Chlorine and other types of disinfectants kill harmful bacteria and viruses, and are used to ensure that tap water remains pathogen-free and safe to drink.
While Singapore’s water treatment regimen removes any DPG leaching into the catchment, the scientists believe it could be leaking into tap water post-treatment – when it comes into contact with rubber parts in plumbing and reacts with chlorine in the water.Researchers from the Nanyang Environment and Water Research Institute at Nanyang Technological University found that the by-product caused some damage to human DNA in lab tests on human cells.
Further studies will be needed to understand how the body metabolises the compound as it goes through the digestive system, said Prof Snyder.The same approach is taken by international regulatory agencies such as WHO and the United States Environmental Protection Agency to address emerging contaminants of concern.
Surprisingly though, when the researchers took water samples from taps in 20 buildings across the island, they found small amounts of DPG in all the samples.In comparison, 6PPD was found in a quarter of the samples, without any formation of obvious by-products. Boiling the tap water did not remove these chemicals, the team found. It is unclear if filtering the water will be beneficial.To better understand the impact on human health, the researchers are now looking to test the DPG-chlorine compound in an “artificial stomach” to see how it gets broken down or if it enters the bloodstream. This would mimic the body’s metabolism more closely, Prof Snyder added.