Risk assessment of metals and α-toxin producing Gram-negative bacteria in leafy vegetables from Akinyele, Oyo State, Nigeria

Risk assessment of metals and α-toxin producing Gram-negative bacteria in leafy vegetables from Akinyele, Oyo State, Nigeria | 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 Risk assessment of metals and α-toxin producing Gram-negative bacteria in leafy vegetables from Akinyele, Oyo State, Nigeria Kubrat Abiola Oyinlola, Fausat Olubusola Odujebe, Oluwarotimi John Joseph, and 3 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6648258/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 Consumption of vegetables confers nutritional health benefits, but are susceptible to metal pollution and microbial contamination, posing significant public health risk. The study aimed to determine the extent of microbial load, metals and risk assessments of some commonly consumed leafy vegetables sold within Akinyele region of Oyo State, Nigeria. The levels of metals (lead Pb , Chromium Cr , Cadmium Cd and Copper Cu ) in the vegetables were determined using Buck Scientific Atomic Absorption Spectrophotometer. Microbial load was estimated using the pour plate method and screening for lecithinase (α-toxin), on egg yolk medium. Average concentrations of Pb, Cd and Cu were in the range of 0.00-17.36 mg.kg − 1 , 0.00-1.15 mg.kg − 1 and 12.53–77.11 mg.kg − 1 , respectively. Chromium was undetected in most of the vegetables. Levels of Cr and Cu were within the safety baseline levels while Pb and Cd levels exceeded the permissible limits for human consumption. Average hazard index (HI) in children was higher than in adults. Average HI of children and adults was > 1, so risk on human health cannot be ignored. Pumpkin and waterleaf contributed mostly to health risks, especially for children. Estimated microbial load from the vegetables did not exceed the threshold of > 7 log 10 CFU/g, but was within the range of 4.67 to 5.34 log 10 CFU/g. Lecithinase production was positive in 32% of the isolates. Toxigenic microbes and metals were present in the sampled vegetables at levels posing carcinogenic and non-carcinogenic risks. Therefore, regular monitoring of vended vegetables is recommended for public safety. Leafy vegetables metals pollution microbial contamination toxin biosynthesis Full Text Additional Declarations No competing interests reported. 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. 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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-6648258","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":456186060,"identity":"f8de3e2c-40a5-46c4-8c0e-bdf355d43909","order_by":0,"name":"Kubrat Abiola Oyinlola","email":"","orcid":"","institution":"University of Ibadan","correspondingAuthor":false,"prefix":"","firstName":"Kubrat","middleName":"Abiola","lastName":"Oyinlola","suffix":""},{"id":456186061,"identity":"8835030a-f470-407d-b12a-f1e54a93c46f","order_by":1,"name":"Fausat Olubusola Odujebe","email":"","orcid":"","institution":"Lagos State University of Science and 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Nigeria\u003c/p\u003e","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":"Leafy vegetables, metals, pollution, microbial contamination, toxin biosynthesis","lastPublishedDoi":"10.21203/rs.3.rs-6648258/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6648258/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eConsumption of vegetables confers nutritional health benefits, but are susceptible to metal pollution and microbial contamination, posing significant public health risk. The study aimed to determine the extent of microbial load, metals and risk assessments of some commonly consumed leafy vegetables sold within Akinyele region of Oyo State, Nigeria. The levels of metals (lead \u003cem\u003ePb\u003c/em\u003e, Chromium \u003cem\u003eCr\u003c/em\u003e, Cadmium \u003cem\u003eCd\u003c/em\u003e and Copper \u003cem\u003eCu\u003c/em\u003e) in the vegetables were determined using Buck Scientific Atomic Absorption Spectrophotometer. Microbial load was estimated using the pour plate method and screening for lecithinase (α-toxin), on egg yolk medium. Average concentrations of Pb, Cd and Cu were in the range of 0.00-17.36 mg.kg\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, 0.00-1.15 mg.kg\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e and 12.53\u0026ndash;77.11 mg.kg\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, respectively. Chromium was undetected in most of the vegetables. Levels of Cr and Cu were within the safety baseline levels while Pb and Cd levels exceeded the permissible limits for human consumption. Average hazard index (HI) in children was higher than in adults. Average HI of children and adults was \u0026gt;\u0026thinsp;1, so risk on human health cannot be ignored. Pumpkin and waterleaf contributed mostly to health risks, especially for children. Estimated microbial load from the vegetables did not exceed the threshold of \u0026gt;\u0026thinsp;7 log\u003csub\u003e10\u003c/sub\u003eCFU/g, but was within the range of 4.67 to 5.34 log\u003csub\u003e10\u003c/sub\u003e CFU/g. Lecithinase production was positive in 32% of the isolates. Toxigenic microbes and metals were present in the sampled vegetables at levels posing carcinogenic and non-carcinogenic risks. Therefore, regular monitoring of vended vegetables is recommended for public safety.\u003c/p\u003e","manuscriptTitle":"Risk assessment of metals and α-toxin producing Gram-negative bacteria in leafy vegetables from Akinyele, Oyo State, Nigeria","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-05-15 16:15:39","doi":"10.21203/rs.3.rs-6648258/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":"b850298d-4201-43c5-a893-079c3aae347f","owner":[],"postedDate":"May 15th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2025-07-08T19:53:22+00:00","versionOfRecord":[],"versionCreatedAt":"2025-05-15 16:15:39","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-6648258","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6648258","identity":"rs-6648258","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}