BACKGROUND: Icaridin and DEET are common insect repellents widely used on human skin and clothing (skin-insect repellents [skin-IR]) to repel common pests, such as mosquitoes and biting flies. Novel analytical methods for urinary skin-IR exposure biomarkers that can be effectively applied in epidemiological studies and provide strong evidence related to risk assessment associated with daily exposure are required. In this study, we aimed to develop a method for analyzing the concentrations of icaridin, DEET, and two DEET metabolites N,N-diethyl-3-(hydroxymethyl) benzamide and 3-(diethylcarbamoyl) benzoic acid in human urine. METHODS: In this analysis, after formic acid-induced acidification of the urine sample, exposure biomarkers were extracted using solid-phase extraction composed of a modified polystyrenedivinylbenzene polymer for reversed phase (hydrophobic) retention. Subsequently, high-performance liquid chromatography-tandem mass spectrometry was performed within 10 min for a separation analysis. The present method was applied to five Japanese adults (aged 20-43 years) who used icaridin or DEET-containing products within a week. RESULTS: Limits of detection were 0.06-0.11 µg/L. Extraction recoveries were 74%-88%. The intraday and interday variations were 1.5-17.5 and 0.9-15.8% relative standard deviation, respectively. All exposure biomarkers were successfully detected in all five adults. Urinary concentrations of exposure biomarkers reached their maximum values within 15 h after starting to use skin-IR. CONCLUSIONS This method was successful in measuring urinary exposure biomarkers of skin-IR, including icaridin and DEET. Moreover, this study presents the first application of biomonitoring of urinary icaridin concentrations after using a commercial product.
Humans ; Solid Phase Extraction/methods* ; Tandem Mass Spectrometry/methods* ; Adult ; Insect Repellents/urine* ; DEET/urine* ; Young Adult ; Male ; Japan ; Female ; Chromatography, Liquid ; Biomarkers/urine* ; Chromatography, High Pressure Liquid ; East Asian People

BACKGROUND/AIMS: This study examined the accuracy of endoscopic evaluation for determining the Helicobacter pylori infection status in patients with mild atrophy who might not exhibit characteristic endoscopic findings. METHODS: Forty endoscopists determined the H. pylori infection status of 50 randomly presented H. pylori-positive and H. pylori-negative cases on the basis of a list of established findings. RESULTS: The median clinical endoscopy experience was 7 years (range, 1–35 years), including 22 board-certified endoscopists (55%) of the Japan Gastroenterological Endoscopy Society. The mean accuracy rate of endoscopic diagnosis was 67% and was unrelated to experience status (experienced vs. trainee: 69% vs. 65%, p=0.089) and total years of experience (R 2 =0.022). The most frequently selected endoscopic findings were regular arrangement of collecting venules (59%), atrophy (45%), and red streak (22%), which had fair accuracy rates of 67%, 65%, and 73%, respectively. By contrast, the accuracy rates of nodularity (89%) and mucosal swelling (77%) were highest. The 20 endoscopists who more frequently identified these findings diagnosed H. pylori infection significantly more accurately than did the other endoscopists (71% vs. 64%, p=0.008). CONCLUSIONS: Careful attention to nodularity and mucosal swelling in patients with mild atrophy may enhance diagnosis, enable prompt treatment, and avoid possible long-term carcinogenesis.
Atrophy ; Carcinogenesis ; Diagnosis* ; Endoscopy ; Gastritis, Atrophic* ; Helicobacter pylori* ; Helicobacter* ; Humans ; Japan ; Venules