Migration of Phthalates from Plastic Containers into Soft Drinks and Mineral Water

Summary The aim of this study was to determine the level of phthalate migration from plastic containers to soft drinks and mineral water and to identify a possible relationship between the amount and type of phthalate migration, type of preservative used, and the pH of the sample. The analysis included 45 samples of products packed in containers made from polyethylene terephthalate. The samples were divided into 5 groups: group 1 (N=9), soft drinks preserved with orthophosphoric acid; group 2 (N=14), soft drinks preserved with Na-benzoate; group 3 (N=5), soft drinks preserved with K-sorbate; group 4 (N=8), soft drinks preserved with a combination of Na-benzoate and K-sorbate; and group 5 (N=9), mineral water without preservatives. The samples were analyzed by the method of gas chromatography, with a detection limit of 0.005 mg/L. The mean pool phthalate level and mean pH value were 91.67 mg/L and 2.82±0.30 in group 1; 116.93 mg/L and 2.75±0.32 in group 2; 819.40 mg/L and 2.88±0.15 in group 3; 542.63 mg/L and 2.82±0.54 in group 4; and 20.22 mg/L and 5.82±1.26 in group 5, respectively. The highest rate of migration to soft drinks was recorded for dimethyl phthalate, ranging from 53.51 to 92.73 %, whereas dibutyl phthalate and diethylhexyl phthalate showed highest rate of migration to the mineral water (56.04 and 43.42 %, respectively). The highest level of phthalate migration from plastic containers to soft drinks was found in the products preserved with K-sorbate. The rate of phthalate migration appears to be influenced also by the drink pH, i.e. the lower the pH value, the greater the phthalate migration. Dimethyl phthalate showed highest migration to preserved drinks as an acidic medium, which might stimulate modification in the composition of plastic containers according to the type and composition of the product. Additional studies in a greater number of samples are needed. Although the phthalate levels measured in these samples pose no risk for human health, it should be borne in mind that the accumulation of small individual amounts taken with time may increase the lifelong phthalate exposure and eventually threaten the exposed person’s life.