The United States remains one of just three countries in the world that doesn’t use the metric system. Although a dedicated group of metric enthusiasts has been attempting to convince the U.S. to switch for years, there hasn’t been much progress in this area over the past four decades. And, according to a new study, our decision to cling to the so-called “English system” isn’t just a source of frustration for those activists; it may also have some serious public health consequences.
Failing to use the metric system ends up leaving parents confused about exactly how much liquid medication to give their kids, according to new research published in the Pediatrics journal. Nearly 40 percent of parents who participated in the study measured wrong when they were given a prescription in teaspoons or tablespoons. Another 40 percent read the prescription dosage wrong.
Why do adults mess up in this area? Busy parents who are multitasking can end up making errors like reading tablespoons for teaspoons — which results in tripling the recommended dose — or using a kitchen spoon if they can’t locate an actual teaspoon. Those simple mistakes can have big consequences. Parents make more than 10,000 annual calls to poison centers because their kids have accidentally ingested medication or taken the wrong dosage of their own prescription.
Pharmacists sometimes make these mistakes, too, because their computers’ default settings are often English measurements. For example, in one case that made headlines a few years ago, a two-year-old child with an ear infection received a dose of antibiotics that was five times greater than she needed. The family’s pharmacist accidentally typed a label that instructed her parents to give her 3.5 teaspoonfuls of antibiotic daily instead of 3.5 mL daily. As a result, the child ended up unnecessarily suffering from diarrhea, a yeast infection, and a possible fungal bacterial infection.
But, according to the Pediatrics study, measuring mistakes were cut in half when the prescriptions were written in metric units instead. Metric measurements are easier to use because they rely on a decimal system that makes it simpler to make conversions; instead of trying to remember how many teaspoons equal a tablespoon, the liter system is all in factors of ten. Converting between measurements simply involves moving a decimal point. The study’s authors conclude that a milliliter-only standard for prescription medications could help prevent errors and the subsequent trips to the ER.
Those researchers aren’t the first to make this argument. The Institute for Safe Medication Practices has been calling for a switch to metric-based prescriptions for over a decade. The U.S. Food and Drug Administration (FDA) and the Centers for Disease Control and Prevention (CDC) have also raised concerns about the use of the English system for oral liquids. And the American Academy of Pediatrics has urged individual doctors to start writing their prescriptions in milliliters even if the U.S. doesn’t make an official switch.
Using the English system could have an indirect impact on other areas of public health and medical research, too. Since the U.S. doesn’t institutionalize metric measurements, some advocates argue that it leaves Americans more uninformed about advances in the field. “If we want to have a scientifically literate populace, we should make sure that scientists and non-scientists speak the same language,” Scientific American argued last year.