Zinc toxicity
| Zinc toxicity | |
|---|---|
| Classification and external resources | |
 Zinc |
|
| ICD-10 | T56.5 |
| ICD-9 | 985.8 |
Even though zinc is an essential requirement for a healthy body, excess zinc can be harmful, and cause zinc toxicity.[1] Excessive absorption of zinc can suppress copper and iron absorption. The free zinc ion in solution is highly toxic to plants, invertebrates, and even vertebrate fish. The Free Ion Activity Model (FIAM) is well-established in the literature, and shows that just micromolar amounts of the free ion kills some organisms. A recent example showed 6 micromolar killing 93% of all Daphnia in water.[2]
The free zinc ion is also a powerful Lewis acid up to the point of being corrosive. Stomach acid contains hydrochloric acid, in which metallic zinc dissolves readily to give corrosive zinc chloride. Swallowing a post-1982 American one cent piece (97.5% zinc) can cause damage to the stomach lining due to the high solubility of the zinc ion in the acidic stomach.[3]
There is evidence of induced copper deficiency at low intakes of 100–300 mg Zn/d. The USDA RDA is 15 mg Zn/d. Even lower levels, closer to the RDA, may interfere with the utilization of copper and iron or to adversely affect cholesterol.[4]
There is also a condition called the zinc shakes or "zinc chills" that can be induced by the inhalation of freshly formed zinc oxide formed during the welding of galvanized materials.[5]
[edit] Poisoning
In 1982, the United States Mint began minting pennies coated in copper but made primarily of zinc. With the new zinc pennies, there is the potential for zinc toxicosis, which can be fatal. One reported case of chronic ingestion of 425 pennies (over 1 kg of zinc) resulted in death due to gastrointestinal bacterial and fungal sepsis, while another patient, who ingested 12 grams of zinc, only showed lethargy and ataxia (gross lack of coordination of muscle movements).[6] Several other cases are reported of humans suffering zinc intoxication by the ingestion of zinc coins.[7][8]
Pennies and other small coins are sometimes ingested by dogs, resulting in the need for medical treatment to remove the foreign body. The zinc content of some coins can also cause zinc toxicity, which is commonly fatal in dogs, where it causes a severe hemolytic anemia, also liver or kidney damage; vomiting and diarrhoea are possible symptoms.[9][10][11] Zinc is highly toxic in parrots and poisoning can often be fatal.[12]
[edit] References
- ^ Fosmire GJ (February 1990). "Zinc toxicity". Am. J. Clin. Nutr. 51 (2): 225–7. PMID 2407097. http://www.ajcn.org/cgi/pmidlookup?view=long&pmid=2407097.
- ^ Muyssen, Brita, T. A.; De Schamphelaere, Karel A. C.; Janssen, Colin R. (2006). "Mechanisms of chronic waterborne Zn toxicity in Daphnia magna". Aquatic Toxicology 77 (4): 393–401. doi:10.1016/j.aquatox.2006.01.006. PMID 16472524.
- ^ Bothwell, Dawn N.; Mair, Eric A.; Cable, Benjamin B. (2003). "Chronic Ingestion of a Zinc-Based Penny". Pediatrics 111 (3): 689–691. doi:10.1542/peds.111.3.689. PMID 12612262. http://pediatrics.aappublications.org/cgi/reprint/111/3/689.
- ^ Fosmire, G. J. (1 February 1990). "Zinc toxicity". American Journal of Clinical Nutrition 51 (2): 225–227. PMID 2407097. http://www.ajcn.org/cgi/content/abstract/51/2/225.
- ^ CRC 2006, pp. 4–41
- ^ Barceloux, Donald G.; Barceloux, Donald (1999). "Zinc". Clinical Toxicology 37 (2): 279–292. doi:10.1081/CLT-100102426.
- ^ Bennett, Daniel R. M.D.; Baird, Curtis J. M.D.; Chan, Kwok-Ming; Crookes, Peter F.; Bremner, Cedric G.; Gottlieb, Michael M.; Naritoku, Wesley Y. M.D. (1997). "Zinc Toxicity Following Massive Coin Ingestion.". American Journal of Forensic Medicine & Pathology 18 (2): 148–153. doi:10.1097/00000433-199706000-00008. http://www.amjforensicmedicine.com/pt/re/ajfmp/abstract.00000433-199706000-00008.htm.
- ^ Fernbach, S. K.; Tucker G. F. (1 February 1986). "Coin ingestion: unusual appearance of the penny in a child". Radiology 158 (2): 512–512. PMID 3941880. http://radiology.rsnajnls.org/cgi/content/abstract/158/2/512.
- ^ Stowe, C. M.; Nelson, R.; Werdin, R.; et al. (1978). "Zinc phosphide poisoning in dogs". Journal of the American Veterinary Medical Association 173 (3): 270. PMID 689968.
- ^ Stowe C. M., Nelson R., Werdin R., et al.: Zinc phosphide poisoning in dogs. JAVMA 173:270, 1978
- ^ Wendy C. Brooks (2008-03-11). "Zinc Poisoning". Pet Health Library. VeterinaryPartner.com. http://www.VeterinaryPartner.com/Content.plx?P=A&C=189&A=565&S=1. Retrieved 2008-12-09.
- ^ "Health Risks - For Your Parrot". Pet Parrots 101. 2006-10-09. http://www.petparrots101.com/parrots-risk.asp. Retrieved 2009-01-20.
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