What is the problem with Zantac antacid?

Valisure LLC and ValisureRX LLC conducted tests, finding very high levels of NDMA in all lots of ranitidine tested.  Valisure tests showed the NDMA concentration in a patient’s urine to be more than 15,000 times higher than the California drinking water limit.  A Stanford study studied NDMA levels in patients 24 before taking ranitidine and 24 hours. They found the NDMA levels in urine increased by 430 times, averaging 47,600 ng per person.  That is 495 times higher than the FDA daily limit of NDMA. Scientists have also tested other heartburn medications such as Prilosec, Nexium, Prevacid, and Pepcid. They did not contain levels of NDMA.  However, they have been linked to kidney disease, renal failure, and other kidney damage.