Newspapers and Newspaper Ink Contain Agonists for the Ah Receptor.
Department of Environmental Toxicology, University of California, Davis 95616.
Ligand dependent activation of the aryl-hydrocarbon receptor (AhR) pathway leads to a diverse array of biological and toxicological effects. The best studied ligands for the AhR include polycyclic and halogenated aromatic hydrocarbons, the most potent of which is 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). However, as new AhR ligands are identified and characterized, their structural and physiochemical diversity continues to expand. Our identification of AhR agonists in crude extracts from diverse materials raises questions as to the magnitude and extent of human exposure to AhR ligands through normal daily activities. We have found that solvent extracts of newspapers from countries around the world stimulate the AhR signaling pathway. AhR agonist activity was observed for DMSO, ethanol, and water extracts of printed newspaper, unprinted virgin paper, and black printing ink, where activation of luciferase reporter gene expression was transient, suggesting that the AhR active chemical(s) was metabolically labile. DMSO and ethanol extracts also stimulated AhR transformation and DNA binding, and also competed with [(3)H]TCDD for binding to the AhR. In addition, DMSO extracts of printed newspaper induced cytochrome P450-1A (CYP1A) associated 7-ethoxyresorufin-O-deethylase (EROD) activity in zebrafish embryos in vivo. While the responsible bioactive chemical(s) remain to be identified, our results demonstrate that newspapers and printing ink contain relatively potent metabolically labile agonists of the AhR. Given the large amount of recycling and re-processing of newspapers throughout the world, release of these easily extractable AhR agonists into the environment should be examined and their potential effects on aquatic organisms assessed. (244 words).
PMID: 18203687 [PubMed - as supplied by publisher]
http://www.ncbi.nlm.nih.gov/pubmed/18203687?dopt=AbstractPlus
