Arsenic residues in pastures and horses after MSMA-based herbicide control of Urochloa decumbens

Arsenic residues in pastures and horses after MSMA-based herbicide control of Urochloa decumbens | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Arsenic residues in pastures and horses after MSMA-based herbicide control of Urochloa decumbens MARIO CESAR GARCIA DUARTE, Janaína Braga do Carmo, Maycon Cristiano Barbosa This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7406781/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract The diet of horses is primarily based on grasses such as Coast Cross (Cynodon spp.), with Urochloa decumbens (formerly Brachiaria decumbens) being the main invasive species. The control of U. decumbens is typically performed using the herbicide MSMA (monosodium methylarsonate), which degrades into four main arsenic species after application: arsenite, arsenate, monomethylarsonic acid, and dimethylarsinic acid. This study aimed to determine whether the spray of MSMA is a determining factor in increasing arsenic concentrations in the environment and in horses. Arsenic levels in soil, plants, and animals were compared following herbicide use. Analytical results revealed higher arsenic accumulation in U. decumbens (26.20 ± 0.08 ppm) compared to Coast Cross (12.66 ± 2.94 ppm) (p < 0.0001). U.decumbens accumulated 10.69 ± 1.69 ppm in the MSMA-treated area versus 6.06 ± 0.96 ppm in the control area (p < 0.0001). Coast Cross showed arsenic concentrations of 10.73 ± 1.22 ppm in the MSMA-treated area and 1.60 ± 0.41 ppm in the control area (p < 0.0001). Horses grazing on MSMA-treated pastures presented significantly higher arsenic levels in blood (1.67 ± 0.047 ppm) compared to the control group (1.35 ± 0.0531 ppm) (p < 0.05). In urine, arsenic levels were 1.62 ± 0.189 ppm in the MSMA group and 1.195 ± 0.111 ppm in the control group (p < 0.05). The results demonstrate that MSMA sprayed in equine pastures leads to significant arsenic accumulation in forage plants and in horses, representing a potential risk to animal health and food safety. Full Text Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-7406781","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":502743723,"identity":"ff334b17-b1f5-4878-bc0e-13b01e970f31","order_by":0,"name":"MARIO CESAR GARCIA DUARTE","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA0ElEQVRIiWNgGAWjYPACZgZ+EJVQQIoWyQaQFgNStBgcANHEaNFtP/zw4Zca68TN51cnfnhgwCDPL3YAvxazM2nGxjLH0hO33Xi7WQLoMMOZsxMIaDmQwyYtwXYYqOXsBpCWBIPbhLScf8P+W+Lf4cTNM85u/kGclhs5bIwf2w4nbuDv3UakLTeeGUsz9qUbz7jBu80iwUCCCL+cT3748cc3a9n+/rObb/6osJHnlyagBQSYeUCkBFilBGHlIMD4A0TyHyBO9SgYBaNgFIw8AAC0k0kxL2GLLgAAAABJRU5ErkJggg==","orcid":"https://orcid.org/0009-0008-9937-290X","institution":"UFSCar: Universidade Federal de Sao Carlos","correspondingAuthor":true,"prefix":"","firstName":"MARIO","middleName":"CESAR GARCIA","lastName":"DUARTE","suffix":""},{"id":502743724,"identity":"a9c4caec-1e19-4f5f-90df-8dc4af72c2cd","order_by":1,"name":"Janaína Braga do Carmo","email":"","orcid":"","institution":"UFSCar: Universidade Federal de Sao Carlos","correspondingAuthor":false,"prefix":"","firstName":"Janaína","middleName":"Braga do","lastName":"Carmo","suffix":""},{"id":502743725,"identity":"aa4d910b-453b-4a0b-a2ac-823b45f7e310","order_by":2,"name":"Maycon Cristiano Barbosa","email":"","orcid":"","institution":"USP: Universidade de Sao Paulo","correspondingAuthor":false,"prefix":"","firstName":"Maycon","middleName":"Cristiano","lastName":"Barbosa","suffix":""}],"badges":[],"createdAt":"2025-08-19 09:16:28","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-7406781/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-7406781/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":90049948,"identity":"76cf2958-fb28-498c-be55-e2fd48c3e2c6","added_by":"auto","created_at":"2025-08-27 20:06:09","extension":"pdf","order_by":1,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":858963,"visible":true,"origin":"","legend":"","description":"","filename":"AsresiduesinpasturesandhorsesafterMSMA.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7406781/v1_covered_02f39e28-3699-4c1e-9749-aa97ece41f94.pdf"}],"financialInterests":"","formattedTitle":"Arsenic residues in pastures and horses after MSMA-based herbicide control of Urochloa decumbens","fulltext":[],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":false,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":true,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":true,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"","lastPublishedDoi":"10.21203/rs.3.rs-7406781/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7406781/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"The diet of horses is primarily based on grasses such as Coast Cross (Cynodon spp.), with Urochloa decumbens (formerly Brachiaria decumbens) being the main invasive species. The control of U. decumbens is typically performed using the herbicide MSMA (monosodium methylarsonate), which degrades into four main arsenic species after application: arsenite, arsenate, monomethylarsonic acid, and dimethylarsinic acid. This study aimed to determine whether the spray of MSMA is a determining factor in increasing arsenic concentrations in the environment and in horses. Arsenic levels in soil, plants, and animals were compared following herbicide use. Analytical results revealed higher arsenic accumulation in U. decumbens (26.20 ± 0.08 ppm) compared to Coast Cross (12.66 ± 2.94 ppm) (p \u0026lt; 0.0001). U.decumbens accumulated 10.69 ± 1.69 ppm in the MSMA-treated area versus 6.06 ± 0.96 ppm in the control area (p \u0026lt; 0.0001). Coast Cross showed arsenic concentrations of 10.73 ± 1.22 ppm in the MSMA-treated area and 1.60 ± 0.41 ppm in the control area (p \u0026lt; 0.0001). Horses grazing on MSMA-treated pastures presented significantly higher arsenic levels in blood (1.67 ± 0.047 ppm) compared to the control group (1.35 ± 0.0531 ppm) (p \u0026lt; 0.05). In urine, arsenic levels were 1.62 ± 0.189 ppm in the MSMA group and 1.195 ± 0.111 ppm in the control group (p \u0026lt; 0.05). The results demonstrate that MSMA sprayed in equine pastures leads to significant arsenic accumulation in forage plants and in horses, representing a potential risk to animal health and food safety.","manuscriptTitle":"Arsenic residues in pastures and horses after MSMA-based herbicide control of Urochloa decumbens","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-08-27 16:55:59","doi":"10.21203/rs.3.rs-7406781/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"42d46b08-3668-4d80-a6d4-ac0dcf615a05","owner":[],"postedDate":"August 27th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2025-08-27T19:58:02+00:00","versionOfRecord":[],"versionCreatedAt":"2025-08-27 16:55:59","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7406781","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7406781","identity":"rs-7406781","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}