The researchers took water and effluent samples from the River Erewash near Nottingham, and from the River Colne near Uxbridge, West London, which all contained the chemicals benzotriazole and tolytriazole used in dishwasher tablets and powders.
Tap-water samples were then also taken and benzotriazole and tolytriazole were detected in all 80 samples analysed.
Lead researcher Dr Mark Scrimshaw from Brunel University explained that because these chemicals are water soluble and not easy to degrade, they enter rivers via wastewater and ultimately make their way into tap water.
’Although the presence of chemicals in the environment and drinking water does not in itself pose a threat to public health and the environment, there is some concern that the possible effects of long-term exposure to individual chemicals or mixtures of chemicals are not fully understood,’ said Dr Scrimshaw.
’The implications of our findings depend to a large extent on the degree of toxicity of benzotriazole and tolytriazole, but there are definitely gaps in scientific knowledge about being exposed to these chemicals. The lack of a complete set of good quality [eco] toxicological data on possible chronic effects of these high-use chemicals should caution against using them in a manner that may have contributed to such widespread environmental contamination,’ he added.
Dr Scrimshaw is director of Brunel University’s Collaborative Research Network in Energy and Environmental Sustainability. He has routinely worked with the UK water industry on approaches for removing chemicals that enter wastewater treatment works and controlling their discharge into the environment.
The study was funded by the Engineering and Physical Sciences Research Council.
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