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Cooking with wood biomass fuels releases hazardous air pollutants, including volatile organic compounds (VOCs), that often disproportionally affect women and children. This study, conducted in Kwale and Siaya counties in Kenya, employed thermal desorption gas chromatography – mass spectrometry to analyse VOC emissions from cooking with a wood biomass three-stone open fire vs. top-lit updraft gasifier stove. In kitchens with adequate ventilation, total VOC levels increased from 35–252 μg∙m⁻³ before cooking to 2235–5371 μg∙m⁻³ during open fire cooking, whereas use of a gasifier stove resulted in reduced emissions from cooking by 48–77 % (506–2778 μg∙m⁻³). However, in kitchens with poor ventilation, there was only a moderate difference in total VOC levels between the two methods of cooking (9034–9378 μg∙m⁻³ vs. 6727–8201 μg∙m⁻³ for the three-stone open fire vs. gasifier stove, respectively). Using a non-target screening approach revealed significantly increased levels of VOCs, particularly benzenoids, oxygenated and heterocyclic compounds, when cooking with the traditional open fire, especially in closed kitchens, highlighting the effects of poor ventilation. Key hazardous VOCs included benzene, naphthalene, phenols and furans, suggesting potential health risks from cooking. In kitchens with good ventilation, use of the gasifier stove markedly reduced emissions of these priority toxic VOCs compared to cooking with an open fire. Thus, substituting open fires with gasifier stoves could help to improve household air quality and alleviate health risks. The study revealed that VOCs were present prior to cooking, possibly originating from previously cooked food (buildup) or the outside environment. VOC emissions were also exacerbated by reduced air flow in high humidity during rainfall, suggesting an area for further research. The findings underscore the importance of adopting cleaner cooking technologies and enhancing kitchen ventilation to mitigate the impacts of VOCs in developing countries.

A time-trend study was carried out for two important Baltic Sea species, blue mussel (1994–2017, 11 samples) and eelpout (1994–2017, 11 samples), to track the changes in levels of regulated persistent organic pollutants (POPs) and show potential increases in the levels of the contaminants of emerging concern (CECs). It was carried out utilizing gas chromatography–high-resolution mass spectrometry (GC-HRMS) based non-target screening (NTS). Data were acquired in two modes – electron ionization (EI) and electron capture negative ion chemical ionization (ECNI) – to widen the contaminant coverage, and treated using a fast semi-automated NTS data processing workflow. The study revealed that >250 tentatively identified compounds show statistically significant temporal trends in Baltic blue mussel and eelpout. A large number of regulated substances, including but not limited to PCBs, DDTs and other organochlorine pesticides (OCPs), chlorobenzenes, and many polybrominated diphenyl ethers (PBDEs), showed significant declining trends, as was expected. Their rates of decline were in good agreement with previously reported data. In contrast, increasing trends were observed for many CECs, some polycyclic aromatic compounds (PAHs), and hydrocarbons. The CEC group included, among others, four compounds, namely, one personal care product ingredient, 2-ethylhexyl stearate, one brominated compound 1,2,3,5-tetrabromobenzene and two intermediates 4-isopropoxyaniline and bilobol dimethyl ether, that were reported in marine biota for the first time to the best of our knowledge. Several compounds, including four CECs and two unknown brominated compounds, showed levels considerably higher than the common legacy pollutants (CB-153 and BDE-99), which might be taken into consideration for future monitoring and risk assessment. In addition, this work revealed the presence of a plethora of organoiodinated compounds that exhibited statistically significant temporal trends in the samples under study, which could be of future interest.

The rate of decline in regulated persistent organic pollutant (POP) concentrations in Baltic Sea biota has leveled off in recent years, with new contaminants frequently being discovered. There is, therefore, a need for comprehensive approaches to study occurrence and temporal trends of a wide range of environmental contaminants, including legacy POPs, contaminants of emerging concern (CECs), and new contaminants. In the current work, non-target screening (NTS) workflows were developed and used for, to the best of our knowledge, the first time-trend directed NTS of biota using gas chromatography–high-resolution mass spectrometry (GC-HRMS). To maximize contaminant coverage, both electron ionization (EI) and electron capture negative ion chemical ionization (ECNI) were used. The EI data were treated using highly automated workflows to find, prioritize, and tentatively identify contaminants with statistically significant temporal trends. The ECNI data were manually processed and reviewed prior to time-trend analysis. Altogether, more than 300 tentatively identified contaminants were found to have significant temporal trends in samples of Baltic guillemot, harbor porpoise, or white-tailed sea eagle. Significant decreases were found for many regulated chemicals, as could be expected, such as PCBs, polychlorinated terphenyls, chlorobenzenes, toxaphenes, DDT, other organochlorine pesticides, and tri- and tetra- bromodiphenyl ethers (BDEs). The rate of decline of legacy POPs agreed well with data reported from targeted analyses. Significant increases were observed for small polycyclic aromatic hydrocarbons, heptaBDEs, CECs, and terpenes and related compounds. The CECs included, among others, one plasticizer tributyl acetylcitrate (ATBC), two antioxidants 2,6-bis(1,1-dimethylethyl)phenol and 2,6-bis(tert-butyl)-4-(4-morpholinyl-methyl)phenol, and two compounds used in polymer production, trimethyl isocyanurate and 2-mercaptobenzothiazole, which had not previously been reported in biota. Their increased concentrations in biota indicate increased use and release. The increase in ATBC may be linked to increased use of it as a substitute for di-2-ethylhexyl phthalate (DEHP), which has been phased out over the last decade.

To enhance knowledge of the environmental distribution and temporal trends of dechloranes and their transformation products (TPs) we performed suspect screening of Baltic Sea biota (eelpout, herring, harbor porpoise, guillemot and white-tailed sea eagle). Evaluation of new and “digitally frozen” gas chromatography/high-resolution mass spectrometry data revealed 31 compounds: five dechloranes (Dechlorane [Mirex], Dechlorane 602, Dechlorane 603, and syn-/anti-Dechlorane Plus [DP]), three isomers, and 23 TPs. Six new Dechlorane 603 TPs and two new DP TPs were detected, including one hydroxy-TP. Some TPs occurred at much higher concentrations than the parent compounds (e.g., Dechlorane 603 TPs were >10-fold more abundant than their parent). Concentrations of contaminants in the most contaminated species (white-tailed sea eagle) changed little over the period 1965–2017. Slow declines were detected for most compounds (median, 2% per year), although concentrations of DP and DP-TPs increased by 1% per year. Ten contaminants biomagnify, and the trophic magnification factors for TPs of Mirex, Dechlorane 602 and Dechlorane 603 (8.2 to 17.8) were similar to the parent compounds (6.6 to 12.4) and higher than that of DP (2.4, nonsignificant). The results are discussed in relation to the current review of DP for potential listing under the Stockholm Convention on POPs.

High-resolution mass spectrometry (HRMS) based non-target screening (NTS) is a powerful approach for the simultaneous determination of multiple environmental contaminant classes in complex biota samples. In this study, trophic biomagnification factor (TMF) directed NTS was performed to find and (tentatively) identify known, emerging, and new chemical contaminants that are persistent and biomagnify in Baltic Sea biota. The investigated food web included seven species: one filter feeder (blue mussel, Mytilus edulis), two fish (eelpout, Zoarces viviparous; herring, Clupea harengus), two marine mammals (harbor porpoise, Phocoena phocoena; grey seal, Halichoerus grypus) and two birds (guillemot, Uria aalge; white-tailed sea eagle, Haliaeetus albicilla). The NTS procedure included extraction with organic solvent mixtures, two-step high-resolution gel permeation chromatography clean-up, Florisil^® fractionation, gas chromatography (GC) HRMS analysis in electron ionization (EI) and electron capture negative ion chemical ionization (ECNI) modes, and NTS data processing. The latter was performed differently for the EI and ECNI data: the EI data were treated using a flexible and highly automated TMF-directed NTS workflow, whereas the ECNI data were treated with a simpler and less automated workflow that specifically screened for brominated compounds. The two workflows collectively revealed biomagnification (statistically significant TMF values) of >250 tentatively identified compounds, including legacy persistent organic pollutants (POPs), such as PCBs and PCB-related compounds, DDT and its metabolites, and organochlorine pesticides (OCPs), contaminants of emerging concern (CECs), and halogenated natural products (HNPs). Among the tentatively identified CECs, nine have not previously been reported in environmental biota samples. These included four polymer additives (used as antioxidants, rubber additives or plasticizers) and two cosmetic product additives (ethyl myristate and isopropyl palmitate). The CECs should be prioritized for future structure verification and quantification using reference standards.

The development of industrial processes in the 19^th and 20^th centuries, in particular oil refining, resulted in a huge discovery and subsequent large-scale production of a variety of chemicals. These useful chemicals supposedly made the everyday lives of people easier and better by, for instance, controlling the spread of diseases such as malaria, through the use of DDT and other organochlorine pesticides (OCPs).

During the 1970s and following decades, it was hypothesized and later shown, that these, and other “helpful chemicals” such as polychlorinated biphenyls (PCBs), played a crucial role in the steep population decline observed for multiple species in the Baltic Sea. They were classified as anthropogenic (man-made) hazardous substances (AHSs). Many AHSs can be stored in fatty tissues of the organisms and magnify in species at high trophic levels (predators) of the food web, as a result of persistence and transfer from lower-level organisms (prey). This process is called biomagnification and is characterized by biomagnification or trophic magnification factors (BMFs or TMFs, respectively). AHSs can be roughly divided into known chemicals of concern, such as persistent organic pollutants (POPs), and contaminants of emerging concern (CECs), that include novel flame retardants, polymer additives, and many more. Both the production and use of a number of AHSs have been regulated since the 1970s. To understand the outcome of the regulations, retrospective analysis of samples from different years, a time-trend study, is often utilized.

The main aim of this work was to develop a non-selective sample extraction, purification, and analysis method, and then find and identify as many biomagnifying contaminants as possible. To assess both biomagnification and temporal trends of a wide range of chemical contaminants in a given Baltic Sea food web, non-target screening (NTS) was used. A clean-up method was established and tested with a satisfactory outcome: processed extracts were pure enough for gas chromatography-mass spectrometry (GC-MS) analysis. Also, accompanying NTS data processing workflows were developed. Application of these resulted in BMFs for more than 100 contaminants (Paper I). The data processing workflow was refined for faster detection of chemicals that demonstrate temporal trends and/or biomagnify. It was possible to detect and tentatively identify more than 300 legacy POPs and CECs with statistically significant temporal trends in three Baltic top consumers (Paper II). Adjusted NTS workflows were used to reveal more than 250 compounds that possessed trophic magnification properties (Paper III). Inspired by the discovery of a novel flame retardant Dechlorane 602 (Paper I), a suspect screening for dechlorane-related compounds and their transformation products was carried out. A total of 31 compounds were detected and tentatively identified, many of which showed significant temporal trends and biomagnification (Paper IV). A number of compounds reported in Papers I–IV were tentatively identified for the first time in wildlife. In addition, the papers provide valuable spectral and retention information for the researchers in the field.

In conclusion, this thesis presents useful GC-MS-based NTS workflows and biomagnification or time-trend data for a plethora of organic contaminants in the Baltic Sea food web. The data can contribute to i) the assessment of the influence pollutants have on the ecosystem and ii) various mitigation actions for AHSs, such as evaluating dechloranes for regulation under the Stockholm Convention on POPs, helping in the fight for a better environment and future.