Recycled paper is an important raw material to provide sustainability of natural resources and reduce the environmental impact of the use of paper from recycled pulp in the packaging industry. Hence, recycled paper production is higher in terms of volume and utilization. Recycled paper products are used in the packaging industry partially or fully. Such usage leads to the presence of heavy metals due to recycled and chemical additive sources. The present study aims at determining the amounts and also identifying the sources of heavy metals such as Pb, Cd, Zn, Ni, and Cu contained in recycled testliner (TL) and fluting (FLT), which are main products used in production of corrugated cardboard. The metals in the structure of the paper used in packages directly or indirectly in contact with foods are heavy metals. Mean values of 2.6 mg kg(-1) Pb (lead), 2.8 mg kg(-1) Zn (zinc), 0.094 mg kg(-1) Cd (cadmium), 1.8 mg kg(-1) Ni (nickel), and 25.4 mg kg(-1) Cu (copper) were detected in test liner and fluting papers using inductively coupled plasma optical emission spectrometry (ICP-OES). The main sources of heavy metals are colorants, mainly consisting of conventional paint and pigments as well as spot and Pantone Matching System (PMS) colorants.