Levels of Antimony, Cadmium, Chromium, Cobalt, Manganese, and Zinc in Institutional Total Diets Gopala K. Murthy, Ulysses Rhea, and James T. Peeler Food and Drug Administration, U.S. Department of Health, Education and Welfare, Cincinnati, Ohio 45226
rn The average trace element content in the diets of children from differentinstitutions, expressed as mg/kg of food, varied as: antimony, 0.209 to 0.693; cadmium, 0.027 to 0.062; chromium, 0.175 to 0.472; cobalt, 0.252 to 0.693; manganese, 0.535 to 1.639; and zinc, 2.67 to 6.36. Similarly, the consumption of food varied from 1.18 to 2.55 kg/day and the milk content of diet varied from 9.5 to 63.8 %. Statistical analyses of the data (mg/day) showed significant seasonal and geographical variations. The samples from Palmer, Alas., and Salt Lake City, Utah, had the lowest trace element concentrations, whereas the concentrations in those from Tampa, Fla., and Jackson, Miss., were consistently high. Monthly averages for all elements showed that cadmium was constant throughout the year and the other elements tended to peak in late spring or summer.
A
dvances in industrial and technological processes have caused some problems associated with pollution of air, water, and food. It has become necessary to determine the nature and extent of this pollution to assess its effects on human health. Because of the increasing awareness of the relationship between disease and trace elements, our attention has been directed to this phase of the problem. Trace elements may be essential to the well being of the life cycle; they may be indifferent; or they may be detrimental if ingested in concentrations above a certain level. All elements are toxic at high concentrations. To determine the body burden, the concentration of trace elements in air, water, and food must be known. Food is the major source of intake. Schroeder et al. (Schroeder and Balassa, 1961a, 1961b, 1965, 1966; Schroeder et al., 1962a, 1962b, 1963a, 1963b, 1964, 1966; Schroeder, 1965; Schroeder et al., 1967a, 1967b) are probably the major contributors to our present accumulation of data on trace elements in various environmental media, the elements both essential and abnormal to man. Their data pertain essentially to individual components of the diet, with very limited data on total diets. Tipton and Stewart (1964) and Tipton et al. (1966) reported data on diets and excreta of two human subjects maintained on a normal diet for a 30-day period. Tipton et al. (1969) reported data on diets and patterns of elemental excretion in long-term balance studies. Harp and Scoular (1952) analyzed for Co by the colorimetric method the diets of 23 young college women maintained on self-selected diets. Similarly, North et al. (1960) reported data on the Mn content of 436 Environmental Science & Technology
the diets of nine college women. Feldman and Jones (1964) determined several trace elements by spectrographic analyses of institutional diets from 10 U S . cities. Kropf et al. (1968) analyzed several hundred samples of foods and drinks for Cd. No systematic analyses of diets have been made for extended periods, however, to determine variations attributable to geographic location and season. Most of the available data are for individual components of the diet and are based upon single samples of dairy products, vegetables, meats, etc. (Schroeder and Balassa, 1961a, 1961b, 1965, 1966; Schroeder et al., 1962a, 196213, 1963a, 1963b, 1964, 1966; Schroeder, 1965; Schroeder et al., 1967a, 1967b). It is difficult, if not impossible, to determine a relation between food supply sampled in such a random manner and a diet, even when the data on food consumption are available. Also, there is wide variation in the dietary habits of different ethnic groups. One solution to the problem may be found in the institutional or hospital diets. Sampling and analysis of such diets from demographically situated areas for extended periods should provide invaluable information. This paper presents data on Sb, Cd, Cr, Co, Mn, and Zn contents of the diets of institutionalized children, aged 9 to 12, in 28 U.S. cities. These institutions ranged from financially well-to-do boarding schools to orphanages with severe economic limitations.
Experimental Materials. Samples used in this study were portions of samples collected for radionuclide analyses by the Bureau of Radiological Health, U.S. Public Health Service. Samples were supplied monthly by each institution. Each sample represented the edible portion of the diet for a full seven-day week (21 meals plus soft drinks, candy bars, or other inbetween-meal snacks) obtained by duplicating the meals of a different individual each day; drinking water was not included. Each day’s sample was kept frozen until the end of the collection period and was then packed in Dry Ice and shipped by air express to one of the Radiological Health laboratories located in the Northeast (Winchester, Mass.), Southeast (Montgomery, Ala.), or Southwest (Las Vegas, Nev.). The processing of food samples, including the ashing techniques, has been described (US. Public Health Service, 1967). Portions of the well mixed ash of food samples from the Radiological Health laboratories were received in our laboratory for trace elemental analyses. About 28 samples were received each month during January and from March through December 1967.
Table I. Range and Average Values for Food Consumption and Antimony, Cadmium, Chromium, Cobalt, Manganese, and Zinc Content of Institutional Total Diets, January to December 1967 Food Milk, Manganeseb- Zince Antimony" Cadmiumb Chromiumb Cobaltb consumption, of Location total food kglday mdkg Juneau, Alas.d 2.15-3.10 4.4-11.6 0,175-0.279 0.020-0.0330.124-0.251 0.194-0.307 0.395-0.7302.13-3.34 (2.67) (0,607) (0.211) (0.027) (0.175) (0.252) (2.55) (9.5) 2.74-4.70 0,364-0.721 1 .22-1.83 17.5-32.0 0,158-0.3630.016~).062 0.092-0.396 0.227W.413 Palmer, Alas. (3.76) (0.546) (1.59) (23.5) (0.033) (0,226) (0.327) (0.238) 1 ,52-2.21 15 .&28.7 0.245-0.458 0.032-0.0650.205-0.6830.310-0.8720.578-1.0133.13-4.16 Phoenix, Ariz. (3.85) (0.794) (1.92) (18.8) (0.378) (0.048) (0.354) (0.523) Little Rock, Ark. 1.14-2.12 33.3-62.3 0,187-0.5330,036-0.0720.2064.466 0.253-0.970 0.575-1.3733.41-4.73 (4.15) (0.813) (1.92) (4315) (0.387) (0.048) (0.324) (0.617) Los Angeles, Calif. 1 .47-2.18 10.9-44.5 0.146-0.3780.022-0.053 0.182-0.4580.224-0.5490,422-0.8172.40-5.90 (3.85) (0.240) (0.033) (0,247) (0.345) (0.614) (1.94) (25.0) San Francisco, Calif. 1.99-2.88 27.1-43.1 0.162-0. 755 3.02-5.78 302 0.025-0.049 0,171-0.3630,205-0.4860.344-0). (0.576) (2.40) (35.2) (0.246) (0.033) (0.258) (0.348) (4,00) 1.98-2.43 26.1-40.6 0.198-0.3420,028-0.0470,145-0.3900.172-0.522 0.352-0.6622.63-5.92 Denver, Colo. (3.89) (2.28) (32.1) (0.545) (0.247) (0.034) (0.287) (0.393) Wilmington, Del. 2.05-2.38 37.6-43.4 0.293-0.571 0.047-0.070 0.136-0.6600.404-0.7810.797-1.212 4.23-8.91 (6.36) (2.20) (0.981) (40.4) (0.419) (0.055) (0.368) (0.593) Tampa, Fla. 1.94-2.18 21.1-48.8 0.348-0.6200.048-0.076 0.155-0.7780.395-0.861 0.598-1.1704.15-5.89 (5.38) (0.922) (2,08) (27,9) (0.446) (0.060) (0.398) (0.680) Idaho Falls, Idaho 1.56-2.16 36.0-44.6 0.257-0.825 0,035-0.0890,145-0.6900.432-1.092 0.678-1.1665.00-6.04 (5.71) (1.97) (0.979) (0.060) (0.410) (0.693) (41.5) (0.458) Chicago, Ill. 1.30-1.95 26.0-49.6 0.316-0.509 0.034-0.082 0.162-0.622 0.384-0.946 0,680-1.2735.51-11.30 (1.58) (6.80) (39.8) (0.910) (0.430) (0.055) (0.396) (0,645) Louisville, Ky. 1.23-2.28 32.8-82.9 0,3654,5670.030-0,079 0.224-0.470 0.261-1.041 0.502-1.1633.61-5.39 (4.78) (1.67) (53.2) (0.846) (0.441) (0.056) (0.346) (0.630) New Orleans, La. 1.42-2.26 37.1-96.1 0.267-0.5200 . 0 4 O,070 0,1624,5770,40550,9740.490-1,050 3.65-5.66 (4.82) (52.6) (1.84) (0.408) (0.056) (0.341) (0.631) (0.787) Boston, Mass. 1.48-2.08 34.3-52.8 0.246-0.661 0.040-0.0890.161-0.6080.252-1.0070,263-0.8904.79-9.70 (1.68) (6.08) (45.3) (0.667) (0,392) (0.052) (0.373) (0.595) Columbia, Miss. 1.79-2.39 39.7-84.4 0,312-0.5800,045-0,071 0.260-0.640 0.424-0.988 0.920-1.8513.82-6.44 (58.6) (1 ,639) (2.17) (5.40) (0.436) (0.058) (0,412) (0.559) St. Louis, M o . ~ 1.33-2.53 40.6-67.0 0.447-0.6880,049-0.0870,313-0.749 0,486-0.8820.567-1.238 5.35-6.21 (1.74) (54.3) (0,830) (5.78) (0.500) (0.064) (0.472) (0.611) Omaha, Neb. 2.07-2.39 39.5-50.9 0.357-0.5060.037-0.108 0.27o-O. 582 0.388-1.026 0,554-0.9895.54-7.73 (2.16) (44.4) (6.74) (0.410) (0.061) (0.406) (0.626) (0.773) Carson City, Nev. 1.04-1.88 11.9-46.9 0.220-0.563 0.030-0.0650,181-0.5860.318-0.9890.518-1.2083.37-8.74 (32.1) (1.42) (0.788) (5.08) (0.372) (0.045) (0.335) (0.562) Albuquerque, N.M. 1.44-2.51 34.2-91.4 0.283-0.5250,032-0.0620.210-0.6090,303-1.0810.578-1.1053.73-6.16 (2.32) (63.8) (4.55) (0 593) (0.785) (0.374) (0,053) (0.368) Cleveland, Ohio 1.17-1.48 28.0-44.4 0 313-0.478 0.036-0.069 0.166-0.581 0.470-0.8430.384-1,487 4.14-5.72 (1.35) (36.9) (5.03) (1.015) (0.401) (0.053) (0.339) (0.616) Woodburn, Ore. 2.18-2.86 19.0-25.1 0.179-0.4790,024-0.0500,147-0.418 0.190-0.550 0.539-0.9162.52-4.21 (2.42) (22.1) (0.699) (3.48) (0.261) (0.032) (0.260) (0.372) Pittsburgh, Pa, 2,06-2.30 31.2-37.6 0.294-0. 488 0.039-0.0740,24(M. 486 0.331-0.791 0,601-0.9904.32-8.23 (2.21) (5.51) (33.0) (0.368) (0.051) (0.334) (0.533) (0.784) Charleston, S.C. 1 .36-2.13 28.4-77.4 0.232-0,5410.034-0,0630,147-0.520 0,309W. 788 0.608-1.2423.38-5.77 (1.64) (48.4) (4I47) (0.913) (0.351) (0.048) (0.317) (0.533) Sioux Falls, S. D. 1.05-1.31 23.3-39.3 0.332-0.5920.028-0). 124 0.113-0.6730.3364. 827 0.535-1.326 3.25-7.75 (1.18) (31.2) (5.28) (0.951) (0.433) (0.058) (0.385) (0.574) Austin, Tex. 1.53-1.88 16,6-48.1 0.2940). 421 0.040-0. 077 0.2264. 375 0.300-0.931 0.558-1.1383.61-5.42 (1.72) (30.9) (4.80) (0.368) (0,054) (0.280) (0.907) (0.582) Salt Lake City, Utah 1.57-2.08 12.2-42.2 0.156-0.302 0,018-0.040 0.101-0.417 0,17741,464 0.420-0. 701 2.01-5.18 (1.91) (34.3) (2.97) (0,209) (0,029) (0.535) (0.197) (0.337) Burlington, Vt. 0.92-1.03 16.9-35.3 0.320.503 0.043-0.091 0.186-0.6080.403-1.0070,695-1.1764.78-7.84 (1.30) (27.4) (6.04) (0.428) (0,062) (0,409) (0.614) (0.958) Seattle, Wash. 1.59-2.23 20.6-51.6 0.1974.304 0.028-0.0470.144-0.4020.262-0.6830.558-1.2213.16-5.69 (1.92) (35.3) (4.18) (0.238) (0.034) (0,682) (0,239) (0,417)
z
I
I
January March-August samples. January-March-December samples. January-Jul scattered samples and August-December samples. Not regular6 collected, deleted for statistical analyses.
Volume 5, Number 5, May 1971 437
Table 11. Analysis of Variance of Data (mgiday) Degrees of Mean Variance Source freedom square ratio Antimony Months (A) 11.50. 6 0.42241 Location (B) 25 0.22388 6.100 AXB 150 0.03672 Cadmium Months (A) 10 0.00312 5.67a Location (B) 10,338 25 0.00568 AXB 250 0.00055 Chromium Months (A) 10 0.65128 20.29. Location (B) 25 0.27020 8.42. AXB 250 0.03210 Cobalt Months (A) 6 1.40138 25.48~ Location (B) 25 0.48253 8.77a 150 0.05499 AXB Manganese Months (A) 10 0.52964 3.248 Location (B) 25 2.07762 12.71. 250 0.16344 AXB a
Significant at CY = 0.01.
Apparatus. The atomic absorption spectrophotometer described previously (Murthy and Rhea, 1967) was used in this study. Procedure. One-half gram of ash placed in a 150-ml beaker was wetted with 3 to 5 ml of double distilled water and dissolved by adding 2.0 ml of concentrated HN03. The solution was evaporated to dryness on a hot plate and treated again with 2.0 ml of concentrated H N 0 3 as before. The residue was dissolved in 1.ON H N 0 3 by warming, and quantitatively transferred to a 35-ml graduated, conical-bottom, glassstoppered centrifuge tube, using 1.ON HN03, mixed well, and centrifuged at 825 G to remove any silica particles. The HNO, used in these studies was previously distilled. The Sb, Cd, Cr, and Zn contents were determined directly on the supernatant solution; for the analyses of Co and Mn; however, 5.0 ml of the supernatant solution was pipetted into a 10-ml volumetric flask, NaCl and CaClzsolutions were added to yield a final concentration of 10,000 and 500 ppm, respectively, and the mixture was diluted to 10 ml with 1.ON "OB. The presence of CaClz and NaCl was necessary to complex the interfering ions and improve flame characteristics. All working standards were made up in 1.ON H N 0 3and, in addition, the Co and Mn standards contained CaCh and NaCl. Results and Discussion
Performance of the atomic absorption spectrophotometer was tested by determining the recoveries of Sb, Cd, Cr, Co, Mn, and Zn and the reproducibility of analyses. Known amounts of Sb (10.0 pg), Cd (10.0 pg), Cr (20.0 pg), Mn (10.0 pg), and Zn (30.0 pg) were added to 0.5-g portions of food ash, and the samples were processed as described under Procedure. Analyses of eight replicate samples indicated recoveries of Sb, 96.4 f 2.1%; Cd, 95.9 + 1.5%; Cr, 98.6 + 3.2%; Co, 101.9 f 2.9%; Mn, 97.7 =t 2.8%; andZn,97.9 f 1.2%. 438
Environmental Science & Technology
In regard to Sb determination in air, Morgan and Homan (1969) reported that when glass-fiber filters impregnated with SbC13 were ashed at 550"C, the recovery of Sb was 46%. Similarly, Gleit and Holland (1962) showed that when lZ4SbCl3was added to blood and ashed at 400°C for 24 hr, the recovery of Sb was 67%. Bowen (1967), in comparing the Sb content of kale analyzed by different methods, claimed that the low results obtained with ashed sample were probably due to high ashing temperature, however, this was not confirmed. Although losses of SbC13 added to air or blood were encountered, it was not evident that the Sb originally present in the sample was lost during ashing. In the present investigation, analyses of portions of diet samples ashed at 450°, 500," and 550°C showed no significant losses, indicating that the nature in which Sb exists in the sample and the sample matrix are important factors. Eight 1-g portions of the same food ash were also analyzed; the reproducibility data showed 43.8 f 1.8 pg Sb, 54.2 f 2.2 pg Cd, 20.6 i 1.3 pg Cr, 40.1 =t 3.7 pg Co, 84.8 f 2.9 pg Mn, and 521.9 =t 14.0 pg Zn, with a coefficient of variation of 4.1, 4.0, 6.3, 9.2, 3.4, and 2.7%, respectively. Similarly, nine individual food ash samples selected at random every month and analyzed in duplicate showed coefficients of variation of 5.0, 4.6, 4.0, 12.2, 3.6, and 3.0%, respectively. These data were assumed satisfactory considering the levels at which the elements were analyzed. Table I presents data by sampling location regarding food consumption, percent of milk in the total food, and the Sb, Cd, Cr, Co, Mn, and Zn contents of the total diets. The average consumption of food among various institutions ranged from 1.18 to 2.55 kg, whereas the percent of milk in the total food ranged from 9.5 to 63.8%, with a weighted average of 37.5%. Similarly, the range of averages at all locations for the various elements, in mg/kg, and the weighted average were: Sb, 0.209 to 0.500, and 0.361; Cd, 0.027 to 0.064, and 0.049; Cr, 0.175 to 0.472, and 0.331; Co, 0.252 to 0.693, and 0.566; Mn, 0.535 to 1.639, and 0.823; and Zn, 2.67 to 6.80, and 4.75. For detailed statistical analyses, data on foods from Juneau, Alas., and St. Louis, Mo., were not included inasmuch as there was no continuity of sample during the year. The data on Zn were not used because analyses were not systematically made. Since assessment of body burden is dependent upon the amount of element ingested, all the observed values (mg/kg) were converted to mg/day using food consumption data. A two-way analysis of variance of the data, based on the assumptions and calculations of Ostle (1963), indicated that the amount of Sb, Cd, Cr, Co, and Mn ingested varied significantly from one sampling period to another and from one institution to another (Table TI). Previous studies (Murthy et al., 1967; Murthy and Rhea, 1968) had shown geographical differences for trace elements in milk, and it was anticipated that similar differences might occur with diets. Thus, the institutions were divided into four groups, based on geographical areas : Far East (Delaware, Florida, Massachusetts, South Carolina, and Vermont) ; Mideast (Arkansas, Illinois, Kentucky, Louisiana, Mississippi, and Ohio); Midwest (Arizona, Colorado, Idaho, Nebraska, Nevada, New Mexico, Texas, and Utah), and Far West (Alaska, California, Oregon, and Washington). Contrasts were made between and among institutions within each group. In addition, contrasts between seasons were also prescribed before sampling periods were examined in a similar manner (Ostle, 1963). Table I11 presents F ratios of various contrasts and signifi-
Table 111. Mean Trace Element Content (mgiday) and F Ratios for Geographical Contrasts
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
a
C
d C
d C
d C
d C
d C
d C
d C
d C
d C
d C
d C
d C
d C
d C
d C
d
Cr
Cd
Sb
Contrast
co
MIl
Mean
F
Mean
F
Mean
F
Mean
F
Mean
F
0.606 0.732
14,67b
0.082 0.096
21.09b
0.586 0.642
8.32b
0.911 1.051
21.24b
1.308 1.675
26.61b
0.663 0.505
15,14b
0.091 0.067
19.45b
0.629 0.509
16.29b
1.003 0.745
11.43b
1.443 1.288
5.32
0.733 0.731
0.77
0.092 0,100
0.18
0.611 0.612
7.01b
1.023 1.078
7.71b
1.742 1.609
0.22
0.812 0.528
7.19b
0.113 0.079
12.06
0.739 0.529
8.72b
1.177 0.758
10.02b
1.732 1.240
8.32b
0.916 0.551
12.126
0.123 0.077
20 73b
0.825 0.518
14.02b
1.394 0.836
19,41b
1.912 1.493
6.56
0.810 0.656
2.59
0.100 0.083
7.82b
0.670 0.551
3.33
1.072 0.974
0.11
2.079 1.404
22.91b
0.726 0.977
15.85b
0.087 0.126
20.36b
0.559 0.893
32.43b
0.982 1.253
15.47b
1,339 3.558
123.90b
0.517 0.936
5.01
0.073 0.102
10.35b
0.493 0.625
0.11
0.824 1,140
29.64b
1.236 1.443
1.49
0.748 0.621
5.99
0.102 0.085
10.91b
0.667 0.611
4.08
1.138 0.935
0.64
1.634 1.347
10.91b
0.636 0.804
3.32
0,093 0.106
2.00
0.483 0.758
16.82b
1.007 1.203
2.50
1.564 1.669
0.36
0.706 0.901
3.73
0,091 0.121
10.36b
0.677 0.840
5.11
0,977 1.429
4.62
1.517 1,822
2.76
0.761 0.480
22.82b
0.105 0.065
47,45b
0.720 0.502
18,35b
1.116 0.754
27.52b
1.566 1.128
21,54b
0.883 0.699
4.27
0.132 0.092
20.18b
0.880 0.639
17.12b
1.348 1.001
10.50b
1.673 1.512
1.26
0.507 0.892
13.75b
0.068 0.116
23.82b
0.455 0.824
13.35’~
0.672 1.329
26.56
1.125 1.899
21,24b
0.557 0.393
2.82
0.077 0.056
4.73
0.653 0.376
12,34b
0.885 0.635
4.76
1.240 1.023
1.56
0.540 0.365
5.39
0.071 0.052
3.27
0.547 0.358
9.25b
0.806 0.502
10.28b
1.393 0.867
14.95b
t
a Contrast: 1 East (c) vs. West (d). 2 Midwest vs. Far West. 3, Mideast vs. Far East; 4,Pa. vs. Vt.; 5, Fla. vs. S.C.; 6 Ark., La., Miss. vs. Ky., Ill., Ohio; 7, Ark., La. vs. Miss.; 8, Ark. bs: La.; 9, Tex., Ariz., N.M. vs. Neb., Colo., Utah, S.D., Nev., Idaho; 10, Tex. vs. Ariz., N.M.; 11, Ariz. vs. N.M.; 12, Neb,,, S.D.,Idaho vs. Colo., Utah, Nev.; 13, Neb. vs. S.D.,Idaho; 14, S.D. vs. Idaho; 15, Colo. vs. Utah; 16, Ore., Wash., Calif. vs. Alas. Significant at a = 0.01. Mean trace element for first part of the contrast. Mean trace element for second part of the contrast.
*
Volume 5, Number 5, May 1971 439
1 1.40 1.20
1.00 0.80
Figure 1. Average consumption of food and trace elements, 1967
5
060
=E
1.00
I
A
ANTIMONY
0 5 1
1 I
A
1
n \ r ed
1
0.4'
I
cant results. The following contrasts were significant for four or five of the elements and represent the most important geographical differences observed in this study : (1) East vs. West, (2) Midwest vs. Far West, (4) Pennsylvania vs. Vermont (within East group), ( 5 ) Florida vs. South Carolina (within East group), (7) Arkansas, Louisiana vs. Mississippi (within East group), (12) north Midwest vs. south Midwest, and (14) South Dakota vs. Idaho. (Parenthetical numbers refer to numbers in legend of Table 111.) In general, the trace element contents in foods from the East were higher than those in foods from the West. Two sublocation contrasts indicated that the trace element contents of foods from Vermont were low in the East, and those from Mississippi were high in the South. This trend was not consistent for all locations in the East or the West as evidenced by large differences within each geographical boundary. Figure 1 illustrates monthly variations in consumption of food, milk, Sb, Cd, Cr, Co, Mn, and Zn. Orthagonal contrasts performed on trace elements did not yield uniform results. Table IV shows contrasts that were significant. Cadmium consumption was constant throughout the year;
Table IV. F Ratios for Monthly Contrasts Con-
trast"
1 2 3 4 5
6 7 8 9 10
0.00 20.01b 2.09 7.62 1.44 37.57b ... ...
... ...
0.40 0.42 0.05 12.65b 6.60 7.966 12.35'~ 0.84 13.24'~ 2.20
0.63 66.04b 40.23b 3.55 0.40 19.136 0.07 59.34' 0.86 12.62b
10.69b 15.09b 64.19b 7.20b 32.92b 22.W ...
... ... ...
0.42 6.66 8.95b 0.22 1.75 0.39 1.68 10.69b 1.41 0.24
a Contrasts: 1, Oct., Nov., Dec., Jan., Mar. vs. Apr., May, June, July, Aug., Sept.; 2, Apr., May, June vs. Oct., Nov., Dec.; 3, Jan., Mar. vs. Oct., Nov., Dec.; 4, Jan. vs. Mar.; 5, Apr. vs. May, June; (6) May vs. June; (7) July vs. Aug., Sept.; (8) Aug. vs. Sept.; (9) Oct. vs. Nov., Dec.; 10. Nov. vs. Dec. 6 Significant at (Y = 0.01.
440 Environmental Science & Technology
other elements tended to peak in late spring or summer. Observations over several years may be necessary to establish a trend, but the curves appear to be cyclic. Examination of correlation coefficients, r , computed for trace element pairs and using means from all locations revealed that the elements were highly correlated; a low r of 0.68 for Co and Mn and a high r of 0.98 for Sb and Cd were observed (Table V). The high positive correlations of the elements indicate that high and low values tend to occur in the same institution-i.e., the means are higher in the samples from eastern than in the samples from western U.S. The means were not well related with time, however, indicating that while the trace elements ingested appear to by cyclic (except for Cd), the peaks did not occur at the same place in time. Further information concerning the supply, distribution, and components of the diet is needed to explore this problem. Rank correlations computed for 26 locations and based on mg/kg and mg/day indicated that diets from Palmer, Alas., and Salt Lake, Utah, had the lowest concentrations of trace elements, whereas those from Tampa, Fla., and Columbia, Miss., had consistently high concentrations (Table VI). Idaho Falls, Idaho, however, was consistently the highest for trace element data expressed as mg/kg. When consumption data were considered the standings of some locations did change, but the extremes stated above were not affected. Thus, location differences tend to exist in data expressed as mg/kg and mg/day in spite of the changes in diet consumption. The ranking in Table VI was the result of examining the ranks of all the trace elements in each
Table V. Correlation Coefficient between Trace Element Means (mg/da y) over Geographical Locations Sb Cd Cr co Mn Zn Sb Cd Cr co Mn Zn
0.98
0.95 0.94
0.97 0.97 0.93
0.79 0.74 0.75 0.68
0.85 0.81 0.88 0.85 0.62
Table VI. Ranking of Geographical Locations Based on mg/kg of Diet and mg/day, 1967 Location Rank, mg/day Rank, mg/kg Location Rank, mg/day Rank, mg/kg 14 12 Boston, Mass. 1. 4 Columbia, Miss. 15 23 San Francisco, Calif. 2 2 Tampa, Fla. 16 20 Denver, Colo. 3 13 Albuquerque, N. M. 17 18 Charleston, S.C. 4 9 Wilmington, Del. 3 18 Burlington, Vt. 8 5 Omaha, Neb. 10 19 Cleveland, Ohio 6 la Idaho Falls, Idaho 19 14 20 Little Rock, Ark. Pittsburgh, Pa. 7 22. 21 11 Seattle, Wash. 8 New Orleans, La. 24 Los Angeles, Calif. 22 9 16 Phoenix, Ariz. 7 Sioux Falls, S. D. 23 6 10 Louisville, Ky. 24 17 11 5 Carson City, Nev. Chicago, Ill. 26. 21 Salt Lake City, Utah 12 2 5. Woodburn, Ore. 2S4 Palmer, Alas. 13 26a Austin, Tex. 5 a
Significant at a: = 0.01,
location. Computation of Kendall’s (1964) coefficient of concordance indicated that a ranking did exist for data expressed both as mg/kg and mg/day. Locations are noted that were consistently high or low at the a = 0.01 level. Hunt (1964) indicates that most of the mineral resources are in the middle, southern, and northern Rocky Mountain provinces, basin and range provinces, and Appalachian highlands. However, the trace mineral content of diets from the West is lower than that of diets from the East, which suggests that possibly the western soils are depleted by over cropping. In addition, the observed results may be influenced by such factors as soil conditions and the availability of minerals and their uptake by plant foods, etc. Data Comparison. It is difficult to compare our data with those in the literature because data on diets are limited and methods of analyses differ; however, some data can be compared. ANTIMONY. Data on the Sb content of individual foods and diets are lacking. The intake values determined in this study were 0.247 to 1.275 mg/day. It has been observed that foods stored in enamel vessels and tin cans may contain appreciable amounts of Sb. The toxic effect of Sb depends upon its solubility and state of oxidation (Monier-Williams, 1950). CADMIUM. Available data indicate wide variations in Cd intake. An intake of approximately 0.115 to 0.330 mg was estimated from analysis of several hundred foods and drinks (Kent and McCance, 1941), whereas analyses of a two-day composite of a hospital diet and a one-day sample of an institutional diet gave Cd values of 0.213 and 0.470 mg, respectively (Schroeder et al., 1967b). Analyses of the normal diets of two individuals showed 0.10 to 0.22 mg of Cd per day (Tipton et al., 1969). In our study, the Cd intake varied between 0.032 and 0.158 mg, with a mean value of 0.092 mg/day. These large differences are related to variations in the composition of the diet and the amount ingested. In addition, the diet of children consisted of 9.5 to 63.8% milk. Previously published data (Murthy and Rhea, 1968) showed Cd content of milk to vary between 0.019 and 0.030 mg/kg. Based on these values, the amount of Cd in the milk portion of the diet was calculated to be 0.0071 to 0.0325 mg, with an average of 0.017 mg or 1 8 . 6 x , indicating that 0.074 mg or 81.4% of Cd ingested originated from food other than milk. Similar data for other elements in milk will be reported in the near future. Correlation between levels of Cd in air (Carroll, 1966)
or in kidneys (Schroeder, 1965) and heart disease has been observed. Cadmium has also been shown to be antagonistic to Zn. In relating Cd to Zn, use of molar ratio has been suggested as an indicator of their abundance (Schroeder et al., 1967b). Our data show that ratios for the two elements vary from 0.0049 to 0.0074, with a mean value of 0.0058. These results are lower than the 0.014 to 0.017 reported by Schroeder et al. (1967b), because of the high Cd values in the diets they studied. CHROMIUM. Although data are available on the Cr content of individual foods analyzed by the colorimetric method (Schroeder et al., 1962b), there is only limited information on diets. Spectrographic analyses of the normal diets of two individuals gave 0.007 to 0.033 mg (Tipton and Stewart, 1964), 0.33 to 0.44 mg (Tipton et al., 1966), and 0.20 to 0.29 mg of Cr per day (Tipton et al., 1969), whereas a single analysis of an institutional diet showed 0.078 mg of Cr per day (Schroeder et al., 1962b). In this study, the Cr intake of children varied from 0.206 to 1.204 mg/day, with a mean value of 0.632 mg. Foods cooked in stainless steel vessels have shown high-Cr content ; it is considered adventitious and is present as Cra+(Monier-Williams, 1950) COBALT. Most of the data available on Co are for individual foods (Schroeder et al., 1967a). Limited data on total diets show wide variations in Co content. Self-selected diets of 23 college women showed intakes of 5.63 to 7.79 pg C o per day (Harp and Scoular, 1952). The normal diets of two individuals showed 0.16 to 0.58 mg (Tipton and Stewart, 1964), 0.16 to 0.17 mg (Tipton et al., 1966), and 0.31 to 0.47 mg of Co per day (Tipton et al., 1969), whereas a two-day composite of a hospital diet and a one-day sample of an institutional diet had 0.166 and 0.436 mg, respectively (Schroeder et al., 1967a). In the present study, the diets of children showed intakes of 0.297 to 1.767 mg of Co with a mean value of 1.024 mg/day. These values are high compared to other data, probably because of differences in composition of the diet. Schroeder et al. (1967a) showed that fish was a good source of Co (>1.0 pg/g), whereas other foods had 0.04 to 0.43 pg/g. Leafy vegetables such as spinach have high-Co content (Underwood, 1962). MANGANESE. The Mn content of diets of teenagers from 10 U S . cities varied from 98 to 145 ppm ash (Feldman and Jones, 1964), whereas the Mn intake of nine college women maintained on low- and high-protein diets was 3.16 to 3.23 mg/day (North et al., 1960). Analyses of the normal diets of Volume 5, Number 5, May 1971 441
two individuals showed 6.4 to 7.5 mg (Tipton et al., 1966) and 3.3 to 5.5 rng of Mn per day (Tipton et al., 1969). In a detailed survey of two adults, the daily intake of Mn was calculated to be 7.0 mg. Of this amount, 3.3 mg came from tea, 2.2 mg from bread, and 1.5 rng from the remainder of the food (Monier-Williams, 1950). The intake of Mn observed in our study varied from 0.631 to 4.18 mg, with a mean value of 1.572 rng/day. Most foods, with the exception of cereal grains and nuts, have low-Mn content (Underwood, 1962). Supplementing the diet with brown bread increased the amount of Mn ingested (Kent and McCance, 1941). ZINC. Although Zn is one of the most abundant of the essential trace elements in the human body, very little data are available on the dietary intake except for individual foods (Schroeder et al., 1967b). Analyses of institutional total diets from 10 U S . cities showed 415 to 965 ppm ash (Tipton and Stewart, 1964), whereas the normal diets of two individuals showed 11 to 18 mg of Zn per day (Tipton et al., 1969). A two-day composite of a hospital diet and a one-day sample of an institutional diet showed intakes of 8.494 and 15.222 mg Zn per day, respectively. Our study showed intakes of 3.15 to 16.22mg, with a mean value of 9.07 mg/day. In conclusion, these data show wide geographical and seasonal variations in the trace element content of diets studied. Several factors, including composition of the diets, water used for cooking the food, contamination from the type of vessel used for cooking, etc., may affect the observed results and should be evaluated. A comprehensive survey of the public water supply of 100 of the largest cities in the U S . has been made and should be useful (Durfor and Becker, 1964) in providing some environmental perspective Acknowledgment The authors are grateful to J. E. Campbell for his interest in the project; to Me1 Carter, S. D. Shearer, and Morgan Seal of the Bureau of Radiological Health for graciously supplying samples; to Rebecca Martin for her help in preparing samples for atomic absorption analyses; and to Helen Bachelor for statistical calculations. Literature Cited Bowen, H. J. M., Analyst 92,118-23 (1967). Carroll, R. E., J. Amer. Med. Ass. 198,267-9 (1966). Durfor, C. N., Becker, E., U.S. Geological Survey Water Supply Paper 1812, 1962, U.S. Govt. Printing Office, Washington, D.C., 1964. Feldman, C., Jones, F. S., Tissue Analysis Laboratory Report (Ann. Prog. Rept., July 31, 1964), Hlth. Phys. Div. ORNL 3697, 178-85 (1964). Gleit, C. E., Holland, W. D., Anal. Chem. 34, 1454-7 (1962).
442 Environmental Science & Technology
Harp, M. J., Scoular, F. I., J Nutri. 47,67-72 (1952). Hunt, C. B., “Physiography of the United States,” W. H. Freeman and Co., San Francisco, Calif., 1964, pp 273-5. Kendall, M. G., “Rank Correllation Methods,” Charles Griffin and Co., Ltd., London, 1964, pp 94-106. Kent, W. L., McCance, R. A., Biochem. J. 35, 877-83 (1941). Kropf, R., Geldmacher, V., Mallinkrodt, M., Arch. Hyg. (Berlin) 152, 218-24 (1968). Monier-Williams, G. W., “Trace Elements in Foods,” John Wiley and Sons, Inc., New York, N. Y . , 1950. Morgan, C. E., Homan, R. E., “Low Temperature Dry Asher-505,’’ Tracer Lab., Division of Laboratory for Electronics, Inc., Waltham, Mass., 1969, pp 1-13. Murthy, G . K., Rhea, U., J . Dairy Sci. 50, 313-7 (1967). Murthy, G. K., Rhea, U., Peeler, J. T., J. Dairy Sci. 50, 651-4 (1967). Murthy, G. K., Rhea, U., J. Dairy Sci. 51,610-13 (1968). North, B. B., Leischserving, J. M., Norris, L. M,, J. Nutri. 72,217-23 (1960). Ostle, B., “Statistics in Research,” 2nd ed., Iowa State Univ. Press, Ames, Iowa, 1963,pp 306-9. Schroeder, H. A,, Balassa, J. J., J. Chron. Dis. 14, 236-58 (1961a). Schroeder, H. A,, Balassa, J. J., ibid., 408-25 (1961b). Schroeder, H. A., Balassa, J. J., Tipton, I. H., ibid., 15, 51-65 (1962a). Schroeder, H. A,, Balassa, J. J., Tipton, I. H., ibid., 941-64 (1962b). Schroeder, H. A., Balassa, J. J., Tipton, I. H., ibid., 16, 55-69 (1963a). Schroeder, H. A,, Balassa, J. J., Tipton, I. H., ibid., 1047-71 (1963b). Schroeder, H. A,, Balassa, J. J., Tipton, I. H., ibid., 17, 483502 (1964). Schroeder, H. A., Balassa, J. J., ibid., 18, 229-41 (1965). Schroeder, H. A,, ibid., 647-56 (1965). Schroeder, H. A,, Balassa, J. J., ibid., 19, 85-106 (1966). Schroeder, H. A,, Balassa, J. J., Tipton, I. H., ibid., 545-71 (1966) Schroeder, H. A., Nason, A. P., Tipton, I. H., Balassa, J. J., ibid., 20, 179-210 (1967a). Schroeder, H. A,, Nason. A. P., Tipton, I. H., ibid., 869-90 (1967b) . Tipton, I. H., Stewart, P. L., Tissue Analysis Laboratory Report (Ann. Prog. Rept., July 31, 1964). Hlth. Phy. Div. ORNL 3697, pp 185-88 (1964). Tipton, I. H., Stewart, P. L., Martin, P. G., Health Phy. 12, 1683-9 (1966). Tipton, I. H., Stewart, P. L., Dickson, J., ibid., 16, 455-62 (1969). Underwood, E. J., “Trace Elements in Human and Animal Nutrition,” 2nd ed., Academic Press, New York, N. Y . , 1962, p 148. US.Public Health Service, “Radioassay Procedures for Environmental Samples,” 999-~~-27,1967. Receioed for reoiew October 24, 1969. Resubmitted January 14, 1971. Accepted January 14,1971.
