@article {290,
	title = {Synthesis and Toxicity Evaluation of -Phenylenediamine-Quinones.},
	journal = {Environ Sci Technol},
	year = {2025},
	month = {2025 Apr 08},
	abstract = {<p>-(1,3-Dimethylbutyl)--phenyl--phenylenediamine-quinone (6PPD-Q), the tire rubber-derived transformation product of 6PPD, was recently discovered to cause the acute mortality of coho salmon (). Aiming to identify potential replacement antiozonants for 6PPD that do not produce toxic quinones, seven PPD-quinones with distinct side chains were synthesized to investigate their structure-related toxicities using rainbow trout (). While 6PPD-Q exerted high toxicity (96 h LC = 0.35 μg/L), toxicity was not observed for six other PPD-quinones despite their similar structures. The fish tissue concentrations of 6PPD-Q after sublethal exposure (0.29 μg/L) were comparable to the other PPD-quinones, which indicated that bioaccumulation levels were not the reason for the selective toxicity of 6PPD-Q. Hydroxylated PPD-quinones were detected as the predominant metabolites in fish tissue. Interestingly, a single major aromatic hydroxylation metabolite was detected for the alternate PPD-quinones, but two abundant OH-6PPD-Q isomers were detected for 6PPD-Q. MS spectra confirmed that hydroxylation occurred on the alkyl side chain for one isomer. The structurally selective toxicity of 6PPD-Q was also observed in a coho salmon (CSE-119) cell line, which further supports its intrinsic toxicity. This study reported the selective toxicity of 6PPD-Q and pinpointed the possibility for other PPDs to be applied as potential substitutes of 6PPD.</p>},
	issn = {1520-5851},
	doi = {10.1021/acs.est.4c12220},
	author = {Nair, Pranav and Sun, Jianxian and Xie, Linna and Kennedy, Lisa and Kozakiewicz, Derek and Kleywegt, Sonya M and Hao, Chunyan and Byun, Hannah and Barrett, Holly and Baker, Joshua and Monaghan, Joseph and Krogh, Erik T and Song, Datong and Peng, Hui}
}
@article {268,
	title = {Unique hepatic maternal transfer pattern of trace metals and perfluoroalkyl substances (PFAS) in a bluntnose sixgill shark (Hexanchus griseus).},
	journal = {Chemosphere},
	volume = {359},
	year = {2024},
	month = {2024 May 10},
	pages = {142315},
	abstract = {<p>The fate and distribution of environmental contaminants includes bioaccumulation within marine organisms. A deceased 4-m long adult female bluntnose sixgill shark, pregnant with 72 pups, was recovered from Coles Bay on Vancouver Island, BC, Canada in 2019. This specimen provided a unique opportunity to examine maternal transfer of contaminants in a yolk-sac viviparous shark species. Liver subsamples of the adult and offspring were analyzed for 18 targeted inorganic elements by inductively coupled plasma optical emission spectroscopy (ICP-OES) and 21 targeted perfluoroalkyl substances (PFAS) by liquid chromatography-electrospray ionization-high resolution mass spectrometry (LC-ESI-Orbitrap MS). The maternal-offspring transfer efficiencies in liver tissue were subsequently examined for both contaminant classes. Concentrations of all detectable metals apart from calcium and magnesium were found to be higher in the mother compared to the offspring, including substantial levels of toxic cadmium (6\&nbsp;{\textpm}\&nbsp;2\&nbsp;mg\&nbsp;kg dw) and lead (7\&nbsp;{\textpm}\&nbsp;3\&nbsp;mg\&nbsp;kg dw). Conversely, high maternal transfer efficiencies were observed for PFAS (i.e., ΣPFAS\&nbsp;=\&nbsp;71\&nbsp;{\textpm}\&nbsp;9\&nbsp;ng\&nbsp;g ww in offspring compared to 13\&nbsp;{\textpm}\&nbsp;9\&nbsp;ng\&nbsp;g ww in the mother). This study highlighted the unique maternal transfer characteristics of PFAS in bluntnose sixgill sharks depending on the structure of the polar head group, with greater liver-to-liver transfer efficiencies observed for perfluorocarboxylic acids (PFCAs) than perfluorosulfonic acids (PFSAs) of the same fluorocarbon chain length.</p>},
	issn = {1879-1298},
	doi = {10.1016/j.chemosphere.2024.142315},
	author = {Zvekic, Misha and Barrett, Holly and Diamente, Peter and Peng, Hui and Krogh, Erik T}
}
