Heavy metals

<p>Living organisms require varying amounts of "heavy metals". <a href="http://en.wikipedia.org/wiki/Iron" title="Iron">Iron</a>, <a href="http://en.wikipedia.org/wiki/Cobalt" title="Cobalt">cobalt</a>, <a href="http://en.wikipedia.org/wiki/Copper" title="Copper">copper</a>, <a href="http://en.wikipedia.org/wiki/Manganese" title="Manganese">manganese</a>, <a href="http://en.wikipedia.org/wiki/Molybdenum" title="Molybdenum">molybdenum</a>, and <a href="http://en.wikipedia.org/wiki/Zinc" title="Zinc">zinc</a> are required by <a href="http://en.wikipedia.org/wiki/Humans" title="Humans" class="mw-redirect">humans</a>. Excessive levels can be damaging to the organism. Other heavy metals such as <a href="http://en.wikipedia.org/wiki/Mercury_%28element%29" title="Mercury (element)">mercury</a>, <a href="http://en.wikipedia.org/wiki/Plutonium" title="Plutonium">plutonium</a>, and <a href="http://en.wikipedia.org/wiki/Lead" title="Lead">lead</a> are <a href="http://en.wikipedia.org/wiki/Toxic_metal" title="Toxic metal" class="mw-redirect">toxic metals</a> and their accumulation over time in the bodies of <a href="http://en.wikipedia.org/wiki/Animal" title="Animal">animals</a> can cause serious illness. Certain elements that are normally toxic are, for certain organisms or under certain conditions, beneficial. Examples include <a href="http://en.wikipedia.org/wiki/Vanadium" title="Vanadium">vanadium</a>, <a href="http://en.wikipedia.org/wiki/Tungsten" title="Tungsten">tungsten</a>, and even <a href="http://en.wikipedia.org/wiki/Cadmium" title="Cadmium">cadmium</a>.

Heavy metal toxicity can result in damaged or reduced mental and <a href="http://en.wikipedia.org/wiki/Central_nervous_system" title="Central nervous system">central nervous function</a>, lower energy levels, and damage to <a href="http://en.wikipedia.org/wiki/Blood" title="Blood">blood</a> composition, <a href="http://en.wikipedia.org/wiki/Lung" title="Lung">lungs</a>, <a href="http://en.wikipedia.org/wiki/Kidneys" title="Kidneys" class="mw-redirect">kidneys</a>, <a href="http://en.wikipedia.org/wiki/Liver" title="Liver">liver</a>, and other vital organs. Long-term exposure may result in slowly progressing physical, muscular, and neurological degenerative processes that mimic <a href="http://en.wikipedia.org/wiki/Alzheimer%27s_disease" title="Alzheimer's disease">Alzheimer's disease</a>, <a href="http://en.wikipedia.org/wiki/Parkinson%27s_disease" title="Parkinson's disease">Parkinson's disease</a>, <a href="http://en.wikipedia.org/wiki/Muscular_dystrophy" title="Muscular dystrophy">muscular dystrophy</a>, and <a href="http://en.wikipedia.org/wiki/Multiple_sclerosis" title="Multiple sclerosis">multiple sclerosis</a>. <a href="http://en.wikipedia.org/wiki/Allergies" title="Allergies" class="mw-redirect">Allergies</a> are not uncommon, and repeated long-term contact with some metals (or their compounds) may cause <a href="http://en.wikipedia.org/wiki/Cancer" title="Cancer">cancer</a>.

Heavy metals have effect on stability of <a href="http://en.wikipedia.org/wiki/Colloid" title="Colloid">colloids</a>. <a href="http://en.wikipedia.org/wiki/Prokaryote" title="Prokaryote">Prokaryotic</a> and <a href="http://en.wikipedia.org/wiki/Eukaryote" title="Eukaryote">eukaryotic</a> cells are colloids, too. Colloids are sensitive to change of ion or heavy metal concentration and it leads to violation of colloid stability and subsequent disintegration. <sup id="cite_ref-2" class="reference"><a href="http://en.wikipedia.org/wiki/Heavy_metals#cite_note-2">[2]</a></sup></p>