Hyo-Bang Moon

Organ-on-a-chip technology can improve human relevance in toxicity testing. However, meeting toxicological evaluation requirements remains challenging, particularly with respect to controlled flow dynamics, usability, and biological replicates. We present a modular, tubing-free liver-on-a-chip platform with a clamping cartridge and software-controlled recirculation that enables 12 parallel channels and reproducible recirculating concentrations. Using the hepatotoxic chemical triphenyl phosphate, the platform enhanced hepatic function compared with static culture, showing higher cytochrome P450 1A2, 3A4, and 2E1 mRNA expression and increased metabolite formation. Exposure to 10 μM triphenyl phosphate altered urea, lactate dehydrogenase, and aspartate aminotransferase levels with responses occurring at lower measured concentrations on-chip than in plate-based cultures. RNA sequencing revealed pathway-level perturbations consistent with triphenyl phosphate-induced hepatotoxicity, including spliceosome and inflammatory signaling pathways. These results demonstrate advances in the toxicological application of organ-on-a-chip platforms, improving toxicity assessment through enhanced flow fidelity and parallel biological replicates.

Following the global and domestic regulations on brominated flame retardants (BFRs), including polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecanes (HBCDDs), novel halogenated flame retardants (HFRs) have been introduced in industrial markets. Legacy and alternative HFRs, such as PBDEs, HBCDDs, novel BFRs (NBFRs), and dechlorane plus, were measured in sediment and bivalves collected from 50 locations along the Korean coast to investigate geographic distribution, contamination sources, and ecological risks. All HFRs were detected in sediment and bivalves, with the highest contamination spots close to industrial complexes, harbors, and aquaculture farms. A shift in HFR usage was observed in bivalves, characterized by the replacement of octa-BDE with 1,2-bis (2,4,6-tribromophenoxy) ethane and deca-BDE with decabromodiphenyl ethane. This trend suggests a clear transition toward the use of alternative HFRs. BDE 47 and α-HBCDD exhibited a biota-sediment accumulation factor exceeding 1, indicating bioaccumulation potential from sediment-associated exposure. Temporal trends between 2004 and 2019 showed a decline in PBDE contamination in sediment and an increase in bivalves, with deca-BDE remaining dominant. The ecological risks of PBDEs and HBCDDs were generally low, though high localized concentrations of BDE 209 posed significant ecological risks in certain coastal regions.

As of 2024, South Korea accounts for approximately 33% of the global display market; however, the environmental occurrence, bioaccumulation, and ecological risks of organic compounds associated with the display industry remain poorly understood. This study investigated the occurrence of display-related organic compounds (DROCs) in sediments from Asan Bay and four adjacent artificial lakes, as well as in freshwater fish collected seasonally from Lake Asan, Korea, and identified priority pollutants. Target compounds included 15 liquid crystal monomers and one organic light-emitting material, quantified using gas chromatography-tandem mass spectrometry (GC-MS/MS). Mean DROC concentrations were 5.8 ng g^–1 dry mass (dm) in artificial lakes and 4.7 ng g^–1 dm in Asan Bay. Benzo[b]anthracene (BbA, 0.56 ng g^–1 dm) exhibited the highest median concentration. Dilution factor analysis revealed that BbA and 4′-hexyloxy-4-biphenylcarbonitrile (6OCB) showed high mobility from freshwater to marine environments. Hazard quotient analysis identified 4,4′-bis(4-propylcyclohexyl)biphenyl (BPCHB) as the primary contributor to predicted ecological risk. DROC concentrations in fish declined seasonally from 860 ng g^–1 lipid mass (lm) in April to 65 ng g^–1 lm in October. Concentrations of all DROCs in fish decreased with increasing trophic position. Multicriteria decision analysis, based on the results of this study, identified BbA, BPCHB, and 6OCB as priority pollutants. These findings provide new insights into the environmental behavior of DROCs and inform their prioritization for environmental management in a global display manufacturing hotspot.

Citrate-based plasticizers such as acetyl tributyl citrate (ATBC) and acetyl triethyl citrate (ATEC) are alternatives to phthalates, yet human exposure data remain scarce. ATBC and ATEC are metabolized to acetyl dibutyl citrate (ADBC) and acetyl diethyl citrate (ADEC), which represent relatively specific biomarkers of their respective parent compounds, whereas dibutyl citrate (DBC) and diethyl citrate (DEC) may reflect combined exposure to multiple acetylated and nonacetylated citrate plasticizers and therefore have lower specificity. This study analyzed household dust (n = 47) and urine (n = 363) from 121 participants across three seasons to characterize population-level exposure. In dust, four parent plasticizers, including ATBC, ATEC, tributyl citrate (TBC), and triethyl citrate (TEC) were quantified, with ATBC detected in 37% of samples and concentrations reaching 93.98 μg/g (95th percentile). Four urinary metabolites, ADBC, DBC, ADEC, and DEC, were quantified. In urine, DBC and DEC were detected in over 70% of samples. Mixed-effects modeling showed a significant association between urinary ADBC and DBC, consistent with a shared metabolic pathway. The median estimated daily intake of ATBC from dust ingestion and dermal contact was 0.50 ng/kg bw/day, several thousand times lower than the European Food Safety Authority tolerable daily intake, indicating negligible risk. These findings provide integrated environmental and biomonitoring evidence of human exposure to citrate plasticizers and highlight the need for continued toxicological evaluation.

Few studies have been conducted on the accumulation of chlorinated, brominated, and fluorinated contaminants in sea turtles. In this study, legacy and emerging persistent organic pollutants (POPs) were measured in various organs and tissues of loggerhead ( Caretta caretta) and green ( Chelonia mydas) sea turtles obtained via stranding or bycatch along the Korean coast. All POPs were detected in organs and tissues of both turtle species. The detected concentrations of all POPs were higher in loggerhead sea turtles than green sea turtles, indicating that trophic level consistently affects POP accumulation. Chlorinated and brominated contaminants primarily accumulated in fat and muscle, whereas PFASs were concentrated in the liver. Longer-chain carboxylates, and F-53B (a PFOS alternative) were found in turtles, indicating growing concern as emerging PFASs. To our knowledge, this report is the first to estimate the body burden of POPs in sea turtles.

Bisphenol A (BPA) has been widely used in various paper products, particularly as a color developer in thermal receipts. Growing concerns about its toxicity have prompted the introduction of other bisphenols as alternatives. This study investigated the occurrence and residue levels of BPA and its analogues in thermal paper receipts ( n = 120) and other paper products ( n = 32) collected in Korea in 2015, with a particular focus on business-type-specific differences during an early phase of BPA substitution. BPA was the dominant compound in most receipts, while bisphenol S (BPS) was the most common substitute in “BPA-free” labeled receipts. Total concentrations of bisphenol analogues in thermal receipts were 2–4 orders of magnitude higher than those in other paper products. Multivariate analysis identified distinct compositional clusters associated with different color developers. Large retail chains showed a higher prevalence of BPS-based receipts, whereas small local stores predominantly relied on BPA-based thermal papers, indicating business-type-specific differences in substitution timing. Dermal exposure estimates indicated that occupational groups, particularly workers in small local stores, experienced substantially higher exposure than the general population. Estimated BPA intakes via paper handling exceeded the revised tolerable daily intake proposed by the European Food Safety Authority, highlighting the need for comprehensive exposure assessments of bisphenol analogues, especially in occupational settings.