| Per- and polyfluoroalkyl substances (PFASs) are widely distributed in the environment as organic pollutants. In recent years, studies of environmental and health toxicologies have shown that they have a certain harm to environmental organisms and humans. Regulators in the United States and Europe have published TDI (Total Daily Intaken) and restrictions on the use of perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) in food. However, there are still many challenges to assess the hazards of perfluorinated compounds on environment ecology and human health.Edible oil is one of the most important ingridients of Chinese diet and there is very limited studies on PFASs in commercial edible oil.Study their contamination levels in edible oil will laid down a solid base for the development of the TDI criteria, which shall be suitable to Chinese dietary structure. PFOA and PFOS, as two typical compounds of PFASs, are the most widely founded in the environment and they often coexist in the environmental compartment and ecology system. There are very a few environmental toxicological studies on the presence of individual and co-existing conditions, especially their acute and chronic toxic effects on aquatic/terrestrial organisms. The joint toxicity of PFOS and PFOA was analyzed by carrying out plants growth test, Daphnia magna acute and chronic toxicity test, and bird chronic toxicity test. The obtained data will be used to evaluate the hazards of PFASs on environmental and ecological system and the potential health risk on human being through oil consumptions.The main contents and results of this thesis are summarized as follows:1. 18 PFASs contents were analyzed in 84 different edible oils from different production areas and enterprises. It were found that 98% of the samples contain PFASs. 68.7% of the total samples was found to have two or more compounds of PFASs,, mainly C6-C9 containing perfluorinated compounds. 88% of all type edible oils samples contains PFOS followed by PFNA (55.4%), PFHxS (39.8%) and PFOA (16.9%). The high content of PFNA was found from lard and rapeseed oil with an average low concentration of 1.14 ng·g-1 and a highest concentration of 6.76 ng g-1.2. The effects of PFOS and PFOA on the growth of rape, soybean and rice and the distribution of vegetative organs have been studied and the results showed that all these three crops could absorb and enrich PFOS-K and PFOA from soil, and a clear pathway from the roots to the stems and leafs were observed. The concentrations of PFOS-K and PFOA in plant roots and shoots were positively correlated with their concentrations in soil. The enrichment ability order of PFOS-K in three plant roots was: rice>soybean>rape, the correspondingenrichment ability order of PFOA was: Rape>rice>soybean.The enrichment ability order of PFOA was higher than that of PFOS-K. The transmission capacity in the three plants was: PFOS-K>PFOA.However, the difference between these two compounds in the three crops was not significant. When PFOS-K and PFOA were both present in the soil, there was no significant difference in the absorption and enrichment of them from all the three crops comapare with PFOA or PFOS-K presenting alone.3. Results from PFOS-K and PFOA on aquatic orgasm studies showed that the toxicity of the mixture was enhanced and the joint effect was observed.The toxicity of PFOS-K and PFOA was significantly higher than that of the control. A strong synergistic effect was observed, with CI index of 0.4-0.7 and 0.1-0.3. Applying the Logit function, Weibull function respectively to analysis and predict concentration response curves for the combined effect of PFOS-K,PFOA; Acute: y=1/(1+exp((-18.78783-4.41531×lgECx)), R2 =0.98879 (in confidence interval 95%); chronic: y= 1-exp(-exp(7.39164+1.21715×lgECx)),R2 = 0.97444 (95% confidence interval), which is more consistent with the experimental results than the widely used concentration plus model (CA) and independent action model (IA).4. In the quail chronic toxicity test, the concentrations of compounds increase in the liver, kidney, fat, blood and fertilized eggs of quail along with the increase of dosage. PFOS-K contents in the quail body was noticed in order: blood>fertilized eggs>liver>kidney>subcutaneous fat while the corresponding PFOA content distributions are blood>fertilized eggs>liver/kidney> subcutaneous fat. When PFOS-K and PFOA were fed to the bird together, the contents in both fertilized eggs and blood increased with the increase of the concentrations of the test compounds. It was also found that the content of PFOS-K, PFOA decreased in the liver and kidneys, with the content increase of the test compounds. The distribution of PFOS-K and PFOA in subcutaneous fat was significantly decreased when they exist together. The results of pathologic analysis showed that when using PFOA alone at both the concentrations 20 mg kg-1 and 200 mg kg-1, hepatocellular swellings were observed with an obvious higher degree at higher concentration of 200 mg kg-1. 200 mg kg-1 treatments can also be found renal tubular epithelial hypertrophy. Infiltration of inflammatory cells in the liver was observed with PFOS-K treatment group. When treat the bird with a mixtures of both compounds, infiltration of inflammatory cells in the liver, and the swelling of the hepatocytes was observed in some animals. With the increase of the dose the degree of infiltrating the inflammatory cells of the kidneys, and the lesion also increased.This study demonstrated that PFASs are widely existing in the commercial edible oil with PFOS as the highest frequently found compound.This study showed that perfluorinated compounds have been distributed into different environment food chains, for example, the edible oil. They could be transferred into the plants through the contaminated soil, through bioaccumulation from water into the aquatic organisms and through contaminated feed into the birds which will seriously affect the development of bird organs and other toxic effects. This study provides measures a for the hazards evaluation of the multi-components low-level exposure and highly persistent organic pollutants (PFASs). The results generated through this thesis can be served as very important reference data and part of scientific base for the development of a Chinese TDI criteria of PFASs in edible oil... |
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