Numbers tell a story, but when they’re wrong, that story can mislead millions. A recent study on black plastic kitchen utensils stirred significant media attention, claiming these utensils might expose users to toxic chemicals. However, an arithmetic error in the study shifted the narrative dramatically, showing just how critical mathematical precision is in scientific communication.
The study, published in the journal Chemosphere, explored the presence of brominated flame retardants, specifically BDE-209, in black plastic kitchen items. These chemicals, often used in electronics to prevent fires, were found in utensils made from recycled electronic waste. The researchers estimated that exposure from cooking with contaminated utensils could lead to a daily intake of 34,700 nanograms of BDE-209, approaching the EPA’s reference dose of 42,000 nanograms per day.
But here’s the twist: the reference dose calculation was wrong. Multiplying 60 kilograms (the weight of an average adult) by the EPA’s reference dose of 7,000 nanograms per kilogram per day yields 420,000 nanograms—not 42,000. The actual exposure estimate was less than 10% of the correct reference dose.
Joe Schwarcz, director of McGill University’s Office for Science and Society, spotted the error while reviewing the paper. The study’s hypothesis—that electronic waste is finding its way into kitchen utensils—is valid and concerning. But the arithmetic mistake overinflated the perceived risk, amplifying public fear unnecessarily.
This highlights an important issue: the role of numerical accuracy in risk communication. As Schwarcz aptly points out, risk expressed in percentages or small units like nanograms can easily sound alarming. Saying “34,700 nanograms per day” may sound catastrophic, but reframing it as “34.7 micrograms per day” could ease undue anxiety without down