The effect of use conditions on leaching of antimony from PET plastic into commercially bottled water in Qatar
Antimony (Sb) is an emerging contaminant in water, and it is classified as a pollutant of priority interest by the European Union (EU) and the United States Environmental Protection Agency (USEPA). Extended exposure to high-level antimony concentrations will lead to acute and chronic health issues. Trivalent antimony (Sb3+) is considered a possible carcinogen according to the 2022 latest classification in the International Agency for Research on Cancer (IARC). The Maximum Contaminant Limit (MCL) set by USEPA for antimony concentration in drinking water is 6 µg/L. However, China had set more strict limits of 5 µg/L. Here in Qatar, KAHRAMAA has adopted the value of the USEPA of 6 µg/L Sb at the delivery point as quality for drinking water. Sb can be released from polyethylene terephthalate (PET) plastic bottles. The PET polymer is made from terephthalic acid (TPA) and ethylene glycol (EG). The two reactants react together to form extended polymer chains and water as a by-product. In polymerization procedures, commonly catalyst is used to increase the reaction rate. Around 90 % of global PET production uses antimony-based catalysts because of their lower cost and efficiency. Thus, antimony can reach more than 100 mg/kg in PET material due to using antimony trioxide (Sb2O3) as a catalyst in producing PET. Several studies reported the leaching of Sb from PET plastic water bottles, producing the highest levels of human exposure to Sb, up to ∼10 μg/L over long storage and especially at warm temperatures. Thus, Sb contamination is a significant concern in Qatar because of the heavy reliance on plastic bottles for drinking water. This work aims to measure the amount of antimony leached to different available brands of bottled waters in the Qatar market under typical and stressful conditions. Several registered brands of bottled water in the Qatar market will be tested. In the first stage, an analytical method should be developed and validated to analyze Sb in drinking water. The analytical method will be based on ion-exchange resin pre-concentration of trace amount of Sb and use the available atomic spectroscopy technique at the University of Doha for Science & Technology (UDST). The pre-concentration will offer a lower detection limit and accurate, reliable and sensitive results. Once the method is ready, the second stage will test the diffusion rate of antimony as a function of contact time under typical and stressful conditions. The selected parameters should mimic Qatar's shipping and storage conditions and include temperature, sunlight irradiation, pH, bottle volume, bottle color, and the ratio of empty bottle mass to its volume. Other attention in this study will be on the concentration of antimony in the material of each PET brand. This study hypothesizes that different brands of drinking water bottles will have different concentrations of antimony depending on the manufacturing processes applied and the use of shipping and storage conditions. The protection of public health is the ultimate goal of the present proposed work. So, this will be the first comprehensive study to document Sb concentration in different available brands of bottled waters in the Qatar market and the crucial parameters that stimulate antimony leaching on each brand. It will also provide baseline information and recommendations for health authorities and regulatory agencies to improve drinking water quality, future importing and monitoring plans, and safety records.
