Emission of volatile organic compounds during open fire cooking with wood biomass: Traditional three-stone open fire vs. gasifier cooking stove in rural Kenya.

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.

Temporal trends of lipophilic organic contaminants in blue mussel (1994-2017) and eelpout (1994-2017) from the southern Baltic Sea.

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.

Comprehensive non-target screening of biomagnifying organic contaminants in the Baltic Sea food web.

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.

Biomagnification and Temporal Trends of New and Emerging Dechloranes and Related Transformation Products in Baltic Sea Biota.

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.

A time-trend guided non-target screening study of organic contaminants in Baltic Sea harbor porpoise (1988-2019), guillemot (1986-2019), and white-tailed sea eagle (1965-2017) using gas chromatography-high-resolution mass spectrometry.

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.

Non-targeted screening workflows for gas chromatography-high-resolution mass spectrometry analysis and identification of biomagnifying contaminants in biota samples.

The health of key species in the Baltic region has been impaired by exposure to anthropogenic hazardous substances (AHSs), which accumulate in organisms and are transferred through food chains. There is, thus, a need for comprehensive characterization of the occurrence and accumulation of AHSs in the ecosystem. In this study, we use a non-target screening (NTS) approach for this purpose. A major challenge in NTS of biological samples is the removal of matrix components such as lipids that may interfere with the detection and identification of compounds of interest. Here, we combine gel permeation chromatography with Florisil® column fractionation to achieve sufficient lipid removal for gas chromatography-high-resolution mass spectrometry analysis using electron ionization (EI) and electron capture negative ion chemical ionization (ECNI). In addition, we present new data processing workflows designed to systematically find and identify frequently occurring and biomagnifying AHSs, including known, emerging, and new contaminants. Using these workflows, we discovered a wide range of contaminants in tissue samples from blue mussels, fish, and marine mammals, and calculated their biomagnification factors (BMFs). Compounds with BMFs above 1 for herring and at least one marine mammal included legacy chlorinated pollutants (polychlorinated biphenyls, DDTs, chloro-benzenes/cyclohexanes, chlordanes, toxaphenes, dieldrin), polybrominated diphenyl ethers (PBDEs), and brominated biphenyls. However, there were also several halogenated natural products (halogenated methoxylated brominated diphenyl ethers, 1'-methyl-1,2'-bipyrroles, 1,1'-dimethyl-2,2'-bipyrroles, and the halogenated monoterpene mixed halogenated compound 1) as well as the novel flame retardant Dechlorane 602 and several polycyclic aromatic hydrocarbons, terpenoids, and steroids. The legacy pollutants exhibited the expected biomagnification behavior, demonstrating the utility of the unguided data processing workflow. Graphical abstract.