Effect of tin on calcium content in the bile of rats

Physiological and toxicological changes in the skin resulting from the action and interaction of metal ions

The human environment contains more than 50 metal or metalloid elements. At least 15 are recognized as trace elements, with zinc, calcium, copper, magnesium, and iron having specific roles in skin morphogenesis and function. The present review focuses on the presumed role of metal ions in the skin, their competition for carrier proteins, and membrane receptors. Evidence presented shows that the balance of trace metal ions is critical for normal skin and repair mechanisms following injury. Xenobiotic ions can impair this balance, leading to pathological change. The skin acts as an organ of elimination of excess trace metals and xenobiotic ions from the body, but mechanisms of voidance vary for different metals. Metal ions are an important cause of allergies, and evidence is presented to show that the majority of metals or metal compounds can induce allergic changes. Except for chromium and nickel, which are among the most common human allergens, animal models have provided little information. At least cadmium, thorium, lead, chromium, nickel, beryllium, and arsenic and proven or putative carcinogens in animals or humans on the basis of cytological or epidemiological evidence. However, only arsenic exhibits a clear predilection for the skin. Other metals such as gold can induce subcutaneous sarcoma following injection, but the relevance of this observation in terms of human occupational risk is discounted.

Metals and the skin

Certain metals, and many metal-based compounds, are inherently toxic, and their presence in occupational and environmental settings raises appropriate questions concerning human exposure. Contact of these materials with the skin represents an important route of exposure, which is not well characterized. The purpose of this review, therefore, is to assemble the available, useful information pertinent to risk assessment following dermal contact. Specifically, we summarize here: (1) data relevant to the qualitative and (where possible) quantitative evaluation of metal compound permeation through the skin; (2) the role of each metal in metabolism, particularly with respect to the skin, and the potentially toxic effects that may result from dermal contact; and (3) the immunological characteristics (including allergenicity) of the metals and their derivatives. In total, information on 31 metals has been reviewed. It is clear that many diverse factors determine the ability of metal-based species to permeate biological membranes, not all of which have been fully defined. Therefore, considerably more experimentation, targeted at the development of high-quality transport data, will be required before the specification of practically useful structure-activity relationships are possible.

Effect of dietary protein and minerals on calcium and zinc utilization

The utilization of most minerals can be altered not only by varying the dietary levels of protein, carbohydrate, fiber, fat, and vitamins but also by varying the forms of macronutrients fed. Interactions among minerals are frequent and sometimes complex. Thus, all assessments of mineral requirements should include discussions of the effects of interactions on mineral bioavailability. Some of these interactions occur in the gut and affect the absorption of minerals. Other interactions affect the metabolism, transport and storage of minerals, and ultimately their excretion in urine or in endogenous gut secretions.

The effect of tin chloride on the structure and function of DNA in human white blood cells

Tin compounds are being used increasingly in the home, in industry and in medicine. There have been relatively few studies on the long term biological effects of this metal, although acute effects have been documented. In this report we describe experiments which show that tin(II), as stannous chloride, is readily taken up by human white blood cells (WBC) and can cause damage to DNA. Damage was detected in WBC after exposure to 10-50 microM tin(II) for 30 min at either 0 degree or 37 degrees C. The amount of damage observed was more extensive than that produced by exposure of cells to equimolar amounts of chromium(VI), a known carcinogen and DNA damaging agent. Additional indication of cellular damage is that exposure of human lymphocytes or mouse splenocytes to tin(II) interfered with their ability to be stimulated by the polyvalent mitogen concanavalin A (Con A). By contrast, tin(IV) was not taken up by cells, did not cause DNA damage nor did it inhibit stimulation of DNA synthesis in cells that were exposed to Con A.

Tin decreases femoral calcium independently of calcium homeostasis in rats

Oral administration of stannous chloride (SnCl2) (1.0 mg Sn2$/kg body weight) to rats, twice daily for 28 days, caused a significant increase in the tin (Sn) content and a corresponding decrease of the calcium (Ca) content in the femoral epiphysis, but was without effect on serum Ca, intestinal Ca absorption, and urinary and fecal Ca excretion. The results indicate that in rats Sn directly inhibits bone formation independently of Ca homeostasis.

Effect of stannous chloride on rat femur

Oral adminitraton of stannous chloride (SnCl2) (1.0 mg Sn2+/kg body weight) to rats, twice daily for 30 or 90 days, caused a significant decrease of the calcium (Ca) content and acid phosphatase activity of the femoral epiphysis but did not reduce those of the femoral diaphysis. 1.0 mg Sn2+/kg for 30 days produced a significant decrease of alkaline phosphatase activity of the femoral epiphysis, but did not lower that of the femoral diaphysis. The results indicate that Sn may inhibit bone formation directly in the femoral epiphysis of rats.