The nutritional observations, on which the activity of selenium is based, are briefly reviewed, and the interactions of the trace element with vitamin E, polyunsaturated fatty acids, and sulfur amino acids at the dietary level highlighted. Brief mention is made of early morphological effects of vitamin E and selenium deficiency and of “classical” interpretations of these in biochemical terms. The concept is developed, based on recent observations in a number of laboratories, that selenium participates in enzyme systems that have an oxidation/reduction role. In this connection, work on glutathione peroxidase on a selenoenzyme of lamb nuscle, on certain bacterial reductases, and on rat liver electron-transfer systems is discussed.The toxicology of selenium is reviewed briefly, and interactions of the element with mercury, cadmium, silver, and arsenic are discussed. Mechanisms for selenium detoxication are considered, and probable biochemical pathways for treatment of toxic amounts of selenium are set out. F...

Metabolic aspects of selenium action and toxicity.

Humans have been in contact with metals almost since the beginning of our existence. In fact, one cannot even think on human evolution without considering the great role played by metals in mankind's development. Metals are common moieties of molecules involved in a wide variety of biological processes, and hence are found in virtually all living organisms. Some metals are essential for human nutrition; others are found as contaminants in foodstuffs. One feature of the normal human diet which is frequently found is the simultaneous presence of both essential and toxic metals. Other factors important in the risk-evaluation analysis of metals are their pharmacokinetics, interactions among them and with other major components of the diet, and, especially, the great differences in the dietary habits of different populations and in the regional distribution of metals. In attempting to understand the role which dietary metals could play in human carcinogenesis, we found that the many factors involved and the lack of specific information made it difficult to reach firm conclusions on the hazards of dietary metals. We hope that this paper will raise the interest of genetic toxicologists in the subject and will consequently facilitate a risk analysis of the carcinogenic potential of dietary metals.

Are metals dietary carcinogens

Selenium poisoning in humans is reviewed from the perspective of the clinical laboratory. While evaluation of selenium poisoning is straightforward when the analytic results are markedly elevated and the patient is acutely symptomatic, distinguishing toxic from non-toxic elevations is a more frequent issue and more challenging. A significant problem is that selenium is determined as its total concentration in spite of the fact that different chemical forms of selenium have different toxic potentials. In the published reports reviewed herein, serum selenium concentrations span the following ranges: 400-30,000 micro g/L associated with acute toxicity, 500-1400 micro g/L associated with chronic toxicity, and 1400 micro g/L. Tissue selenium levels show a complex pattern and significant elevations in organs such as kidney are not always indicative of toxicity. As with many trace elements, measuring selenium concentrations in body fluids and tissues tends to be easier than understanding what the results mean.

Evaluating Selenium Poisoning

SELENIUM ii DISCLAIMER The use of company or product name(s) is for identification only and does not imply endorsement by the Agency for Toxic Substances and Disease Registry. A Toxicological Profile for selenium, Draft for Public Comment was released in September, 2001. This edition supersedes any previously released draft or final profile. Toxicological profiles are revised and republished as necessary, but no less than once every three years. For information regarding the update status of previously released profiles, contact ATSDR at: Toxicological Profiles are a unique compilation of toxicological information on a given hazardous substance. Each profile reflects a comprehensive and extensive evaluation, summary, and interpretation of available toxicologic and epidemiologic information on a substance. Health care providers treating patients potentially exposed to hazardous substances will find the following information helpful for fast answers to often-asked questions. Chapter 1: Public Health Statement: The Public Health Statement can be a useful tool for educating patients about possible exposure to a hazardous substance. It explains a substance's relevant toxicologic properties in a nontechnical, question-and-answer format, and it includes a review of the general health effects observed following exposure. Chapter 3: Health Effects: Specific health effects of a given hazardous compound are reported by type of health effect (death, systemic, immunologic, reproductive), by route of exposure, and by length of exposure (acute, intermediate, and chronic). In addition, both human and animal studies are reported in this section. NOTE: Not all health effects reported in this section are necessarily observed in the clinical setting. Please refer to the Public Health Statement to identify general health effects observed following exposure. The following additional material can be ordered through the ATSDR Information Center: Case Studies in Environmental Medicine: Taking an Exposure History—The importance of taking an exposure history and how to conduct one are described, and an example of a thorough exposure history is provided. Other case studies of interest include Reproductive and Developmental Hazards; Skin Lesions and Environmental Exposures; Cholinesterase-Inhibiting Pesticide Toxicity; and numerous chemical-specific case studies. SELENIUM viii Managing Hazardous Materials Incidents is a three-volume set of recommendations for on-scene (prehospital) and hospital medical management of patients exposed during a hazardous materials incident. Volumes I and II are planning guides to assist first responders and hospital emergency department personnel in planning for incidents that involve hazardous materials. Volume III— Medical Management Guidelines for Acute Chemical Exposures—is a guide for health care professionals treating patients …

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Toxicological profile for selenium

The possible carcinogenicity of cobalt, iron, lead, manganese, mercury, platinum, selenium, and titanium is reviewed, taking into account epidemiological data, the results of animal experimental studies, data on mutagenic effects and on other in vitro test systems. Of the great variety of occupations where exposure to one of these metals may occur, only haematite mining has been clearly shown to involve an increased human cancer risk. While the possibility that haematite might in some way act as a carcinogen has to be taken into consideration it is more likely that other carcinogens are responsible. Certain platinum coordination complexes are used in cancer chemotherapy, are mutagenic, and likely to be carcinogenic. Cobalt, its oxide and sulfide, certain lead salts, one organomanganese, and one organotitanium compound have been shown to have a limited carcinogenic effect in experimental animal studies, and except for titanium appear to be mutagenic. Certain mercury compounds are mutagenic but none have been shown to be carcinogenic. The presently available data are inadequate to assess the possible carcinogenicity of selenium compounds, but a few observations suggest that selenium may suppress the effect of other carcinogens administered to experimental animals and may even be associated with lower cancer mortality rates in man. Epidemiological observations are essential for the assessment of a human cancer risk, but the difficulty in collecting past exposure data in occupational groups and the complexity of multiple occupational exposures with changes over time, limits the usefulness of retrospective epidemiological studies.

J R Glover

Papers

Selenium and its industrial toxicology.