If you have always believed that water which comes packaged in clean, sealed plastic bottles are 'safe', here's a shocker - a German study has suggested these very bottles contaminate drinking water with estrogenic chemicals.
Martin Wagner and Jorg Oehlmann, from the Department of Aquatic Ecotoxicology at the Goethe University in Frankfurt am Main, analysed commercially available mineral waters, and found evidence of estrogenic compounds leaching out of the plastic packaging into the water.
The researchers say that these chemicals are potent in vivo and result in an increased development of embryos in the New Zealand mud snail.
This is the first time that any research team have shown that substances leaching out of plastic food packaging materials act as functional estrogens.
Wagner and Oehlmann looked at whether the migration of substances from packaging material into foodstuffs could contribute to human exposure to man-made hormones.
The researchers analysed 20 brands of mineral water available in Germany - nine bottled in glass, nine bottled in plastic, and two bottled in composite packaging (paperboard boxes coated with an inner plastic film).
Water samples were taken from the bottles, and tested for the presence of estrogenic chemicals in vitro.
The study group later conducted a reproduction test with the New Zealand mud snail to determine the source and potency of the xenoestrogens.
Wagner and Oehlmann say that they found estrogen contamination in 60 per cent of the samples they had analysed.
According to the researchers, mineral waters in glass bottles were less estrogenic than waters in plastic bottles.
They said that 33 per cent of all mineral waters bottled in glass compared with 78 per cent of waters in plastic bottles, and both waters bottled in composite packaging, showed significant hormonal activity.
When the researcher bred the New Zealand mud snail in both plastic and glass water bottles, they observed more than double the number of embryos in plastic bottles compared with glass bottles.
Together, said the team, the findings showed widespread contamination of mineral water with potent man-made estrogens that partly originate from compounds leaching out of the plastic packaging material.
The authors concluded: "We must have identified just the tip of the iceberg in that plastic packaging may be a major source of xenohormone contamination of many other edibles. Our findings provide an insight into the potential exposure to endocrine-disrupting chemicals due to unexpected sources of contamination."
The study has been published in Springer's journal Environmental Science and Pollution Research.