Persistent Chemicals Research Articles

Persistent Organic Pollutants- A Silent Threat to the Agro-ecosystem and Surrounding Environment

Persistent organic pollutants (POPs) are a class of hazardous, bio-accumulative, biomagnified, and extremely persistent chemicals with plausible extended off-site mobility in the environment or agro-ecosystem. These constitute a wide variety of chemicals, their sources may be either natural or anthropogenic. These are contaminants of emerging concerns for researchers as well as environmentalists. These contaminants are supposed to cause toxicity in terms of their carcinogenic, genotoxic, neurotoxic, and endocrine disruptors nature. Therefore, it is very important to discuss various kinds of POPs present in the environment and their detection methods. Various extraction and analytical techniques have been strategized to determine the POPs in soil and food samples either quantitatively or qualitatively. The literature lacks a comprehensive review over various POPs present in the environment, different techniques of their extraction and analysis, along with their toxicity in agro-ecosystem. The present review is expected to fulfills this gap by considering all the necessary aspects discussed above.

Concentrations of Per- and Polyfluoroalkyl Substances in Paired Maternal Plasma and Human Milk in the New Hampshire Birth Cohort.

Per- and polyfluoroalkyl substances (PFAS) are environmentally persistent endocrine-disrupting chemicals associated with long-term health outcomes. PFAS are transferred from maternal blood to human milk, an important exposure source for infants, and understanding of this transfer is evolving. We characterized concentrations of 10 PFAS in human milk (n = 426) and compared milk-to-plasma concentrations of 9 PFAS among a subset of women with paired samples (n = 294) from the New Hampshire Birth Cohort Study using liquid chromatography-isotope dilution tandem mass spectrometry. We examined the relationship between perfluorooctanoate (PFOA) and perfluorooctane sulfonate (PFOS) in plasma versus milk and fit linear regression models to assess relationships between milk PFOA and PFOS and participant characteristics. The median plasma PFOA concentration was 0.94 ng/mL (interquartile range, IQR, 0.59-1.34) and that of PFOS was 2.60 ng/mL (IQR 1.80-3.90); the median milk PFOA concentration was 0.017 ng/mL (IQR 0.012-0.027) and that of PFOS was 0.024 ng/mL (IQR 0.016-0.036). PFOA and PFOS plasma and milk concentrations showed correlations of ρ = 0.83 and 0.77, respectively (p < 0.001). Parity, previous lactation, week of milk collection, and body mass index were inversely associated with milk PFAS. We estimate that even among our general population cohort, some infants (∼6.5%) are exposed to amounts of PFAS via milk that may have long-term health impacts.

Can cost‐effectiveness analysis of control measures for persistent chemicals be improved? A critical evaluation of approaches for assessing “effectiveness”

AbstractPersistence, that is the ability of a chemical to accumulate in the environment over time, is a core concern triggering regulatory action under the European chemicals legislation REACH. Due to lacking quantitative information about environmental impacts and damage costs, cost‐effectiveness analysis (CEA) has been applied for evaluating the performance of regulatory control measures. Different indicators for assessing the effectiveness of a control measure have been used, (i) the expected aggregate emission reduction, (ii) the change of the environmental mass at steady‐state, and (iii) the change of the cumulative environmental stock. This paper examines the conceptual characteristics of these indicators when being used in CEA. The analysis elaborates on an illustrative example of three persistent chemicals with different intrinsic properties. We find that estimates of aggregate emission reduction and of the change of steady‐state mass misrepresent the environmental pollution burden of persistent chemicals because they ignore the time path of pollution in the environment. This can induce misleading conclusions on the relative cost‐effectiveness of control measures and can lead to an erroneous prioritization of measures. Cumulative stock estimates, while not being equivalent to quantitative risk or impact assessment, capture the time path of pollution in environmental media and, therefore, provide an approximation of the environmental impact potential of persistent chemicals. This is a prerequisite for a concern‐driven evaluation of risk‐management measures for persistent chemicals.

Mobility in the context of exposure-based assessment of chemicals for drinking water resourceprotection.

In order to protect European Union (EU) drinking water resources from chemical contamination, criteria for identifying persistent, mobile, and toxic (PMT) chemicals and very persistent and very mobile (vPvM) chemicals under the EU REACH Regulation were proposed by the German Environment Agency (Umweltbundesamt-UBA). Additionally, new hazard classes for PMT and vPvM substances in the revised EU classification, labeling, and packaging (CLP Regulation) are intended. Therefore, a reliable approach in theidentificationof potential drinking water resource contaminants is needed. The scientific basis of the property-based PMT/vPvM criteria, focusing on mobility, which dictates the migration of chemicaldrinking water sources, was evaluated, and a critical analysis of the deviation of sorption metrics from simple behavior was carried out. Based on our evaluation, a Koc may be used for nonionic substances on a screening level only, requiring a higher tier assessment. It is considered inappropriate for hydrophilic and ionizable chemicals, particularly for soils with low organic carbon contents. The nonextractable residue formation is complex and not well understood but remains significant in limiting the mobility of chemicals through soils and sediments. In order to inform the EU commission's work on the introduction of new hazard classes for PMT and vPvM substances into the European legislation, the derivation of a tiered approach is proposed,which utilizes the weight of evidence available, with adoption of appropriate higher tier models commensurate with the nature of the substance and the data available. Integr Environ Assess Manag 2023;19:775-791. © 2022 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).

Role of Substituents in the Removal of Emerging Fluorinated Liquid Crystal Monomer Pollutants under the UV/Peroxydisulfate Treatment

Fluorinated liquid crystal monomers (LCMs) have been identified as emerging persistent and bioaccumulative chemicals with non-negligible environmental concentrations. Herein, 12 fluorinated LCMs including highly detected 4-ethoxy-2,3-difluoro-4′-(trans-4-propylcyclohexyl)biphenyl (EDPB) were selected as target fluorinated LCMs to investigate their structure–reactivity relationships by the ultraviolet/peroxydisulfate (UV/PDS) treatment. EDPB with biphenyl and ethoxy showed the highest first-order degradation rate constant of 1.93 h–1, while that of fluorinated LCMs with ethoxy (1.10–1.26 h–1) and biphenyl (0.45–0.56 h–1) and without biphenyl or ethoxy (0.27–0.30 h–1) decreased sequentially. HO• and SO4•– were identified as the main oxidative species in the UV/PDS treatment. Theoretical calculation suggested that biphenyl and ethoxy can significantly alter the electron distribution of LCM molecules, providing more attackable sites for HO• and SO4•– on LCMs with biphenyl or ethoxy. Oxalic acid, cyclohexane, and bicyclohexane were the main degradation products of fluorinated LCMs even though their degradation pathways were determined by their different molecular structures. Toxicity estimation revealed that fluorinated LCMs with high acute toxicity and developmental toxicity could be decomposed into some final products with less toxicity. This study is expected to fill knowledge gaps in the structure–activity relationships of fluorinated LCMs by the UV/PDS treatment.

Mechanism involved in cell death induced by DEHP (Di-ethylhexyl phthalate) on primary brain cells from Zebrafish (Danio rerio)

Human and ecological exposure to chemical contaminants continue to increase given anthropogenic activities and sources. Phthalates are among the most persistent toxic chemicals found in aquatic systems. Phthalates belong to a family of chemical compounds that are heavily used in global manufacturing, distinguished for being able to provide durability and elasticity to plastic products, with poor water solubility and low evaporation. In terms of health impact, these compounds have been shown to breach the placental barrier having effect on human development and neurodegeneration. The main purpose of our study has been to assess the neurotoxicity of phthalates implementing the zebrafish (Danio rerio) model to determine the cell death induction of DEHP on brain cells. For many years, the zebrafish embryonic model has been used to study vertebrate development. Our study, in contrast, used adult zebrafish to resemble mature species that can be continuously exposed to low concentrations of DEHP. To assess the neurotoxicity, brain tissue from zebrafish was extracted via dissection, and primary neural cells dissociated to obtain primary cell subcultures. The neural cells where subsequently exposed to DEHP (Di-ethylhexyl phthalate) at concentrations from 10µM to 100µM for 48 hours to observe cell growth inhibition (GI50). The results indicate neural cell death at a GI50 of 62.9 µM. Apoptosis induction, caspase activation, mitochondrial membrane damage as well as autophagy cell death were analyzed to identify DEHP cell death mechanism at the GI50 concentration. In conclusion, this study clearly demonstrated that DEHP can induce apoptosis cell death on zebrafish neural brain cells in culture through the activation of an intrinsic apoptotic pathways with caspases 3 and 7 activation as well as autophagic pathway and mitochondrial damage. The presence of phthalates as well as other chemical contaminants on aquatic environments needs to be earnestly controlled in order to reduce neurotoxicity to aquatic species as well as human.

BDE-99 (2,2′,4,4′,5 - pentain polybrominated diphenyl ether) induces toxic effects in Oreochromis niloticus after sub-chronic and oral exposure

PBDEs are toxic, lipophilic, hydrophobic, and persistent artificial chemicals, characterized by high physical and chemical stability. Although PBDEs are known to disturb hormone signaling, many effects of 2,2′,4,4′,5 - pentain polybrominated diphenyl ethers (BDE-99) in fish remain unclear. The current study investigates the effects of BDE-99 in Oreochromis niloticus where sixty-four juvenile fish were orally exposed to 0.294, 2.94, 29.4 ng g−1 of BDE-99, every 10 days, during 80 days. The results showed histopathological findings in liver and kidney, increasing acetylcholinesterase activity in muscle, disturbs in the antioxidant system in liver and brain and decreasing the plasmatic levels of vitellogenin in females. According to multivariate analysis (IBR), the higher doses are related to the interaction of oxidative and non-oxidative enzymes. The present study provided evidence of deleterious effects after sub-chronic exposure of BDE 99 to O. niloticus, increasing the knowledge about its risk of exposure in fish.

The burden of emerging contaminants upon an Atlantic Ocean marine protected reserve adjacent to Camps Bay, Cape Town, South Africa

The presence and levels of fifteen chemicals of emerging concerns, including five perfluorinated compounds (PFCs), two industrial chemicals, seven pharmaceuticals and one personal care product, were evaluated in biota, seawater and sediments obtained from near-shore coastal zone in Camps Bay, Cape Town, South Africa. Eight compounds were found in seawater, and between nine to twelve compounds were quantified in marine invertebrates, sediment and seaweed. Diclofenac was the prevalent pharmaceutical with a maximum concentration of 2.86 ng/L in seawater, ≥110.9 ng/g dry weight (dw) in sediments and ≥67.47 ng/g dw in marine biotas. Among PFCs, perfluoroheptanoic acid was predominant in seawater (0.21–0.46 ng/L). Accumulation of perfluorodecanoic acid (764 ng/g dw) as well as perfluorononanoic acid and perfluorooctanoic acid (504.52 and 597.04 ng/g dw, respectively) was highest in samples of seaweed. The environmental risk assessment carried out in this study showed that although individual pollutants pose a low acute and chronic risk, yet individual compounds each had a high bioaccumulation factor in diverse marine species, and their combination as a complex mixture in marine organisms might have adverse effects upon aquatic organisms. Data revealed that this Atlantic Ocean marine protected environment is affected by the presence of numerous and diverse emerging contaminants that could only have originated from sewage discharges. The complex mixture of persistent chemicals found bioaccumulating in marine organisms could bode ill for the propagation and survival of marine protected species, since many of these compounds are known toxicants.

In silico prediction of persistent, mobile, and toxic pharmaceuticals (PMT): A case study in São Paulo Metropolitan Region, Brazil

Computational modelling (in silico) methods based on quantitative structure-activity relationship ((Q)SAR) models, are powerful tools for the assessment of the potential “persistency, mobility, and toxicity” (PMT) of pharmaceuticals compounds. Moreover, the use of (Q)SAR models, is recommended by European Union’s REACH Regulation. In this context, the aims of this research were estimating, for the first time and based by REACH guidelines, the PMT potentials of 115 most sold pharmaceuticals in São Paulo Metropolitan Region (a megacity with 21 million of Brazilian), through five (Q)SAR updated models, namely: the OPERA QSAR; the VEGA QSAR (Version 1.1.5); the EPI Suite (Version 4.11); the ECOSAR (Version, 2.0); and the QSAR Toolbox (Version 4.5). This study prioritized the in-silico predictions from the OPERA and the VEGA, because both QSARs can generate reliable predictions, i.e., they have detailed information about the applicability domains. In silico predictions were performed considering ten endpoints: (i) Molecular weight (MW); (ii) “STP total removal”: Sewage Treatment Plant; (iii) Octanol-water partition coefficient (KOW); (iv) Predicted ready biodegradability; (v) Soil organic adsorption coefficient (KOC); (vi) “Short-term and long-term ecological assessments”; (vii) “Carcinogenicity”; (viii) “Mutagenicity”; (ix) “Estrogen receptor binding”; (x) “Cramer decision tree”. The main results showed that: (a) These 115 pharmaceuticals cover a wide range of so-called small molecules (range from 100 to 600 MW); (b) In STP, a predicted removal lower than 10 % was found for 76 pharmaceuticals; (c) Additionally, 101 chemicals has low (Log KOW <2.5), or medium sorption potential (2.5< log KOW <4.0); (d) Ultimately, 36 PPCPs were considered “persistent” after a weight-of-evidence assessment. In addiction, 17 among these 36 persistent chemicals, were classified as “very mobile” in water (log KOC <3). Finally, only three among 17 PPCPs, namely ciprofibrate, fluconazole and metoclopramide, exhibited one or more toxic characteristics (described in items vi – x). These results it will be possible to alert about the potential risks arising from the indiscriminate disposal of these PPCPs along the water sources of this Brazilian mega metropolis.

BDE-47, -99, -209 and Their Ternary Mixture Disrupt Glucose and Lipid Metabolism of Hepg2 Cells at Dietary Relevant Concentrations: Mechanistic Insight through Integrated Transcriptomics and Proteomics Analysis.

Polybrominated diphenyl ethers (PBDEs) are persistent organic chemicals implied as flame retardants. Humans are mainly exposed to BDE-47, -99, and -209 congeners by diet. PBDEs are metabolic disruptors with the liver as the main target organ. To investigate their mode of action at a human-relevant concentration, we exposed HepG2 cells to these congeners and their mixture at 1 nM, analyzing their transcriptomic and proteomic profiles. KEGG pathways and GSEA Hallmarks enrichment analyses evidenced that BDE-47 disrupted the glucose metabolism and hypoxia pathway; all the congeners and the MIX affected lipid metabolism and signaling Hallmarks regulating metabolism as mTORC1 and PI3K/AKT/MTOR. These results were confirmed by glucose secretion depletion and increased lipid accumulation, especially in BDE-47 and -209 treated cells. These congeners also affected the EGFR/MAPK signaling; further, BDE-47 enriched the estrogen pathway. Interestingly, BDE-209 and the MIX increased ERα gene expression, whereas all the congeners and the MIX induced ERβ and PPARα. We also found that PBDEs modulated several lncRNAs and that HNRNAP1 represented a central hub in all the four interaction networks. Overall, the PBDEs investigated affected glucose and lipid metabolism with different underlying modes of action, as highlighted by the integrated omics analysis, at a dietary relevant concentration. These results may support the mechanism-based risk assessment of these compounds in relation to liver metabolism disruption.

Aquatic environmental fates and risks of benzotriazoles, benzothiazoles, and p-phenylenediamines in a catchment providing water to a megacity of China

Wearing of vehicle parts could release many chemical additives into the environment, such as benzotriazoles (BTRs), benzothiazoles (BTHs), and p-phenylenediamines (PPDs), which are potentially toxic to wildlife and humans. This study investigated the occurrence, source, and risks of BTRs, BTHs, and PPDs in a source catchment providing water to Guangzhou, a megacity in South China, covering groundwater, surface water, and stormwater. The results showed that BTRs and BTHs were predominant in surface water and groundwater. Unexpectedly, the BTR and BTH concentrations were lower in surface water than groundwater in a third of the paired samples. For the first time, 6PPD-quinone, a toxic ozonation product of N-(1,3-dimethylbutyl)-N′-phenyl-1,4-phenylenediamine (6PPD), was extensively detected in source waters. Stormwater decreased the BTR concentrations but increased the 6PPD-quinone concentrations in surface water owing to their affiliation to suspended particles. From natural to urban segments of Liuxi river, a downstream increasing trend in BTR and BTH concentrations was observed, confirming that they are indicative of urban anthropogenic activities. Strong correlations between industrial activities and BTR or BTH concentrations in surface water indicated that industrial activities were their main sources. Six compounds were prioritized as potentially persistent, mobile, and toxic (PMT) chemicals, combing our monitoring results and REACH criterion. This study improves our understanding of the environmental fates and risks of water-soluble tire-wear chemicals, which provides important information for chemical management, and indicates attention should be paid to the risk posed by 6PPD-quinone in the source water.

Genotoxicity assessment of per- and polyfluoroalkyl substances mixtures in human liver cells (HepG2)

Per- and polyfluoroalkyl substances (PFAS) are ubiquitous, toxic, and persistent environmental chemicals of concern that have been widely detected in all environmental matrices including human biological fluids. Although humans are exposed to complex mixtures of PFAS, it remains uncertain whether the co-exposure to PFAS mixtures could induce genotoxic damage in humans. Hence, this study evaluated the combined genotoxicity of PFAS mixtures in a human cell line system. To assess the possible genotoxic damage caused by human exposure to PFAS and their mixtures, we investigated their potential to induce cytotoxicity (cell viability) and genotoxicity (DNA damage) in a human liver cell line (HepG2). The selected PFAS include perfluorononanoic acid (PFNA), perfluorooctane sulfonic acid (PFOS), perfluorodecanoic acid (PFDA), perfluorooctanoic acid (PFOA), and perfluorohexane sulfonic acid (PFHxS). The interaction toxicities of these PFAS in binary mixtures were also determined using the additive index approach. The results revealed that exposure to PFNA, PFOS, PFDA, PFOA, and PFHxS singly and in binary mixtures induced a concentration-dependent decrease in cell viability. The additive index values indicated that the binary mixtures of PFOS + PFNA, PFOS + PFDA, and PFOS + PFOA displayed synergistic interaction, whereas the binary mixtures of PFOS + PFHxS, PFOA + PFNA, PFOA + PFDA, and PFOA + PFHxS behaved additively. Using the alkaline Comet assay, the potential of PFAS and their mixtures to induce DNA damage was evaluated based on a 1:1 ratio of the concentration of respective compounds required to produce a 1/10th of effective concentrations causing 50 % inhibition in cell viability (EC50). The results revealed that exposure to PFNA, PFOS, PFDA, PFOA, and PFHxS singly and in binary mixtures (PFOS + PFNA, PFOS + PFDA, PFOS + PFOA, PFOS + PFHxS, PFOA + PFNA, PFOA + PFDA, and PFOA + PFHxS) caused a moderate increase in cellular DNA damage, but no dose-response relationship was observed. Overall, this study indicates that the tested PFAS causes a concentration-dependent decrease in cell viability and only a modest increase in cellular DNA damage under these conditions.

Effects of vegetables and fruit with varying physical damage, fungal infection, and soil contamination on stability of aqueous ozone

The application of aqueous solutions of ozone for surface disinfection is an effective novel green technology with a potential for replacing the use of persistent chemicals in postharvest treatments. However, successful disinfection requires certain levels of ozone to be maintained throughout the process. The decay rates of aqueous ozone were found to vary with the presence of different fruit and vegetables commodities (apples, carrots, onions, celeriac, and pears). Pure aqueous ozone had a half-life of 3200 s, whereas the half-life of ozone was found to range with increasing cross-cut areas between 2177 and 291 s for apples, 573 and 345 s for carrots, 541 and 113 s for onions, 2800 and 253 s for pears, and 362 and 165 s for celeriac. With soil particles present, the ozone half-life dropped to 59 s for celeriac. Parallel measurements reported strong to moderate effect of soil particles (51–626 s, 10 g soil/L ozonated water), and naturally occurring fungi (850–2294 s, 0.25 g fungi mix/L ozonated water) on ozone half-life. In summary, presence of organic compounds, notably by damaged commodities, increase ozone decay and illustrate the need to correctly identify important ozone-depleting parameters, which is crucial for understanding the efficiency of ozone-based washing systems.

Sources of polychlorinated biphenyls to Upper Hudson River fish post-dredging

Polychlorinated biphenyls (PCBs) are persistent, bioaccumulative, and toxic chemicals that are the dominant contaminant in the Upper Hudson River (UHR) in New York State where two General Electric (GE) plants historically discharged PCBs to the river. Portions of the UHR were dredged from 2009 to 2015 to address PCB contamination. In 2017, the first post-dredging survey of yearling feeder fish and sediment PCB contamination was conducted to establish a baseline for the recovery of the river. Prior analysis of the sediment data from the 2017 survey indicated that ∼2% of the PCBs in the surface sediment were higher in molecular weight than the formulation used by GE and therefore arose from non-GE sources. In this work, the fish PCB data from the 2017 survey were analyzed using Positive Matrix Factorization (PMF). Empirical Bayesian Kriging (EBK) was used to estimate PCB concentrations in the sediment at the locations where fish were collected. The results suggest that PCBs that are the products of microbial dechlorination bioaccumulate in the fish and represent 7% of the PCB mass in the fish data set. Further, the results suggest that about 13% of the PCBs in the fish may have come from non-GE sources. This is higher than the percentage of non-GE PCBs in the sediment, but can be explained by the higher molecular weight of the non-GE mixture which causes it to bioaccumulate more effectively than GE PCBs. Concentrations of the non-GE PCBs averaged about 240 ppb wet weight (whole body) in yearling feeder fish. The remedial goals range from 50 to 400 ppb ww in fillet for fish including piscivorous species that are likely to have higher PCB concentrations than feeder fish.

Rapid determination of serum albumin partition coefficients using affinity chromatography

• Affinity chromatography is a fast alternative to determine serum albumin sorption. • Evaluation of approach with respect to differences compared to standard methods. • Comparison of chromatographic approach to LSER predictions. • Application for a large dataset of environmentally relevant chemicals. Sorption to serum albumin is essential for characterizing the distribution of chemicals in organisms. It impacts the concentration of the freely dissolved chemical in vivo and in vitro , and needs to be considered when effect concentrations at the target side are derived from nominal concentrations. Sorption to serum albumin is often characterized by the serum albumin-water partition coefficient K SA/W , which is traditionally determined using dialysis experiments. However, dialysis approaches are time-consuming and require a large amount of pure protein. Thus, we investigated affinity chromatography as a fast alternative to characterize the sorption of chemicals to serum albumin. To this end, the application of two types of serum albumin columns (bovine vs. human), different temperature settings (30°C vs. 37°C), and the impact of 2-propanol as modifier in the mobile phase were evaluated. Moreover, a linear regression model was calibrated with 49 experimentally determined log K SA/W values from the literature to predict sorption to serum albumin directly from the retention factor log k HSA . In addition, we tested a prediction approach based on linear solvation energy relationships and compared the two procedures. Further, we compiled a dataset of log k HSA values for 378 chemicals, which we classified according to their ionization state and structure, and according to environmentally relevant classes like persistent, mobile, and toxic chemicals, pesticides, and plastic additives. There was no specific trend observed for particular classes of chemicals, which means that there is a demand for determining the sorption to serum albumin for these chemicals for the correction of the effect concentration in bioassays, e.g., and to assess bioaccumulation in higher tier organisms such as fish or rodents.

Nutritional Quality and Assessment of Contaminants in Farmed Atlantic Salmon (Salmo salar L.) of Different Origins

Atlantic salmon represents an important source of valuable proteins and lipids rich in n-3 fatty acids and micronutrients. However, there are reports that these marine fish still contain contaminants at levels that raise health concerns. Although the Stockholm Convention already bans some compounds, they can still be detected because of their persistence. The present study reports nutritional parameters and the occurrence of persistent and bioaccumulative chemicals in the tissues of fifty-five salmon from several major farming areas. The protein content of all samples was almost identical, averaging to 19.2% w/w, while lipids averaged 14.9% w/w. Fish from Chilean farms contained 6.0% less fat and a lower level of vitamin E than from other sources, that is, 2.2 mg per 100 g (w/w). Fish from Scottish farms contained higher levels of eicosapentaenoic and docosahexaenoic acid. Halogenated contaminants from polychlorinated biphenyls, organochlorinated pesticides, brominated flame retardants, and perfluoroalkylated and polyfluoroalkylated substances were measured, and generally, they were found to be at very low concentrations that did not exceed the legislation limits applicable in the European Union. These results showed that the compositional differences between Atlantic salmon from several important farming areas were only minor, but some significant differences were demonstrated in total fat content and fatty acid profiles.

Mixtures of persistent and non-persistent chemicals and associations with pregnancy outcomes in the Atlanta African American Maternal Child Cohort

Mixtures of persistent and non-persistent chemicals and associations with pregnancy outcomes in the Atlanta African American Maternal Child Cohort

Serum half-life of PFOA after end of exposure: a highly exposed community in the Veneto Region

Background and aim. Perfluoroalkyl substances (PFAS) are widely used, ubiquitous and highly persistent man-made chemicals. Groundwater of a vast area of the Veneto Region (North-Eastern Italy) was found to be contaminated by PFAS from a manufacturing plant active since the late 1960s. As a result, residents were exposed to PFAS through drinking water until autumn 2013. The aim of the present study was to estimate the decline rates in serum PFAS, and their corresponding serum half-lives, while characterizing their determinants. Methods. The population investigated in this study is a subgroup of the Regional health surveillance program target population consisting of subjects who enrolled in the second surveillance wave (n=2,619). The two blood samples were collected between January 2017 and December 2021. Four of the twelve measured PFAS were detected in greater than 50% of participants: PFOA (100%), PFOS (99.89%), PFHxS (99.01%) and PFNA (61.82%). Serum PFAS excretion rates and half-lives were estimated based on linear mixed effect models, adjusting for a set of contributing factors on PFAS pharmacokinetics such as age, sex, BMI, smoke-habit and eGFR. Results. Median initial serum concentrations were 62.6 ng/mL for PFOA, (range:0.6-1064), 4.6 ng/mL (range:0.5-142) for PFOS, 4.9 ng/mL (range:0.5-109.2) for PFHxS and, 0.6 (range:0.5-0.8) PFNA, with median declines of 61.18%, 36.96%, 40.82% and 41.67%, respectively. The median estimated PFOA’s half-life was 2.90 years (95%CI:2.83-2.95). We found suggestive evidence that half-lives varied when stratified by gender and tertile of exposure, with more rapid elimination in men and higher tertiles of exposure. Conclusions. Drinking water was the dominant route of exposure for PFOA so this study, the largest on PFOA half-life, offers great potential for studying interactions and risk modifications. Other PFAS longer half-lives than reported in other studies might be due to ongoing exposure to PFAS via other routes. Keywords. perfluoroalkyl substances; contaminated water; half-life.

Prenatal exposure to mixtures of replacement flame retardant chemicals and children’s neuro-behavioral outcomes in a sample of children from socioeconomically disadvantaged communities

BACKGROUND. Organophosphate ester flame retardants (OPFRs) are persistent organic chemicals that are commercially applied to a wide variety of consumer products including electronics, building materials, foam-based furniture and children’s clothing that have individually been shown to adversely impact neurodevelopmental outcomes including hyperactivity symptoms, working memory, IQ and depressive symptoms. METHODS. We quantified nine prenatal OPFR urinary metabolites [DPHP, DNBP+DIBP, BDCIPP, BCEP, BBOEP, BCIPP, BMPP, BEHP and DPRP] by HPLC-MS/MS in samples from participants in the MADRES cohort--an ongoing pregnancy cohort in urban Los Angeles. Detection frequencies ranged from 99.8% for DPHP to 24.2% for DPRP. Specific-gravity adjusted OPFR metabolites detected in 60% or greater samples [DPHP, DNBP+DIBP, BDCIPP, BCEP, and BBOEP] were modeled continuously and log transformed, and values &amp;#x2264; LOD were imputed as LOD/√2. The remaining four metabolites were modeled as detect/non-detect [BCIPP, BMPP, BEHP, and DPRP]. We assessed prenatal OPFR exposure associations with neurodevelopmental outcomes from the Child Behavior Checklist 1.5/5 in 151 predominantly Hispanic/Latino (~78%) children at age 3 years. RESULTS. We found significant associations between several OPFR metabolite concentrations and neurobehavioral outcomes in single metabolite adjusted models [e.g., a 10% increase in DNBP+DIBP concentration was associated with a 3.3% (95% CI 0.02%-6.49%) increase in internalizing symptoms score and a 4.8% (0.82%-8.95%) increase in DSM pervasive symptoms score]. However, exposure to a particular compound does not occur in isolation; thus it is critical that multiple exposures be considered jointly in human studies. We will discuss various analytical approaches to quantify the effects of environmental mixtures and apply them to understand multiple OPFR chemical exposure effects on early childhood neurobehavioral outcomes in a highly exposed, socioeconomically disadvantaged population. CONCLUSIONS. The application of mixtures methods will yield important insight into the conditional associations of co-exposures and enhance health risk assessment for child neurodevelopmental outcomes. KEYWORDS. Neurodevelopment, children, chemical mixtures

A recent overview of per- and polyfluoroalkyl substances (PFAS) removal by functional framework materials

Per- and polyfluoroalkyl substances (PFAS) are a class of toxic and bioaccumulative compounds affecting environmental and human health. Conventional wastewater treatment processes are ineffective at remediating these persistent chemicals. While functional framework materials have been shown to remove PFAS via adsorption and catalytic degradation, there is an on-going debate about their practical use in water purification. Inspired by recent research on typical functional framework materials, including zeolites, metal-organic frameworks (MOFs), and covalent organic frameworks (COFs), our review summarizes the principles of their design, properties, and applications with a special emphasis on PFAS removal. The potential of framework material for catalytic degradation of PFAS is constructively discussed, based on limited studies thus far. Finally, the challenges of using framework materials to remove and degrade PFAS in wastewater are presented along with sustainable design prospects to improve the technology. The current review provides new insights in advancing framework materials for PFAS elimination from contaminated waters.