Lieven Bervoets

Feral pigeons (Columba livia domestica) are among the most abundant urban bird species and are exposed to anthropogenic metal pollution. It is unclear, however, whether this exposure translates into measurable physiological consequences, and whether melanin-based plumage may serve as a detoxification pathway. To address this, we sampled blood and feathers from 100 pigeons across 21 locations in Antwerp (Belgium), and quantified the concentrations of lead (Pb), cadmium (Cd), copper (Cu), and zinc (Zn). We additionally assessed body condition, Chlamydia psittaci infection status, feather corticosterone, and feather brightness as a proxy for melanisation. Pigeons in Antwerp showed generally low to moderate metal concentrations. Blood and feather concentrations were largely uncorrelated, except for Pb, suggesting these tissues reflect different temporal aspects of exposure. Blood Pb and feather Zn were negatively associated with body condition, while blood Cu was positively associated with Chlamydia psittaci infection probability. No relationship was found between metals and feather corticosterone; instead, variation in corticosterone was better explained by location, indicating that spatial rather than chemical factors drive individual stress responses. Feather brightness was negatively associated with feather Zn and Cd, suggesting that more heavily melanised individuals accumulate more of these metals in their feathers, consistent with melanin-based metal sequestration. Overall, the physiological consequences of metal exposure were limited and metal-specific, likely reflecting differences in the regulation of essential and non-essential metals alongside the relatively low concentrations recorded. The detectable association between Pb and body condition nonetheless suggests that populations in more heavily contaminated cities may face greater physiological costs.

The extensive production and use of per- and polyfluoroalkyl substances (PFAS) over recent decades have resulted in their pervasive distribution in environmental compartments worldwide. PFAS concentrations in soil and biota near fluorochemical manufacturing facilities tend to be typically higher near hotspots, which suggests that the consumption of home-produced foods near such hotspots most likely results in higher human exposure. One prominent European hotspot is located near the 3M fluorochemical production facility in Zwijndrecht (Belgium), where the relative contributions of different exposure pathways remain insufficiently characterised. This study therefore aimed to assess the PFAS concentrations and compositional profiles in serum, dwellings and gardens of teenagers residing near this hotspot. Serum samples from teenagers, along with multiple environmental matrices (i.e., soil, compost, vegetables/fruits/nuts, chicken eggs, rainwater and indoor house dust) were analysed for 21 selected PFAS. Additionally, potential determinants of PFAS occurrence and distribution across matrices were investigated using detailed questionnaire data. We found perfluorooctane sulfonic acid (PFOS) to be the predominant compound in both soil and serum, while perfluorobutanoic acid (PFBA) was most dominant in rainwater, compost, house dust and pods. Perfluorobutane sulfonic acid (PFBS) was most abundant in fruits and chicken eggs, while perfluorododecanoic acid (PFDoDA) was predominant in rooting vegetables and nuts. N-methylperfluorooctane sulfonamidoacetic acid (MePFOSAA) was the dominant compound in fruiting, stem, and leafy vegetables. These results indicate differences in accumulation pathways among the different media and/or differences in affinities of different PFAS in the matrices. Additionally, several environmental and behavioural factors were identified as determinants for PFAS in soil, compost, tree fruits, fruiting vegetables, chicken eggs and house dust, providing insight into potential drivers of exposure variability. The most important factors were related to the soil characteristics, the composting of grass and weeds, the chicken feed (i.e., bread, commercial feed), the type and frequency of ventilation and the frequency of cleaning.

This study examined the effects of pollution from the Shituru hydrometallurgic complex on the Upper Lufira Basin, Democratic Republic of the Congo, between September 2015 and September 2017. Physico-chemical water variables and trace metal elements in water and sediment, as well as diversity and infection parameters of monopisthocotylan parasites infesting Clarias ngamensis, were assessed at three sites: the Lufira River, Panda River, and Lake Tshangalele. We hypothesised that low pollution would correlate with greater ectoparasite species richness and higher infection parameters. Results indicated severe ecological degradation in the highly polluted Panda River (with high concentrations of TMEs; e.g., 510.830 ± 0.86; 82.470 ± 0.200 µg/L for Co²⁺ and Cu²⁺ in water; 15,771 ± 7068 and 1585 ± 1450 µg/g for Cu²⁺ and Zn²⁺ in the sediment), where neither fish nor parasites were present. Across the other sites, eight parasite species were identified. Seven species occurred on fish from the slightly polluted Lufira River (mean intensity (MI) of 31.28 ± 28.95 parasites per infested fish), while five were found in Lake Tshangalele (MI: 3.23 ± 2.89 parasites per infested fish), confirming the hypothesis. Three species, Quadriacanthus halajiani, Q. domatanai, and Macrogyrodactylus clarii, demonstrated potential as sensitive bioindicators of aquatic pollution in the region.

Short-chain per- and polyfluorinated substances (PFAS) are widely distributed in the environment, but their chronic effects on soil organisms exposed over multiple generations remain largely unknown. The present study therefore aimed to investigate the toxicity of perfluorobutane sulfonic acid (PFBS) and its precursor perfluorobutane sulfonamide (FBSA) to the springtail Folsomia candida during five successive generations, with adult survival (LC50), reproduction (EC50_repro), and population growth rate (EC50_r) as endpoints. The LC50 and EC50_r of PFBS were above the highest test concentration (1300 mg/kg dry soil) for all generations, while the EC50_repro was 1260 and 762 mg/kg dry soil in F2 and F4, respectively, though the difference was not significant owing to wide 95% confidence intervals. In contrast, FBSA exhibited significant reproductive toxicity and thereby affected population growth rate, with LC50, EC50_repro and EC50_r values of 10.3, 1.14, and 1.67 mg/kg dry soil in F0, respectively. The extinction of the populations exposed to the two highest FBSA concentrations (8.85 and 88.3 mg/kg dry soil) in F0 hindered toxicity assessment in subsequent generations, with only an EC50_repro of 0.965 mg/kg dry soil determined in F1. Although the effect concentrations were above environmental levels, the more pronounced reproductive toxicity made FBSA over 1140 and 1350 times more toxic to F. candida reproduction than PFBS in F0 and F1, respectively. These findings reveal that understudied PFAS may pose hidden risks, and emphasize the need to expand the currently limited spectrum of PFAS considered in environmental risk assessment. This study also highlights the value of long-term hazard assessment of PFAS in multigeneration scenarios, which could better capture the potential risks posed by these very persistent chemicals.

This study investigated the distribution of 29 legacy and emerging per- and polyfluoroalkyl substances (PFASs) in soil, nettles, invertebrates, and plasma and feathers of great tits (Parus major) of a terrestrial ecosystem near a fluorochemical plant. Additionally, the vertical distribution of PFASs in soil was assessed, as well as taxon-specific differences among terrestrial invertebrate species. Finally, associations between soil and biota, and among biological matrices, were assessed. Most accumulation profiles were dominated by long-chained PFASs, mainly perfluorooctane sulfonic acid (PFOS), while short-chained PFASs were less detected. Long-chained perfluoroalkyl carboxylic acids (PFCAs) adsorbed in the upper soil layers, while short-chained PFAS and perfluoroalkyl sulfonic acids (PFSAs) tended to migrate deeper. The several taxon-specific differences were likely due to dietary differences. Significant associations, especially for long-chained PFCAs and PFOS, were found among most matrices. This indicates that (1) these PFASs found in these matrices are most likely originating from the same pollution source, (2) there is a possible transfer of these PFASs between matrices, (3) there is bioaccumulation from one to another matrix, and (4) some matrices might be used as proxies to estimate PFAS concentrations in other terrestrial matrices. Finally, feathers accumulated more PFASs than plasma, as they were most likely exposed through different routes of exposure and PFAS affinity. Therefore, they are not suitable for internal PFAS monitoring but can provide complementary information about the exposure and about the presence/absence of PFASs in certain habitats.