Analysis of Time-Dependent Mercury Flows Through the Use of Thermometers and Sphygmomanometers in Thailand

Abstract

Thermometers and sphygmomanometers pose a potentially large source of mercury emissions to the environment due to their high elemental mercury content. Many countries, e.g. most European countries, US have banned their uses already and many more strictly limited their use. However, in Thailand these mercury-based devices are still used, accumulating large stocks in the use phase as well as in landfills. To understand the development of mercury stocks and flows from thermometers and sphygmomanometers, a time-dependent mathematical material flow model is used in this study. The flows of mercury through these two products were calculated based on data between the years of 1962 and 2013. The simulation showed that the stock of mercury in thermometers is about 20 times smaller than the stock in sphygmomanometers. However the sum of waste flows and emissions to air and water from thermometers is 3 times larger than from sphygmomanometers. The reason is the lifetime of thermometers which is about 70 times shorter than the lifetime of sphygmomanometers. The calculated emission to air from mercury thermometers in hospitals can explain the higher mercury level measured in urine of health care staff. In order to reduce the mercury flows to the environment mercury thermometers should be replaced by alternative products as soon as possible.