Editing Ammonia (section)

== Toxicity ==
The toxicity of ammonia solutions does not usually cause problems for humans and other mammals, as a specific mechanism exists to prevent its build-up in the bloodstream. Ammonia is converted to [[carbamoyl phosphate]] by the enzyme [[carbamoyl phosphate synthetase]], and then enters the [[urea cycle]] to be either incorporated into [[amino acid]]s or excreted in the urine.<ref>{{cite book |last1=Berg |first1=J. M. |last2=Tymoczko |first2=J. L. |last3=Stryer |first3=L. |title=Biochemistry |url=https://www.ncbi.nlm.nih.gov/books/NBK22450/ |edition=5th |year=2002 |section=23.4: Ammonium Ion is Converted into Urea in Most Terrestrial Vertebrates}}</ref> [[Fish]] and [[amphibian]]s lack this mechanism, as they can usually eliminate ammonia from their bodies by direct excretion. Ammonia even at dilute concentrations is highly toxic to aquatic animals, and for this reason it is [[Directive 67/548/EEC|classified]] as ''"dangerous for the environment"''. Atmospheric ammonia plays a key role in the formation of [[fine particulate matter]].<ref>{{Cite journal |last1=Wang |first1=Mingyi |last2=Kong |first2=Weimeng |last3=Marten |first3=Ruby |last4=He |first4=Xu-Cheng |last5=Chen |first5=Dexian |last6=Pfeifer |first6=Joschka |last7=Heitto |first7=Arto |last8=Kontkanen |first8=Jenni |last9=Dada |first9=Lubna |last10=Kürten |first10=Andreas |last11=Yli-Juuti |first11=Taina |date=2020-05-13 |title=Rapid growth of new atmospheric particles by nitric acid and ammonia condensation |journal=Nature |language=en |volume=581 |issue=7807 |pages=184–189 |doi=10.1038/s41586-020-2270-4 |pmid=32405020 |pmc=7334196 |bibcode=2020Natur.581..184W |issn=1476-4687}}</ref>

Ammonia is a constituent of [[tobacco smoke]].<ref name="Talhout-2011">{{cite journal |last1=Talhout |first1=Reinskje |last2=Schulz |first2=Thomas |last3=Florek |first3=Ewa |last4=Van Benthem |first4=Jan |last5=Wester |first5=Piet |last6=Opperhuizen |first6=Antoon |title=Hazardous Compounds in Tobacco Smoke |journal=International Journal of Environmental Research and Public Health |volume=8 |issue=12 |year=2011 |pages=613–628 |issn=1660-4601 |doi=10.3390/ijerph8020613 |pmid=21556207 |pmc=3084482 |doi-access=free}}</ref>

=== Coking wastewater ===
Ammonia is present in coking wastewater streams, as a liquid by-product of the production of [[Coke (fuel)|coke]] from [[coal]].<ref>{{Cite web|title = Cutting-Edge Solutions For Coking Wastewater Reuse To Meet The Standard of Circulation Cooling Systems|url = http://www.wateronline.com/doc/cutting-edge-solutions-for-coking-wastewater-reuse-to-meet-the-standard-of-circulation-cooling-systems-0001|website = www.wateronline.com|access-date = 2016-01-16}}</ref> In some cases, the ammonia is discharged to the [[marine environment]] where it acts as a pollutant. The [[Whyalla Steelworks]] in [[South Australia]] is one example of a coke-producing facility that discharges ammonia into marine waters.<ref name="Rajaram-2005">{{cite book |author1=Vasudevan Rajaram |author2=Subijoy Dutta |author3=Krishna Parameswaran |title=Sustainable Mining Practices: A Global Perspective |url=https://books.google.com/books?id=5uTM2jFMzH4C&pg=PA113 |date=30 June 2005 |publisher=CRC Press |isbn=978-1-4398-3423-7 |page=113}}</ref>

=== Aquaculture ===
Ammonia toxicity is believed to be a cause of otherwise unexplained losses in [[fish hatcheries]]. Excess ammonia may accumulate and cause alteration of metabolism or increases in the body pH of the exposed organism. Tolerance varies among fish species.<ref name="Oram">{{Cite web|url = http://www.water-research.net/index.php/ammonia-in-groundwater-runoff-and-streams|title = Ammonia in Groundwater, Runoff, and Streams|access-date = 3 December 2014|website = The Water Centre|last = Oram|first = Brian}}</ref> At lower concentrations, around 0.05&nbsp;mg/L, un-ionised ammonia is harmful to fish species and can result in poor growth and feed conversion rates, reduced fecundity and fertility and increase stress and susceptibility to bacterial infections and diseases.<ref>{{Cite book|title = Managing ammonia in fish ponds|last1 = Hargreaves|first1 = J.A.|publisher = Southern Regional Aquaculture Center|year = 2004|last2 = Tucker|first2 = C.S.}}</ref> Exposed to excess ammonia, fish may suffer loss of equilibrium, hyper-excitability, increased respiratory activity and oxygen uptake and increased heart rate.<ref name="Oram" /> At concentrations exceeding 2.0&nbsp;mg/L, ammonia causes gill and tissue damage, extreme lethargy, convulsions, coma, and death.<ref name="Oram" /><ref name="Sergeant-2014">{{Cite journal|url = http://www.pollutionsolutions-online.com/articles/water-wastewater/17/chris_sergeant/the_management_of_ammonia_levels_in_an_aquaculture_environment/1557/|title = The Management of Ammonia Levels in an Aquaculture Environment|last = Sergeant|first = Chris|date = 5 February 2014|journal = Water/Wastewater|access-date = 3 December 2014}}</ref> Experiments have shown that the lethal concentration for a variety of fish species ranges from 0.2 to 2.0&nbsp;mg/L.<ref name="Sergeant-2014" />

During winter, when reduced feeds are administered to aquaculture stock, ammonia levels can be higher. Lower ambient temperatures reduce the rate of algal photosynthesis so less ammonia is removed by any algae present. Within an aquaculture environment, especially at large scale, there is no fast-acting remedy to elevated ammonia levels. Prevention rather than correction is recommended to reduce harm to farmed fish<ref name="Sergeant-2014" /> and in open water systems, the surrounding environment.

=== Storage information ===
Similar to [[propane]], [[anhydrous]] ammonia boils below room temperature when at atmospheric pressure. A storage vessel capable of {{convert|250|psi|MPa|abbr=on|lk=on}} is suitable to contain the liquid.<ref>[http://ecfr.gpoaccess.gov/cgi/t/text/text-idx?c=ecfr;sid=3a1341f81fbe762466a07d33da2361fb;rgn=div8;view=text;node=29%3A5.1.1.1.8.8.33.11;idno=29;cc=ecfr Electronic Code of Federal Regulations:] {{webarchive|url=https://web.archive.org/web/20111104165051/http://ecfr.gpoaccess.gov/cgi/t/text/text-idx?c=ecfr%3Bsid%3D3a1341f81fbe762466a07d33da2361fb%3Brgn%3Ddiv8%3Bview%3Dtext%3Bnode%3D29%3A5.1.1.1.8.8.33.11%3Bidno%3D29%3Bcc%3Decfr |date=4 November 2011 }}. Ecfr.gpoaccess.gov. Retrieved on 22 December 2011.</ref> Ammonia is used in numerous different industrial applications requiring carbon or stainless steel storage vessels. Ammonia with at least 0.2% by weight water content is not corrosive to carbon steel. {{NH3}} [[carbon steel]] construction storage tanks with 0.2% by weight or more of water could last more than 50 years in service.<ref>{{Cite web|title=Ammonia Tanks – Carbon and Stainless Steel Construction|url=https://ammoniatanks.com/|archive-url=https://web.archive.org/web/20031118224657/http://ammoniatanks.com/|url-status=usurped|archive-date=18 November 2003|access-date=2021-06-28|website=ammoniatanks.com}}</ref> Experts warn that ammonium compounds not be allowed to come in contact with [[base (chemistry)|bases]] (unless in an intended and contained reaction), as dangerous quantities of ammonia gas could be released.

=== Laboratory ===
[[File:Ammonia solution (25-28%).jpg|thumb|155px|A standard laboratory solution of 28% ammonia]]
The hazards of ammonia solutions depend on the concentration: 'dilute' ammonia solutions are usually 5–10% by weight (<&nbsp;5.62&nbsp;mol/L); 'concentrated' solutions are usually prepared at >25% by weight. A 25% (by weight) solution has a density of 0.907&nbsp;g/cm<sup>3</sup>, and a solution that has a lower density will be more concentrated. The [[Directive 67/548/EEC|European Union classification]] of ammonia solutions is given in the table.

<!-- EU Index no. 007-001-01-2 -->
{| class="wikitable"
|-
! [[Concentration]]<br />by weight (w/w)
! [[Molarity]]
! [[Concentration]]<br />mass/volume (w/v)
! [[GHS pictograms]]
! [[H-phrases]]
|-
| 5–10%
| 2.87–5.62&nbsp;mol/L
| 48.9–95.7&nbsp;g/L
| {{GHS07}}
| {{H-phrases|314}}
|-
| 10–25%
| 5.62–13.29&nbsp;mol/L
| 95.7–226.3&nbsp;g/L
| {{GHS05}}{{GHS07}}
| {{H-phrases|314|335|400}}
|-
| >25%
| >13.29&nbsp;mol/L
| >226.3&nbsp;g/L
| {{GHS05}}{{GHS07}}{{GHS09}}
| {{H-phrases|314|335|400|411}}
|}

The ammonia vapour from concentrated ammonia solutions is severely irritating to the eyes and the [[respiratory tract]], and experts warn that these solutions only be handled in a [[fume hood]]. Saturated ('0.880'–see ''{{slink|#Properties}}'') solutions can develop a significant pressure inside a closed bottle in warm weather, and experts also warn that the bottle be opened with care. This is not usually a problem for 25% ('0.900') solutions.

Experts warn that ammonia solutions not be mixed with [[halogen]]s, as toxic and/or explosive products are formed. Experts also warn that prolonged contact of ammonia solutions with [[silver]], [[mercury (element)|mercury]] or [[iodide]] salts can also lead to explosive products: such mixtures are often formed in [[qualitative inorganic analysis]], and that it needs to be lightly acidified but not concentrated (<6%&nbsp;w/v) before disposal once the test is completed.

=== Laboratory use of anhydrous ammonia (gas or liquid) ===
<!-- EU index no. 007-001-00-5 -->
<!-- R10, 23, 34, 50; S1/2, 9, 16, 26, 36/37/39, 45, 61 -->
Anhydrous ammonia is classified as toxic ('''T''') and dangerous for the environment ('''N'''). The gas is flammable ([[autoignition temperature]]: 651&nbsp;°C) and can form explosive mixtures with air (16–25%). The [[permissible exposure limit]] (PEL) in the United States is 50&nbsp;[[Parts per million|ppm]] (35&nbsp;mg/m<sup>3</sup>), while the [[IDLH]] concentration is estimated at 300&nbsp;ppm. Repeated exposure to ammonia lowers the sensitivity to the smell of the gas: normally the odour is detectable at concentrations of less than 50&nbsp;ppm, but desensitised individuals may not detect it even at concentrations of 100&nbsp;ppm. Anhydrous ammonia corrodes [[copper]]- and [[zinc]]-containing [[alloy]]s, which makes [[brass]] fittings not appropriate for handling the gas. Liquid ammonia can also attack [[rubber]] and certain plastics.

Ammonia reacts violently with the [[halogen]]s. [[Nitrogen triiodide]], a [[primary explosive|primary]] [[high explosive]], is formed when ammonia comes in contact with [[iodine]]. Ammonia causes the explosive [[polymerisation]] of [[ethylene oxide]]. It also forms explosive [[Detonation|fulminating]] compounds with compounds of [[gold]], [[silver]], [[Mercury (element)|mercury]], [[germanium]] or [[tellurium]], and with [[stibine]]. Violent reactions have also been reported with [[acetaldehyde]], [[hypochlorite]] solutions, [[potassium ferricyanide]] and [[peroxide]]s.