Heavy metals (HM) are one of the main agents that threaten human health. The most important source that release heavy metals (As, Cd, Cu, Cr, Pb, Ni, V, and Zn) in the environment is Petrochemical industries. This study was investigated the carcinogenic risk assessment, health endpoint and source identification of heavy metals. Samples were taken from the different regions: parks, residential, industrial, administrative and central and high traffic areas in Mahshahr, southwest, Iran and investigate the environmental impacts of the studied petrochemical industry. Measurement of heavy metals performed by Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES). Results of the PCA showed that As had a different source than other heavy metals, which can be owing to numerous human and industrial activities in the region. Based on the results, the Igeo factor was assessed at high levels for Ni, Pb, and Cd metals. Moreover, the results demonstrated high intensities of pollution for Pb, Zn, Cd, and Ni metals under the application of PI and IPI indices, and for Ni, Pb, and Cd metals under the application of the EF index. The index of the risk index (RI) average of the studied metals represented a significant risk for Ni, Cr and As metals on children and adults. In addition, Pb isotopic results showed high levels of 208Pb/206Pb to 207Pb/206Pb, which indicated that the increase of the Pb isotope in the studied region was concerned with petrochemical activities of human origin. In this study, it was found that the soils of the Mahshahr port industrial zone have high anomalies of some metals, especially Ni, Pb, Zn and Cd, which were due to the growth of traffic and economic and industrial activities in the region. However, heavy metals such as As and V exhibited the lowest risk and very low pollution in all indicators. [ABSTRACT FROM AUTHOR]