Assessing the Emission Levels of Acetaldehyde in Workplace Air from Domestically Produced Polyethylene Terephthalate during the Production Process of Preforms and Bottles

Abstract

Background: Polyethylene terephthalate (PET) is sensitive to heat and oxidation, and it degrades at elevated temperatures typically used in the production process of preforms and bottles, resulting in the generation of various volatile compounds, with acetaldehyde being the primary one. Few studies are found on the emission levels of acetaldehyde in workplace air from PET. Therefore, this study aimed to determine the emission levels of acetaldehyde in workplace air from domestically produced PET during the production process of preforms and bottles. Methods: This descriptive-analytical, cross-sectional study was conducted in 2019 at a PET preform and bottle manufacturing plant. Sampling was performed based on the methodologies 2538 and 2549, established by the National Institute for Occupational Safety and Health (NIOSH), employing workplace air sampling and the analysis of samples using gas chromatography-mass spectrometry (GC-MS). Data analysis was conducted using SPSS software. Findings: The mean concentration of acetaldehyde in the workplace air during the production processes of preforms and bottles was 0.3108 ± 0.8079 mg/m³ and 0.0180 ± 0.0145 mg/m³, respectively, with no statistically significant difference found. Statistical tests indicated significant differences in the concentration of airborne acetaldehyde related to the injection machinery model and PET's intrinsic viscosity. The Spearman correlation coefficient revealed a significant relationship between acetaldehyde concentration in workplace air and the mean cylinder temperature as well as the maximum cylinder temperature; however, no significant statistical relationship was found between the nozzle temperature, mold temperature, residence time, and drying time with acetaldehyde concentration in workplace air. Qualitative analysis identified 34 pollutants emitted from PET, with a diagnostic certainty exceeding 80. Conclusion: Acetaldehyde is produced under normal processing conditions in the PET production processes of preforms and bottles. Given acetaldehyde's carcinogenic and irritant properties, the low concentrations observed do not necessarily indicate safety and warrant further attention. © 2026, Isfahan University of Medical Sciences(IUMS). All rights reserved.