California may declare acetaminophen a known human carcinogen

Acetaminophen is one of the most common over-the-counter drugs in the world. It is known by the brand names Tylenol and Excedrin, and it is found in many OTC remedies for pain, flu and fever. It has been available without a prescription in the U.S. since 1955. Now, the State of California is considering labeling it a known human carcinogen.

The reason California is doing this is a law called Proposition 65, which requires the State to warn consumers when it learns that any chemical causes cancer or reproductive toxicity. The State’s list is extensive – containing around 900 chemicals, the carcinogenic nature of which are sometimes disputed.

Critics argue that regulators have been overzealous in their use of the Prop 65 list, but supporters say that both Californians and consumers nationwide are served by the list and its tendency to pressure manufacturers to make safer products.

The evidence is conflicting but persistent

According to the Associated Press, regulators in California reviewed 133 peer-reviewed studies about acetaminophen. Some of those studies found an increased risk of certain cancers, although others did not. The review noted that it is hard to isolate the effect of the common drug from other things known to cause cancer.

Mostly, the concern comes from acetaminophen’s relationship with a drug known as phenacetin. That drug was once commonly used, but the FDA banned it in 1983 after it was found to cause cancer.

However, the Consumer Healthcare Products Association, a trade group for OTCmedicines and dietary supplements, performed its own review of the science. While it found no additional risk for most types of cancer, some studies indicated an increased risk for kidney, liver and some blood cancers.

The International Agency for Research on Cancer reviewed acetaminophen in 1990 and again in 1999 and declined to label it a possible carcinogen. The FDA has warned California that listing acetaminophen as a carcinogen might be false and misleading or even federally illegal.

Nevertheless, the California Office of Environmental Health Hazard Assessment believes there is enough evidence to show that acetaminophen is carcinogenic. The listing is currently in a public comment period, which closes on Jan. 27. Later, there will be a public hearing on the listing.

If California designates acetaminophen as a known human carcinogen, it could lead to litigation. There may be people with evidence tending to show that their cancers were caused by the drug, and the designation could bolster their claims.

We will keep an eye on further developments on this potential action by California.

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