The concentrations of per- and polyfluoroalkyl substances (PFASs) in the Finnish aquatic environment were measured in riverine waters and in inland, coastal and open sea fish. In addition, the PFAS load to the Baltic Sea from 11 rivers was calculated. Measurements show that PFASs, including restricted perfluorooctane sulfonic acid (PFOS), are widely present in the Finnish aquatic environment. At three out of 45 sampling sites, the concentration of PFOS in fish exceeded the environmental quality standard (EQS) of the Water Framework Directive (WFD). The annual average (AA) ∑₂₃PFAS concentration in surface waters ranged from 1.8 to 42 ng L⁻¹ and the concentration of PFOS exceeded the AA-EQS in three out of 13 water bodies. In European perch (Perca fluviatilis) and Baltic herring (Clupea harengus membras), the ∑PFAS concentration ranged from 0.98 to 1 µg kg⁻¹ f.w. (fresh weight) and from 0.2 to 2.4 µg kg⁻¹ f.w., respectively. The highest concentrations in both surface water and fish were found in waters of southern Finland. The riverine export of ∑₁₀PFAS to the Baltic Sea from individual rivers ranged from 0.4 kg yr⁻¹ to 18 kg yr⁻¹. PFAS concentrations in fish of point-source-polluted sites and coastal sites were higher compared to fish of open sea or diffusely polluted sites. The PFAS profiles in surface waters of background sites were different from other sites. This study shows that PFASs are widely found in the Finnish aquatic environment. Different PFAS profiles in samples from background areas and densely populated areas indicate diverse sources of PFASs. Although atmospheric deposition has a substantial influence on PFAS occurrence in remote areas, it is not the dominant source of all PFASs to the aquatic environment of Finland. Rather, wastewaters and presumably contaminated land areas are major sources of PFASs to this aquatic environment.

Occurrence and distribution of perfluoroalkyl acids (PFAAs), a sub-category of per- and polyfluoroalkyl substances (PFASs), is widespread in the environment. Food, especially fish meat, is a major pathway via which humans are exposed to PFAAs. As fish is an integral part of Nordic diet, therefore, in this study, several fish species, caught in selected Baltic Sea basins and freshwater bodies of Finland, were analysed for PFAAs. Perfluorooctane sulfonate (PFOS) was detected in all Baltic Sea fish samples and in >80% fish samples from freshwaters. PFOS contributed between 46 and 100% to the total PFAA concentration in Baltic Sea fish samples and between 19 and 28% in fish samples from freshwaters. Geographically, concentration ratios of PFOS to other PFAAs differed between fish from the Baltic Sea and Finnish lakes suggesting that distribution of PFAAs differ in these environments. Results were compared with current safety thresholds - environmental quality standard for biota (EQS_biota) set by the European Commission and a group tolerable weekly intake (TWI) for the sum of four PFASs (∑PFAS-4) i.e. perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), perfluorohexane sulfonate (PFHxS) and PFOS, recommended by the European Food Authority (EFSA). EQS_biota compliance was observed for PFOS in all species except smelt caught in the Baltic Sea and also in the River Aurajoki, where smelt had migrated from the Baltic Sea for spawning. Moderate consumption of most Baltic fishes (200 g week^-1) results in an exceedance of the new TWI (4.4 ng kg^-1 body weight week^-1) for ∑PFAS-4.

Hazardous substances in demolition waste are often deemed a barrier to a circular economy owing to concerns about their fate in recycled materials. However, with the growing demand for recycling materials, it is essential to find circular solutions for construction materials but still protect health and the environment by managing hazardous substances. In this study, selected hazardous substance groups were analysed from demolition waste samples. Most of the concentrations did not raise any concerns when the safety of recycling materials was considered. However, the detection limits of laboratory chemical analysis can be discussed, as bromine was found in samples by an X-ray fluorescence (XRF)-analyser, but only one laboratory detected brominated flame retardants (BRFs). New technologies and practices are needed to follow the chemical content of materials used in the construction phase. Detecting hazardous substances in recyclable materials is the only way to achieve harmless material cycles.

Per- and polyfluoroalkyl substances (PFAS) are a large group of compounds with a wide range of sources, uses and physicochemical properties, resulting in highly variable environmental behaviour and analytical detectability. This study investigates the occurrence of a large spectrum of PFAS, including precursors of perfluoroalkyl acids, in the River Porvoonjoki system in Southern Finland during two contrasting hydrological periods: high flow (April 2024) and low flow (June 2024). Surface water from up to ten sampling sites, including a stormwater ditch, and three wastewater treatment plants (WWTPs) discharging into the river were analysed using target analysis, Total Oxidizable Precursors (TOP) assay and suspect screening supported by non-target analysis (NTA). Short-chain perfluorocarboxylic acids dominated the PFAS profile in the river. Higher concentrations were observed during the low flow period, suggesting an increased impact from wastewater discharges when dilution is limited. However, mass load calculations propose that a substantial fraction of total PFAS load originates from diffuse sources, such as stormwater, snowmelt-driven surface runoff and background catchment inputs. Oxidizable precursors contributed substantially to total PFAS loads in both wastewater effluents and the four surface water samples that were analysed for TOP in both hydrological periods. Their contribution in these samples was higher in April than in June, potentially reflecting enhanced mobilization during spring snowmelt and wet-weather conditions. Suspect screening showed the presence of four previously unreported PFAS, however, the suspects or their semi-quantitative concentrations could not explain the TOP assay results. The findings emphasize the importance of integrating precursor analysis in PFAS monitoring and to consider varying hydrological conditions, to improve load estimation and to establish management strategies for reducing PFAS inputs to surface waters.