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Composition of the human body
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<h2 id="elements">Elements</h2> The main elements that comprise the human body (including water) can be summarized as <a href="/facts/CHNOPS/lI4Wve8U">CHNOPS</a>.<table><tbody><tr><td rowspan="13"></td><th scope="col">Element</th><th scope="col">Symbol</th><th scope="col">percentmass</th><th scope="col">percentatoms</th></tr><tr><td>Oxygen</td><td>O</td><td>65.0</td><td>24.0</td></tr><tr><td>Carbon</td><td>C</td><td>18.5</td><td>12.0</td></tr><tr><td>Hydrogen</td><td>H</td><td>9.5</td><td>62.0</td></tr><tr><td>Nitrogen</td><td>N</td><td>2.6</td><td>1.1</td></tr><tr><td>Calcium</td><td>Ca</td><td>1.3</td><td>0.22</td></tr><tr><td>Phosphorus</td><td>P</td><td>0.6</td><td>0.22</td></tr><tr><td>Sulfur</td><td>S</td><td>0.3</td><td>0.038</td></tr><tr><td>Potassium</td><td>K</td><td>0.2</td><td>0.03</td></tr><tr><td>Sodium</td><td>Na</td><td>0.2</td><td>0.037</td></tr><tr><td>Chlorine</td><td>Cl</td><td>0.2</td><td>0.024</td></tr><tr><td>Magnesium</td><td>Mg</td><td>0.1</td><td>0.015</td></tr><tr><td>All others</td><td></td><td>< 0.1</td><td>< 0.3</td></tr></tbody></table> <p>About 99% of the mass of the human body is made up of six elements: <a href="/facts/Oxygen/acyn6o8r">oxygen</a>, <a href="/facts/Carbon/ukrgQexo">carbon</a>, <a href="/facts/Hydrogen/BoYHjl0J">hydrogen</a>, <a href="/facts/Nitrogen/Nf1QpGDz">nitrogen</a>, <a href="/facts/Calcium/hf252CC0">calcium</a>, and <a href="/facts/Phosphorus/27xCeIqs">phosphorus</a>. Only about 0.85% is composed of another five elements: <a href="/facts/Potassium/5lcumVgo">potassium</a>, <a href="/facts/Sulfur/IK0amTfM">sulfur</a>, <a href="/facts/Sodium/eYuSPu2V">sodium</a>, <a href="/facts/Chlorine/y27UwYBM">chlorine</a>, & <a href="/facts/Magnesium/XyIhd2FG">magnesium</a>. All 11 are necessary for life. The remaining elements are <a href="/facts/Trace_element/fcIekKdo">trace elements</a>, of which more than a dozen are thought on the basis of good evidence to be necessary for life.<a class="footnote-ref" id="fnref:1" href="#fn:1"><sup>1</sup></a> All of the mass of the trace elements put together (less than 10 grams for a human body) do not add up to the body mass of magnesium, the least common of the 11 non-trace elements. </p> <h3>Other elements</h3> <p>Not all elements which are found in the human body in trace quantities play a role in life. Some of these elements are thought to be simple common contaminants without function (examples: caesium, titanium), while many others are thought to be active toxins, depending on amount (cadmium, mercury, lead, radioactives). In humans, <a href="/facts/Arsenic/k1c4f44D">arsenic</a> is toxic, and its levels in foods and <a href="/facts/Dietary_supplement/SHXNNxaS">dietary supplements</a> are closely monitored to reduce or eliminate its intake.<a class="footnote-ref" id="fnref:2" href="#fn:2"><sup>2</sup></a> </p><p>Some elements (silicon, boron, nickel, vanadium) are probably needed by mammals also, but in far smaller doses. Bromine is used by some (though not all) bacteria, fungi, <a href="/facts/Diatoms/x2oEcP1P">diatoms</a>, and <a href="/facts/Seaweeds/thLwLBk8">seaweeds</a>, and opportunistically in <a href="/facts/Eosinophil/yhIKA8bE">eosinophils</a> in humans. One study has indicated bromine to be necessary to <a href="/facts/Collagen_IV/v6JPysy9">collagen IV</a> synthesis in humans.<a class="footnote-ref" id="fnref:3" href="#fn:3"><sup>3</sup></a> <a href="/facts/Fluorine/YUV0Fb8m">Fluorine</a> is used by a number of plants to manufacture toxins but in humans its only known function is as a local topical hardening agent in tooth enamel.<a class="footnote-ref" id="fnref:4" href="#fn:4"><sup>4</sup></a> </p> <h3>Elemental composition list</h3> <p class="note">Main article: <a href="/facts/Mineral_(nutrient)/ACv8EG7f">mineral (nutrient)</a></p> <p>The average 70 kg (150 lb) <a href="/facts/Human_body/WP1QbDTn">adult human body</a> contains approximately 7×1027 <a href="/facts/Atom/69syB8dH">atoms</a> and contains at least detectable traces of 60 <a href="/facts/Chemical_element/0jducgWD">chemical elements</a>.<a class="footnote-ref" id="fnref:5" href="#fn:5"><sup>5</sup></a> About 29 of these elements are thought to play an active positive role in life and health in humans.<a class="footnote-ref" id="fnref:6" href="#fn:6"><sup>6</sup></a> </p><p>The relative amounts of each element vary by individual, mainly due to differences in the proportion of fat, muscle and bone in their body. Persons with more fat will have a higher proportion of carbon and a lower proportion of most other elements (the proportion of hydrogen will be about the same). The numbers in the table are averages of different numbers reported by different references. </p><p>The adult human body averages ~53% water.<a class="footnote-ref" id="fnref:7" href="#fn:7"><sup>7</sup></a> This varies substantially by age, sex, and adiposity. In a large sample of adults of all ages and both sexes, the figure for water fraction by weight was found to be 48 ±6% for females and 58 ±8% water for males.<a class="footnote-ref" id="fnref:8" href="#fn:8"><sup>8</sup></a> Water is ~11% hydrogen by <a href="/facts/Mass/HHdc8XmF">mass</a> but ~67% hydrogen by <a href="/facts/Atomic_percent/rT4aRoNm">atomic percent</a>, and these numbers along with the complementary % numbers for oxygen in water, are the largest contributors to overall mass and atomic composition figures. Because of water content, the human body contains more oxygen by mass than any other element, but more hydrogen by atom-fraction than any element. </p><p>The elements listed below as "Essential in humans" are those listed by the US <a href="/facts/Food_and_Drug_Administration/rCEnh9WB">Food and Drug Administration</a> as essential nutrients,<a class="footnote-ref" id="fnref:9" href="#fn:9"><sup>9</sup></a> as well as six additional elements: oxygen, carbon, hydrogen, and nitrogen (the fundamental building blocks of life on Earth), sulfur (essential to all cells) and cobalt (a necessary component of vitamin B12). Elements listed as "Possibly" or "Probably" essential are those cited by the US <a href="/facts/National_Research_Council_(United_States)/AdYmBBGV">National Research Council</a> as beneficial to human health and possibly or probably essential.<a class="footnote-ref" id="fnref:10" href="#fn:10"><sup>10</sup></a> </p> <table><tbody><tr><th>Atomic number</th><th>Element</th><th>Fraction of mass<a class="footnote-ref" id="fnref:11" href="#fn:11"><sup>11</sup></a><a class="footnote-ref" id="fnref:12" href="#fn:12"><sup>12</sup></a><a class="footnote-ref" id="fnref:13" href="#fn:13"><sup>13</sup></a><a class="footnote-ref" id="fnref:14" href="#fn:14"><sup>14</sup></a><a class="footnote-ref" id="fnref:15" href="#fn:15"><sup>15</sup></a></th><th>Mass (kg)<a class="footnote-ref" id="fnref:16" href="#fn:16"><sup>16</sup></a></th><th><a href="/facts/Atomic_percent/rT4aRoNm">Atomic percent</a></th><th>Essential in humans<a class="footnote-ref" id="fnref:17" href="#fn:17"><sup>17</sup></a></th><th>Negative effects of excess</th><th><a href="/facts/Periodic_table_group/YGBcUabv">Group</a></th></tr><tr><td>8</td><td><a href="/facts/Oxygen/acyn6o8r">Oxygen</a></td><td>0.65</td><td>45</td><td>26</td><td><a href="/facts/Dioxygen_in_biological_reactions/MW7vayxF">Yes</a> (e.g. <a href="/facts/Water/0lkXnJPK">water</a>, <a href="/facts/Electrophile/1AHFg1zm">electron acceptor</a> and <a href="/facts/DNA/nB89Iauz">DNA</a>)<a class="footnote-ref" id="fnref:18" href="#fn:18"><sup>18</sup></a></td><td><a href="/facts/Reactive_oxygen_species/GpwSRugH">Reactive oxygen species</a></td><td>16</td></tr><tr><td>6</td><td><a href="/facts/Carbon/ukrgQexo">Carbon</a></td><td>0.18</td><td>13</td><td>9.5</td><td><a href="/facts/Organic_compound/gqCNaN45">Yes</a><a class="footnote-ref" id="fnref:19" href="#fn:19"><sup>19</sup></a> (<a href="/facts/Organic_compound/gqCNaN45">organic compounds</a>)</td><td></td><td>14</td></tr><tr><td>1</td><td><a href="/facts/Hydrogen/BoYHjl0J">Hydrogen</a></td><td>0.10</td><td>7</td><td>63</td><td><a href="/facts/Organic_compound/gqCNaN45">Yes</a><a class="footnote-ref" id="fnref:20" href="#fn:20"><sup>20</sup></a> (e.g. <a href="/facts/Water/0lkXnJPK">water</a> and <a href="/facts/DNA/nB89Iauz">DNA</a>)</td><td><a href="/facts/Acidosis/hmfAo1uR">Acidosis</a></td><td>1</td></tr><tr><td>7</td><td><a href="/facts/Nitrogen/Nf1QpGDz">Nitrogen</a></td><td>0.02–0.03</td><td>1.8</td><td>1.1</td><td><a href="/facts/Nitrogen/Nf1QpGDz">Yes</a><a class="footnote-ref" id="fnref:21" href="#fn:21"><sup>21</sup></a> (e.g. <a href="/facts/DNA/nB89Iauz">DNA</a> and <a href="/facts/Amino_acid/WDxYwBny">amino acids</a>)</td><td><a href="/facts/Nitrogen_narcosis/R3Fuvddy">Nitrogen narcosis</a></td><td>15</td></tr><tr><td>20</td><td><a href="/facts/Calcium/hf252CC0">Calcium</a></td><td>0.011–0.015</td><td>1.0</td><td>0.21</td><td><a href="/facts/Calcium_in_biology/wgUxKej5">Yes</a><a class="footnote-ref" id="fnref:22" href="#fn:22"><sup>22</sup></a><a class="footnote-ref" id="fnref:23" href="#fn:23"><sup>23</sup></a><a class="footnote-ref" id="fnref:24" href="#fn:24"><sup>24</sup></a> (e.g. <a href="/facts/Calmodulin/CbEnEYHE">Calmodulin</a> and <a href="/facts/Hydroxylapatite/SqcXuXVQ">Hydroxylapatite</a> in <a href="/facts/Bone/pCU37jBe">bones</a>)</td><td><a href="/facts/Hypercalcaemia/kdEeLaVd">Hypercalcaemia</a></td><td>2</td></tr><tr><td>15</td><td><a href="/facts/Phosphorus/27xCeIqs">Phosphorus</a></td><td>5–7×10−3 <a class="footnote-ref" id="fnref:25" href="#fn:25"><sup>25</sup></a></td><td>0.78</td><td>0.12</td><td><a href="/facts/Phosphorus/27xCeIqs">Yes</a><a class="footnote-ref" id="fnref:26" href="#fn:26"><sup>26</sup></a><a class="footnote-ref" id="fnref:27" href="#fn:27"><sup>27</sup></a><a class="footnote-ref" id="fnref:28" href="#fn:28"><sup>28</sup></a> (e.g. <a href="/facts/DNA/nB89Iauz">DNA</a>, <a href="/facts/Phospholipid/u6GhNCF5">Phospholipids</a> and <a href="/facts/Phosphorylation/LXUEEeIL">Phosphorylation</a>)</td><td><a href="/facts/Hyperphosphatemia/mbCIQHbx">Hyperphosphatemia</a></td><td>15</td></tr><tr><td>19</td><td><a href="/facts/Potassium/5lcumVgo">Potassium</a></td><td>1.5–2×10−3<a class="footnote-ref" id="fnref:29" href="#fn:29"><sup>29</sup></a></td><td>0.14</td><td>0.029</td><td><a href="/facts/Potassium/5lcumVgo">Yes</a><a class="footnote-ref" id="fnref:30" href="#fn:30"><sup>30</sup></a><a class="footnote-ref" id="fnref:31" href="#fn:31"><sup>31</sup></a> (e.g. <a href="/facts/Na%252B%2fK%252B-ATPase/SuA4d4Na">Na+/K+-ATPase</a>)</td><td><a href="/facts/Hyperkalemia/epfvUg5w">Hyperkalemia</a></td><td>1</td></tr><tr><td>16</td><td><a href="/facts/Sulfur/IK0amTfM">Sulfur</a></td><td>2.5×10−3</td><td>0.14</td><td>0.049</td><td><a href="/facts/Sulfur/IK0amTfM">Yes</a><a class="footnote-ref" id="fnref:32" href="#fn:32"><sup>32</sup></a> (e.g. <a href="/facts/Cysteine/kbqvUm6d">Cysteine</a>, <a href="/facts/Methionine/7neydPKo">Methionine</a>, <a href="/facts/Biotin/WAaVxyB7">Biotin</a>, <a href="/facts/Thiamine/37RC4MCS">Thiamine</a>)</td><td><a href="/facts/Sulfhemoglobinemia/7FwFcqry">Sulfhemoglobinemia</a></td><td>16</td></tr><tr><td>11</td><td><a href="/facts/Sodium/eYuSPu2V">Sodium</a></td><td>1.5×10−3</td><td>0.10</td><td>0.041</td><td><a href="/facts/Sodium/eYuSPu2V">Yes</a><a class="footnote-ref" id="fnref:33" href="#fn:33"><sup>33</sup></a> (e.g. <a href="/facts/Na%252B%2fK%252B-ATPase/SuA4d4Na">Na+/K+-ATPase</a>)</td><td><a href="/facts/Hypernatremia/IKu0CwLv">Hypernatremia</a></td><td>1</td></tr><tr><td>17</td><td><a href="/facts/Chlorine/y27UwYBM">Chlorine</a></td><td>1.5×10−3</td><td>0.095</td><td>0.027</td><td><a href="/facts/Serum_chloride/U4j7LXkK">Yes</a><a class="footnote-ref" id="fnref:34" href="#fn:34"><sup>34</sup></a><a class="footnote-ref" id="fnref:35" href="#fn:35"><sup>35</sup></a> (e.g. <a href="/facts/Cl-transporting_ATPase/8X8ARGyC">Cl-transporting ATPase</a>)</td><td><a href="/facts/Hyperchloremia/dY9DV7qG">Hyperchloremia</a></td><td>17</td></tr><tr><td>12</td><td><a href="/facts/Magnesium/XyIhd2FG">Magnesium</a></td><td>500×10−6</td><td>0.019</td><td>< 0.01</td><td><a href="/facts/Magnesium/XyIhd2FG">Yes</a><a class="footnote-ref" id="fnref:36" href="#fn:36"><sup>36</sup></a><a class="footnote-ref" id="fnref:37" href="#fn:37"><sup>37</sup></a> (e.g. binding to <a href="/facts/Magnesium_in_biology/ENuowoyY">ATP and other nucleotides</a>)</td><td><a href="/facts/Hypermagnesemia/D1vCcEYC">Hypermagnesemia</a></td><td>2</td></tr><tr><td>26</td><td><a href="/facts/Iron/DkICCKIC">Iron</a>*</td><td>60×10−6</td><td>0.0042</td><td>< 0.01</td><td><a href="/facts/Iron/DkICCKIC">Yes</a><a class="footnote-ref" id="fnref:38" href="#fn:38"><sup>38</sup></a><a class="footnote-ref" id="fnref:39" href="#fn:39"><sup>39</sup></a> (e.g. <a href="/facts/Hemoglobin/RsD1MzYA">Hemoglobin</a>, <a href="/facts/Cytochrome/VF51IeGv">Cytochromes</a>)</td><td><a href="/facts/Iron_overload/b7jEdAGr">Iron overload</a></td><td>8</td></tr><tr><td>9</td><td><a href="/facts/Fluorine/YUV0Fb8m">Fluorine</a></td><td>37×10−6</td><td>0.0026</td><td>< 0.01</td><td>Yes (<a href="/facts/Australia/qLHpbppq">AUS</a>, <a href="/facts/New_Zealand/4mpSlJdg">NZ</a>),<a class="footnote-ref" id="fnref:40" href="#fn:40"><sup>40</sup></a> No (<a href="/facts/United_States_of_America/P0sCdLe5">US</a>, <a href="/facts/European_Union/6GYcR8qM">EU</a>),<a class="footnote-ref" id="fnref:41" href="#fn:41"><sup>41</sup></a><a class="footnote-ref" id="fnref:42" href="#fn:42"><sup>42</sup></a> Maybe (<a href="/facts/World_Health_Organization/YNN3bgug">WHO</a>)<a class="footnote-ref" id="fnref:43" href="#fn:43"><sup>43</sup></a></td><td>Fluorine: <a href="/facts/Biological_aspects_of_fluorine/B1EjTETc">Highly toxic</a><p>Fluoride: <a href="/facts/Fluoride_toxicity/gVfNmgaC">Toxic in high amounts</a></p></td><td>17</td></tr><tr><td>30</td><td><a href="/facts/Zinc/80b1qgk3">Zinc</a></td><td>32×10−6</td><td>0.0023</td><td>< 0.01</td><td><a href="/facts/Zinc/80b1qgk3">Yes</a><a class="footnote-ref" id="fnref:44" href="#fn:44"><sup>44</sup></a><a class="footnote-ref" id="fnref:45" href="#fn:45"><sup>45</sup></a> (e.g. <a href="/facts/Zinc_finger_protein/dWrlw4t7">Zinc finger proteins</a>)</td><td><a href="/facts/Zinc_toxicity/FILEAfrr">Zinc toxicity</a></td><td>12</td></tr><tr><td>14</td><td><a href="/facts/Silicon/cgWx0hdr">Silicon</a></td><td>20×10−6</td><td>0.0010</td><td>< 0.01</td><td><a href="/facts/Silicon/cgWx0hdr">Probably</a><a class="footnote-ref" id="fnref:46" href="#fn:46"><sup>46</sup></a></td><td></td><td>14</td></tr><tr><td>31</td><td><a href="/facts/Gallium/EucevDs9">Gallium</a></td><td>4.9×10−6</td><td>0.0007</td><td>< 0.01</td><td>No</td><td><a href="/facts/Gallium/EucevDs9">Gallium halide</a> poisoning<a class="footnote-ref" id="fnref:47" href="#fn:47"><sup>47</sup></a></td><td>13</td></tr><tr><td>37</td><td><a href="/facts/Rubidium/KDHSe2HM">Rubidium</a></td><td>4.6×10−6</td><td>0.00068</td><td>< 0.01</td><td>No</td><td></td><td>1</td></tr><tr><td>38</td><td><a href="/facts/Strontium/ABaA5qQK">Strontium</a></td><td>4.6×10−6</td><td>0.00032</td><td>< 0.001</td><td>No</td><td><a href="/facts/Calcium/hf252CC0">Calcium</a> replacement</td><td>2</td></tr><tr><td>35</td><td><a href="/facts/Bromine/oLfj3C7D">Bromine</a></td><td>2.9×10−6</td><td>0.00026</td><td>< 0.001</td><td>Maybe<a class="footnote-ref" id="fnref:48" href="#fn:48"><sup>48</sup></a></td><td><a href="/facts/Bromism/oPgKIXbN">Bromism</a></td><td>17</td></tr><tr><td>82</td><td><a href="/facts/Lead/EYljasJN">Lead</a></td><td>1.7×10−6</td><td>0.00012</td><td>< 0.001</td><td>No</td><td><a href="/facts/Lead_poisoning/STwlKj7c">Lead poisoning</a></td><td>14</td></tr><tr><td>29</td><td><a href="/facts/Copper/I8PEE8oX">Copper</a></td><td>1×10−6</td><td>0.000072</td><td>< 0.001</td><td><a href="/facts/Copper/I8PEE8oX">Yes</a><a class="footnote-ref" id="fnref:49" href="#fn:49"><sup>49</sup></a><a class="footnote-ref" id="fnref:50" href="#fn:50"><sup>50</sup></a> (e.g. <a href="/facts/Copper_proteins/g9k6KFdg">copper proteins</a>)</td><td><a href="/facts/Copper_toxicity/qM6ApMo7">Copper toxicity</a></td><td>11</td></tr><tr><td>13</td><td><a href="/facts/Aluminium/7wmR8jYE">Aluminium</a></td><td>870×10−9</td><td>0.000060</td><td>< 0.001</td><td>No</td><td><a href="/facts/Aluminium_poisoning/7wmR8jYE">Aluminium poisoning</a></td><td>13</td></tr><tr><td>48</td><td><a href="/facts/Cadmium/wXkV2eIX">Cadmium</a></td><td>720×10−9</td><td>0.000050</td><td>< 0.001</td><td>No</td><td><a href="/facts/Cadmium_poisoning/tKRPXnz6">Cadmium poisoning</a></td><td>12</td></tr><tr><td>58</td><td><a href="/facts/Cerium/a7UjMBQ6">Cerium</a></td><td>570×10−9</td><td>0.000040</td><td>< 0.001</td><td>No</td><td></td><td></td></tr><tr><td>56</td><td><a href="/facts/Barium/IkL09XHQ">Barium</a></td><td>310×10−9</td><td>0.000022</td><td>< 0.001</td><td>No</td><td>toxic in higher amounts</td><td>2</td></tr><tr><td>50</td><td><a href="/facts/Tin/vxbbBgNz">Tin</a></td><td>240×10−9</td><td>0.000020</td><td>< 0.001</td><td>Maybe<a class="footnote-ref" id="fnref:51" href="#fn:51"><sup>51</sup></a></td><td></td><td>14</td></tr><tr><td>53</td><td><a href="/facts/Iodine/JlfMecMf">Iodine</a></td><td>160×10−9</td><td>0.000020</td><td>< 0.001</td><td><a href="/facts/Iodine/JlfMecMf">Yes</a><a class="footnote-ref" id="fnref:52" href="#fn:52"><sup>52</sup></a><a class="footnote-ref" id="fnref:53" href="#fn:53"><sup>53</sup></a> (e.g. <a href="/facts/Thyroxine/9k4xJtCq">thyroxine</a>, <a href="/facts/Triiodothyronine/MPBz6ApV">triiodothyronine</a>)</td><td>Iodine-induced <a href="/facts/Hyperthyroidism/H9Eqmbgk">hyperthyroidism</a></td><td>17</td></tr><tr><td>22</td><td><a href="/facts/Titanium/53ArnDoy">Titanium</a></td><td>130×10−9</td><td>0.000020</td><td>< 0.001</td><td>No</td><td></td><td>4</td></tr><tr><td>5</td><td><a href="/facts/Boron/Pmwgd7Mf">Boron</a></td><td>690×10−9</td><td>0.000018</td><td>< 0.001</td><td><a href="/facts/Boron/Pmwgd7Mf">Probably</a><a class="footnote-ref" id="fnref:54" href="#fn:54"><sup>54</sup></a><a class="footnote-ref" id="fnref:55" href="#fn:55"><sup>55</sup></a></td><td></td><td>13</td></tr><tr><td>34</td><td><a href="/facts/Selenium/k975NApC">Selenium</a></td><td>190×10−9</td><td>0.000015</td><td>< 0.001</td><td><a href="/facts/Selenium/k975NApC">Yes</a><a class="footnote-ref" id="fnref:56" href="#fn:56"><sup>56</sup></a><a class="footnote-ref" id="fnref:57" href="#fn:57"><sup>57</sup></a> (e.g. <a href="/facts/Selenocysteine/9ovfzrXW">selenocysteine</a>)</td><td><a href="/facts/Selenium/k975NApC">Selenium toxicity</a></td><td>16</td></tr><tr><td>28</td><td><a href="/facts/Nickel/KwMCHYRP">Nickel</a></td><td>140×10−9</td><td>0.000015</td><td>< 0.0001</td><td><a href="/facts/Nickel/KwMCHYRP">Maybe</a><a class="footnote-ref" id="fnref:58" href="#fn:58"><sup>58</sup></a></td><td><a href="/facts/Nickel/KwMCHYRP">Nickel Toxicity</a></td><td>10</td></tr><tr><td>24</td><td><a href="/facts/Chromium/6sVk6Uu7">Chromium</a></td><td>24×10−9</td><td>0.000014</td><td>< 0.0001</td><td><a href="/facts/Chromium/6sVk6Uu7">Maybe</a><a class="footnote-ref" id="fnref:59" href="#fn:59"><sup>59</sup></a><a class="footnote-ref" id="fnref:60" href="#fn:60"><sup>60</sup></a><a class="footnote-ref" id="fnref:61" href="#fn:61"><sup>61</sup></a></td><td></td><td>6</td></tr><tr><td>25</td><td><a href="/facts/Manganese/j9ELd1TL">Manganese</a></td><td>170×10−9</td><td>0.000012</td><td>< 0.0001</td><td><a href="/facts/Manganese/j9ELd1TL">Yes</a><a class="footnote-ref" id="fnref:62" href="#fn:62"><sup>62</sup></a><a class="footnote-ref" id="fnref:63" href="#fn:63"><sup>63</sup></a> (e.g. <a href="/facts/Mn-SOD/pgDtrG8U">Mn-SOD</a>)</td><td><a href="/facts/Manganism/G4AtRyFu">Manganism</a></td><td>7</td></tr><tr><td>33</td><td><a href="/facts/Arsenic/k1c4f44D">Arsenic</a></td><td>260×10−9</td><td>0.000007</td><td>< 0.0001</td><td><a href="/facts/Arsenic/k1c4f44D">Maybe</a><a class="footnote-ref" id="fnref:64" href="#fn:64"><sup>64</sup></a><a class="footnote-ref" id="fnref:65" href="#fn:65"><sup>65</sup></a></td><td><a href="/facts/Arsenic_poisoning/JCLk4S68">Arsenic poisoning</a></td><td>15</td></tr><tr><td>3</td><td><a href="/facts/Lithium/7vXX6BWA">Lithium</a></td><td>31×10−9</td><td>0.000007</td><td>< 0.0001</td><td><a href="/facts/Lithium/7vXX6BWA">Possibly</a> (intercorrelated with the functions of several <a href="/facts/Enzymes/DSI1Fh7y">enzymes</a>, <a href="/facts/Hormones/WFnBnINJ">hormones</a> and <a href="/facts/Vitamin/SnW0LYBL">vitamins</a>)</td><td><a href="/facts/Lithium_toxicity/wlPELAqG">Lithium toxicity</a></td><td>1</td></tr><tr><td>80</td><td><a href="/facts/Mercury_(element)/WlxfoHva">Mercury</a></td><td>190×10−9</td><td>0.000006</td><td>< 0.0001</td><td>No</td><td><a href="/facts/Mercury_poisoning/xdSGkWLU">Mercury poisoning</a></td><td>12</td></tr><tr><td>55</td><td><a href="/facts/Caesium/dXKN1S5k">Caesium</a></td><td>21×10−9</td><td>0.000006</td><td>< 0.0001</td><td>No</td><td></td><td>1</td></tr><tr><td>42</td><td><a href="/facts/Molybdenum/RX6vp2bF">Molybdenum</a></td><td>130×10−9</td><td>0.000005</td><td>< 0.0001</td><td><a href="/facts/Molybdenum/RX6vp2bF">Yes</a><a class="footnote-ref" id="fnref:66" href="#fn:66"><sup>66</sup></a><a class="footnote-ref" id="fnref:67" href="#fn:67"><sup>67</sup></a> (e.g. the <a href="/facts/Molybdenum_oxotransferase/jYma7GNI">molybdenum oxotransferases</a>, <a href="/facts/Xanthine_oxidase/5AfnaJpl">Xanthine oxidase</a> and <a href="/facts/Sulfite_oxidase/WnrJJ489">Sulfite oxidase</a>)</td><td></td><td>6</td></tr><tr><td>32</td><td><a href="/facts/Germanium/wtoALHGs">Germanium</a></td><td>5×10−6</td><td></td><td>< 0.0001</td><td>No</td><td></td><td>14</td></tr><tr><td>27</td><td><a href="/facts/Cobalt/gqhScEw4">Cobalt</a></td><td>21×10−9</td><td>0.000003</td><td>< 0.0001</td><td><a href="/facts/Cobalt/gqhScEw4">Yes</a> (e.g. <a href="/facts/Vitamin_B12/vCk613gD">Cobalamin/Vitamin B12</a>)<a class="footnote-ref" id="fnref:68" href="#fn:68"><sup>68</sup></a><a class="footnote-ref" id="fnref:69" href="#fn:69"><sup>69</sup></a></td><td></td><td>9</td></tr><tr><td>44</td><td><a href="/facts/Ruthenium/uzCm4ufn">Ruthenium</a></td><td>22×10−9</td><td>0.000007</td><td>< 0.0001</td><td>No <a class="footnote-ref" id="fnref:70" href="#fn:70"><sup>70</sup></a></td><td></td><td>8</td></tr><tr><td>51</td><td><a href="/facts/Antimony/YsA7lVgT">Antimony</a></td><td>110×10−9</td><td>0.000002</td><td>< 0.0001</td><td><a href="/facts/Antimony/YsA7lVgT">No</a></td><td>toxic</td><td>15</td></tr><tr><td>47</td><td><a href="/facts/Silver/xXe41BGg">Silver</a></td><td>10×10−9</td><td>0.000002</td><td>< 0.0001</td><td>No</td><td></td><td>11</td></tr><tr><td>41</td><td><a href="/facts/Niobium/3zNI8AKp">Niobium</a></td><td>1600×10−9</td><td>0.0000015</td><td>< 0.0001</td><td>No</td><td></td><td>5</td></tr><tr><td>40</td><td><a href="/facts/Zirconium/y7gsoQFz">Zirconium</a></td><td>6×10−9</td><td>0.000001</td><td>< 0.0001</td><td>No</td><td></td><td>4</td></tr><tr><td>57</td><td><a href="/facts/Lanthanum/Uhmmy1sB">Lanthanum</a></td><td>1370×10−9</td><td>8×10−7</td><td>< 0.0001</td><td>No</td><td></td><td></td></tr><tr><td>52</td><td><a href="/facts/Tellurium/v7QvfIvS">Tellurium</a></td><td>120×10−9</td><td>7×10−7</td><td>< 0.0001</td><td>No</td><td></td><td>16</td></tr><tr><td>39</td><td><a href="/facts/Yttrium/BlX6rj99">Yttrium</a></td><td></td><td>6×10−7</td><td>< 0.0001</td><td>No</td><td></td><td>3</td></tr><tr><td>83</td><td><a href="/facts/Bismuth/75FLjkoX">Bismuth</a></td><td></td><td>5×10−7</td><td>< 0.0001</td><td>No</td><td></td><td>15</td></tr><tr><td>81</td><td><a href="/facts/Thallium/v35pGMJB">Thallium</a></td><td></td><td>5×10−7</td><td>< 0.0001</td><td>No</td><td>highly toxic</td><td>13</td></tr><tr><td>49</td><td><a href="/facts/Indium/zRq3stVb">Indium</a></td><td></td><td>4×10−7</td><td>< 0.0001</td><td>No</td><td></td><td>13</td></tr><tr><td>79</td><td><a href="/facts/Gold/1znknojp">Gold</a></td><td>3×10−9</td><td>2×10−7</td><td>< 0.0001</td><td>No</td><td>uncoated nanoparticles possibly <a href="/facts/Genotoxic/fRUJaqxo">genotoxic</a><a class="footnote-ref" id="fnref:71" href="#fn:71"><sup>71</sup></a><a class="footnote-ref" id="fnref:72" href="#fn:72"><sup>72</sup></a><a class="footnote-ref" id="fnref:73" href="#fn:73"><sup>73</sup></a></td><td>11</td></tr><tr><td>21</td><td><a href="/facts/Scandium/TJRt1chg">Scandium</a></td><td></td><td>2×10−7</td><td>< 0.0001</td><td>No</td><td></td><td>3</td></tr><tr><td>73</td><td><a href="/facts/Tantalum/VwaxMm33">Tantalum</a></td><td></td><td>2×10−7</td><td>< 0.0001</td><td>No</td><td></td><td>5</td></tr><tr><td>23</td><td><a href="/facts/Vanadium/UvKkKTSm">Vanadium</a></td><td>260×10−9</td><td>0.000020</td><td>< 0.0001</td><td><a href="/facts/Vanadium/UvKkKTSm">Possibly</a><a class="footnote-ref" id="fnref:74" href="#fn:74"><sup>74</sup></a> (suggested osteo-metabolism (bone) growth factor)</td><td></td><td>5</td></tr><tr><td>90</td><td><a href="/facts/Thorium/ysdWH470">Thorium</a></td><td></td><td>1×10−7</td><td>< 0.0001</td><td>No</td><td>toxic, radioactive</td><td></td></tr><tr><td>92</td><td><a href="/facts/Uranium/n2sGWBzU">Uranium</a></td><td></td><td>1×10−7</td><td>< 0.0001</td><td>No</td><td>toxic, radioactive</td><td></td></tr><tr><td>62</td><td><a href="/facts/Samarium/09K3kl93">Samarium</a></td><td></td><td>5.0×10−8</td><td>< 0.0001</td><td>No</td><td></td><td></td></tr><tr><td>74</td><td><a href="/facts/Tungsten/WYwbNDYX">Tungsten</a></td><td></td><td>2.0×10−8</td><td>< 0.0001</td><td>No</td><td></td><td>6</td></tr><tr><td>4</td><td><a href="/facts/Beryllium/dv295voP">Beryllium</a></td><td></td><td>3.6×10−8</td><td>< 0.0001</td><td>No</td><td>toxic in higher amounts</td><td>2</td></tr><tr><td>88</td><td><a href="/facts/Radium/VWo5gkzn">Radium</a></td><td></td><td>3×10−14</td><td>< 0.0001</td><td>No</td><td>toxic, radioactive</td><td>2</td></tr><tr><td>2</td><td><a href="/facts/Helium/yRul93TG">Helium</a></td><td>20.39×10−21</td><td>2.4×10−14</td><td>< 0.0001</td><td>No</td><td>noble gas</td><td>18</td></tr><tr><td>10</td><td><a href="/facts/Neon/5bF1FwGL">Neon</a></td><td>8.5×10−23</td><td>1×10−14</td><td>< 0.0001</td><td>No</td><td>noble gas</td><td>18</td></tr><tr><td>18</td><td><a href="/facts/Argon/QX6NRH6d">Argon</a></td><td>4.25×10−23</td><td>0.5×10−14</td><td>< 0.0001</td><td>No</td><td>noble gas</td><td>18</td></tr><tr><td>36</td><td><a href="/facts/Krypton/llkNlCke">Krypton</a></td><td>2.125×10−23</td><td>0.25×10−14</td><td>< 0.0001</td><td>No</td><td>noble gas</td><td>18</td></tr></tbody></table> <p>*Iron = ~3 <a href="/facts/Gram/CNAPqWKz">g</a> in males, ~2.3 g in females </p><p>Of the 94 naturally occurring chemical elements, 76 are listed in the table above. Of the remaining 18, it is not known how many occur in the human body. </p><p>Most of the elements needed for life are relatively <a href="/facts/Abundance_of_the_chemical_elements/CE9WehBl">common in the Earth's crust</a>. <a href="/facts/Aluminium/7wmR8jYE">Aluminium</a>, the third most common element in the <a href="/facts/Earth%2527s_crust/VSy2u31r">Earth's crust</a> (after <a href="/facts/Oxygen/acyn6o8r">oxygen</a> and <a href="/facts/Silicon/cgWx0hdr">silicon</a>), serves no function in living cells, but is toxic in large amounts, depending on its physical and chemical forms and magnitude, duration, frequency of exposure, and how it was absorbed by the human body.<a class="footnote-ref" id="fnref:75" href="#fn:75"><sup>75</sup></a> <a href="/facts/Transferrin/qgoowcCD">Transferrins</a> can bind aluminium.<a class="footnote-ref" id="fnref:76" href="#fn:76"><sup>76</sup></a> </p> <h3>Periodic table</h3> <table><tbody><tr><th colspan="120">Essential elements for higher organisms (eucarya).<a class="footnote-ref" id="fnref:77" href="#fn:77"><sup>77</sup></a><a class="footnote-ref" id="fnref:78" href="#fn:78"><sup>78</sup></a><a class="footnote-ref" id="fnref:79" href="#fn:79"><sup>79</sup></a><a class="footnote-ref" id="fnref:80" href="#fn:80"><sup>80</sup></a><a class="footnote-ref" id="fnref:81" href="#fn:81"><sup>81</sup></a><a class="footnote-ref" id="fnref:82" href="#fn:82"><sup>82</sup></a><a class="footnote-ref" id="fnref:83" href="#fn:83"><sup>83</sup></a><ul><li>v</li><li>t</li><li>e</li></ul></th></tr><tr><td>H</td><td colspan="16"> </td><td>He</td></tr><tr><td>Li</td><td>Be</td><td colspan="10"> </td><td>B</td><td>C</td><td>N</td><td>O</td><td>F</td><td>Ne</td></tr><tr><td>Na</td><td>Mg</td><td colspan="10"> </td><td>Al</td><td>Si</td><td>P</td><td>S</td><td>Cl</td><td>Ar</td></tr><tr><td>K</td><td>Ca</td><td>Sc</td><td>Ti</td><td>V</td><td>Cr</td><td>Mn</td><td>Fe</td><td>Co</td><td>Ni</td><td>Cu</td><td>Zn</td><td>Ga</td><td>Ge</td><td>As</td><td>Se</td><td>Br</td><td>Kr</td></tr><tr><td>Rb</td><td>Sr</td><td>Y</td><td>Zr</td><td>Nb</td><td>Mo</td><td>Tc</td><td>Ru</td><td>Rh</td><td>Pd</td><td>Ag</td><td>Cd</td><td>In</td><td>Sn</td><td>Sb</td><td>Te</td><td>I</td><td>Xe</td></tr><tr><td>Cs</td><td>Ba</td><td>Lu</td><td>Hf</td><td>Ta</td><td>W</td><td>Re</td><td>Os</td><td>Ir</td><td>Pt</td><td>Au</td><td>Hg</td><td>Tl</td><td>Pb</td><td>Bi</td><td>Po</td><td>At</td><td>Rn</td></tr></tbody></table> <table><tbody><tr><td>Legend: The <a href="/facts/CHON/lI4Wve8U">four basic organic elements</a> Quantity elements Essential <a href="/facts/Dietary_element/ACv8EG7f">trace elements</a> Essentiality or function debated Not essential in humans, but essential/beneficial for some non-human eucarya</td></tr></tbody></table> <h2 id="composition">Composition</h2> <p>The composition of the human body can be classified as follows: </p> <ul><li><a href="/facts/Water/0lkXnJPK">Water</a></li> <li><a href="/facts/Protein/Jxmagu3E">Proteins</a></li> <li><a href="/facts/Fat/87HcP11s">Fats</a> (or <a href="/facts/Lipid/TdQR87HX">lipids</a>)</li> <li><a href="/facts/Hydroxyapatite/SqcXuXVQ">Hydroxyapatite</a> in bones</li> <li><a href="/facts/Carbohydrates/Geuuzxsf">Carbohydrates</a> such as <a href="/facts/Glycogen/kWa8fPFE">glycogen</a> and <a href="/facts/Glucose/oUSkoLCD">glucose</a></li> <li><a href="/facts/DNA/nB89Iauz">DNA</a> and <a href="/facts/RNA/HxPeNfNj">RNA</a></li> <li>Inorganic <a href="/facts/Ion/wrbwhF3z">ions</a> such as <a href="/facts/Sodium/eYuSPu2V">sodium</a>, <a href="/facts/Potassium/5lcumVgo">potassium</a>, <a href="/facts/Chloride/m9NUaUDR">chloride</a>, <a href="/facts/Bicarbonate/zzSVVAl1">bicarbonate</a>, <a href="/facts/Phosphate/FDGVCxUG">phosphate</a></li> <li><a href="/facts/Gas/hVVAoodV">Gases</a> mainly being <a href="/facts/Oxygen/acyn6o8r">oxygen</a>, <a href="/facts/Carbon_dioxide/xGzpppEp">carbon dioxide</a></li> <li>Many <a href="/facts/Cofactor_(biochemistry)/AGo0PCUU">cofactors</a>.</li></ul> <p>The estimated contents of a typical 20-micrometre human cell is as follows:<a class="footnote-ref" id="fnref:84" href="#fn:84"><sup>84</sup></a> </p> <table><tbody><tr><th>Compound type</th><th>Percent of mass</th><th>Mol. weight (daltons)</th><th>Compound</th><th>Percent of molecules</th></tr><tr><td><a href="/facts/Water/0lkXnJPK">Water</a></td><td>65</td><td>18</td><td>1.74×1014</td><td>98.73</td></tr><tr><td>Other <a href="/facts/Inorganic/TfFfzxSz">inorganics</a></td><td>1.5</td><td>N/A</td><td>1.31×1012</td><td>0.74</td></tr><tr><td><a href="/facts/Lipid/TdQR87HX">Lipids</a></td><td>12</td><td>N/A</td><td>8.4×1011</td><td>0.475</td></tr><tr><td>Other <a href="/facts/Organic_compound/gqCNaN45">organics</a></td><td>0.4</td><td>N/A</td><td>7.7×1010</td><td>0.044</td></tr><tr><td><a href="/facts/Protein/Jxmagu3E">Protein</a></td><td>20</td><td>N/A</td><td>1.9×1010</td><td>0.011</td></tr><tr><td><a href="/facts/RNA/HxPeNfNj">RNA</a></td><td>1.0</td><td>N/A</td><td>5×107</td><td>3×10−5</td></tr><tr><td><a href="/facts/DNA/nB89Iauz">DNA</a></td><td>0.1</td><td>1×1011</td><td>46</td><td>3×10−11</td></tr></tbody></table> <h2 id="tissues">Tissues</h2> The main cellular components of the human body<a class="footnote-ref" id="fnref:85" href="#fn:85"><sup>85</sup></a><a class="footnote-ref" id="fnref:86" href="#fn:86"><sup>86</sup></a><a class="footnote-ref" id="fnref:87" href="#fn:87"><sup>87</sup></a><table><tbody><tr><td rowspan="6"></td><th scope="col">Cell type</th><th scope="col">% mass</th><th scope="col">% cell count</th></tr><tr><td>Erythrocytes (red blood cells)</td><td>4.2</td><td>85.0</td></tr><tr><td>Muscle cells</td><td>28.6</td><td>0.001</td></tr><tr><td>Adipocytes (fat cells)</td><td>18.6</td><td>0.2</td></tr><tr><td>Other cells</td><td>14.3</td><td>14.8</td></tr><tr><td>Extracellular components</td><td>34.3</td><td>-</td></tr></tbody></table> <p><a href="/facts/Body_composition/nUrhSQF1">Body composition</a> can also be expressed in terms of various types of material, such as: </p> <ul><li><a href="/facts/Muscle/dmxrL8pH">Muscle</a></li> <li><a href="/facts/Adipose_tissue/PxxedB6e">Fat</a></li> <li><a href="/facts/Bone/pCU37jBe">Bone</a> and <a href="/facts/Human_tooth/SVkPCLal">teeth</a></li> <li><a href="/facts/Nervous_tissue/YY7qG0WD">Nervous tissue</a> (<a href="/facts/Human_brain/qfSwSB8K">brain</a> and <a href="/facts/Nerve/q7GsAfYV">nerves</a>)</li> <li><a href="/facts/Hormones/WFnBnINJ">Hormones</a></li> <li><a href="/facts/Connective_tissue/mal3fc7k">Connective tissue</a></li> <li><a href="/facts/Body_fluid/RkAXIBVN">Body fluids</a> (<a href="/facts/Blood/03zEulkj">blood</a>, <a href="/facts/Lymph/SL1xvRhq">lymph</a>, <a href="/facts/Urine/oNUYVtvX">urine</a>)</li> <li>Contents of <a href="/facts/Digestive_tract/nK2zwqBS">digestive tract</a>, including <a href="/facts/Intestinal_gas/XMAcIUru">intestinal gas</a></li> <li><a href="/facts/Air/6IyFHIpG">Air</a> in lungs</li> <li><a href="/facts/Epithelium/ecKHcHC3">Epithelium</a></li></ul> <h3>Composition by cell type</h3> <p class="note">Main article: <a href="/facts/List_of_distinct_cell_types_in_the_adult_human_body/IjWXx31l">List of distinct cell types in the adult human body</a></p> <p class="note">Main article: <a href="/facts/Human_microbiome/xJIRMUAY">Human microbiome § Relative numbers</a></p> <p>There are many species of <a href="/facts/Bacteria/wC8xSCsU">bacteria</a> and other <a href="/facts/Microorganism/pysJYcE2">microorganisms</a> that live on or inside the healthy human body. In fact, there are roughly as many microbial as human cells in the human body by number.<a class="footnote-ref" id="fnref:88" href="#fn:88"><sup>88</sup></a><a class="footnote-ref" id="fnref:89" href="#fn:89"><sup>89</sup></a><a class="footnote-ref" id="fnref:90" href="#fn:90"><sup>90</sup></a><a class="footnote-ref" id="fnref:91" href="#fn:91"><sup>91</sup></a><a class="footnote-ref" id="fnref:92" href="#fn:92"><sup>92</sup></a> (much less by mass or volume). Some of these <a href="/facts/Symbiont/MrBArRGa">symbionts</a> are necessary for our health. Those that neither help nor harm humans are called <a href="/facts/Commensal/KnJkboX0">commensal</a> organisms. </p> <h2 id="see-also">See also</h2> <ul><li><a href="/facts/List_of_organs_of_the_human_body/QeKhm6jr">List of organs of the human body</a></li> <li><a href="/facts/Hydrostatic_weighing/XJ7U4mzv">Hydrostatic weighing</a></li> <li><a href="/facts/Dietary_element/ACv8EG7f">Dietary element</a></li> <li><a href="/facts/Reference_ranges_for_blood_tests/Fls5Gbtb">Composition of blood</a></li> <li><a href="/facts/List_of_human_blood_components/L3XsUys5">List of human blood components</a></li> <li><a href="/facts/Body_composition/nUrhSQF1">Body composition</a></li> <li><a href="/facts/Abundance_of_elements_in_Earth%2527s_crust/UDSVHH56">Abundance of elements in Earth's crust</a></li> <li><a href="/facts/Abundance_of_the_chemical_elements/CE9WehBl">Abundance of the chemical elements</a></li></ul> <h2 id="references">References</h2> <ol> <li id="fn:1"><p>Zoroddu MA, Aaseth J, Crisponi G, Medici S, Peana M, Nurchi VM (June 2019). 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