First evidence of high urinary 1-hydroxypyrene level among rural school children during smoke haze episode in Chiang Mai Province, Thailand

Smoke haze from biomass burning has been a crisis in northern Thailand. There have been plenty of reports on ambient PM10 and PAHs but not on individual exposure during smoke haze episodes. The present study aimed to quantify urinary 1-OHP, a predominant biomarker of PAH exposure, among 200 rural school children in Om Koi and Mae Chaem districts, Chiang Mai Province, northern Thailand. Questionnaires for information regarding environmental exposure and health diaries were given out. Urine samples were collected to measure 1-OHP using high-performance liquid chromatography-fluorescence detection, HPLC-FLD (HP1100 Series/HP1046A). Proficiency testing materials were obtained from the participation of German External Quality Assessment Scheme (G-EQUAS, Erlangen, Germany) and analyzed as part of the method validation of our urinary 1-OHP method. The median urinary 1-OHP level in the school children from Om Koi District was significantly higher than that in Mae Chaem District (0.70 versus 0.24 μmol/mol cr). The present study showed the evidence that urinary 1-OHP level among school children from the selected study sites during haze episode in northern Thailand is higher than those reported in other region of Thailand and other countries.