Remember the recent stories about the dangers of black plastic kitchen utensils? Turns out the panic arose from a simple mathematical error.

For those who paid attention in your school days, you may recall a simple way of multiplying large numbers ending with one or more zeroes. For example, to multiply 6,000 by 3,000, you simply multiply the non-zero numbers (6 and 3), then append the total number of zeroes (in this case, there are six of them). So the answer is 18,000,000.

Forgetting that little math hack appears to have sent untold thousands of black plastic spatulas and other kitchen utensils into the trash. In October and November, scores of articles from CNN to The Atlantic to SCMP to the Food Network exhorted consumers to throw out their black kitchen utensils.

However, according to a report in the National Post, a simple arithmetic error has cast doubt on alarming claims about toxic chemicals leaching from black plastic kitchen utensils. Joe Schwarcz, Director of McGill University’s Office for Science and Society, uncovered the mistake while reviewing a research paper published in the journal Chemosphere.

The study, conducted by advocacy group Toxic-Free Future, examined whether brominated flame retardants—chemicals used in electronic plastics—were present in black plastic kitchenware. It suggested these toxins, such as BDE-209, could migrate into food during cooking and pose significant health risks.

Schwarcz discovered the miscalculation while reviewing a research paper in the journal Chemosphere. “I’m not bad at math,” Schwarcz noted after spotting that multiplying 60 by 7,000 should yield 420,000—not the 42,000 stated in the study.

The paper claimed that using contaminated utensils could result in a median daily intake of 34,700 nanograms of BDE-209—almost 83% of what it said was the U.S. EPA’s reference dose of 42,000 nanograms for a 60-kilogram adult. But Schwarcz noticed an error in the calculations: multiplying 60 kilograms by the EPA limit of 7,000 nanograms per kilogram yields 420,000, not 42,000. This means the estimated exposure is, in fact, less than 10% of the actual safety threshold.

SOME CONCERNS STILL REMAIN

Lead author Megan Liu acknowledged the error, calling it a “typo,” and said a correction had been submitted to the journal. “However, it is important to note that this does not impact our results,” she told the National Post. “The levels of flame retardants that we found in black plastic household items are still of high concern, and our recommendations remain the same.”

The study highlights how black plastic, often recycled from electronic waste, can find its way into household items like spatulas. Because black plastic cannot be easily recycled through conventional methods, it is sometimes sourced from cheaper, recycled electronics. While such recycling might seem environmentally friendly, it could reintroduce harmful chemicals into products meant for food preparation.

The study emphasized the potential dangers of BDE-209, which has been linked to cancer, hormone disruption, and damage to the nervous and reproductive systems. These risks prompted Schwarcz to caution against exaggeration, pointing out the importance of clear and accurate risk communication. “You have to make sure your numbers are correct before you scare the pants off people,” he said.

QUESTIONS SURROUNDING RISK ANALYSIS

Schwarcz also criticised the choice to express results in nanograms—a unit so small it can amplify perceived danger. “Using absolute numbers, rather than percentages or tiny units, often presents a clearer picture,” he noted. He compared it to lottery odds, where buying a second ticket and doubling a one-in-a-million chance to two-in-a-million is a 100% increase in the odds of winning—but still results in an insignificant probability.

The study’s underlying hypothesis remains credible: black plastic from recycled electronics is likely making its way into American supply chains. Whether this translates to substantial health risks requires further investigation. While the error has dampened the study’s urgency, those wanting to minimize exposure to any level of such chemicals might still consider discarding black plastic utensils.

This incident underscores the importance of presenting scientific findings responsibly. While researchers aim to inform public health policy, errors—however unintentional—can lead to unnecessary fear or confusion. Schwarcz noted, “Risk analysis is a sketchy business in the first place, very difficult to do, especially if you don’t express units properly. You can make things sound worse.”

IMPLICATIONS MOVING FORWARD

Despite the correction, the debate around black plastic’s safety continues. Studies like this underscore the complexities of balancing sustainability efforts, such as recycling, with public health concerns. Scientists and policymakers must ensure accuracy and transparency to build public trust and make informed decisions.

So what’s the bottom line? Though there’s probably no great urgency to purge your kitchen of all things black plastic, it’s a good idea to keep this study in mind when replacing things. Quality wood utensils can be an excellent choice, and for certain applications, it’s hard to beat stainless steel.