Dottorato in SCIENZE CHIMICHE

Titolo della tesi: Distribution and evaluation of emerging organic pollutants and POPs in the environment and in food matrices

Since the twentieth century, the industrial and technological development has led to an increase in productivity and improvement of the quality of life, but in parallel has led to an intentional and unintentional release of many anthropogenic compounds into the environment. Some of these substances have exhibited alarming properties such toxicological adverse effects and persistence in the environment. Thanks to synergic work of the scientific community and of the international Authorities, several measures were applied to reduce or ban their production, such as for the POPs (persistent organic pollutants) that have been defined and regulated by the Stockholm Convention since 2001. Despite, the measures taken against of the use of well-known harmful pollutants, the need of alternative substances has led to the introduction of a variety of other chemicals. The contaminants of emerging concern (CECs) are chemicals currently unregulated and not subject to a routine monitoring or emission control because of the lack of enough information regarding environmental occurrence, bioaccumulation and toxicity characteristics mandatory for risk assessment and subsequent regulation. Since the organic contaminants are present both in the environment and in food, the human exposure to legacy and to new generation organic pollutants is given by the combination of environmental and dietary exposure. In particular, the concentration of organic pollutants in indoor environments can be orders of magnitude higher than in outdoor. Indoor exposure may also be relevant in some industrial activities in which the workers are involved in the production or use of such substances, and for workers involved in tasks involving contact with treated materials. The organic pollutants can be adsorbed onto the atmospheric particulate matter (PM) and settled dust, which both represent a medium for exposure. Environmental pollutants such as POPs and CECs can also contaminate water and soil, so they can enter and concentrate in the trophic chain. In addition, the food contamination can occur during the processing stages of food products as well as by migration of additives from food contact material (FCM). Unluckily, the lack of information about the occurrence, concentration and toxicological effects hinders the production of regulation for many substances of emerging concern. This PhD project focused on the development of analytical methods able to determine organic CECs, alongside already regulated organic pollutants, to be applied to real matrices such as particulate matter, dust, food and food contact materials, not only for mere monitoring, but also to help building a solid basis for regulatory actions ensuring the public health. In fact, the development of suitable and reliable analytical methods is a fundamental tool for subsequent risk assessment and for the development of appropriate regulations by authorities. The approach used in this study is the targeted monitoring of previously selected harmful compounds for humans, in particular the investigations included the legacy flame retardants: Polyclorobiphenyls (PCB), polybrominated diphenyl ethers (PBDEs), 1,2,5,6,9,10-hexabromocyclododecane (HBCD), alongside to the novel brominated flame retardants (nBFRs) and the organophosphate esters (OPEs) used alternatively, in addition to the increasingly widespread perfluoroalkyl substances (PFAS) and to the harmful polycyclic aromatic hydrocarbons (PAHs) and their derivatives . To obtain the sensitivity and specificity required for the analysis of these compounds present in traces, in this study, the techniques of mass spectrometry, MS and MS/MS, coupled with gas chromatography (GC) and high-performance liquid chromatography (HPLC) respectively, were used for the qualitative/quantitative purposes. In addition, particular attention was paid to the development of sample treatment methods able to simultaneously extract and purify more classes of pollutants starting from the same sample, giving advantages in term of cost and time in sampling and analysis. The environmental matrices investigated were PM and settled dust collected in living and working places. A preliminary study was carried out to assess the mass distribution and perform a risk evaluation of PM in workplaces where high concentrations were expected. The results, compared with concentrations found in urban and background atmospheres, showed that people working in solid waste composting plant and in WEEE (waste electrical and electronic equipment) treatment plant were exposed to a not negligible additional risk respect to citizens. Therefore, a suitable analytical method to monitor the contamination of PCBs, PBDEs, HBCD and nBFRs was developed and was applied to PM and settled dust samples collected in a WEEE treatment plant. Afterwards, the method was extended to a higher number of polluting agents and applied to the airborne PM collected in outdoor workplaces and in a background area. A total 66 contaminants were monitored and an evaluation about their associated toxicity in such environment was presented. Since the contamination of the indoor dust can be an indicator of the healthiness of an environment, settled dust samples were collected in in houses and workplaces such as one office and two electrotechnical and mechanical workshops and 99 contaminants belonging to PCBs, PBDEs, nBFRs, PAHs, NPAHs, OPAHs and PFASs were monitored in these environments. The electronic and mechanical workshops showed the highest contamination for legacy BFRs as PCBs and PBDEs, while nBFRs contamination was heterogeneous. The method was then extended to 11 organophosphate esters (OPEs) and 26 polyfluoroalkyl substances (PFASs) and applied to the Standard Reference Material SRM 2585 of National Institute of Standard and Technology NIST and to settled dust samples from four workplaces. In conclusion, the full method was applied to the PM fractions collected in a WEEE management plant allowing the monitoring of about 140 compounds belonging to the eight contaminants classes. The results of these studies highlighted that legacy flame retardants can still be found in indoor environment and suggested the need to monitor nBFRs and OPEs in particular in the working places involved in activities with electronic products. In addition, the presented developed method is a useful tool to collect more data, allowing to have a more exhaustive contamination profile starting from a single sample. As concern the dietary exposure, the investigation involved the contamination given by food processing. The migration of PFASs and OPEs and BFRs from food contact material (FCMs) was investigated. In the last period, within the framework of the joint project for the mobility abroad of PhD students, a work aimed to extend the knowledge about the nitro and oxy PAHs derivatives (NPAHs and OPAHs) contamination in smoked products was carried out at the EU reference laboratory for the food processing contaminants (National Food Institute, Lyngby, Denmark). An analytical method for the determination of PAHs was optimized to extend the investigation to NPAHs and OPAHs. The results highlighted that OPAHs could be found in higher concentration than the PAHs, suggesting, indeed, the importance to extend the monitoring in processed food products to these contaminants.