A Colorado man is suing Pfizer, Sanofi, GlaxoSmithKline and other pharmaceutical companies, saying that a popular heartburn drug caused his bladder cancer. Law360 reports that Mark Allan Blake is accusing manufacturers of Zantac of producing, marketing, and selling a product that produces a cancer-causing chemical when the product is digested. Blake’s lawsuit comes on the heels of several other lawsuits filed after the U.S. Food and Drug Administration (FDA) issued a warning about products containing the active ingredient in Zantac.

Blake’s complaint says that when the human body digests Zantac, it produces N-Nitrosodimethylamine (NDMA), a chemical linked to cancer. While NDMA previously was a byproduct of the production of rocket fuel, the chemical is now used in scientific research to induce cancer in lab animals. According to Blake, “Its only function is to cause cancer. It has no business being in a human body.”

The liver can metabolize small amounts of NDMA, Blake says, but higher amounts can remain in the body and become dangerous. So the FDA sets a maximum permissible limit of NDMA in any drug at 96 nanograms. A filtered tobacco cigarette contains between 5 and 43 nanograms of NDMA. Valisure, an online pharmacy and analytical laboratory, has recently tested Zantac for the presence of NDMA. Its testing revealed that each tablet of Zantac 150 had, on average, 2,692,291 nanograms of NDMA. This is over 28,000 times the legal limit. Blake says that when subject to conditions similar to the human body, a person would have to smoke over 500 cigarettes to reach the levels of NDMA in a single tablet of Zantac 150.

Zantac was developed by GlaxoSmithKline and approved by the FDA in 1983. It quickly became one of the best-selling antacids, reaching $1 billion in sales only three years after its approval by the FDA. Though generic products have reduced the sales of Zantac, it remains a popular drug.

Blake’s suit says that as early as 1981, two years before the approval of Zantac, research showed that there was a link between Zantac’s active ingredient and the production of the potentially carcinogenic NDMA. Indeed, Blake claims that the manufacturers of Zantac should have known about this research and should have reported it to the FDA when they were seeking approval of the drug. Instead, Blake says that the manufacturers deliberately concealed this early research and rigged later studies so they would not show the presence of NDMA.

Blake is seeking both compensatory and punitive damages against the companies.