Freeze–melting process significantly decreases phthalate ester plasticizer levels in drinking water stored in polyethylene terephthalate (PET) bottles

Abstract

Bottled water consumption has increased significantly in recent decades. Eighty percent of bottled water is sold in plastic containers usually made from polyethylene terephthalate (PET). Trace leaching of phthalate esters (PEs) from these bottles into the water and their effects on human health has become a serious concern. In this study, the effects of freezing on the release of PEs from PET bottles have been investigated. Four common PEs were determined in bottled water samples before and after freezing–remelting by a dispersive liquid–liquid micro-extraction method and gas chromatography–mass spectrometry (GC/MS) analysis. PE levels after freezing–remelting of samples were significantly lower than before (mean ± SD = 0.71 ± 0.28 and 0.33 ± 0.003 ppb, respectively). Electrical conductivity (EC) also decreased after freezing–remelting of the water (mean ± SD = 260.2 ± 80.6 and 130.6 ± 17.4 μs/cm, respectively). Significant correlation has been detected between reduction in water EC and elimination of PEs from water. Dissolved minerals and contaminants in water concentrate and conglomerate in the center of the ice during the freezing process and form white sediments mainly of calcium bicarbonate after remelting of the water. It seems that calcium bicarbonate effectively adsorbs PEs and traps them in its structures. These sediments do not have significant gastrointestinal absorption and cannot pose health consequences. The freezing–remelting process could be introduced as an effective procedure for water treatment.