Summary:
The impact of environment on human health is a scientific field very important for public health attracting interest from researchers worldwide, since there are adequate indications that the pathogenesis of major chronic conditions is caused by the combination of genetic and environmental factors. Despite the fact that the human genome has been decoded, analytical tools that will contribute to the “quantification” of the totality of environmental exposures need to be developed. “Exposome” represents the totality of internal and external human exposures from conception onwards. Exposome research requires the development of analytical methods for the determination of environmental exposures.
Persistent organic pollutants, POPs, are very stable, toxic and harmful compounds for humans and for the environment and tend to bioaccumulate in humans and in animal organisms. The aim of the present doctoral thesis is the development of analytical tools in order to examine the impact of POPs on human health. Recent studies have shown that the aforementioned compounds may present their deleterious effects even in very low concentrations (ppt). Consequently monitoring POPs levels is of major importance for the protection of public health and the environment. The present study focuses on dioxin and dioxin-like compounds as well as on perfluoralkylated substances. In particular, a specific analytical method for food analysis was developed and applied for the estimation of dietary exposure which forms the principal route of “external” exposure. Furthermore, a specific analytical method of high sensitivity, necessary due to the limited sample volume, was developed and applied to serum analysis to determine “internal” exposure to these compounds. In the context of the protection of public health, the analytical tools can be used for monitoring of these pollutants on a regular basis.
The applied analytical methodology for dioxin compounds in food was based on the use of an active carbon material in combination with other chromatographic materials (silica and alumina) for the specific separation of the compounds of interest. Quality criteria examined (% recovery, accuracy, reproducibility, specificity, limit of quantification), proved the method sensitive and specific enough for food, feed and biological sample analysis. Furthermore the developed method is in accordance with the European Regulation requirements. Application of the method in interlaboratory trials samples as well as in real food samples showed that the new carbon material has high fat capacity and excellent efficiency for the separation of the congeners with good recovery values. Therefore, this method is suitable for the determination of dioxins and dioxin-like compounds (PCDDs, PCDFs and non-ortho PCBs). The above-mentioned analytical method developed for food analysis was adjusted in a lower scale to be applicable to the limited volume (1mL) of serum samples. For this purpose one chromatographic column with a combination of two materials (silica and alumina) was used. During sample preparation, the reduction of experimental steps led to lower sample losses. The total cost as well as the short time required render the method suitable for large sample population. This method was applied to serum samples for the determination of polychlorinated biphenyles (PCBs) which are compounds belonging to the dioxin group. The serum samples were collected from volunteers residing in various areas of the Prefecture of Athens, as well as from volunteers form Aspropyrgos. The results showed higher levels of PCBs in samples of Aspropyrgos inhabitants compared to the rest of the samples. Metabolomic analysis also showed that samples with higher PCB levels presented higher concentrations in metabolites which have been proposed as possible biomarkers of exposure to PCBs. Concerning perfluorinated substances (PFASs), which were also determined in serum samples, concentration levels were in the same range in both populations studied.
In the context of the doctoral thesis an estimation of the dietary intake in PCDDs, PCDFs and PCBs of the general population in Greece was attempted for the first time. Representative samples from various food categories were collected and analyzed during 15 years. For the time period 2016-2018, analyses of food products were carried out with the method developed in the present study. Occurrence data were combined with food availability data collected through household budget surveys presented by the Data Food Networking (DAFNE) initiative, in order to assess the dietary exposure of the Greek population. The food group with the highest total mean upperbound WHO-TEQ concentration (PCDDs, PCDFs and dioxin- like PCBs) was fish and seafood and the one with the lowest mean WHO-TEQ concentration was vegetable oil group. For adult Greek population the average daily intake in PCDDs, PCDFs and dioxin-like PCBs is 1.27 pg WHO-TEQ kg-1 body weight and the average weekly intake is 8.89 pg WHO-TEQ kg-1 body weight. The main contributor to the total dietary intake is the fish and seafood group. Given the current toxicological data, the general background dietary exposure of the Greek population to these compounds is within the tolerable daily intake (TDI) range of 1-4 pg WHO-TEQ kg-1 body weight day-1 proposed by the WHO. However, recently the scientific panel of European Food Safety Authority (EFSA) suggested a tolerable weekly intake of 2 pg WHO-TEQ kg-1 body weight, based on new experimental and epidemiological data.
Concerning perfluoroalkylated substances (PFASs), for the general Greek population the estimated average daily dietary intake in PFOA and PFOS, when applying the lowerbound concentrations of food samples is 0.48 and 0.90 ng kg-1 body weight day-1 respectively. Exposure due to tap water estimated for PFOA is 0.006 ng kg-1 body weight day-1 and negligible for PFOS. Oral weekly intake estimated is 6.37 ng kg-1 body weight for PFOS and 3.43 ng kg-1 body weight for PFOA. All estimated values are below the tolerable weekly intake values set by EFSA, 13 ng kg-1 body weight week-1 for PFOS and 6 ng kg-1 body weight week-1 for PFOA.
Keywords:
Dietary exposure, biomonitoring, polychlorinated dibenzodioxins/furans and polychlorinated biphenysl, perfluorinated substances, exposome
