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Toxics 2017, 5(1), 3; doi:10.3390/toxics5010003

Urinary Naphthol as a Biomarker of Exposure: Results from an Oral Exposure to Carbaryl and Workers Occupationally Exposed to Naphthalene

Health and Safety Executive, Harpur Hill, Buxton SK17 9JN, UK
Academic Editor: David Bellinger
Received: 27 October 2016 / Revised: 28 December 2016 / Accepted: 30 December 2016 / Published: 6 January 2017
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Abstract

Urinary naphthol is an established human biomarker used for assessing both occupational and environmental exposure. However, 1-naphthol is a metabolite of the insecticide carbaryl while both the 1- and 2-isomers are metabolites of naphthalene. Thus, urinary 1-naphthol levels will reflect combined exposure to both substances, particularly at environmental levels. The interpretation of biomarkers is aided by knowledge of levels following well-characterised exposure scenarios. This study reports urinary 1-naphthol levels in five volunteers administered an oral dose of carbaryl at the acceptable daily intake (ADI, 0.008 mg/kg). The elimination half-life was 3.6 h and the mean 1-naphthol level in 24 h total urine collections, normalised for a 70 kg individual, was 37.4 µmol/mol creatinine (range 21.3–84.3). Peak levels in spot-urine samples were around 200 µmol/mol creatinine. For comparison, 327 post-shift urine samples obtained from 90 individual workers exposed occupationally to naphthalene had 1-naphthol levels from below the limit of detection (<LoD) to 1027 µmol/mol creatinine (median = 4.2, mean = 27.2). The 2-naphthol levels ranged from <LoD to 153 µmol/mol creatinine (median = 4.0, mean = 8.1). Background ranges have been reported for urine naphthols in several populations, with upper limits between 10 and 20 µmol/mol creatinine. The data reported here suggest that environmental exposure to carbaryl and naphthalene in these populations is well controlled. View Full-Text
Keywords: carbaryl; exposure assessment; human biomonitoring; naphthalene; naphthol carbaryl; exposure assessment; human biomonitoring; naphthalene; naphthol
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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. (CC BY 4.0).

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Sams, C. Urinary Naphthol as a Biomarker of Exposure: Results from an Oral Exposure to Carbaryl and Workers Occupationally Exposed to Naphthalene. Toxics 2017, 5, 3.

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