Editing Pyrethrin (section)

==Toxicity==
Pyrethrins are among the safest insecticides on the market due to their rapid degradation in the environment.

Similarities between the chemistry of pyrethrins and synthetic pyrethroids include a similar mode of action and almost identical toxicity to insects (i.e., both pyrethrins and pyrethroids induce a toxic effect within the insect by acting on sodium channels).<ref>{{cite journal |last1=Matsuo |first1=Noritada |title=Discovery and development of pyrethroid insecticides |journal=Proceedings of the Japan Academy, Series B |date=31 July 2019 |volume=95 |issue=7 |pages=378–400 |doi=10.2183/pjab.95.027 |pmc=6766454 |pmid=31406060 |bibcode=2019PJAB...95..378M }}</ref>

Some differences in the chemistry between pyrethrins and synthetic pyrethroids have the result that synthetic pyrethroids have relatively longer environmental persistence than do pyrethrins. Pyrethrins have shorter environmental persistence than synthetic pyrethroids because their chemical structure is more susceptible to the presence of UV light and changes in pH.{{citation needed|date=August 2021}}
  
The use of pyrethrin in products such as natural insecticides and pet shampoo, for its ability to kill fleas, increases the likelihood of toxicity in mammals that are exposed. Medical cases have emerged showing fatalities from the use of pyrethrin, prompting many organic farmers to cease use. One fatal case of an 11-year-old girl with a known asthmatic condition and who used shampoo containing only a small amount (0.2% pyrethrin) to wash her dog was documented.<ref>{{cite journal |pmid=10924422 |pmc=1071005 |year=2000 |last1=Wagner |first1=S. L. |title=Fatal asthma in a child after use of an animal shampoo containing pyrethrin |journal=The Western Journal of Medicine |volume=173 |issue=2 |pages=86–7 |doi=10.1136/ewjm.173.2.86}}</ref>

===Chronic pyrethrin toxicity in humans===
[[Chronic toxicity]] in humans occurs most quickly through [[Breathing|respiration]] into the lungs, or more slowly through absorption through the skin.<ref name="Pyrethrins 1994"/> [[Allergic reactions]] may occur after exposure, leading to itching and irritated skin as well as burning sensations.<ref>{{cite journal |doi=10.3109/10408449009089874 |pmid=2083034 |title=An Assessment of the Toxicological Properties of Pyrethroids and Their Neurotoxicity |journal=Critical Reviews in Toxicology |volume=21 |issue=2 |pages=89–104 |year=1990 |last1=Aldridge |first1=W. N. }}</ref> These types of reactions are rare because the allergenic component of pyrethrin in semi-synthetic pyrethroids has been removed.<ref name="EPA review"/> The metabolite compounds of pyrethrin are less toxic to mammals than their originators, and compounds are either broken down in the [[liver]] or [[gastrointestinal tract]], or excreted through feces; no evidence of storage in tissues has been found {{citation needed|date=July 2021}}.

=== {{anchor|Pyrethrum}} Pyrethrum toxicity===
Exposure to pyrethrum, the crude form of pyrethrin,<ref name="EPA review"/> causes harmful health effects for mammals. Pyrethrum also has an allergenic effect that commercial pyrethroids don't have.<ref name="EPA review">{{cite web |title=Review of the Relationship between Pyrethrins, Pyrethroid Exposure and Asthma and Allergies |publisher=US Environmental Protection Agency Office of Pesticide Programs |date=Sep 2009 |url=http://www.epa.gov/oppsrrd1/reevaluation/paw-factsheet.html}}</ref>
In mammals, toxic exposure to pyrethrum can lead to tongue and lip numbness, [[drooling]], [[lethargy]], muscle [[tremor]]s, [[respiratory failure]], [[vomiting]], [[diarrhea]], seizures, [[paralysis]], and [[death]].<ref name="Pyrethrins 1994">{{cite web |title=Pyrethrins |url=http://extoxnet.orst.edu/pips/pyrethri.htm |publisher=Extension Toxicology Network |year=1996}}</ref>
Exposure to pyrethrum in high levels in humans may cause symptoms such as asthmatic breathing, sneezing, nasal stuffiness, headache, nausea, loss of coordination, tremors, convulsions, facial flushing, and swelling.<ref>Occupational Health Services, Inc. "Pyrethrum." Material Safety Data Sheet. 1 April 1987. New York: OHS, Inc.</ref>{{unreliable source?|should reference a more recent date|date=April 2015}} A possibility of damage to the immune system exists that leads to a worsening of allergies following toxicity.<ref name="Pyrethrins 1994"/> Infants are unable to resourcefully break down pyrethrum due to the ease of skin penetration, causing similar symptoms as adults, but with an increased risk of death.<ref>{{cite web |title=Public Health Statement for Pyrethrins and Pyrethroids |url=https://wwwn.cdc.gov/TSP/PHS/PHSLanding.aspx?id=785&tid=153 |publisher=Agency for Toxic Substances & Disease Registry |date=Sep 2003}}</ref>