Dottorato in SCIENZE CHIMICHE

Titolo della tesi: Organic contaminants in depositions and airborne particulates from schools, homes and hospitals

Humans spend ca. 90% of their life in interiors; despite that, exposure to indoor toxicants was neglected long time, and only in recent years indoor environments have begun subject of extensive researches. In particular, the concern for deposition dusts is increasing nowadays, because they seem to contribute actively to toxicants’ intake by humans. The work here presented aimed at clarifying the levels of contamination in homes, schools and hospitals, associated to deposition dusts and fine aerosol. Our concern was focused on contaminants ascertained as toxic (polycyclic aromatic hydrocarbons PAHs; phthalate esters) or known as capable of providing information about nature and importance of sources (alkanes; psychotropic substances). Investigations inside a frequent smoker home allowed to index the contribution of tobacco smoke to ambient particulates. Seven universities investigated across Italy revealed chemical shapes different from both dwellings lying in the neighborhood and outdoors. Analogously, a primary school was examined contemporarily to smoker home, displaying a distinct behaviour. The composition of deposition dust was elucidated in five hospitals; there, contaminants could be more than in homes and in open air. Depositions and fine particulates looked distinct in terms of compound mass fractions as well as molecular signatures of alkanes, PAHs, psychotropic substances and phthalates. The analysis of untargeted compounds revealed the occurrence of plasticizers (e.g.,diethylhexyl adipate), flame retardants (organic phosphates), dyes, personal care products (cosmetics and fragrances), alkyl halides (chlorinat-ed and brominated paraffins) and lipids (cholesterol). This latter, combined with the unusual molecular signature of short-chain alkanes (up to docosane n-C22) seemed to suggest that microorganisms and humans are unsuspected important emitters heavily impacting in the chemistry of interiors. The comparison with literature showed that our targeted sites (in particular, hospitals and universities) often hosted deposition dusts rich of organic contaminants. Future efforts will be addressed: i) to pursuit the chemical characterization of interiors through novel contaminants like pharmaceuticals and manmade lipids; ii) to identify sources of indoor pollution and assess the respective relevance; and iii) to assess exposure and incremental risk associated to depositions.