Iatrogenic exposure

Another source of chronic iatrogenic exposure to metals may be medical implants, which are widely used for dental restorations and prosthetics as well as for orthopedic, restorative, and replacement surgery (see Part II, Chapter 5). 

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Acute-Duration Exposure. No human data are available for acute exposures following any route except through incidental, iatrogenic exposures from medicinal practices and a limited oral study. Additional efforts to quantify these exposures and measure their effects on target tissues such as the liver and kidney would be useful when such research efforts are consistent with standard medical practices. 

It remains remarkable that, after the discovery of chronic Al encephalopathy and numerous reports of patients suffering from this syndrome, fourteen years passed before the first publication on acute Al neurotoxicity appeared [62], Acute Al encephalopathy is a devastating, often fatal disease that is the result of iatrogenic exposure to Al. Unfortunately, in spite of efforts to avoid Al exposure as much as possible, recently new sources of serious exposure have been added to the growing list of sources of Al exposure. In contrast to a fascinating history and abundant literature, many uncertainties about Al toxicity still exist. Clinical data in humans on acute Al neurotoxicity are very limited and we will, therefore, compare our experience in one of the two documented outbreaks in dialysis centers, with that of the literature. 

Environmental and iatrogenic exposure can result in aluminum overload in dialysis patients and evident osteomalacia, anemia and dementia [46]. Furthermore, acute intoxication with aluminum can lead to encephalopathy and death [47]. Hemoperfusion, hemodialysis, or hemofiltration combined with desferoxamine (DFO) can effectively remove aluminum [48]. Hemodialysis with a high flux dialyzer and hemofiltration are likely superior to charcoal hemoperfusion [48, 49]. In aluminum intoxicated dialysis patients, improvements in osteomalacia [50], anemia [51], and dementia [52] have been demonstrated with chelation. 

Iatrogenic exposure to nickel may result from implants and prostheses made from nickel-containing alloys, from intravenous or dialysis fluids, and from radiographic contrast media. An estimated average of intravenous nickel uptake from dialysis fluids is 100 p.g per treatment [21-23]. 

In humans with environmental, occupational, or iatrogenic exposures to nickel, the kinetics of nickel uptake, distribution, and elimination depend upon the physical and chemical properties of the specific nickel compound. 

Iatrogenic exposure from prosthetic devices has also been considered, but it is apparent that analyses of body fluids adequate to assess the extent of leaching have seldom if ever been achieved. Potential exposures are usually multiple, arising from alloys such as TiAlV and the presence of other alloys that may contain Co, Cr, or Ni and could account for cases of tumorigenicity in experimental animals [10]. Therefore, it is difficult to attribute any adverse effects to Ti-containing implants. 

Because Al toxicity is a serious iatrogen complication, any preventive measures to avoid exposure to Al is incumbent. Unfortunately, with the current treatment practices, there continues to be a risk that patients receive excessive amounts of Al orally or parenterally. If Al compounds cannot be avoided in patients with renal failure, routine Al tests performed every 3-4 months in serum will identify persons at greatest risk (s-Al levels >100 to 150 pg/L) for chronic Al intoxication. Ideally, any patient with s-Al higher than 40 to 50 pg/L should discontinue Al gels and use other substitutes. These patients should also be warned not to ingest these compounds with liquids containing citrate, for example, fruit juices. 

In 1980 the APA produced a detailed analysis of the iatrogenic disease in its Task Force Report Tardive Dyskinesia. The task force made it clear that TD is a serious, usually irreversible, largely untreatable, and highly prevalent disease resulting from therapy with neuroleptics. The task force estimated the prevalence rate for TD in routine treatment (several months to 2 years) as at least 10% to 20% for more than minimal disease. For long-term exposure to neuroleptics, the rate was at least 40% for more than minimal disease. 

The very old and the very young are most susceptible to toxicity. Intravenous exposure results in a more rapid manifestation of symptoms, and toxicity is often iatrogenic. Even in therapeutic doses, parenteral administration may cause apnea and hypotension, especially with rapid administration of the drug. 

Iatrogenic hypothyroidism follows exposure to radiation (radioiodine or external radiation) or surgery. Hypothyroidism occurs within 3 months to a year after I therapy in most patients treated for Graves ... 

In 1879, human chemical exposures were studied during the Industrial Revolution period. It was found that chronic dermal contact with shale oil, coal distillates, petroleum products, or chimney soot could cause skin cancer. An inordinate prevalence of lung cancer was exhibited among coal miners and was the first internal cancer associated with a known occupational exposure. An iatrogenic cancer of the skin, due to long-term ingestion of potassium arsenite from Fowler s solution (used as a tonic in small doses), was recorded by 1887. In 1895, excessive cancer of the urinary bladder was identified in workers from the aniline dye industry. 

Ghronic intoxication by metals or metal compounds is usually derived from chronic exposure in the indoor area, the environment, or the workplace. Also, incidences of chronic iatrogenic toxicity have been recognized. Since the placenta provides the route of transfer of both essential and non-essential metals from mother to fetus, prenatal intoxications are also known. (Genetic influence see Part II, Chapter 10.)... 

Iatrogenic aluminium poisoning is now one of the most important clinical problems involving trace metal toxicity. Several thousand determinations are performed daily around the world in order to monitor exposure to aluminium in patients with chronic renal failure being treated with intermittent hemodialysis. 

Chronic exposure to subacute doses of trichothecene mycotoxins is not thought to be an effect of biological warfare. This type of exposure, however, was responsible for ATA toxicosis in humans and mycotoxicosis in domestic animals. In addition, chronic toxicity has been iatrogenically induced when repeated subacute doses of a trichothecene mycotoxin were administrated intravenously to cancer patients as a chemotherapy for colon adenocarcinoma. Alimentary Toxic Aleukia Toxicosis... 

The determination of nickel in blood or plasma/serum is used for the biological monitoring of occupationally exposed persons and for the surveillance of subjects with potential iatrogenic sources of exposure to nickel such as dialysis treatment, leaching of nickel from nickel-containing alloys as prostheses and implants, and contaminated intravenous medications [2,22,61]. Contamination of the blood specimens from the needles for venipuncture has been reported. But recent experiences show that after using stainless steel cannulas with the common analytical methods an increase of the nickel concentration in blood could not be detected. 

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