THESIS
2018
xxiv, 167 pages : illustrations ; 30 cm
Abstract
Carcinogenic nitrated aromatic hydrocarbons (nitro-PAHs) are a group of nitro-derivatives
of polycyclic aromatic hydrocarbons (PAHs), which have aroused increasing attentions due to
their wide occurrence and potent toxicity. Though their concentration levels are lower than
respective parent PAHs, nitro-PAHs exhibit higher cancer risks to human and are proven to be
direct mutagens. Previous studies focused on analyzing nitro-PAHs in atmospheric samples
and revealing their formation mechanisms or emission sources. Comparing to the well-documented
parent PAHs, studies on nitro-PAHs are at the initial stage and regulations on them
are still lacking. My thesis research is directed at developing sensitive and efficient analytical
methods to estimate the exposure risks of representativ...[
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Carcinogenic nitrated aromatic hydrocarbons (nitro-PAHs) are a group of nitro-derivatives
of polycyclic aromatic hydrocarbons (PAHs), which have aroused increasing attentions due to
their wide occurrence and potent toxicity. Though their concentration levels are lower than
respective parent PAHs, nitro-PAHs exhibit higher cancer risks to human and are proven to be
direct mutagens. Previous studies focused on analyzing nitro-PAHs in atmospheric samples
and revealing their formation mechanisms or emission sources. Comparing to the well-documented
parent PAHs, studies on nitro-PAHs are at the initial stage and regulations on them
are still lacking. My thesis research is directed at developing sensitive and efficient analytical
methods to estimate the exposure risks of representative nitro-PAHs via dietary intake.
Firstly, I reported a novel ultraperformance liquid chromatography coupled with
fluorescence detection (UPLC-FLD) method, which combined pre-column nitro-reduction and
fluorescence detection, to analyze nitro-PAHs in meat products. A follow-up work was
conducted on rice grains and vegetables, and QuEChERS based sample extraction was applied
to determine nitro-PAHs. Dietary exposure risks of nitro-PAHs were evaluated based on the
monitoring results and Hong Kong diet. The results suggested that more than 90% of the tested
samples were detected with nitro-PAHs and the concentration levels were higher than expected.
Moreover, the fate of model nitro-PAH, 1-nitropyrene, was explored on a plant-soil system for
the first time and compared with pyrene. The fate study revealed that the more carcinogenic
nitro-PAHs might be more stable in the agricultural soil, and were susceptible to plant uptake,
particularly in the root part of plant. Ultimately, biomarkers (DNA and protein adduct)
associated risk assessment was conducted both in vitro and in Sprague Dawley rats. In contrast
to the in vitro result, protein adduct level was more than 100 times higher than that of DNA
adduct in vivo, which could be a more valuable biomarker for nitro-PAHs exposure.
It is anticipated that the food monitoring study and fate study of nitro-PAHs could
contribute to the dietary exposure risk assessment via direct or modeling estimation.
Furthermore, we hope the development of biomarkers for 1-nitropyrene could help assess the
toxicity of nitro-PAHs and thus facilitate implementing regulations on nitro-PAHs.
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