{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,4]],"date-time":"2026-05-04T04:48:41Z","timestamp":1777870121594,"version":"3.51.4"},"reference-count":17,"publisher":"Wiley","issue":"3","license":[{"start":{"date-parts":[[2026,4,22]],"date-time":"2026-04-22T00:00:00Z","timestamp":1776816000000},"content-version":"vor","delay-in-days":52,"URL":"http:\/\/creativecommons.org\/licenses\/by-nc-nd\/4.0\/"},{"start":{"date-parts":[[2026,3,1]],"date-time":"2026-03-01T00:00:00Z","timestamp":1772323200000},"content-version":"tdm","delay-in-days":0,"URL":"http:\/\/doi.wiley.com\/10.1002\/tdm_license_1.1"}],"funder":[{"DOI":"10.13039\/100032300","name":"National Center for Toxicological Research","doi-asserted-by":"publisher","id":[{"id":"10.13039\/100032300","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["Environ and Mol Mutagen"],"published-print":{"date-parts":[[2026,3]]},"abstract":"<jats:title>ABSTRACT<\/jats:title>\n                  <jats:p>\n                    Conducting S9\u2010mediated preincubations at slightly acid pHs (e.g., pH\u20095.0 to pH\u20096.5) has been reported to enhance the mutagenicity of small\u2010molecule nitrosamines in the Ames test. In this study, we have evaluated the effect of adjusting the preincubation mix used in the Enhanced Ames Test (EAT) from pH\u20097.4 to pH\u20096.0 and supplying the activation mix with preformed reducing equivalents (NADPH and NADH). Abbreviated EAT assays were conducted on five small\u2010molecule\n                    <jats:italic>N<\/jats:italic>\n                    \u2010nitrosamines and 10 nitrosamine drug substance\u2010related impurities (NDSRIs) with tester strains TA1535 and WP2 uvrA (pKM101) and using S9 mixes containing 30% hamster liver S9. Testing on small\u2010molecule nitrosamines found that the pH\u20096.0 preincubation mix enhanced the mutagenicity of\n                    <jats:italic>N<\/jats:italic>\n                    \u2010nitroso\u2010dimethylamine and\n                    <jats:italic>N<\/jats:italic>\n                    \u2010nitroso\u2010diethylamine but not\n                    <jats:italic>N<\/jats:italic>\n                    \u2010nitroso\u2010diphenylamine,\n                    <jats:italic>N<\/jats:italic>\n                    \u2010nitroso\u2010methyl\u20104\u2010aminobutyric acid or\n                    <jats:italic>N<\/jats:italic>\n                    \u2010(2,2\u2010diethoxyethyl)\u20102,2\u2010diethoxy\u2010\n                    <jats:italic>N<\/jats:italic>\n                    \u2010nitrosoethanamine. Of the 10 NDSRIs that were tested,\n                    <jats:italic>N<\/jats:italic>\n                    \u2010nitroso\u2010phenylephrine was consistently positive with the pH\u20096.0 preincubation mix, while it was generally negative with pH\u20097.4 preincubation mixes. The mutagenicity of the nine other NDSRIs that were tested was not changed by the slightly acid preincubation mix. The results indicate that performing preincubation reactions under slightly acid conditions increases the mutagenicity of some small\u2010molecule nitrosamines, and in one case, produced a positive mutagenic response with an NDSRI that was otherwise negative in the EAT.\n                  <\/jats:p>","DOI":"10.1002\/em.70041","type":"journal-article","created":{"date-parts":[[2026,4,22]],"date-time":"2026-04-22T16:12:04Z","timestamp":1776874324000},"update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Adjusting the Preincubation Conditions to Enhance the Ames Test for Detecting the Mutagenicity of\n                    <i>N<\/i>\n                    \u2010Nitrosamines"],"prefix":"10.1002","volume":"67","author":[{"given":"Michelle E.","family":"Bishop","sequence":"first","affiliation":[{"name":"US Food and Drug Administration National Center for Toxicological Research  Jefferson Arkansas USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Audrey M.","family":"Sims","sequence":"additional","affiliation":[{"name":"US Food and Drug Administration National Center for Toxicological Research  Jefferson Arkansas USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Sharon K.","family":"Guerrero","sequence":"additional","affiliation":[{"name":"US Food and Drug Administration National Center for Toxicological Research  Jefferson Arkansas USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Kamela","family":"Mitchell","sequence":"additional","affiliation":[{"name":"US Food and Drug Administration National Center for Toxicological Research  Jefferson Arkansas USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3501-9014","authenticated-orcid":false,"given":"Nan","family":"Mei","sequence":"additional","affiliation":[{"name":"US Food and Drug Administration National Center for Toxicological Research  Jefferson Arkansas USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Hannah","family":"Xu","sequence":"additional","affiliation":[{"name":"US Food and Drug Administration National Center for Toxicological Research  Jefferson Arkansas USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Naomi L.","family":"Kruhlak","sequence":"additional","affiliation":[{"name":"U.S Food and Drug Administration Center for Drug Evaluation and Research  Silver Spring Maryland USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Sruthi T.","family":"King","sequence":"additional","affiliation":[{"name":"U.S Food and Drug Administration Center for Drug Evaluation and Research  Silver Spring Maryland USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Robert T.","family":"Dorsam","sequence":"additional","affiliation":[{"name":"U.S Food and Drug Administration Center for Drug Evaluation and Research  Silver Spring Maryland USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Aisar H.","family":"Atrakchi","sequence":"additional","affiliation":[{"name":"U.S Food and Drug Administration Center for Drug Evaluation and Research  Silver Spring Maryland USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Timothy J.","family":"McGovern","sequence":"additional","affiliation":[{"name":"U.S Food and Drug Administration Center for Drug Evaluation and Research  Silver Spring Maryland USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Robert H.","family":"Heflich","sequence":"additional","affiliation":[{"name":"US Food and Drug Administration National Center for Toxicological Research  Jefferson Arkansas USA"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"311","published-online":{"date-parts":[[2026,4,22]]},"reference":[{"key":"e_1_2_10_2_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.yrtph.2025.105835"},{"key":"e_1_2_10_3_1","first-page":"81","article-title":"Correlation Between the Stability of Ethyl Nitrosourea in Aqueous Solution at Different pH and Temperature and Its Mutagenic Effectiveness for \n                     Salmonella typhimurium\n                   Strain TA100","volume":"120","author":"Kok A. 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EMA\/120337\/2024.https:\/\/www.ema.europa.eu\/en\/documents\/other\/appendix\u20103\u2010enhanced\u2010ames\u2010test\u2010conditions\u2010n\u2010nitrosamines_en.pdf."},{"key":"e_1_2_10_5_1","unstructured":"FDA (US Food and Drug Administration).2023.Recommended Acceptable Intake Limits for Nitrosamine Drug Substance\u2010Related Impurities (NDSRIs): Guidance for Industry.https:\/\/www.fda.gov\/media\/170794\/download."},{"key":"e_1_2_10_6_1","unstructured":"FDA (US Food and Drug Administration).2024a.CDER Nitrosamine Impurity Acceptable Intake Limits.https:\/\/www.fda.gov\/regulatory\u2010information\/search\u2010fda\u2010guidance\u2010documents\/cder\u2010nitrosamine\u2010impurity\u2010acceptable\u2010intake\u2010limits."},{"key":"e_1_2_10_7_1","unstructured":"FDA (US Food and Drug Administration).2024b.Guidance for Industry: Control of Nitrosamine Impurities in Human Drugs.https:\/\/www.fda.gov\/media\/141720\/download."},{"key":"e_1_2_10_8_1","doi-asserted-by":"publisher","DOI":"10.1093\/mutage\/gev039"},{"key":"e_1_2_10_9_1","doi-asserted-by":"publisher","DOI":"10.1016\/0165-1161(79)90004-9"},{"key":"e_1_2_10_10_1","doi-asserted-by":"publisher","DOI":"10.1093\/carcin\/1.5.439"},{"key":"e_1_2_10_11_1","unstructured":"Health Canada.2024.Guidance on Nitrosamine Impurities in Medications Evaluating and Managing the Risks ofN\u2010Nitrosamine Impurities in Human Pharmaceutical Biological and Radiopharmaceutical Products. Appendix\u00a03: Enhanced Ames Assay Test Conditions.https:\/\/www.canada.ca\/content\/dam\/hc\u2010sc\/documents\/services\/drugs\u2010health\u2010products\/compliance\u2010enforcement\/information\u2010health\u2010product\/drugs\/nitrosamine\u2010impurities\/medications\u2010guidance\/guidance\u2010nitrosamine%20impurities\u2010medications.pdf."},{"key":"e_1_2_10_12_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.yrtph.2024.105709"},{"key":"e_1_2_10_13_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.yrtph.2024.105640"},{"key":"e_1_2_10_14_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.yrtph.2023.105410"},{"key":"e_1_2_10_15_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.mrgentox.2021.503351"},{"key":"e_1_2_10_16_1","doi-asserted-by":"publisher","DOI":"10.1016\/0165-1218(80)90069-5"},{"key":"e_1_2_10_17_1","unstructured":"OECD (Organisation for Economic Cooperation and Development).2020.OECD Guideline for the Testing of Chemicals: Bacterial Reverse Mutation Test. Test Guideline 471.https:\/\/www.oecd\u2010ilibrary.org\/environment\/oecd\u2010guidelines\u2010for\u2010the\u2010testing\u2010of\u2010chemicals\u2010section\u20104\u2010health\u2010effects_20745788."},{"key":"e_1_2_10_18_1","doi-asserted-by":"publisher","DOI":"10.1093\/mutage\/gew009"}],"container-title":["Environmental and Molecular Mutagenesis"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/onlinelibrary.wiley.com\/doi\/pdf\/10.1002\/em.70041","content-type":"application\/pdf","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/onlinelibrary.wiley.com\/doi\/full-xml\/10.1002\/em.70041","content-type":"application\/xml","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/onlinelibrary.wiley.com\/doi\/pdf\/10.1002\/em.70041","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,4,30]],"date-time":"2026-04-30T15:23:56Z","timestamp":1777562636000},"score":1,"resource":{"primary":{"URL":"https:\/\/onlinelibrary.wiley.com\/doi\/10.1002\/em.70041"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,3]]},"references-count":17,"journal-issue":{"issue":"3","published-print":{"date-parts":[[2026,3]]}},"alternative-id":["10.1002\/em.70041"],"URL":"https:\/\/doi.org\/10.1002\/em.70041","archive":["Portico"],"relation":{},"ISSN":["0893-6692","1098-2280"],"issn-type":[{"value":"0893-6692","type":"print"},{"value":"1098-2280","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,3]]},"assertion":[{"value":"2025-08-18","order":0,"name":"received","label":"Received","group":{"name":"publication_history","label":"Publication History"}},{"value":"2025-10-20","order":2,"name":"accepted","label":"Accepted","group":{"name":"publication_history","label":"Publication History"}},{"value":"2026-04-22","order":3,"name":"published","label":"Published","group":{"name":"publication_history","label":"Publication History"}}],"article-number":"e70041"}}