Publications by authors named "Carla A Ng"

Per- and polyfluoroalkyl substances (PFAS) are synthetic chemicals used extensively across industries, including semiconductor manufacturing. Semiconductors are ubiquitous, and there is increasing global demand for semiconductors, e.g.

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Per- and polyfluoroalkyl substances (PFASs) are a class of synthetic organic chemicals of global concern. A group of 36 scientists and regulators from 18 countries held a hybrid workshop in 2022 in Zürich, Switzerland. The workshop, a sequel to a previous Zürich workshop held in 2017, deliberated on progress in the last five years and discussed further needs for cooperative scientific research and regulatory action on PFASs.

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Article Synopsis
  • PFAS (per- and polyfluoroalkyl substances) are harmful environmental pollutants that have not been extensively studied in low- and middle-income countries like Samoa; this study aimed to investigate their presence in infants' blood.
  • The research analyzed blood samples from infants at birth and 4 months old, finding 19 PFAS in cord blood and 12 in dried blood spots, with notable associations to factors like sex, maternal age, and socio-economic status.
  • Results indicated that PFAS levels were generally lower than in other reported studies, except for one type (PFHxS), while feeding practices also influenced PFAS concentrations, showing higher levels in formula-fed infants compared to those who were exclusively breastfed.
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Article Synopsis
  • PFAS (Per- and polyfluoroalkyl substances) are long-lasting environmental contaminants linked to health risks, but research on their effects in low- and middle-income countries like Samoa is limited.
  • A study analyzed 40 PFAS compounds in infant cord blood from 66 newborns and dried blood samples from 50 infants at four months old, finding that 19 PFAS were present in cord blood and 12 in dried blood.
  • The study revealed associations between PFAS concentrations and factors like sex, socioeconomic status, and feeding methods, marking the first evidence of PFAS contamination in Samoa and highlighting the need for further research on its health impacts.
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Catchment discretization plays a key role in constructing stormwater models. Traditional methods usually require aerial or topographic data to manually partition the catchment, but this approach is challenging in areas with poor data access. Here, we propose an alternative approach, by drawing Thiessen polygons around sewer nodes to construct a sewershed model.

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As demand for sustainable marine aquaculture (mariculture) and marine food supply surges worldwide, there is a growing need for new tools to assess mariculture impacts on local ecosystems, including the cycling of toxic organic contaminants. With this in mind, we developed the Contaminant Fate in Aquaculture-Modified Ecosystems (CFAME) model. The current model was designed to explore the fate of mariculture-derived organic contaminants in the Marlborough Sounds, New Zealand, known for its Chinook salmon farming industry.

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Physiologically based pharmacokinetic (PBPK) modeling is a powerful technique to inform risk assessment of xenobiotic substances such as perfluorooctanoic acid (PFOA). In our previous study, a permeability-limited PBPK model was developed to simulate the toxicokinetics and tissue distribution of PFOA in male rats. However, due to limited information on some key model parameters (, protein binding and active transport rates), the uncertainty of the permeability-limited PBPK model was quite high.

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  • Polycyclic aromatic hydrocarbons (PAHs) are environmental contaminants that can stay in the environment for a long time and may degrade into numerous harmful products, increasing their mutagenicity.
  • Microbial degradation is the main process that helps break down these compounds, but it can also create new mutagenic substances similar to those found in living organisms.
  • A novel machine learning approach combining clustering and regression techniques provides improved predictions of mutagenic potential for PAH transformation products, offering better tools for hazard assessment and remediation efforts.
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Per- and polyfluoroalkyl substances (PFAS) are a class of substances for which there are widespread concerns about their extreme persistence in combination with toxic effects. It has been argued that PFAS should only be employed in those uses that are necessary for health or safety or are critical for the functioning of society and where no alternatives are available ("essential-use concept"). Implementing the essential-use concept requires a sufficient understanding of the current uses of PFAS and of the availability, suitability, and hazardous properties of alternatives.

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  • The essential-use concept helps to phase out harmful substances like PFAS by evaluating whether their use is truly necessary.
  • To determine essentiality, three key factors are considered: the chemical's function, its necessity for health and safety, and the availability of alternatives.
  • This approach shifts chemicals management from addressing substances individually to assessing groups of chemicals, making it a faster and more effective method for regulation and elimination.
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Per- and polyfluoroalkyl substances (PFAS) have been found to be associated with gestational diabetes mellitus (GDM) development, a maternal health disorder in pregnancy with negative effects that can extend beyond pregnancy. Studies that report on this association are difficult to summarize due to weak associations and wide confidence intervals. One way to advance this field is to sharpen the biologic theory on a causal pathway behind this association, and to measure it directly by way of molecular biomarkers.

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Per- and polyfluoroalkyl substances (PFAS) are a class of synthetic organic substances with diverse structures, properties, uses, bioaccumulation potentials and toxicities. Despite this high diversity, all PFAS are alike in that they contain perfluoroalkyl moieties that are extremely resistant to environmental and metabolic degradation. The vast majority of PFAS are therefore either non-degradable or transform ultimately into stable terminal transformation products (which are still PFAS).

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Per- and polyfluoroalkyl substances (PFAS) are of concern because of their high persistence (or that of their degradation products) and their impacts on human and environmental health that are known or can be deduced from some well-studied PFAS. Currently, many different PFAS (on the order of several thousands) are used in a wide range of applications, and there is no comprehensive source of information on the many individual substances and their functions in different applications. Here we provide a broad overview of many use categories where PFAS have been employed and for which function; we also specify which PFAS have been used and discuss the magnitude of the uses.

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Article Synopsis
  • Fluoropolymers, part of the PFAS group, have significant environmental and health concerns linked to their entire life cycle due to toxic processing aids and emissions during production.
  • Concerns arise from the adverse effects of various PFAS emitted during manufacturing, usage, and disposal, with limited recycling options for consumer products.
  • The analysis emphasizes that fluoropolymers pose a risk to human health and the environment, suggesting their production should be limited to essential applications only.
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Polycyclic aromatic hydrocarbons (PAHs) are a diverse group of environmental contaminants released during the combustion of organic materials and the production and utilization of fossil fuels. Once released, PAHs deposit in soil and water bodies where they are subjected to environmental transport and transformations. As they degrade, intermediate transformation products may play an important role in their environmental impact.

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Grouping strategies are needed for per- and polyfluoroalkyl substances (PFAS), in part, because it would be time and resource intensive to test and evaluate the more than 4700 PFAS on the global market on a chemical-by-chemical basis. In this paper we review various grouping strategies that could be used to inform actions on these chemicals and outline the motivations, advantages and disadvantages for each. Grouping strategies are subdivided into (1) those based on the intrinsic properties of the PFAS (e.

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More than 1000 per- and polyfluoroalkyl substances (PFASs) have been discovered by nontarget analysis (NTA), but their prioritization for health concerns is challenging. We developed a method by incorporating size-exclusion column co-elution (SECC) and NTA, to screen PFASs binding to human liver fatty acid binding protein (L-FABP). Of 74 PFASs assessed, 20 were identified as L-FABP ligands in which eight of them have high binding affinities.

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A recent OECD report estimated that more than 4000 per- and polyfluorinated alkyl substances (PFASs) have been produced and used in a broad range of industrial and consumer applications. However, little is known about the potential hazards (e.g.

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Perfluorooctane sulfonate (PFOS) is a member of the anthropogenic class of perfluorinated alkyl acids (PFAAs) and one of the most frequently detected PFAAs in water, humans, mammals, and fish around the world. The zebrafish (Danio rerio) is a small freshwater fish considered an appropriate vertebrate model for investigating the toxicity of compounds. Previous investigations showed tissue-specific bioaccumulation and alterations in the expression of fatty acid-binding proteins (fabps) in male and female zebrafish, potentially due to interactions between PFAA and fatty acid transporters.

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Because of the extreme persistence of per- and polyfluoroalkyl substances (PFASs) and their associated risks, the Madrid Statement argues for stopping their use where they are deemed not essential or when safer alternatives exist. To determine when uses of PFASs have an essential function in modern society, and when they do not, is not an easy task. Here, we: (1) develop the concept of "essential use" based on an existing approach described in the Montreal Protocol, (2) apply the concept to various uses of PFASs to determine the feasibility of elimination or substitution of PFASs in each use category, and (3) outline the challenges for phasing out uses of PFASs in society.

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Correction for 'Why is high persistence alone a major cause of concern?' by Ian T. Cousins et al., Environ.

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Persistence is a hazard criterion for chemicals enshrined in chemical regulation worldwide. In this paper, we argue that the higher the persistence of a chemical, the greater the emphasis that it should be given in chemicals assessment and decision making. We provide case studies for three classes of highly persistent chemicals (chlorofluorocarbons, polychlorinated biphenyls, and per- and polyfluoroalkyl substances) to exemplify problems unique to highly persistent chemicals, despite their otherwise diverse properties.

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  • A population-based bioaccumulation fugacity model is created to simulate how polychlorinated bisphenols (PCBs) move and accumulate in aquatic environments.
  • This model builds on earlier research, focusing on each species in the ecosystem as a separate part and mapping out how they interact with each other and their environment.
  • By using PCB loading as an input, the model provides a comprehensive view of how PCBs are distributed across different organisms and environmental compartments.
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Organisms have long been treated as receptors in exposure studies of polychlorinated biphenyls (PCBs) and other persistent organic pollutants (POPs). The influences of environmental pollution on organisms are well recognized. However, the impact of biota on PCB transport in an environmental system has not been considered in sufficient detail.

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With the phasing out of long-chain per- and polyfluoroalkyl substances (PFASs), production of a wide variety of alternative PFASs has increased to meet market demand. However, little is known about the bioaccumulation potential of these replacement compounds. Here, we developed a modeling workflow that combines molecular docking and molecular dynamics simulation techniques to estimate the relative binding affinity of a total of 15 legacy and replacement PFASs for human and rat liver-type fatty acid binding protein (hLFABP and rLFABP).

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