Occurrence and estrogenicity of phenolics in paper-recycling process water: pollutants originating from thermal paper in waste paper.

Eight phenolics were detected in samples collected from areas where paper-recycling process water is discharged. The detected concentration levels were up to 270 microg/L and 230 microg/g in water samples and sediment samples, respectively, obtained from both the outfall of the paper-recycling process water and its downstream areas. In particular, totarol (compound 4), 2,4-bis(1-phenylethyl)phenol (compound 6), 4,4'-butylidenebis(6-t-butyl-m-cresol) (compound 7), 2,4-bis(1-phenylethyl)-6-chlorophenol (compound 8), and 4-hydroxy-4'-isopropoxydiphenyl sulfone (compound 9) were identified for the first time as environmental pollutants. The estrogenicities of the identified compounds were assessed by yeast two-hybrid assays incorporating either the human or medaka fish (Oryzias latipes) estrogen receptor alpha (hERalpha and medERalpha, respectively) and an estrogen receptor competitive enzyme-linked immunosorbent assay (ER-ELISA) both with and without metabolic activation by a rat liver S9 mix. Bisphenol A (compound 3) and 2-naphthol (compound 1) exhibited activity in the assays of both hERalpha and medERalpha without the S9 mix. The relative activity (%) to 17beta-estradiol was 0.0015% for compound 3 and 0.0009% for compound 1 in the hERalpha assay and 0.027% for compound 3 and 0.0093% for compound 1 in the medERalpha assay. These compounds were attenuated by the S9 mix. The binding affinity was evaluated using an ER-ELISA. Compounds 3, 4, 6, and 7 exhibited affinity without the S9 mix. After exposure to the S9 mix, however, the binding affinity of compound 7 was eliminated by the S9 mix; those of compounds 3, 4, and 6 were attenuated; and that of compound 8 exhibited affinity. A comprehensive assessment of the estrogenicities of the phenolics originating from thermal paper and their implications for an aquatic environment may require an examination of the components of the phenolics, as in the present study.