Abstract
Bisphenol A (BPA: 2, 2-bis (4-hydroxyphenyl) propane) released from waste paper during pulping was analyzed in sample solutions prepared by a laboratory pulping equipment. Of 8 kinds of waste paper tested, BPA was detected at a high concentration, 440 mg/l, only in the solution prepared from thermal papers. Therefore, we analyzed sample solutions prepared from 11 thermal papers, used in word processors or facsimile equipment. BPA was detected at concentrations ranging from 170 to 460 mg/l in those thermal papers manufactured in 1999 or before, but at lower concentrations in thermal papers manufactured after that year. Bisphenol S (BPS: bis (4-hydroxyphenyl) sulfone) and BPS-monoP (4-hydroxyphenyl 4-isopropoxyphenyl sulfone) were also detected. These chemicals appear to have been used as color developers for thermal paper in recent years. Also detected were M-terphenyl, 4-benzylbiphenyl, 1, 2-bis (3-methylphenoxy) ethane and benzyl 2-naphtyl ether. These compounds are used as sensitizers in thermal paper.
The estrogenic agonist activities of the chemicals detected in thermal papers were measured using the yeast two-hybrid assay system. Only benzyl 4-hydroxybenzoate and triphenylmethane exhibited activity.
