Selenium, molybdenum, and vanadium in human blood

Interaction of molybdenum with human erythrocyte membrane proteins

This study describes the interaction of molybdenum with blood components. Molybdenum-99 was added to blood, and after four washings, 3% of the total radioactivity was found in red cells. More specifically, the radioactivity was determined to be associated with the cell membrane.Molybdenum-99 in the +VI form did not interact with the human erythrocyte membrane; however, Mo(V) forms did interact. Of five different compounds, the highes uptake was observed with a brown Mo(V)-ascorbate complex generated from Mo(VI) and ascorbic acid in the molar ratio 1∶20. A membrane suspension of Mo-ascorbate-treated human erythrocytes was prepared and the solubilized proteins were separated on a polyacrylamide gel in the presence of sodium dodecyl sulfate (SDS). Molybdenum-99 binding to spectrin was demonstrated, as well as some minor interactions with membrane hemoglobin and bands 6 and 8.

Biochemical abnormalities in workers exposed to molybdenum dust

Exposure to molybdenum in dust was measured in a molybdenite roasting plant. This exposure was accompanied by large elevations of serum ceruloplasmin and smaller increases in mean serum uric acid levels in the workers. Absorption of molybdenum from the dust was demonstrated by increases in plasma and urinary molybdenum levels. It remains necessary to demonstrate whether such exposure results in long-term health effects.

Is the selenium drinking water standard justified?

Four cases are presented which suggest that the present U.S.E.P.A. drinking water standard for selenium of 10 micrograms/L in inappropriate. The rationale upon which this standard is based is that selenium is carcinogenic, induces dental caries formation, and is highly toxic to animals. However, a critical assessment of this literature can not support these claims. Case no. 1 demonstrates that there is insufficient evidence to classify selenium as a carcinogen. Data derived from the three respective groups of researchers claiming a carcinogenic effect induced by selenium are obscure due to 1) the inability to accurately identify malignancies, 2) the apparent opposite effects of different selenium compounds, and 3) the lack of proper controls. Case no. 2 reviews recent evidence that selenium reduces the incidence of cancer in laboratory animals and in man, an effect which can probably be attributed to the antioxidant properties of selenium compounds. Case no. 3 provides evidence which does not permit the classification of selenium as a cariogenic element. Epidemiological studies supporting such a claim are inadequate since they lack properly matched control groups. Animal data do not support this link as well. Case no. 4 is a review of studies which clearly demonstrate the essentiality of selenium, an aspect of selenium metabolism that was not considered when the 10 micrograms/L standard was promulgated. In light of the four cases presented and an assessment of selenium toxicity in man, it is concluded that the 10 micrograms/L standard can not be justified. Instead, it is suggested that 50 micrograms/L selenium should provide sufficient protection from the toxic effects of this element. This is consistent with the current state of knowledge with respect to the potential adverse health effects associated with selenium.

Selenium and total parenteral nutrition

Despite the increasing recognition of selenium (Se) as an essential trace element in man, little is known about its metabolism during total parenteral nutrition (TPN) and the possible development of Se deficiency in high risk patients. From a general population known by its geographical location to have low Se blood levels, we studied a group of 23 surgical patients receiving TPN for at least one week. Whole blood Se levels were less than in the normal general population and, being some of the lowest observed in adult man, approached levels observed in animals with Se-responsive syndromes. Se continued to be lost predominantly in the urine although the Se content of the TPN fluids was very low (less than 0.6 micrograms/24 hr). Patients with excessive volumes of gastrointestinal excretion lost more Se. Se supplementation may be required in some patients receiving TPN.

Selenium in human nutrition: dietary intakes and effects of supplementation

The dietary selenium intakes of a young couple residing in Southern California were determined to be 107 and 99 micrograms/day for the husband and the wife, respectively, on the basis of a 30 day study. For other young adult Californians, the selenium intakes were estimated from 90 to 168 micrograms/day. The highest intakes were observed in individuals subsisting on diets rich in whole wheat grain cereal products and seafoods. The selenium concentrations in whole blood of the subjects under study correlated with the dietary selenium intakes directly (P less than 0.001). The administration of 150 micrograms of selenium/day in the form of commercially available supplements increases the blood selenium concentrations. After 3 weeks of supplementation, the selenium concentrations in whole blood of our subjects reached 0.21 micrograms/ml. Prolonged supplementation at higher Se dosage levels causes further increases of the blood concentrations: Two individuals who had been ingesting 350 and 600 micrograms/day for 18 months exhibited blood selenium levels of 0.35 and 0.62 micrograms/ml. The blood selenium concentration of all subjects declined slowly after cessation of supplementation. Selenium uptake from the supplements was not affected by the joint administration of zinc supplements at 15 mg zinc/day. Glutathione peroxidase blood levels did not correlate with blood Se concentrations.

Determination of selenium in biological samples by gas-liquid chromatography with electron-capture detection

Selenium can be determined quantitatively in biological samples after nitric acid-magnesium nitrate digestion and formation of 5-nitropiazselenole, by extraction into toluene for gas-liquid chromatography with electron-capture detection. The method is suitable for the determination of selenium in orchard leaves, bovine liver and human placenta, hair, blood and urine.

Cancer mortality correlation studies--IV: associations with dietary intakes and blood levels of certain trace elements, notably Se-antagonists

The per-capita intakes of zinc, cadmium, copper and of chromium were estimated from food consumption data in 28 countries and were found to correlate directly with the age-corrected mortalities from cancers of intestine, prostate, breast, leukemia, skin and of other organs, suggesting that the anticarcinogenic effect of selenium is counteracted by other trace elements. Similarly calculated dietary intakes of manganese are inversely correlated, particularly with the mortalities from cancer of pancreas, an organ normally known to contain high concentrations of this element. Arsenic intakes correlate inversely with the male lung cancer mortalities. A number of other direct and inverse associations were observed which suggest that trace elements in the human diet may hav both benign and adverse effects on tumor development. The zinc concentrations in whole blood collected from healthy donors in the U.S. correlate directly with regional mortalities from cancers of intestine, breast and of other sites. The origin of these associations is discussed primarily in terms of the seleium-antagonistic effect of zinc and of some of the other elements considered. Results of animal experiments and of other studies are cited which support hypotheses that link human cancer development to possible deficiencies or excesses in the dietary trace element intakes.

Cancer mortality correlation studies--III: statistical associations with dietary selenium intakes

Age-corrected mortalities from cancer at 17 major body sites were correlated with the apparent dietary selenium intakes estimated from food-consumption data in 27 countries. Significant inverse correlations were observed for cancers of large intestine, rectum, prostate, breast, ovary, lung and with leukemia; weak inverse associations were found for cancers of pancreas, skin and bladder. Similar inverse corelations were found between cancer mortalities at the above sites and the selenium concentrations in whole blood collected from healthy human donors in the U.S. and different countries. The results support the hypothesis that selenium has cancer-protecting effects in man. Other studies are cited which demonstrate that selenium prevents or retards tumor development in animals. A change of diet aimed at increasing the dietary selenium supply is suggested as a possible means of lowering the human cancer risk. It is postulated that the cancer mortalities in the U.S. and other Western industrialized nations would decline significantly if the dietary selenium intakes were increased to approximately twice the current average amount supplied by the U.S. diet.

Balance study of twenty trace elements during total parenteral nutrition in man

1. Balances of twenty trace elements (silver, arsenic, gold, bromine, cadmium, cobalt, chromium, caesium, copper, iron, mercury, lanthanum, molybdenum, rubidium, antimony, scandium, selenium, samarium, tungsten and zinc) have been determined in four male patients during total parenteral nutrition incliding fat emulsion and a special solution for addition of Fe, Zn, manganese, Cu, fluorine and iodine, besides calcium and magnesium, to the infusion solutions. 2. The analyses for trace elements were made with the aid of an ion-exchange technique based on neutron activation, and combined with subsequent gamma spectrometry. 3. The intended intravenous supply of trace elements correspond approximately to the analysed supply. However, all the other trace elements determined were found to be unintentionally administered in small amounts. 4. There was a substantial retention of Fe. Other elements retained were Ag, Co, Cr, Cu, Sb, Sc, and W. 5. Particularly Br and Rb were lost by the patients, but negative balances were also found for As, Au, Cd, Cs, Mo, Se and Zn. However, Zn was retained by one patient with short bowel syndrome. 6. The serum concentrations of thirteen (Ag, Br, Co, Cs, Cu, Fe, Hg, Mo, Rb, Sc, Se, W and Zn) of the trace elements were found to have some decrease during the period of total parenteral nutrition, mostly in accordance with the corresponding balance values, Fe, in particular, was found to have the derectional change in concentration. 7. The administration of trace elements is recommended in long-term total parenteral nutrition.

Selenium, vitamin E and copper in multiple sclerosis

There has been accumulation of the nutritional muscular dystrophy of the cattle in a certain western district of Finland where the prevalence of multiple sclerosis (MS) is also highest. This animal disease is due to lack of selenium (Se) and vitamin E. The Se content of whole blood was low (52.6 +/- 11.3 ng/ml) in MS patients from this high-risk area compared to the controls (68.8 +/- 11.0). The data for serum failed to confirm this tendency. All Se values appeared to be lower than international values suggested. The values for both vitamin E and copper were within the international normal range.

Antioxidants and cancer. Part VI. Selenium and age-adjusted human cancer mortality

The possible epidemiologic relationship between selenium occurrence and cancer mortality was studied in cities and states located in areas with different levels of selenium bioavailability. Statistically significant differences were found in age-specific cancer death rates among states with high, medium, and low selenium levels. The death rates for specific types of cancer showed a larger difference in males than in females in the states with high selenium levels. The greater difference between males and females may be related to sex difference or to the fact that males are heavier smokers and are aslo more likely to be exposed to industrial pollution. In the states with high selenium levels, there was significantly lower mortality in both males and females from several types of cancer, particularly the environmental problem indicators, such as gastrointestinal and urogenital types of cancer.

Mercury and selenium distribution in a defined area and in its population

In the Amiata Mountain area of Tuscany, Italy, a survey has examined the concentrations of mercury and selenium in the environment, in the food chain, and in human biological samples of blood, urine, and hair. This area was selected for study because of its large mineral deposits and concentration of elements, e.g., iron, copper, silver, antimony, and particularly mercury. Subjects consisted of a group with high occupational exposure to mercury vapor, a group randomly exposed to mercury dust, and a group nonoccupationally exposed to mercury. The selenium and mercury contents in all samples were determined by nondestructive neutron activation analysis, and results showed that the human metabolism of mercury is different from that of selenium and that the selenium retention in man could be influenced by the mercury intake. Furthermore, a great part of selenium introduced through the diet passes into the blood, where it is mainly associated with blood cells.

Elemental analysis of honey as an indicator of pollution. Forty-seven elements in honeys produced near highway, industrial, and mining areas

Nineteen samples of honey taken from grocery shelves, near zinc mines, adjacent to an industrial area, and near a major highway, and one sample collected in 1899 were subjected to spark source mass spectrometry to determine the concentration of most of 47 elements in the honey. Certain samples of honey produced by bees in the vicinity of the New York State Thruway appeared to contain elevated levels of certain elements known to be emitted by traffic, such as aluminum, barium, calcuim, copper, magnesium, nickel, palladium, and silicon, but the true source of these elements was uncertain. Honey that had come into contact with metal containers in processing contained the greatest amounts of zinc and tin.

Geographic distribution of selenium in human milk

Data were collected on the selenium concentration in human mature milk from a total of 241 subjects who resided in or near cities located in 17 states across the United State. The overall mean value for the selenium content of mature human milk was 0.018 ppm Se. Most of the individual values for selenium in human milk fell within the narrow range of 0.007 to 0.033 ppm Se, yet there was evidence for geographic variations in the selenium content of milk collected from the various cities.