Is the FDA's PPA Scare BS?

"Ready, fire ... aim!" must be the Food and Drug Administration's motto. The FDA again is using premature science to force from the market popular consumer health care products. 

The targets this time are cold medicines and appetite suppressants — including such brand names as Acutrim, Alka-Seltzer, Comtrex, Contac, Dexatrim, Dimetapp, Robitussin CF and Triaminic — that contain phenylpropanolamine (PPA). The move follows a new study by Yale University researchers reporting a slightly increased risk of stroke among young women who used PPA-containing products. 

But "plop-plop, fizz-fizz," oh what junk it is. The study doesn't credibly implicate PPA as causing stroke. Even accepting the results at face value, the claimed risk is essentially trivial. 

The study involved 702 male and female stroke victims and 1,376 healthy men and women. The researchers compared the use of PPA-containing products among the stroke victims and healthy individuals. The researchers assumed that increased use of the products among the stroke victims — compared with the healthy subjects — implicates PPA. 

There was, however, no difference in use of PPA-containing products between male stroke victims and healthy males. The FDA's alarm relies solely on the women's data. 

Female stroke victims were twice as likely as healthy women to use PPA-containing products, the researchers reported. This result was based on only 21 stroke victims who reported use of PPA-containing products. But the reported increase was not statistically significant, meaning that result may have occurred by chance — the same sort of chance that makes lottery winners. 

More importantly, the researchers didn't determine the actual causes of any of the strokes. Though the researchers blame PPA, this blame is based on statistical, not clinical, evaluation. Fifty-seven percent of the female stroke victims were either smokers, had high blood pressure or both. The researchers made no effort to rule out these and other known risk factors for stroke on a clinical basis. 

This problem is especially evident for women who used appetite suppressants. The researchers reported that female stroke victims were 16 times more likely than healthy females to use PPA-containing appetite suppressants. This result, however, is only based on six stroke victims, four of whom were smokers, had high blood pressure or both. 

Making matters worse, the 16-fold result was derived by comparing the six stroke victims to only one healthy female — a ridiculously small comparison. Its statistical absurdity is reflected by its error bar, which is 10 times as large as the reported result. 

Finally, the researchers offered no biological explanation for how PPA could possibly have caused the strokes. The study is not science; it's statistical malpractice. 

Prior to the Yale study, the evidence against PPA consisted of an epidemiological study that reported no association between PPA and stroke, and 44 case reports of stroke among PPA users. But as acknowledged by the Yale researchers, these reports did not compare stroke victims with healthy subjects and so do not constitute scientific evidence against PPA. 

It's difficult to believe that PPA causes stroke considering the flimsy evidence gleaned from billions and billions of uses of PPA-containing products over the last 50 years. 

Even accepting the study's results at face value, the FDA's alarmism still falls short of being justifiable. The researchers estimate one woman may have a stroke due to PPA for every 107,000 to 3,268,000 women who use PPA-containing appetite suppressants. This level of risk is so small that it's essentially immeasurable in the real world. If this slight risk concerned a toxic waste dump, no clean-up action would be required under Environmental Protection Agency policy, which tends to be far more proactive on minute risks than FDA policy. 

So does the "A" in FDA stand for "Administration" or "Alarmism?" You be the judge:  

— The FDA banned silicone breast implants in 1992 despite a lack of scientific evidence they caused autoimmune diseases such as rheumatoid arthritis. Though subsequent epidemiological studies exculpated the implants, the FDA ban helped personal injury lawyers extort a multibillion-dollar settlement from implant manufacturers. 

— The FDA forced the "fen" part of the diet-drug combination "fen-phen" from the market in 1997. The withdrawal wasn't based on any scientific study — just 24 case reports of heart-valve problems among millions of fen-phen users. Despite numerous studies, the jury is still out on whether fen-phen posed a significant risk. 

— The FDA forced laxative products containing phenolphthalein (like Ex-Lax) off the market in 1997. A study reported increased cancer among mice that were genetically engineered to be susceptible to cancer and administered phenolphthalein at levels 30 times greater than human exposures. Phenolphthalein had been used for more than 100 years without evidence of cancer risk in humans. 

It's enough to give you a headache. We'd better buy some aspirin before the FDA bans that too. 

— Steven Milloy is a biostatistician, lawyer, adjunct scholar at the Cato Institute and publisher of