endothall

{{cite web |last1=Menninger |first1=Holly |title=Endothall FAQ |url=https://ccetompkins.org/environment/aquatic-invasives/hydrilla/management-options/herbicides/endothall/endothall-faq |website=Cornell Cooperative Extension |access-date=9 January 2024}}{{Chembox

| ImageFile = Endothal.svg

| ImageSize = 150px

| ImageAlt =

| IUPACName = 7-Oxabicyclo[2.2.1]heptane-2,3-dicarboxylic acid

| OtherNames = Endothal; 3,6-Endoxohexahydrophthalic acid

| Section1 = {{Chembox Identifiers

| CASNo = 145-73-3

| CASNo_Ref = {{cascite|correct|CAS}}

| ChEMBL = 8080

| ChemSpiderID = 3112

| EC_number = 205-660-5

| UNII_Ref = {{fdacite|correct|FDA}}

| UNII = 18F7018HG1

| PubChem = 3225

| UNNumber = 2811

| SMILES = C1CC2C(C(C1O2)C(=O)O)C(=O)O

| InChI=1S/C8H10O5/c9-7(10)5-3-1-2-4(13-3)6(5)8(11)12/h3-6H,1-2H2,(H,9,10)(H,11,12)

| InChIKey = GXEKYRXVRROBEV-UHFFFAOYSA-N

}}

| Section2 = {{Chembox Properties

| C=8|H=10|O=5

| Appearance =

| Density = 1.431 g/cm³ (20 °C){{GESTIS|ZVG=530043}}

| MeltingPtC = 144

| MeltingPt_ref =

| BoilingPt =

| Solubility = 100 g/L (20 °C)

}}

| Section3 = {{Chembox Hazards

| MainHazards =

| FlashPt =

| AutoignitionPt =

| LD50 = 38 mg/kg (oral, rat)

}}

}}

Endothall (3,6-endoxohexahydrophthalic acid) is used as an herbicide for terrestrial and aquatic plants. It is used as an aquatic herbicide for submerged aquatic plants and algae in lakes, ponds and irrigation canals.[http://www.tompkinscountyny.gov/files/health/eh/water/hydrilla/Endothall-Public-Health-Flyer.pdf "Herbicides against Hydrilla"] {{Webarchive|url=https://web.archive.org/web/20170207162948/http://www.tompkinscountyny.gov/files/health/eh/water/hydrilla/Endothall-Public-Health-Flyer.pdf |date=2017-02-07 }}. Tompkins County NY website. It is used, as a desiccant on potatoes, hops, cotton, clover and alfalfa. It is used as a biocide to control mollusks and algae in cooling towers.

Endothall is a selective contact herbicide that has been used to manage submerged aquatic vegetation for over 50 years. The herbicide damages the cells of susceptible plants at the point of contact but does not affect areas untouched by the herbicide, like roots or tubers (underground storage structures).[https://ccetompkins.org/environment/aquatic-invasives/hydrilla/management-options/herbicides/endothall/endothall-faq Cornell Cooperative Extension, Tompkins County, Endothall FAQ],

The chemical formula for endothall is C₈H₁₀O₅. Its Chemical Abstracts Service (CAS) name is 7-oxabicyclo[2.2.1]heptane-2,3-dicarboxylic acid. It is an organic acid but is used as the dipotassium salt or the mono-N, N-dimethylalkylamine salt.{{cite web|title=Reregistration Eligibility Decision for Endothall |url=http://www.epa.gov/oppsrrd1/REDs/endothall_red.pdf |publisher=EPA |accessdate=16 July 2012 |url-status=dead |archiveurl=https://web.archive.org/web/20141016104429/http://www.epa.gov/oppsrrd1/REDs/endothall_red.pdf |archivedate=16 October 2014 }}

It is considered safe in drinking water by the EPA up to a maximum contaminant level of 0.1 mg/L (100 ppb). Some people who drink water contaminated above this level for many years experience stomach or intestine problems.{{cite web|title=Basic Information about Endothall in Drinking Water|url=http://water.epa.gov/drink/contaminants/basicinformation/endothall.cfm|publisher=EPA|accessdate=16 July 2012}}

Endothall is chemically related to cantharidin.{{cite journal |last1=Li |first1=YM |last2=Casida |first2=JE |title=Cantharidin-binding protein: identification as protein phosphatase 2A. |journal=Proceedings of the National Academy of Sciences of the United States of America |date=15 December 1992 |volume=89 |issue=24 |pages=11867–70 |pmid=1334551 |pmc=50658|doi=10.1073/pnas.89.24.11867 |bibcode=1992PNAS...8911867L |doi-access=free }} Both compounds are protein phosphatase 2A inhibitors.{{cite journal |last1=Liu |first1=Ji-Yuan |last2=Chen |first2=Xi-En |last3=Zhang |first3=Ya-Lin |title=Insights into the key interactions between human protein phosphatase 5 and cantharidin using molecular dynamics and site-directed mutagenesis bioassays |journal=Scientific Reports |date=20 July 2015 |volume=5 |issue=1 |pages=12359 |doi=10.1038/srep12359 |pmid=26190207 |pmc=4507179|bibcode=2015NatSR...512359L }}

== Toxicity ==

There is limited data on human toxicity, although cases of lethal deliberate self-poisoning have been reported with as little as a mouthful of Endothall concentrate.{{cite journal |last1=Sulaeman |first1=Siba J. |last2=Glengarry |first2=Joanna |last3=Bedford |first3=Paul |last4=O’Sullivan |first4=Patrick |last5=Rotella |first5=Joe-Anthony |title=Two fatal cases of endothall poisoning |journal=Toxicology Communications |date=31 December 2024 |volume=8 |issue=1 |doi=10.1080/24734306.2024.2407235|doi-access=free }}{{cite journal |last1=Day |first1=LC |last2=Broders |first2=AC |title=Delayed death by endothall, a herbicide |journal=Veterinary and Human Toxicology |date=1988 |volume=30 |issue=4}}{{cite journal |last1=Allender |first1=W.J. |title=Suicidal Poisoning by Endothall |journal=Journal of Analytical Toxicology |date=1 March 1983 |volume=7 |issue=2 |pages=79–82 |doi=10.1093/jat/7.2.79|pmid=6855208 }} Features of toxicity include corrosive injury to the oropharynx and gastrointestinal tract, metabolic acidosis, coagulopathy, and multi-organ failure.