 327 45 124 Rusk . . . . . . . . . . . . . . . . . . . . . . . . . . 1 2 262 71 167 IODINE IN DRINKING WATERS, VEGETABLES, COTTONSEED MEAL, ETC. 17 Table 7. Iodine (parts per billion) in samples of cottonseed meal—Continued Primary_ Number _ ' County geographic of High Low Average division samples (Fig. 1) San Patricio . . . . . . . . . . . . . . . . . . . 7 1 . . . . . . . . . . . . . . . . . . . . 115 9 1 . . . . . . . . . . . . . . . . . . . . 86 1 1 . . . . . . . . . . . . . . . . . . . . 156 5 1 . . . . . . . . . . . . . . . . . . . . 128 9 1 . . . . . . . . . . . . . . . . . . . . 156 1 1 . . . . . . . . . . . . . . . . . . . . 67 3 2 241 37 139 3 2 235 159 197 Upshur . . . . . . . . . . . . . 1 1 . . . . . . . . . . . . . . . . . . . . 166 ‘ Victoria. . . . . . . . 7 6 291 32 142 Walker... 1 1 . . . . . . . . . . . . . . . . . . .. 170 Wharton. . . . . . . 2 3 200 87 133 - Wheeler. . .. 9 2 211 61 136 Wilbarger. .. ..... " 9 1 . . . . . . . . . . . . . . . . . . .. 512 Williamson.. . . . . . . . . . . . . . . . . 3, 1 4 405 61 173 0o . . . . . . . . . . . . . . . . . . . . . . . . . 1 2 33 38 Young . . . . . . . . . . . . . . . . . . . . . . . . . 5 1 . . . . . . . . . . . . . . . . . . . . 52 L Table 8. Distribution of samples of cottonseed meal from difierent geographic divisions in various ranges ofiodine content (parts per billion) Average Distribution Geographic division iodine Above Total p. p. b. Below 50- 101- 151- 200 50 100 150A 200 West Cross Timbers . . . . . . . . . .» . . . . . . 92 3 4 3 O 1 11 East Texas Timber Country. . .. . . . . . 96 11 33 12 8 3 67 Gulf Coast Prairie . . . . . . . . . . . . . . . . . 131 1 2 1 2 1 7 Rolling Plains . . . . . . . . . . . . . . . . . . . . . 141 5 12 10 4 7 38 High Plains . . . . . . . . . . . . . . . . . . . . . . . 144 3 6 3 4 4 2O Blackland Prairies . . . . . . . . . . . . . . . . . 240 O 12 16 14 27 69 Rio Grande Plain . . . . . . . . . . . . . . . .. 251 3 5 ~ 7 1 7 23 Total . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 74 52 33 50 235 As percentage of all samples . . . . . . . . . . . . . . . . . 11 31 22 14 22 100 Table 9. ‘ Mean iodine content of cottonseed meals (parts per billion) and of soils (parts. per million) for various geographic divisions Iodine in cottonseed meal Average _ ' " p. p. . Number iodine Geographic Division of in soils Standard samples p. p. m. Mean High Low deviation West Cross Timbers . . . . . . . . . . . .. 92 207 27 6 11 5.0 East Texas Timber Country . . . . .. 96 262 23 5 67 2.2 ~ Gulf_ Coast _Prairie . . . . . . . . . . . . . . 131 210 4O 6 7 3.5 ' Rolling Plains . . . . . . . . . . . . . . . . . . . 141 534 41 11 38 7.1 High Plains . . . . . . . . . . . . . . . . . . . 144 441 42 1O 2O 3.9 Blackland Prairies . . . . . . . . . . . . . .. 240 899 5O 19 69 5.8 19 23 8.0 I Rio Grande Plain . . . . . . . . . . . . . .. 251 1420 29 18 BULLETIN NO. 595, TEXAS AGRICULTURAL EXPERIMENT STATION in a variety of climatic conditions, it is a good means of comparing th possibility of the soils to furnish iodine to plants. Iodine was determin in 235 samples of cottonseed meal sent in by inspectors of the Feed Contr_ Service. Samples were used only from mills located in smaller towns these were probably from seed produced in the locality of the mills, ,wher : 1 samples from large mills in the larger cities might have come from w? from much larger areas. 1 The analyses of the cottonseed meals are summarized by counties ' Table 7. The iodine content of different cottonseed meal samples rang’ from 23 to 1420 parts per billion. Considerable differences occur in differen samples from the same. county. The data for variation and distributio" and the variation in the different sections of the state (see Fig. 1), ar summarized in Table 8. Of the 235 samples, 26 contained less than I parts per billion of iodine, 126 contained between 51 and 150 parts p, billion of iodine, and 50 contained more than 200 parts per billion. If the different geographic divisions, however, the relative proportion o, samples in the different iodine groups varied considerably. For exampl’ 84 per cent of the samples from the East Texas Timber Country cont tained less than 150 parts per billion, while 60 per cent of the sample from the Blackland Prairies contained over 150 parts per billion. l The mean iodine content, high and low analyses, and standard deviatio of cottonseed meals from the different geographic divisions (Fig. 1) ar shown in Table 9. The average iodine content of samples from the dif; ferent divisions ranged from 92 to 251 parts per billion but in no cas was it low. The average iodine content of the soils of the geographi divisions (20) is also shown in Table 9. The relative standing of the dif’ ferent divisions with respect to the iodine content of the meals is abou the same as it is with respect to the iodine in the soils, with the exce, tions that the iodine in the samples from the West Cross Timbers an Rolling Plains is comparatively low and that in the samples from th Blackland Prairies comparatively high. In general, however, there is ‘g close relation between the iodine content of the meals and that of the soil The iodine content of cottonseed meal can contribute effectively to th’ needs of animals for iodine. i Iodine in Roughages and Grasses The iodine content of 20 samples of roughages and grasses is shown " Table 10. Iodine in 6 samples of coarse roughage (fodders, silage, an stover) ranged from 53 to 115 parts per billion, with an average of 7 parts per billion. One sample of sumac silage, however, contained 835 pa > per billion of iodine. Iodine in 5 samples of hay varied from 90 to 55 parts per billion, with an average of 2'71 parts per billion. Iodine in I samples of grass varied from 92 to 1086 parts per billion with an avera of 492 parts per billion. A sample of chapparo prieto (Condalia obtus’ flora) contained only 21 parts per billion, while a sample of prickly pea (Opuntia sp.) tips contained 1125 parts per billion. There was thus :1 IODINE IN DRINKING WATERS, VEGETABLES, COTTONSEED MEAL, ETC. 19 Table l0. Iodine (parts per billion) in various roughages and grasses Geographic _ Laboratory Forage Locality division Iodine Number (Fig. 1) 37753 Sumac fodder . . . . . . . . . . . . . . . Big Spring . . . . . . . . 10 53 37618 Kafir fodder . . . . . . . . . . . . . . . . Spur . . . . . . . . . . . . . 9 55 37615 Red Top fodder . . . . . . . . . . . . Spur . . . . . . . . . . . . . 9 58 37617 Hegari fodder . . . . . . . . . . . . . . Spur . . . . . . . . . . . . . 9 69 37600 Silage . . . . . . . . . . . . . . . . . . . . . . East Texas . . . . . . . 1 95 39323 Sumac silage . . . . . . . . . . . . . . . . Spur . . . . . . . . . . . . . 9 835 39064 Hegari stover . . . . . . . . . . . . . . . Beeville . . . . . . . . . . 7 115 37731 Sorgo hay . . . . . . . . . . . . . . . . . . East Texas . . . . . . . 1 90 37512 Alfalfa hay . . . . . . . . . . . . . . . . . Bosser . . . . . . . . . . . 3 92 37732 Alfalfa hay . . . . . . . . . . . . . . . . . East Texas . . . . . . . 1 168 37645 Alfalfa hay (medium). . . . . . . Balmorhea. . . . . . . . 11 455 37644 Alfalfa hay (grassy) . . . . . . . . . Balmorhea . . . . . . . . 11 550 34277 Buffalo grass . . . . . . . . . . . . . . . Sonora . . . . . . . . . . . 8 92 40607 Dallis grass . . . . . . . . . . . . . . . . Tyler . . . . . . . . . . . . 1 303 40611 Dallis grass . . . . . . . . . . . . . . . . Angleton . . . . . . . . . 2 336 37784 Sudan grass . . . . . . . . . . . . . . . . Beeville . . . . . . . . . . 7 358 40609 Bermuda grass . . . . . . . . . . . . . . Tyler . . . . . . . . . . . . 1 778 40606 Carpet grass . . . . . . . . . . . . . . . . Tyler . . . . . . . . . . . . 1 1086 33419 Cha arro prieta . . . . . . . . . . . . Laredo . . . . . . . . . . . 7 21 39334 Pric ly pear tips . . . . . . . . . . .. Sonora . . l . . . . . . .. 8 1125 Table 11. lodine content (parts per billion) of young Bermuda and young and mature little bluestem grasses ‘ Bluestem Bluestem Soil type Bermuda young mature Susquehanna silt loam . . . . . . . . . . . . . . . . . . . . . . . .. 124 120 20 Lufkin fine sandy loam . . . . . . . . . . . . . . . . . . . . . . .. 120 123 24 Susquehanna fine sandy loam . . . . . . . . . . . . . . . . .. 78 44 25 Ochlockonee fine sandy loam . . . . . . . . . . . . . . . . . . . . 35 35 31 Victoria clay loam . . . . . . . . . . . . . . . . . . . . . . . . . . .. 387 35 33 Ruston fine sandy loam . . . . . . . . . . . . . . . . . . . . . . . . 162 347 34 Susquehanna fine sandy loam . . . . . . . . . . . . . . . . . . . 121 61 40 Susquehanna fine sandy loam . . . . . . . . . . . . . . . . . . . 521 254 52 Norfolk fine sandy loam . . . . . . . . . . . . . . . . . . . . . . . . 126 789 53 Nacogdochcs gravelly fine sandy loam. . . . . . . . . . . . 17 465 61 Susquehanna fine sandy loam . . . . . . . . . . . . . . . . . . . 161 151 90 Bowie fine sandy loam . . . . . . . . . . . . . . . . . . . . . . . . . 34 209 173 Average . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 157 220 53 considerable range in the iodine content of different samples of the same type of forage, and a large range in the average iodine content of different types of forage. The influence of the species and age of grass upon the average iodine content of some grasses is shown in Table 11. The results are somewhat erratic, but the average iodine content of young bluestem was appreciably higher than that of young Bermuda and about four times as high as that of mature bluestem. Discussion of Results While the necessity for small amounts of iodine in the development and healthful maintenance of the body has long been recognized, the quantities required have only recently been estimated. The requirements may be 20 BULLETIN NO. 595, TEXAS AGRICULTURAL EXPERIMENT STATION increased by certain unfavorable physiological, dietary, and environmen- tal conditions. Under normal conditions, however, the quantity required is very small. The daily iodine requirements for humans has been estimated by Marine, Lenhart, and Kimball (44) to be about 85 micrograms (a microgram is one one-millionth of a gram, or about two one-billionths of a pound), by ' Meerburg (54) from 80 to 100 micrograms, by Hercus and Purves (26), from 120 to 160 micrograms, by Cameron (9) from. 35 to 70 micrograms, by Orr and Leitch (61), 45 micrograms for an adult male and 150 micro- grams for a child, and by Levine, Remington, and von Kolnitz (35) and Mitchell and McClure (55) from 60 to 120 micrograms. McClendon (48) states that if the daily intake is less than 1 microgram per kilogram (2.2 pounds) of weight, danger of goiter in man exists; if it is near or above 2 micrograms, there is no danger of goiter, even though the susceptibility to goiter is increased by infectious disease or high fat or high cabbage diet. Remington and Levine (65) state that a diet probably does not produce goiter if it contains more than 35 parts per billion of iodine. The daily iodine requirement for farm animals has been estimated by Levine, Remington, and von Kolnitz (35) to be from 20 to 40 micrograms per 1000 Calories of the ration. Using this estimate as a basis, Mitchell and McClure (55) estimate that the daily iodine requirement of a chicken l is from 4.5 to 9 micrograms, of a sheep from 50 to 100 micrograms, of a f pig from 80 to 160 micrograms, and of a cow giving 40 pounds of milk from 400 to 800 micrograms. Orr and Leitch (61) estimate that in non- goitrous regions the daily iodine intake of a fowl is 5 micrograms, of a sheep from 120 to 2,000, of a pig from 40 to 80, of a sow, about 200, and of a cow, from 3,000 to 30,000 micrograms; evidently, there may be con- p’ siderable excess iodine at the higher levels, but the lower figures given by Orr and Leitch are in fair agreement with the estimates of Mitchell and McClure. The iodine required by the body comes both from the water and from the food ingested. The mean iodine content of the 103 samples of water (Table 3) from cities in Texas was 56 parts per billion. average Texas city water would thus contain about 100 micrograms of iodine, or suflicient iodine for a day’s requirement without including the iodine in the food consumed. Most people in Texas probably {lrink consid- erably more than that quantity per day and in so doing ingest in their drinking water alone, sufficient iodine for proper development and main- tenance. Iodine in Texas vegetables has also been shown to be high, and in addition, people in many parts of Texas consume considerable quantities of sea food, which is very high in iodine. Very few of the roughages, grasses, and cottonseed meals contained less than 35 parts per billion;_ most of them contained much more than this amount. It seems highly probable, therefore, that in very few areas in Texas is the supply of iodine in drinking waters, foods, and feeds sufficiently low to be a dietary problem, and that goiter produced by an insufficient supply of iodine is of comparatively rare occurrence in Texas. Two quarts of' IODINE IN DRINKING WATERS, VEGETABLES, COTTONSEED MEAL, ETC. 21 That this conclusion is warranted is shown by a survey of goiter among men drafted during the World War (37). The incidence of goiter among these men ranged from 2.691 per cent among men from Idaho to .025 per cent among men from Florida; Texas was second from the bottom of the list, with a goiter incidence of only .030 per cent. Reports of later goiter surveys in the United States (57, 58) corroborated these results; goiter among Texas school children (58) in Austin, Denton, El Paso, and Hidalgo was extremely rare. Since it is well known that mature indi- viduals are much more resistant to the development of simple goiter than are children, it may safely be concluded that iodine deficiency in Texas is of comparatively minor importance and rare occurrence. Goiter among animals in Texas is also comparatively rare. In cases where iodine is markedly deficient, pigs and lambs are often born hairless; no cases of hairless pigs or lambs have been reported from Texas. Goiter in cattle is extremely noticeable, the enlargement in the throat being very marked; this condition is not known among Texas cattle. Fenger, Andrew, and Vollertsen*(17) reported that the yearly average iodine content of thyroid glands from hogs from North Dakota was 0.32 per cent on the desiccated, fat-free basis, while that in thyroids from hogs from Texas was 0.60 per cent, or nearly twice as great. The seasonal variations in the iodine content of the thyroid was much greater in the hogs from North Dakota, as compared with those from Texas. Throughout Texas, the iodine content of waters, foods, and feeds is sufficiently high to insure that the occurrence of simple goiter, due to a deficiency of iodine, will be extremely’rare. In cases where it does occur, it seems probable that simple adjustments of the diet will provide suffi- cient iodine. » The Use of Iodine in Table Salt and in Mineral Mixtures During recent years, considerable interest has arisen concerning the use of iodized table salt for human consumption and iodized mineral mix- tures for livestock. The use of iodized table salt and the addition of iodine to water supplies has been recommended by a number of investigators (8, 36, 42, 43, 44, 45, 47, 48, 49) in areas where a deficiency of iodine is definitely known to exist. However, there may be some danger from excess iodine, even in these deficient areas, when too much iodine is used (5). The value of iodine in mineral mixtures for animals is doubtful, even in areas which are known to be deficient in iodine. Fairbanks and Curzon (15A) concluded that, except in special cases, it was uneconomical to sup- plement rations with iodine. The majority of the work done on this question indicates either that no beneficial effects were secured from its use, or that detrimental results were secured. With poultry, the use of iodine salts greatly increased the iodine content of the eggs (62, 67, 70, 75) but did not improve the nutritive value of the ration (28), egg production, or rate of mortality (18, 29, 33). Iodine in 22 BULLETIN NO. 595, TEXAS AGRICULTURAL EXPERIMENT STATION feeds containing high amounts of iodine was considerably better than iodine in mineral mixtures (2, 75). The iodine in the eggs immediately decreased upon discontinuance of the iodine feeding, indicating that the bird was simply using the egg as an outlet from the body for excess iodine (75). The size and calcium content of the eggs may be decreased by iodine feeding (62). Goiter in poultry is exceedingly rare (30), except in certain minor areas (73). With sheep, Malan, DuToit, and Groenewald (41) report that among ewes fed 50 milligrams of potassium iodide daily, only slightly more than the quantity recommended by Nichols (56), reproduction was abnormal; the condition was aggravated by feed low in carotene and was not over- come by more protein. Forbes and his associates (18) found no significant difierence, except that the lambs fed iodine required more feed per 100 pounds of gain than did the lambs which received no additional iodine. With hogs, Forbes and others (18) obtained no beneficial results with the use of iodine, while McClure and Mitchell (55) found no effect of iodine on the weight of the pigs but some indication that the retention of calcium was adversely affected. Evvard (15) recommends the use of iodine for hogs in goitrous regions. With cattle (18), milk and cream from cows fed iodine had an objec- tionable odor and contained very large amounts of iodine. Calves that received iodine ate less hay and made appreciably less gains in weight than did those receiving no iodine. All of the work discussed above, in which the use of iodine rarely gave any beneficial results and sometimes gave detrimental ones, was done in areas in which the iodine supply is known to be low and goiter is of considerable importance. In Texas, Where the iodine content of waters, foods, and feeds has been shown by the work here reported to be high, and where goiter is of rare occurrence, it is certainly not "to be expected that favorable results would be secured from the feeding of iodine in table salt or mineral mixtures. The addition of iodine to a diet already high in iodine results in more iodine being excreted in the urine (38, 39). The use of iodized table salt for human consumption in Texas is not recommended, except under the supervision of a competent physician. The use of iodized mineral mixtures for livestock in Texas is not rec- ommended. IODINE IN DRINKING WATERS, VEGETABLES, COTTONSEED MEAL, ETC. 23 SUMMARY This bulletin presents the results of a study of the iodine content of vegetables, cottonseed meals, and roughages grown in Texas, and the iodine and salt content of 103 samples of city waters and 12 rural waters in Texas. 1 Iodine in city waters varied from 4 to 312 parts per billion, with an average of 56 parts per billion and a standard deviation of 60 parts per billion. Only 3 samples of city water contained less than 10 parts per c billion iodine, the quantity thought by some investigators to be suflicient. Water from 3 cisterns contained from 3 to 5 parts per billion, and is com- paratively low. Compared with waters from other areas, city and well waters in Texas are high in iodine. Iodine in 37 samples of vegetables varied from 112 to 3502 parts per billion. Leafy vegetables contained much more iodine than root or fruit vegetables. Iodine varied with the part of the plant used for food, the variety, location, and soil. Compared with vegetables from other areas, vegetables grown in Texas are high in iodine. Iodine in 235 samples of cottonseed meal varied from 32 to 1420 parts per billion. Twenty-six samples contained less than 50 parts per billion, 126 contained from 51 to 150 parts per billion, and 50 contained more than 200 parts per billion iodine. Iodine in cottonseed meals varied con- siderably in the different geographical divisions of the state; in general, there was good agreement between average iodine in cottonseed meal and average iodine in the soils of the several divisions. Iodine in 6 samples of coarse roughage varied from 53 to 835 parts per billion; in 5 samples of hay, from 90 to 550 parts per billion, and in 42 samples of grass, from 17 to 1086 parts per billion. The average iodine content of young bluestem was higher than that of young Bermuda and mature bluestem grasses. I ' Iodine in Texas city waters, well waters, vegetables, cottonseed meals, roughages, and grasses is sufliciently high to insure adequate iodine intake by man and animals under ordinary conditions. In most cases, much more iodine is present than is required. Iodine in Texas foods, feeds, and , waters is much higher than in similar material from goitrous areas. The use of iodized table salt for human consumption in Texas is not recommended, except under the supervision of a competent physician. The use of iodized mineral mixtures for livestock in Texas is not recommended. 24 EPFIFFPPF?‘ 11. 12. 13. 14. 15A. 16. 17. 18. 19. 20. 21. 22. 23. 24. 26. 27. 28. 29. 30. 31. 32. 33. 34. 35. 36. 37. 38. BULLETIN NO. 595, TEXAS AGRICULTURAL EXPERIMENT STATION LITERATURE CITED Adolph, W. H., and Prochaska, F. J. 1929. I Med. Assoc. 92 :2158. s Almquist, H. J., and Givens, J. W. 1935. Effects of common feed ingredients on » I iodine content of hen eggs. Poultry Sci. 14:182. Balks, Rudolf. 1936. 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