<p>Waste paper represents a valuable secondary source of cellulose fibres, contributing to the reduction of virgin wood consumption in paper production. To support sustainable development objectives, the integration of natural fibres with synthetic polymers is increasingly explored across industrial sectors. Reliable use of waste paper materials requires baseline data on pollutant content and migration potential. In this study, cellulose fibres were separated using 0.2&#xa0;M acetic acid (CH₃COOH) extraction, followed by washing. This method effectively removed precipitated calcium carbonate-based filler from office paper, achieving an extraction efficiency of 86%. A total of 138 compounds were identified in waste paper, originating from: virgin wood (<i>n</i> = 31), paper manufacturing and recycling processes (<i>n</i> = 19 + 15 fragrance compounds), and printing inks (<i>n</i> = 67), with solvents (<i>n</i> = 25) forming the largest subgroup. Additional substances were associated with surface treatments and ink formulations. Compound hazard profiles were assessed using the Globally Harmonized System (GHS). The identified substances were, among others, persistent organic pollutants, including benzophenone<i>,</i> butylated hydroxytoluene<i>,</i> and bis(2-ethylhexyl) phthalate<i>,</i> bisphenol A, and bisphenol S<i>,</i> while solvents exhibited the highest proportion of hazardous classifications. Following CH₃COOH extraction, concentrations of hazardous solvents were reduced by 93%, indicating the method’s potential for pollutant mitigation in fibre recovery.</p>