Perfluorooctanesulfonate and related fluorochemicals in human blood samples from China and biochemical pathway affected by perfluorooctanoic acid

Abstract

Perfluorinated compounds (PFCs) have been used for more than 50 years in both industrial and everyday applications. Concerns about these types of compounds have been increasing as they are bioaccumulative and environmentally persistent. Recent studies show that these types of compounds are found in the environment, biota and humans. In China, very little information about PFCs regarding the distribution and degree of contamination in Chinese population is available. Perfluorooctanoic acid (PFOA), one of the most predominant PFCs found in the environment is of great concern. PFOA is regarded as peroxisome proliferators and it can affect the lipid and fatty acid metabolism. However, the detailed mechanisms affected are still unknown. This research study consists of two main parts; the first part investigates the gene expression profiles in liver samples of rats exposed to PFOA using microarray techniques, the second part is concerned with the distribution pattern and risk assessment of PFCs in the Chinese population. Results of the study on gene expression profiles of rats exposed to PFOA showed that the expression of over 500 genes was significantly (two-fold changes; P<0.0025) altered by PFOA exposure compared to control. The major categories of induced genes were those involved in transport and metabolism of lipids, particularly fatty acids. Expressions of genes related to transport of lipids, inflammation and immunity and cell adhesion were suppressed. In addition, mechanisms of β-oxidation of peroxisomal and mitochondrial fatty acid were also affected by PFOA. In the second part of the study, concentrations of perfluorohexanesulfonate (PFHxS), perfluorobutanesulfonate (PFBS), perfluorooctanesulfonate (PFOS), perfluorohexanoic acid (PFHxA), PFOA, perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA), perfluoroundecanoic acid (PFUnDA), perfluorododecanoic acid (PFDoDA) and PFOSA were measured in 85 samples of whole human blood collected from nine cities (in eight provinces) in China, including Shenyang (Liaoning), Beijing (Hebei), Zhengzhou (Henan), Jintan (Jiangsu), Wuhan (Hubei), Zhoushan (Zhejiang), Guiyang (Guizhou), Xiamen (Fujian) and Fuzhou (Fujian). Among the ten perfluorinated compounds (PFCs) measured, PFOS was the predominant compound found in the whole blood samples. Mean concentration of PFOS was greatest in samples collected from Shenyang (Liaoning) (79.2ng/mL) and least in Jintan (Jiangsu) (3.72ng/mL). PFHxS was the next most abundant perfluorochemicals in the samples. A preliminary risk assessment indicates that PFOS poses little or no immediate risk to the Chinese population. However, it is recognized that toxicities of PFOA and PFOS are still not clearly known, and the sources and pathways of PFOS exposure to the Chinese population remain unclear. These conclusions, coupled with the fact that PFOS is moderately bioaccumulative, indicate future risks that may increase if releases are not properly controlled.

Date of Award	14 Jul 2006
Original language	English
Awarding Institution	City University of Hong Kong
Supervisor	Kwan Sing Paul LAM (Supervisor)