Geology topics

Di Fang

Publications and source records attributed to Di Fang.

4 recordsLinked to original sources

USGS2025

Risks of per- and polyfluoroalkyl substance exposure through marine fish consumption

Global food trade expansion has enriched diets worldwide but also heightened concerns about contaminant spread. Per- and polyfluoroalkyl substances (PFAS) can persist in the environment for decades, yet their risks through food trade remain unclear. The global median estimated daily intake (EDI) of C8-PFAS (perfluorooctanoic acid and perfluorooctane sulfonate) (0.023 nanograms per kilograms per day) was mapped from 212 marine fish species, which indicated higher EDIs in North America, Oceania, and Europe. Furthermore, European countries play a pivotal role in C8-PFAS trade flows, markedly reshaping exposure pathways and driving increased exposure in many nations. These dynamics highlight the importance of establishing food-safety regulations and international trade standards. Although perfluorooctane sulfonate hazard index decreased by 72% after its 2009 regulations, unregulated long-chain PFAS continue to pose elevated risks.

Science↗

USGS2025

Perfluorodecanoic acid (PFDA) disrupts immune regulation via the toll-like receptor signaling pathway in zebrafish

As there are a growing number of per- and polyfluoroalkyl substances (PFAS) alternative substitutes applied globally, it remains paramount to characterize their potential health risks. Perfluorodecanoic acid (PFDA) is the most common alternative PFAS detected in the environment; however, its toxic effects and underlying mechanism of action to aquatic biota remains unclear. In this study, we present in vitro evidence of PFDA-induced immunotoxicity and gain insight into underlying molecular mechanisms. PFDA induced immune dysfunction in zebrafish primarily through immunosuppression, apoptosis, and inflammatory response which further cascaded to suppress innate and adaptive immunities, ultimately weaking the ability of larvae to defend against pathogenic infection. PFDA-induced immunotoxicity was driven by a dysregulation in the toll-like receptor (TLR) signaling pathway, which was validated through a cotreatment of PFDA with either a morpholino knockdown or inhibitor of myeloid differentiation factor 88. Comparative toxicity studies were carried out with a subset of other alternative PFAS (PFBA, PFOA, PFNA) and it was found that PFDA posed a greater immunotoxic response than other commonly identified PFAS in the environment. This work identified a major target of PFDA, disrupting immune function through the TLR signaling pathway, while inducing a greater toxic response among other tested PFAS, which provides novel insights into understanding the potential environmental risks of PFAS substitutes.

Environmental Science & Technology↗

USGS2025

Perfluorodecanesulfonate (PFDS) induces innate immune toxicity through the NF-κB pathway in early life stage zebrafish

Perfluorodecanesulfonate (PFDS), a long-chain polyfluoroalkyl substance (PFAS), is widely detected in aquatic environments and increasingly recognized for its environmental persistence and bioaccumulative potential; however, its immunotoxicity remains poorly understood in aquatic biota. In this study, early life stage zebrafish ( Danio rerio ) were exposed to environmentally relevant concentrations of PFDS and PFOS for 120 h to better characterize the adverse effects of PFDS on aquatic organisms. Additionally, the toxicological differences between PFDS and PFOS at the same exposure concentrations were compared, as PFDS is a known substitute for PFOS. PFDS bioaccumulated in zebrafish larvae at environmentally relevant concentrations, which disrupted immune function by altering the number of macrophages and neutrophils, inducing oxidative stress, and dysregulating immune markers such as interleukins and immunoglobulins. Mechanistically, PFDS activated the nuclear factor kappa B (NF-κB) signaling pathway, driving pro-inflammatory cytokine expression and immune dysfunction. Furthermore, the use of a NF-κB morpholino knockdown confirmed the role of the NF-κB pathway in mediating PFDS-induced immunotoxicity. These findings provide the first comprehensive evidence of PFDS-induced immunotoxicity being mediated through NF-κB activation, offering novel insights into the ecological risks of long-chain perfluorosulfonic acids. Notably, PFDS exhibited a stronger immunotoxic response relative to PFOS, indicating that its adverse effects may be more severe. Overall, these findings provide valuable insights for the ecological risk assessment of PFDS and the toxic potential that unregulated PFAS can have to aquatic systems.

Environment International↗

USGS2024

A universal method for the simultaneous determination of environmental pollutants in marine biological samples: Per- and polyfluoroalkyl substances and antibiotics as a case study

Conventional detection technologies for environmental contaminants have primarily focused on providing accurate qualitative and quantitative evaluations for single pollutant types, leading to increased costs and an inability to satisfy the growing demand for detecting a broader spectrum of pollutants. Here, we introduced a novel analytical method to simultaneously measure the concentration levels of diverse environmental pollutants, characterized by their distinct properties, across complex biological samples. Per- and polyfluoroalkyl substances (PFAS) and antibiotics were used as a case study due to their frequency of detection in the environment and known impacts Our method harnesses the salting-out effect of sodium chloride on proteins within the muscle tissues of 178 marine species, which significantly reduces the addition of extraneous substances, mitigates matrix interference, and avoids reliance on solid-phase extraction or dispersive extraction agents. The method provides a simultaneous pretreatment for the detection of several compounds, with detection limits from 0.002 to 0.41 ng/g dry weight, which are substantially lower than conventional methods. Overall, this method streamlines efficiency, decreases costs, lessens matrix effects, and sets a solid groundwork for future applications in the concurrent detection of a broader spectrum of environmentally pertinent pollutants with varied characteristics.

ACS ES&T Water↗