French scientists have identified heartburn drug ranitidine, one of the most- used drugs in the UK, as a potential source of the carcinogenic drinking water contaminant N-nitro-sodimethylamine (NDMA).1
NDMA can be formed at water treatment works but its provenance is often mysterious. Known risk factors include the use of amine-based coagulants and chloramine instead of chlorine as a disinfectant.
There have been isolated incidents of NDMA found in UK drinking water, but these were linked to a contaminated iron sulphate coagulant (ENDS Report 405, pp 20-21).
The scientists measured the NDMA formation potential of five pharmaceuticals and pesticides during test disinfection with chloramine.
Conversion was particularly high for heartburn drug ranitidine, sold over the counter and prescribed in the UK as Zantac. For every 100 molecules of ranitidine about 40 molecules of NDMA could be formed, they found.
There were more than three million ranitidine prescriptions in the UK
Drinking water treatment plants drawing on effluent-impacted rivers could be particularly at risk from ranitidine as a source of NDMA, the authors say.