It's been one year since a recall for a popular blood pressure medication created fear for patients across the country: an impurity had been found that came with a risk of developing cancer. For people who use these medications every day, choosing to not take them could be life-threatening. But would continued use lead to cancer?

It was just the first notice. Dozens of recalls of similar medications were issued for the same reason -- a potentially cancer-causing impurity.

Since then, we've learned more about what may have led to this problem and, more importantly, the level of cancer risk and why experts say it's more dangerous to quit taking the medications in the short-term.

Here is what we know, one year later.

How many recalls have been issued?

There have been 53 recall announcements issued, according to FDA press officer Jeremy Kahn. The first announcement posted by the FDA was in July 2018.

Some of the recalls have come rapidly -- four recalls came in a one-week span between February and March 2019. Sometimes, weeks go by without hearing about another recall.

There is no telling when they will end.

“They have to go through hundreds of different manufacturers and companies that make these medications. It probably takes a lot of time," said Dr. Eugene Yang, a physician with UW Medicine in Seattle and an associate professor of Cardiology and Medicine at the University of Washington.

While there have been 53 announcements, those involve more than 1,000 lots of the medications. 

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Which types of blood pressure medications are involved?

The medications recalled are those containing Valsartan, Losartan and Irbesartan. They are Angiotensin II Receptor Blockers (ARB) and are used to treat high blood pressure and heart failure.

These ARBs are produced by multiple pharmaceutical companies, so these recalls are not nailed down to one manufacturer. It's important to note that not all medications containing Valsartan, Losartan and Irbesartan have been recalled.

“Some of them use the same factories to make the actual medications and then they’re packaged by a specific generic manufacturing company. The problem is that the ability to tag where the medication is being manufactured and then which company is making them, you don’t necessarily have that ability to do that easily," Yang said.

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Which ARBs are not involved?

Plenty. There are several others in which no recalls have been issued, such as Candesartan.

What are the impurities?

The three nitrosamine impurities that have been identified as N-Nitrosodimethylamine (NDMA), N-Nitrosodiethylamine (NDEA) and N-Nitroso-N-methyl-4-aminobutyric acid (NMBA). The FDA says NDMA and NDEA are probable human carcinogens while NMBA is a potential human carcinogen. The FDA says nitrosamines can be found in water, meats, dairy products and vegetables.

How did they get into the medications?

Nitrosamine impurities may be generated when specific chemicals and reaction conditions are present in the manufacturing process of the drug’s active pharmaceutical ingredient, according to the FDA. It could also be due to reuse of materials, such as solvents.

What are the risks of getting cancer?

The risks of developing cancer from these are low and won't happen overnight according to the FDA. The agency says if someone were to take the highest daily dose of Valsartan that contained NDMA, and took that medication for four years, the odds of getting cancer are an increased 1-in-8,000 patients. 

Yang says that this number is just the best estimate based on previous testing and studies.

"This is the problem. We're scaring people about these risks, without really giving them the background because you can't expect a layperson to understand this," Yang said. He also notes that a lot of patients don't take the highest dose, so that would change the 1-in-8,000 to a lower chance of developing cancer.

Should I quit using my medication right away?

No. Doctors say the short-term risk to your health may be greater than the long-term risk of developing cancer.

"Your blood pressure is significantly elevated by discontinuing the medication which increases your risk of a heart attack or stroke. That's a very dangerous thing to do," Yang said. 

Also, doctors say you should not switch to another medication without first consulting a physician. In other words, if your friend has a non-recalled blood pressure medication and offers to loan you some, don't take it.

Yang says some blood pressure medications do the jobs that others don't.

"For patients with heart failure, only one out of the three medications -- Valsartan -- has been proven to be beneficial," Yang said, adding that an alternative for those with certain types of heart failure should be Candesartan. But he says each type of medication has different benefits and drawbacks.

"A patient should not independently stop the medication, and be aware that the risk of cancer, in many cases, is very low and they should consult with their physician before they make any decision about discontinuing the medication," Yang said.

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