'Zombie facts' live on after black plastic and other studies get corrected or retracted

This story is part of CBC Health's Second Opinion, a weekly analysis of health and medical science news emailed to subscribers on Saturday mornings. If you haven't subscribed yet, you can do that by clicking here.

Headlines warning people to throw out their black plastic kitchen utensils live on, as do social media posts warning of "secret toxins" in your kitchen.

Less prominent? A correction to the peer-reviewed study those headlines were based on.

In October, the journal Chemosphere published a study by researchers in the U.S. and Netherlands that found brominated fire retardants (BFR) in black plastic household products sold in the U.S., including kitchen items.

But there was a math error when the study's authors calculated the risk — and it was off by an order of magnitude. 

The authors said they regret the error, but it "does not affect the overall conclusion of the paper," as it was part of an example used to compare exposure levels to add context, not a core finding. 

"The key thing our study does is provide evidence that when toxic flame retardants are used in electronics, they can make their way into household products where they are not needed or expected," said Megan Liu of Seattle environmental group Toxic-Free Future, who co-wrote the study. 

The flame retardants are typically used in black plastic, such as television casings, and when those plastics are recycled the chemicals can make their way into products that touch food.

While media coverage of the study often focused on what individuals could do, like ditch black plastic spatulas, Liu said the ultimate solution is more regulation. 

Though regrettable, errors happen, including in studies that have been peer-reviewed. They can range from a typo or miscalculation that gets a correction, to mistakes so large the paper is retracted, to rare but full-blown fraud. The promise of the scientific process is that by exposing work to the scrutiny of others, any problems will be corrected over time. 

The trouble is, it does take time — and the resulting fixes rarely get the public attention of the original errors, say journal editors. 

Tim Caulfield, author of The Certainty Illusion: What You Don't Know and Why It Matters, and a professor at the faculty of law and school of public health at the University of Alberta, studies the twisting of facts and information. 

"It was interesting, exciting, it was scary and it got over-promoted," Caulfield said of the black plastic study. "The correction happens and the problem is, there's almost always less uptake of the correction and the original story lives on, right? It becomes a zombie fact that just won't die."

There may be no bigger shadow cast by a retracted paper than Andrew Wakefield's fraudulent and discredited 1998 study on what he claimed was a link between the measles, mumps, rubella (MMR) vaccine and autism.