Bottled drinking water: Water contamination from bottle materials (glass, hard PET, soft PET), the influence of colour and acidification

摘要

A test comparing concentrations of 57 chemical elements (Ag, Al, As, B, Ba, Be, Bi, Ca, Cd, Ce, Co, Cr, Cs, Cu, Dy, Er, Eu, Fe, Ga, Gd, Ge, Hf, Ho, I, K, La, Li, Lu, Mg, Mn, Mo, Na, Nb, Nd, Ni, Pb, Pr, Rb, Sb, Se, Sm, Sn, Sr, Ta, Tb, Te, Th, Ti, Tl, Tm, U, V, W, Y, Yb, Zn and Zr) determined by inductively coupled plasma quadrupole mass spectrometry (ICP-QMS) in 294 samples of the same bottled water (predominantly mineral water) sold in the European Union in glass and PET bottles demonstrates significant (Wilcoxon rank sum test, α= 0.05) differences in median concentrations for Sb, Ce, Pb, Al, Zr, Ti, Th, La, Pr, Fe, Zn, Nd, Sn, Cr, Tb, Er, Gd, Bi, Sm, Y, Lu, Dy, Yb, Tm, Nb and Cu. Antimony has a 21× higher median value in bottled water when sold in PET bottles (0.33 vs. 0.016μg/L). Glass contaminates the water with Ce (19× higher than in PET bottles), Pb (14×), Al (7×), Zr (7×), Ti, Th (5×), La (5×), Pr, Fe, Zn, Nd, Sn, Cr, Tb (2×), Er, Gd, Bi, Sm, Y, Lu, Yb, Tm, Nb and Cu (1.4×). Testing an additional 136 bottles of the same water sold in green and clear glass bottles demonstrates an important influence of colour, the water sold in green glass shows significantly higher concentrations in Cr (7.3×, 1.0 vs. 0.14μg/L), Th (1.9×), La, Zr, Nd, Ce (1.6×), Pr, Nb, Ti, Fe (1.3×), Co (1.3×) and Er (1.1×).One hundred and twenty-six bottles of three different materials (glass, hard PET and soft PET) in 5 principal colours (clear, light and dark green and blue, brown) were subsequently washed and then filled with high purity water (18.2MΩcm). A portion of the bottles where left at the original average pH of the water (pH 6.5) while the remaining bottles were acidified to pH 3.5 with HNO_3. Concentrations of the same 57 elements as above were determined after 1, 2, 3, 4, 5, 15, 30, 56, 80 and 150days of leaching. Results substantiate the observations from the direct comparison of the same water sold in different bottle types (colour). For most elements leaching is enhanced at pH 3.5, and dark coloured bottles leach more than clear bottles, independent of bottle material. Values are still on the increase at the end of the test at 150days. At that date the leachates showed a maximum concentration of 0.45μg/L Sb, 0.3μg/L Ce, 0.61μg/L Pb, 68μg/L Al and 0.06μg/L Cr (all in glass at pH 3.5). None of the leachates approaches the maximum concentrations for drinking water as defined in European jurisdiction.