Effects of ocean warming on the fatty acid and epigenetic profile of Acartia tonsa: A multigenerational approach.

The effects of climate change are becoming more prevalent, and it is important to know how copepods, the most abundant class in zooplankton, will react to changing temperatures as they are the main food source for secondary consumers. They act as key transferers of nutrients from primary producers to organisms higher up the food chain. Little is known about the effects of temperature changes on copepods on the long term, i.e., over several generations. Especially the epigenetic domain seems to be understudied and the question remains whether the nutritional value of copepods will permanently change with rising water temperatures. In this research, the effects of temperature on the fatty acid and epigenetic profiles of the abundant planktonic copepod Acartia tonsa were investigated, since we expect to see a link between these two. Indeed, changing methylation patterns helped copepods to deal with higher temperatures, which is in line with the relative abundance of the most important fatty acids, e.g., DHA. However, this pattern was only observed when temperature increased slowly. A sudden increase in temperature showed the opposite effect; Acartia tonsa did not show deviant methylation patterns and the relative abundance of DHA and other important fatty acids dropped significantly after several generations. These results suggest that local fluctuations in temperature have a greater effect on Acartia tonsa than an elevation of the global mean.

The immunostimulatory activity of sea spray aerosols: bacteria and endotoxins activate TLR4, TLR2/6, NF-κB and IRF in human cells.

Frequent exposure to sea spray aerosols (SSA) containing marine microorganisms and bioactive compounds may influence human health. However, little is known about potential immunostimulation by SSA exposure. This study focuses on the effects of marine bacteria and endotoxins in SSA on several receptors and transcription factors known to play a key role in the human innate immune system. SSA samples were collected in the field (Ostend, Belgium) or generated in the lab using a marine aerosol reference tank (MART). Samples were characterized by their sodium contents, total bacterial counts, and endotoxin concentrations. Human reporter cells were exposed to SSA to investigate the activation of toll-like receptor 4 (TLR4) in HEK-Blue hTLR4 cells and TLR2/6 in HEK-Blue hTLR2/6 cells, as well as the activation of nuclear factor kappa B (NF-κB) and interferon regulatory factors (IRF) in THP1-Dual monocytes. These responses were then correlated to the total bacterial counts and endotoxin concentrations to explore dose-effect relationships. Field SSA contained from 3.0 × 103 to 6.0 × 105 bacteria/m3 air (averaging 2.0 ± 1.9 × 105 bacteria/m3 air) and an endotoxin concentration ranging from 7 to 1217 EU/m3 air (averaging 389 ± 434 EU/m3 air). In contrast, MART SSA exhibited elevated levels of total bacterial count (from 2.0 × 105 to 2.4 × 106, averaging 7.3 ± 5.5 × 105 cells/m3 air) and endotoxin concentration from 536 to 2191 (averaging 1310 ± 513 EU/m3 air). SSA samples differentially activated TLR4, TLR2/6, NF-κB and IRF. These immune responses correlated dose-dependently with the total bacterial counts, endotoxin levels, or both. This study sheds light on the immunostimulatory potential of SSA and its underlying mechanisms, highlighting the need for further research to deepen our understanding of the health implications of SSA exposure.

Contribution of combined stressors on density and gene expression dynamics of the copepod Temora longicornis in the North Sea.

The impact of multiple environmental and anthropogenic stressors on the marine environment remains poorly understood. Therefore, we studied the contribution of environmental variables to the densities and gene expression of the dominant zooplankton species in the Belgian part of the North Sea, the calanoid copepod Temora longicornis. We observed a reduced density of copepods, which were also smaller in size, in samples taken from nearshore locations when compared to those obtained from offshore stations. To assess the factors influencing the population dynamics of this species, we applied generalised additive models. These models allowed us to quantify the relative contribution of temperature, nutrient levels, salinity, turbidity, concentrations of photosynthetic pigments, as well as chemical pollutants such as polychlorinated biphenyls and polycyclic aromatic hydrocarbons (PAHs), on copepod density. Temperature and Secchi depth, a proxy for turbidity, were the most important environmental variables predicting the densities of T. longicornis, followed by summed PAH and chlorophyll concentrations. Analysing gene expression in field-collected adults, we observed significant variation in metabolic and stress-response genes. Temperature correlated significantly with genes involved in proteolytic activities, and encoding heat shock proteins. Yet, concentrations of anthropogenic chemicals did not induce significant differences in the gene expression of genes involved in the copepod's fatty acid metabolism or well-known stress-related genes, such as glutathione transferases or cytochrome P450. Our study highlights the potential of gene expression biomonitoring and underscores the significance of a changing environment in future studies.

Accelerated fragmentation of two thermoplastics (polylactic acid and polypropylene) into microplastics after UV radiation and seawater immersion.

To better understand the fate and assess the ingestible fraction of microplastics (by aquatic organisms), it is essential to quantify and characterize of their released from larger items under environmental realistic conditions. However, the current information on the fragmentation and size-based characteristics of released microplastics, for example from bio-based thermoplastics, is largely unknown. The goal of our work was to assess the fragmentation and release of microplastics, under ultraviolet (UV) radiation and in seawater, from polylactic acid (PLA) items, a bio-based polymer, and from polypropylene (PP) items, a petroleum-based polymer. To do so, we exposed pristine items of PLA and PP, immersed in filtered natural seawater, to accelerated UV radiation for 57 and 76 days, simulating 18 and 24 months of mean natural solar irradiance in Europe. Our results indicated that 76-day UV radiation induced the fragmentation of parent plastic items and the microplastics (50 - 5000 µm) formation from both PP and PLA items. The PP samples (48 ± 26 microplastics / cm2) released up to nine times more microplastics than PLA samples (5 ± 2 microplastics / cm2) after a 76-day UV exposure, implying that the PLA tested items had a lower fragmentation rate than PP. The particles' length of released microplastics was parameterized using a power law exponent (α), to assess their size distribution. The obtained α values were 3.04 ± 0.11 and 2.54 ± 0.06 (-) for 76-day UV weathered PP and PLA, respectively, meaning that PLA microplastics had a larger sized microplastics fraction than PP particles. With respect to their two-dimensional shape, PLA microplastics also had lower width-to-length ratio (0.51 ± 0.17) and greater fiber-shaped fractions (16%) than PP microplastics (0.57 ± 0.17% and 11%, respectively). Overall, the bio-based PLA items under study were more resistant to fragmentation and release of microplastics than the petroleum-based PP tested items, and the parameterized characteristics of released microplastics were polymer-dependent. Our work indicates that even though bio-based plastics may have a slower release of fragmented particles under UV radiation compared to conventional polymer types, they still have the potential to act as a source of microplastics in the marine environment, with particles being available to biota within ingestible size fractions, if not removed before major fragmentation processes.

History of exposure to copper influences transgenerational gene expression responses in Daphnia magna.

The establishment of transgenerational effects following chemical exposure is a powerful phenomenon, capable of modulating ecosystem health beyond exposure periods. This study assessed the transgenerational effects occurring due to copper exposure in the invertebrate D. magna at the transcriptional level, while evaluating the role of exposure history on such responses. Thus, daphnids acclimated for several generations in a copper vs. clean medium were then exposed for one generation (F0) to this metal, and monitored for the following non-exposed generations (F1, F2 and F3). Organisms differing in exposure histories showed remarkably different transcriptional profiles at the F0, with naïve organisms being more profoundly affected. These trends were confirmed for F3 treatments, which presented different transcriptional patterns for genes involved in detoxification, oxidative stress, DNA damage repair, circadian clock functioning and epigenetic regulation. Furthermore, regardless of exposure history, a great number of histone modifier genes were always found transcriptionally altered, thus suggesting the involvement of histone modifications in the response of Daphnia to metal exposure. Lastly, remarkably distinct transgenerational transcriptional responses were found between naïve and non-naïve organisms, thereby highlighting the influence of exposure history on gene expression and confirming the capacity of metals to determine transgenerational transcriptional effects across non-exposed generations.

Cellular and bioenergetic effects of polystyrene microplastic in function of cell type, differentiation status and post-exposure time.

The ubiquity of microplastics (MPs) in food sources and personal care products increasingly raises concerns on human health. However, little is known about the duration of the effects of MPs and whether effects depend on cellular differentiation status. Herein, cellular and bioenergetic effects of MPs in different exposure scenarios on four types of human cell lines derived from lung (A549 and BEAS-2B), colon (Caco-2) and liver (HepG2) were investigated. These cell lines are models for the major exposure routes in the body (inhalation, ingestion and physiological transport through the liver by the portal vein). To this aim, different scenarios were implemented by exposing undifferentiated and differentiated cells to single dosing of 2-µm polystyrene (PS) (102-105 particles/mL) for 48 h and 12 days. The undifferentiated Caco-2 cells with short exposure (48 h) showed the highest uptake rate of PS yet without significant cellular and mitochondrial responses. The biological effects, with the exception of ROS production, were not influenced by differentiation states of A549 and Caco-2 cells although differentiated cells showed much weaker ability to internalize PS. However, PS had significantly long-term impacts on cellular and mitochondrial functions even after the initial exposure period. In particular, Caco-2 cells that were post-exposed for 12 days after single PS dosing suffered higher oxidative stress and exhibited mitochondrial dysfunction than that for short exposure. Correspondingly, we observed that PS particles still remained in cell membrane and even in nuclei with high retention rate by 14-d post exposure during which metabolism and exchange of internalization and release occurred in cells. This indicates PS could induce chronic stress and even harmful effects on human cells after single intake that persists for a long time. This study paves the way for assessing the influence of PS on human health at low particle concentrations and with multiple exposure scenarios.

A review on aquatic toxins - Do we really know it all regarding the environmental risk posed by phytoplankton neurotoxins?

Aquatic toxins are potent natural toxins produced by certain cyanobacteria and marine algae species during harmful cyanobacterial and algal blooms (CyanoHABs and HABs, respectively). These harmful bloom events and the toxins produced during these events are a human and environmental health concern worldwide, with occurrence, frequency and severity of CyanoHABs and HABs being predicted to keep increasing due to ongoing climate change scenarios. These contexts, as well as human health consequences of some toxins produced during bloom events have been thoroughly reviewed before. Conversely, the wider picture that includes the non-human biota in the assessment of noxious effects of toxins is much less covered in the literature and barely covered by review works. Despite direct human exposure to aquatic toxins and related deleterious effects being responsible for the majority of the public attention to the blooms' problematic, it constitutes a very limited fraction of the real environmental risk posed by these toxins. The disruption of ecological and trophic interactions caused by these toxins in the aquatic biota building on deleterious effects they may induce in different species is paramount as a modulator of the overall magnitude of the environmental risk potentially involved, thus necessarily constraining the quality and efficiency of the management strategies that should be placed. In this way, this review aims at updating and consolidating current knowledge regarding the adverse effects of aquatic toxins, attempting to going beyond their main toxicity pathways in human and related models' health, i.e., also focusing on ecologically relevant model organisms. For conciseness and considering the severity in terms of documented human health risks as a reference, we restricted the detailed revision work to neurotoxic cyanotoxins and marine toxins. This comprehensive revision of the systemic effects of aquatic neurotoxins provides a broad overview of the exposure and the hazard that these compounds pose to human and environmental health. Regulatory approaches they are given worldwide, as well as (eco)toxicity data available were hence thoroughly reviewed. Critical research gaps were identified particularly regarding (i) the toxic effects other than those typical of the recognized disease/disorder each toxin causes following acute exposure in humans and also in other biota; and (ii) alternative detection tools capable of being early-warning signals for aquatic toxins occurrence and therefore provide better human and environmental safety insurance. Future directions on aquatic toxins research are discussed in face of the existent knowledge, with particular emphasis on the much-needed development and implementation of effective alternative (eco)toxicological biomarkers for these toxins. The wide-spanning approach followed herein will hopefully stimulate future research more broadly addressing the environmental hazardous potential of aquatic toxins.

Decadal decline of dominant copepod species in the North Sea is associated with ocean warming: Importance of marine heatwaves.

Time-series are crucial to understand the status of zooplankton communities and to anticipate changes that might affect the entire food web. Long-term time series allow us to understand impacts of multiple environmental and anthropogenic stressors, such as chemical pollution and ocean warming, on the marine ecosystems. Here, a recent time series (2018-2022) of abundance data of four dominant calanoid and one harpacticoid copepod species from the Belgian Part of the North Sea was combined with previously collected (2009-2010, 2015-2016) datasets for the same study area. The time series reveals a significant decrease (up to two orders of magnitude) in calanoid copepod abundance (Temora longicornis, Acartia clausi, Centropages spp., Calanus helgolandicus), while this was not the case for the harpacticoid Euterpina acutifrons. We applied generalized additive models to quantify the relative contribution of temperature, nutrients, salinity, primary production, turbidity and pollution (anthropogenic chemicals, i.e., polychlorinated biphenyls and polycyclic aromatic hydrocarbons) to the population dynamics of these species. Temperature, turbidity and chlorophyll a concentrations were the only variables consistently showing a relative high contribution in all models predicting the abundances of the selected species. The observed heat waves which occurred during the summer periods of the investigated years coincided with population collapses (versus population densities in non-heatwave years) and are considered the most likely cause for the observed copepod abundance decreases. Moreover, the recorded water temperatures during these heatwaves correspond to the physiological thermal limit of some of the studied species. As far as we know, this is the first study to observe ocean warming and marine heat waves having such a dramatic impact (population collapse) on the dominant zooplankton species in shallow coastal areas.

Assessment of road run-off and domestic wastewater contribution to microplastic pollution in a densely populated area (Flanders, Belgium).

Plastics are omnipresent in our daily life. Unfortunately, the produced plastics will partly end up in the environment including aquatic ecosystems. People often refer to littering or illegal waste dumping as sources of plastic emission to the environment. However, daily-life sources could also, unknowingly, contribute considerably to the total microplastic pollution in the ecosystem. Hence, there is an urgent need to study these potential sources. In this research, two common sources, i.e. domestic wastewater and road run-off from tire and road wear particles, were studied in detail to quantify the relative contribution of both domestic sources towards microplastic pollution in freshwater ecosystems in Flanders, Belgium. This assessment shows that every person (in studied area) emits on average 1145 microplastics (25-1000 µm) daily through domestic wastewater, resulting in a yearly discharge of 418,000 microplastic particles per person. The road run-off samples contained between 0.02 and 9.2 mg tire wear particles per litre per day, which corresponds to an emission of 10.8 mg tire wear particles per driven vehicle km. The gross and net emissions of both above mentioned microplastic sources were extrapolated to the whole Flanders region using an emission model. From the yearly gross microplastic pollution in the domestic wastewater, 623 kg (20%) will be discharged in the freshwater. The highest losses originated from the households that have a private drain or are not (yet) connected to an active wastewater treatment plant. In Flanders, the yearly net microplastic emission into the aquatic environment of tire wear particles is estimated to be 246 tonnes (38%), mainly from the direct run-off from the road surface. Based on the results, specific mitigation measures can be installed to reduce the emission of microplastics towards the freshwater ecosystem. Other sources should be quantified in a similar way for a more holistic strategy to counteract plastic pollution.

Micro- and nanoplastics transfer from seawater to the atmosphere through aerosolization under controlled laboratory conditions.

Sea spray has been suggested to enable the transfer of micro- and nanoplastics (MNPs) from the ocean to the atmosphere, but only a few studies support the role of sea spray aerosols (SSAs) as a source of airborne particles. We demonstrated that MNPs are aerosolized during wave action, via SSAs, under controlled laboratory conditions. We used a mini-Marine-Aerosol-Reference-Tank (miniMART), a device that mimics naturally occurring physical mechanisms producing SSAs, and assessed the aerosolization of fluorescent polystyrene beads (0.5-10 µm), in artificial seawater. The SSAs contained up to 18,809 particles/mL of aerosols for 0.5 µm beads, with an enrichment factor of 19-fold, and 1977 particles/mL of aerosols for 10 µm beads with a 2-fold enrichment factor. Our study demonstrates that the use of the miniMART is essential to assess MNPs aerosolization in a standardized way, supporting the hypothesis which states that MNPs in the surface of the ocean may be transferred to the atmosphere.

Distribution of microplastics in freshwater systems in an urbanized region: A case study in Flanders (Belgium).

Microplastics (MPs) are an emerging pollutant of concern in all known aquatic ecosystems. However, studies at a regional scale on MP pollution in freshwater systems and the necessary risk assessments are limited. Therefore, in this study, we examined microplastic concentrations, size distributions, and polymer types in surface waters and sediments in the geographic region Flanders (Belgium), as a case study for a densely populated region and one of the most developed parts of Europe. Samples have been taken on nine different locations, of which five were repeated in a different weather condition. In total 43 aqueous and nine sediment samples have been collected. The quantity and identity of the microplastics in the samples were determined with µFTIR spectroscopy in the range of 25-1000 µm. The MPs' abundances in surface waters and sediments ranged from 0 to 4.8 MP L-1 (average = 0.48 MP L-1) and from 0 to 9558 MP kg-1 dry weight (average = 2774.57 ± 2317.93 MP kg-1 DW), respectively. Polystyrene and polypropylene were the most common polymer compositions found. No correlations were observed between microplastic concentrations in the sediment/the surface water samples and the measured environmental variables rainfall, conductivity, pH, dissolved oxygen content, waterway flow rate and width, and surrounding land use. Risk assessment results for the measured surface water concentrations through the risk quotient (RQ) method and the probabilistic risk assessment framework suggest that most of the sampled sites in Flanders posed negligible risks to freshwater biota, while this was not the case for some of the sediment concentrations. Our results illustrate the need to urgently develop analytical methods that can routinely measure the full size range of MP in environmental samples to adequately assess risks for the environment.

Synthesizing the impact of sea-dumped munition and related chemicals on humans and the environment.

Marine environments are globally impacted by vast quantities of munition disposed following both World Wars. Dumped munitions contain conventional explosives, chemicals warfare agents as well as a variety of metals. Field monitoring studies around marine dumpsites report the presence of munition constituents in water and sediment samples. The growing interest and developments in the ocean as a new economic frontier underline the need to remediate existing dumpsites. Here, we provide a comprehensive assessment of the magnitude and potential risks associated with marine munition dumpsites. An overview of the global distribution of dumpsites identifying the most impacted areas is provided, followed by the currently available data on the detection of munition constituents in environmental samples and evidence of their toxic potential to human and environmental health. Finally, existing data gaps are identified and future research needs promoting better understanding of the impact of the dumped material on the marine environment suggested.

Evaluating ecotoxicological assays for comprehensive risk assessment of toxic metals present in industrial wastewaters in the Republic of Korea.

Toxicity tests represent a rapid, user-friendly and cost-effective means to assess the impact of wastewater quality on aquatic ecosystems. There are not many cases where wastewater management standards are set based on various bio-based ecotoxicity values. Here, we tested a novel multitaxon approach to compare standard water quality indices to toxicity metrics obtained from ecotoxicity tests, conducted using aquatic organisms representing several trophic levels (Aliivibrio, Ulva, Daphnia, and Lemna), for 99 industrial wastewater samples from South Korea. For five wastewater samples, the concentrations of Se, Zn, or Ni exceeded the permissible limits (1, 5, and 3 mg L-1, respectively). All the four physiochemical water quality indices tested were positively correlated with Se and Pb concentrations. The toxicity unit (TU) scores indicated a declining sensitivity to pollutants, in the order Lemna (2.87) >Daphnia (2.24) >Aliivibrio (1.78) >Ulva (1.42). Significant correlations were observed between (1) Cd and Ni, and Aliivibrio, (2) Cu and Daphnia, (3) Cd, Cu, Zn, and Cr and Lemna, and (4) Cu, Zn, and Ni and Ulva. Daphnia-Lemna and Lemna-Ulva were found to be good indicators of ecologically harmful Se and Ni contents in wastewater, respectively. We suggest that regulatory thresholds based on these bioassays should be set at TU = 1 for all the species or at TU = 1 for Aliivibrio and Ulva and TU = 2 for Daphnia and Lemna, if the number of companies whose wastewater discharge exceeds the allowable TU levels is <1 % or 5 % of the total number of industries, respectively. Taken together, these findings could help in establishing a rapid, ecologically relevant wastewater quality assessment system that would be useful for developing strategies to protect aquatic ecosystems.

Allometric scaling improves the characterization of complex community transcriptomes.

Allometric scaling, that is scaling patterns in physiological processes relative to body size, can be used to overcome the current limitations in metatranscriptomics. Metatranscriptomics refers to the use of RNA transcripts to characterize a complex community. In contrast to metagenomics, metatranscriptomics allows one to simultaneously address community composition and functionality through the characterization of the community transcriptome. Hence, insights into metabolic processes and molecular pathways can also be obtained. Despite its increasing use in community ecology, a major limitation and source of error is the variation in RNA transcript abundance across organisms varying in body size. Hence, this may lead to incorrect estimations of the community structure and functioning as larger RNA quantities from larger individuals may overestimate their community contribution.

Toward a Better Understanding of the Contribution of Wastewater Treatment Plants to Microplastic Pollution in Receiving Waterways.

Microplastics (1 µm-5 mm), are ubiquitous in daily-use products and regularly end up in the wastewater. The main part of the wastewater is treated in wastewater treatment plants (WWTPs), which allow for at least partial removal of microplastics. The present study aimed to understand the contribution of domestic wastewater to microplastic pollution in Flanders (Belgium) via two main discharge routes of microplastics: (1) the effluent, and (2) removed fractions. Furthermore the effect of effluent discharge on the microplastic contamination in the waterway was studied in both surface water and sediment samples of upstream and downstream locations of the discharge from three WWTPs. On average, 12.64 ± 20.20 microplastic/L entered a WWTP (10 µm-5 mm). The effluent contained on average 0.41 ± 0.91 microplastic/L, resulting in an average removal efficiency of 97.46% ± 2.33%, which is comparable with various (non-)European countries. Removal efficiencies are both polymer- and size-specific, and data suggest that smaller particles are less efficiently removed from the wastewater, which also causes an increased input of smaller particles to the environment. The sludge is the most efficient treatment process to remove microplastics. Despite the high removal efficiencies, still 1.11 × 107 ± 3.07 × 107 microplastics end up in the nearby waterway daily. Nonetheless, based on the results gathered in the present study, this does not seem to impact the microplastic concentration in the waterway significantly. In summary, the present study offers a holistic approach in the research on the impact of wastewater on microplastic pollution in the ecosystem, integrating different discharge routes and measuring the impact on environmental microplastic pollution. Environ Toxicol Chem 2023;42:642-654. © 2022 SETAC.

A Ten-Minute Bioassay to Test Metal Toxicity with the Freshwater Flagellate Euglena agilis.

A chemical analysis of water quality cannot detect some toxicants due to time constraints, high costs, and limited interactions for detection. Bioassays would offer a complementary means to assess pollution levels in water. Euglena is a flagellate green alga and an excellent system for toxicity testing thanks to its ease of culture, rapid growth, and quick response to environmental stresses. Herein, we examined the sensitivity of E. agilis to seven heavy metals by analyzing six end-point parameters: motility, velocity, cell compactness, upward swimming, r-value, and alignment. Notably, the velocity of E. agilis was most sensitive to cadmium (96.28 mg·L-1), copper (6.51 mg·L-1), manganese (103.28 mg·L-1), lead (78.04 mg·L-1), and zinc (101.90 mg·L-1), while r-values were most sensitive to arsenic (12.84 mg·L-1) and mercury (4.26 mg·L-1). In this study, velocity and r-values are presented as useful biomarkers for the assessment of metal toxicity in Euglena. The metals As, Cd, Cu, and Pb were suitable for this test. The advantages of the ecotoxicity test are its rapidity: It takes 10 min to obtain results, as opposed to the typical 3-4 d of exposure time with intensive labor. Moreover, this test can be performed at room temperature under dark conditions.

Multigenerational DNA methylation responses to copper exposure in Daphnia: Potential targets for epigenetic biomarkers?

Epigenetic mechanisms are moving to the forefront of environmental sciences, as environmentally induced epigenetic changes shape biological responses to chemical contamination. This work focused on Daphnia as a representative of potentially threatened freshwater biota, aiming to gain an insight into the involvement of epigenetic mechanisms in their response and eventual adaptation to metal contamination. Copper-induced DNA methylation changes, their potential transgenerational inheritance, and life-history traits were assessed. Organisms with different histories of past exposure to copper were exposed to toxic levels of the element for one generation (F0) and then monitored for three subsequent unexposed generations (F1, F2, and F3). Overall, methylation changes targeted important genes for counteracting the effects of metals and oxidative stress, including dynein light chain, ribosomal kinase and nuclear fragile X mental retardation-interacting protein. Also, contrasting overall and gene-specific methylation responses were observed in organisms differing in their history of exposure to copper, with different transgenerational methylation responses being also identified among the two groups, without apparent life-history costs. Taken together, these results demonstrate the capacity of copper to promote epigenetic transgenerational inheritance in a manner related explicitly to history of exposure, thereby supporting the development and incorporation of epigenetic biomarkers in risk assessment frameworks.

Sea Spray Aerosols Contain the Major Component of Human Lung Surfactant.

Marine phytoplankton influence the composition of sea spray aerosols (SSAs) by releasing various compounds. The biogenic surfactant dipalmitoylphosphatidylcholine (DPPC) is known to accumulate in the sea surface microlayer, but its aerosolization has never been confirmed. We conducted a 1 year SSA sampling campaign at the Belgian coast and analyzed the SSA composition. We quantified DPPC at a median and maximum air concentration of 7.1 and 33 pg m-3, respectively. This discovery may be of great importance for the field linking ocean processes to human health as DPPC is the major component of human lung surfactant and is used as excipient in medical aerosol therapy. The natural airborne exposure to DPPC seems too low to induce direct human health effects but may facilitate the effects of other marine bioactive compounds. By analyzing various environmental variables in relation to the DPPC air concentration, using a generalized linear model, we established that wave height is a key environmental predictor and that it has an inverse relationship. We also demonstrated that DPPC content in SSAs is positively correlated with enriched aerosolization of Mg2+ and Ca2+. In conclusion, our findings are not only important from a human health perspective but they also advance our understanding of the production and composition of SSAs.