Evaluation of heavy metal content in plastic bags used as improvised food cooking covers: a case study from the Mozambican community

The widespread use of plastic bags as improvised food cooking covers in Mozambican communities has raised public health concerns, increasing interest in studying these plastic bags, which contain heavy metals additives used to improve their physical and chemical properties. This study aims to evaluate the levels of heavy metals commonly used in plastic bags used as improvised food cooking covers, focused on Mozambican communities that have this habit. Using spectroscopic techniques, Fourier Transform Infrared Spectroscopy (FTIR) and Atomic Absorption Spectroscopy (AAS), we analyzed plastic bag samples to identify polymer types, chemical composition, and heavy metal concentrations. FTIR analysis confirmed low- and high-density polyethylene (LDPE and HDPE) as the primary materials, with spectra peaks between 2800 and 3000 cm−1, indicating stretching vibrations characteristic of LDPE and HDPE. The density measurements varied between 0.04 and 0.08 g/cm3 with very low uncertainty values (0.27% and 0.098%). The heavy metal analysis revealed concentrations higher than those stipulated in international standards. The results in terms of the percentage of LDPE samples in relation to the HDPE samples are as follows: Cd: 69.71% (LDPE < HDPE); Cu: 220.44% (LDPE > HDPE); Pb: 24% (LDPE < HDPE); and Zn: 51.53% (LDPE < HDPE). These findings highlight the potential public health risks associated with the use of plastic bags in cooking and underscore the need for regulatory intervention.