Dear Dr. Yin, As both a practicing pharmacist and as an officer in the U.S. Metric Association (USMA), Inc., I believe it is time for U.S. healthcare to take action to eliminate all reference to units of volume other than milliliters for measuring the doses of over-the-counter liquid medications.
In the16 December 2010 New York Times article "Awareness: Of Medicines and Measurements" (http://www.nytimes.com/2010/12/21/health/research/21awareness.html?ref=science), you warned parents, "a tablespoon is three times as large as a teaspoon." Such confusion does not exist in the decimal metric system. Your warning suggests to me what is the real problem regarding the "inconsistencies" in packaging vs. measuring cups in over-the-counter liqud medications: the use of two systems of measurement. The direction of measurement in the U.S., and in U.S. healthcare, has been toward changing over to the metric system as the sole meausrement system in the U.S, which will be national process called metrication. The trend toward a metric-only measurement in healthcare can be plotted on the following timeline: 1. 1866 - Congress passes the Metric Act, making the use of the metric system lawful "throughout the United States of America." 2. 1875 - The U.S joins other countries in signing the Treaty of the Meter, establishing the International Bureau of Weights and Measures to oversee a single measurement system (metric) for the world 3. 1893 - The U.S. Superintendent of Weights and Measures orders that the meter and the kilogram become the fundamental standards of length and mass in the U.S. 4. 1971 - Responding to the mandate of the Metric Study Act of 1968, the Commerce Department releases a report recommending that the U.S. change over to the metric system over a 10-year period (A Metric America: A Decision Whose Time Has Come) 5. 1975 - Congress passes the Metric Conversion Act to coordinate U.S. metrication 5. 1988 - Congress amends the Metric Conversion Act by declaring the metric system to be the "preferred" system of measurement for U.S. trade and commerce 6. 1994 - Congress amends the Fair Packaging and Labeling Act to require metric units to appear alongside traditional measurement units on all U.S. consumer product packaging and labeling 6. 1995 - The U.S. Pharmacopeia bans the apothecary system of measurement from official use in American medicine 7. 2008 - The Joint Commission recommends that pediatric patient weights be measured and stated in kilograms only 7. 2009 - The Insitute for Safe Medication Practices recommends eliminating the teaspoon and the tablespoon from all aspects of medication prescribing and dispensing With all of these American actions on metric measurement, both commercial and health-professional, we must conclude that it is time to use milliliters (mL) only, in package directions and on measuring devices in this country.. This improvement in dosing would be aided by a broad-based public education campaign on what the milliliter is and how to use it. It is way past the time for us to stop ignoring America's systemic problem in dosing errors due to measurement. Also, the use of the correct symbol for the milliliter, "mL," will give the public a symbol to watch for in reading the correct dose volume on the label and the measuring cup. Last week, in the usual course of my pharmacy practice, I recelved a telephone call from a physician (!) who called me for one reason only: to find out how many milliliters were in a teaspoonful and how many in a tablespoonful. He cinched the case for metric-only OTC liquid measurement in the U.S. SIncerely, Paul Trusten, R.Ph. , Vice President U.S. Metric Association, Inc. www.metric.org [email protected] +1(432)528-8824
