{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,3]],"date-time":"2026-08-03T17:53:25Z","timestamp":1785779605931,"version":"3.56.0"},"reference-count":14,"publisher":"Wiley","issue":"8","license":[{"start":{"date-parts":[[2026,5,25]],"date-time":"2026-05-25T00:00:00Z","timestamp":1779667200000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/onlinelibrary.wiley.com\/termsAndConditions#vor"},{"start":{"date-parts":[[2026,5,25]],"date-time":"2026-05-25T00:00:00Z","timestamp":1779667200000},"content-version":"tdm","delay-in-days":0,"URL":"http:\/\/doi.wiley.com\/10.1002\/tdm_license_1.1"}],"content-domain":{"domain":["analyticalsciencejournals.onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["Drug Testing and Analysis"],"published-print":{"date-parts":[[2026,8]]},"abstract":"<jats:title>ABSTRACT<\/jats:title>\n                  <jats:p>\n                    Hair analysis for drugs of abuse is widely applied in forensic contexts, particularly in family law cases where child protection is a critical consideration. It is recognised that adulteration of hair samples via chemical treatments can occur; however, the specific influences of dye colour on parent drug and metabolite levels have yet to be systematically examined. In this study, 100 authentic hair samples positive for tetrahydrocannabinol (THC), 11\u2010nor\u20109\u2010carboxy\u2010\u03949\u2010tetrahydrocannabinol (THC\u2010COOH), cocaine (COC) and benzoylecgonine (BZE) were treated with nine permanent dyes and one bleach product. Concentrations were quantified using validated LC\u2013MS\/MS methods, and original and post\u2010treatment values were compared statistically via the two\u2010tailed matched pairs\n                    <jats:italic>t<\/jats:italic>\n                    \u2010test. Results demonstrated no consistent influence from dye colour on analyte concentrations. Following treatment, THC and COC concentrations predominantly decreased, consistent with oxidative degradation and reduced binding to the hair matrix. In contrast, THC\u2010COOH and BZE concentrations increased in the majority of samples, suggesting in\u00a0situ formation from peroxide\u2010mediated oxidation of parent compounds, as well as increased residue release from damaged keratin structures. Bleaching produced the most pronounced changes, with significant decreases in THC, THC\u2010COOH and COC levels and significant increases in BZE. COC was the analyte least affected by treatments overall. These findings indicate that dye colour itself is irrelevant, although chemical treatments can significantly impact toxicological results. Broader implications, such as increased risks of misinterpretation of results from artificially increased or decreased levels (shifted above or below reporting thresholds) and subsequent inaccurate conclusions regarding drug use, must be considered when analysing chemically treated hair samples.\n                  <\/jats:p>","DOI":"10.1002\/dta.70098","type":"journal-article","created":{"date-parts":[[2026,5,25]],"date-time":"2026-05-25T23:34:47Z","timestamp":1779752087000},"page":"1054-1064","update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["The Effect of Permanent Dye Colour on Illicit Drug and Metabolite Levels in Chemically Treated Hair"],"prefix":"10.1002","volume":"18","author":[{"ORCID":"https:\/\/orcid.org\/0009-0000-4857-9865","authenticated-orcid":false,"given":"Amy","family":"Duda","sequence":"first","affiliation":[{"name":"Cansford Laboratories Ltd  Cardiff UK"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"311","published-online":{"date-parts":[[2026,5,25]]},"reference":[{"key":"e_1_2_8_2_1","doi-asserted-by":"publisher","DOI":"10.1007\/s004140050056"},{"key":"e_1_2_8_3_1","unstructured":"Society of Hair Testing \u201cSoHT Consensus on General Recommendations for Hair Testing \u201d (2022) revised 27 September 2022 accessed 01 December 2025 https:\/\/www.soht.org\/images\/pdf\/General_Consensus_Hair_Testing_2022.pdf."},{"key":"e_1_2_8_4_1","doi-asserted-by":"publisher","DOI":"10.1002\/dta.3741"},{"key":"e_1_2_8_5_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.ecoenv.2021.112542"},{"key":"e_1_2_8_6_1","doi-asserted-by":"publisher","DOI":"10.1002\/(SICI)1099\u20100801(199906)13:4<257::AID\u2010BMC830>3.0.CO;2\u2010V"},{"key":"e_1_2_8_7_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.forsciint.2019.02.030"},{"key":"e_1_2_8_8_1","unstructured":"Office for National Statistics \u201cDrug Misuse in England and Wales: Year Ending March 2024 \u201d (2024) published 12 December 2024 accessed 01 December 2025 https:\/\/www.ons.gov.uk\/peoplepopulationandcommunity\/crimeandjustice\/articles\/drugmisuseinenglandandwales\/yearendingmarch2024."},{"key":"e_1_2_8_9_1","unstructured":"Home Office \u201cUnited Kingdom Drug Situation 2019: Summary \u201d (2021) updated 31 March 2021 accessed 01 December 2025 https:\/\/www.gov.uk\/government\/publications\/united\u2010kingdom\u2010drug\u2010situation\u2010focal\u2010point\u2010annual\u2010report\/uk\u2010drug\u2010situation\u20102019\u2010summary#main\u2010drugs\u2010used\u2010in\u2010the\u2010uk."},{"key":"e_1_2_8_10_1","unstructured":"Compound Interest \u201cThe Chemistry of Permanent Hair Dyes \u201d accessed 07 April 2025 https:\/\/www.compoundchem.com\/2015\/05\/14\/hair\u2010dyes\/."},{"key":"e_1_2_8_11_1","unstructured":"C.Goebel \u201cChemistry of Hair Coloring \u201d Presentation presented at: Cosmetic Ingredient Review Expert Panel Meeting December (2017) Washington DC USA accessed 08 April 2025 https:\/\/www.cir\u2010safety.org\/sites\/default\/files\/Chemistry%20of%20Hair%20Coloring%20\u2010%20Carsten%20Goebel.pdf."},{"key":"e_1_2_8_12_1","doi-asserted-by":"publisher","DOI":"10.1016\/s0379\u20100738(99)00152\u20108"},{"key":"e_1_2_8_13_1","doi-asserted-by":"publisher","DOI":"10.1097\/01.ftd.0000197091.07807.22"},{"key":"e_1_2_8_14_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.forsciint.2014.06.035"},{"key":"e_1_2_8_15_1","doi-asserted-by":"publisher","DOI":"10.1002\/bmc.170"}],"container-title":["Drug Testing and 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