246 Australian Dental Journal 2000;45:4. The environmental effects of dental amalgam

Dental amalgam is one of the most commonly used materials in restorative dentistry. However, one of its major components, mercury, is of particular concern due to its potential adverse effects on humans and the environment. In this review, the environmental impact of dental amalgam will be discussed, with particular reference to the effects attributed to its mercury component. Mercury commonly occurs in nature as sulfides and in a number of minerals. Globally, between 20,000-30,000 tons of mercury are discharged into the environment each year as a result of human activities. According to a recent German report, approximately 46 per cent of the freshly triturated amalgam is inserted as new amalgam restorations and the rest is waste. Depending on the presence of an amalgam separating unit, some of the generated amalgam-contaminated sludge is discharged into the sewage system. Lost or extracted teeth with amalgam fillings and amalgam-contaminated waste, such as trituration capsules and cotton rolls are discharged with the solid waste and, in most instances, are incinerated. Use of disinfectants containing oxidizing substances in dental aspirator kits may contribute to remobilization of mercury and its subsequent release into the environment. Nevertheless, dental mercury contamination is only a small proportion of terrestrial mercury (3-4 per cent), which is quite insignificant compared with industrial pollution and combustion of fossil fuels by vehicles. The environmental impact of dental mercury is mainly due to the poor management of dental amalgam waste. Proper collection of mercury-contaminated solid waste prevents the release of mercury vapour during combustion. In addition, the use of amalgam separating devices reduces the amount of amalgam-contaminated water released from dental clinics