Mercury and Cremation Issues Revisited

By Paul Rahill

Paul Rahill is President of the Matthews International Cremation Division (MCD) headquartered in Orlando, Florida. Matthews Cremation designs and manufactures cremation equipment systems, caskets and urns as well as providing service and repairs for cremation equipment, and crematory supplies for the Cremation Industry.

Paul's involvement with the cremation industry began in 1973. He has worked in various capacities in the design, manufacturing and service of cremation equipment, as well as research, development, environmental and regulatory issues. Paul also develops and implements seminars, training and certification programs for the cremation industry.

Questions and concerns regarding mercury emissions from crematories in the United States and Canada continue to arise from time to time. Minimizing emissions of all types are certainly a priority to crematory owners, operators and cremator manufacturers who have developed training programs to minimize many types of emissions common to crematories. These training programs which include special sections on cremator design, the environment and proper operations have been presented to thousands of operators over the last 20 years.

North American cremator designs have typically performed better environmentally due to designs that included large afterchambers for the reburning and scanning of the exhaust prior to discharge into the atmosphere. These types of designs are important as the locations where crematories have often been built in North America are light commercial and adjoining residential properties.

The most extensive cremation equipment emissions research ever undertaken confirmed that the design and operation of typical North American crematories provided significantly better emissions than regulations required, and even exceeded expectations with older operating systems.

However, issues will continue to come up and it is important to address them by revisiting the information that is available to us, updating both the facts and accuracy at each opportunity. It is important to acknowledge that often those raising these issues and questions, though well-meaning, base their concerns on inadequate information or un-answered questions. In this article, I would like to specifically review how the cremation process correlates to mercury emissions into the atmosphere, the effect on the surrounding environment and the trends for the future that will impact mercury emissions.

The United States Environmental Protection Agency (EPA) describes mercury as a "naturally occurring element that can be found throughout the environment". Although naturally occurring, different activities by humans can increase the amount of mercury that is moving between the atmosphere, bodies of water, soils and within themselves.

Some of these human activities that recycle mercury in the environment are: municipal incinerators, breaking of fluorescent lamps, dental facilities operations, production and disposal of batteries, household waste disposal and the operation of crematories as well as other sources.

As this naturally occurring element cycles through our environment, particularly in water, it is ingested by small organisms as they feed. These organisms become part of nature's food chain. The accumulation of mercury we are most familiar with tends to center on fish. Different types of fish have differing levels of mercury.

The lower a fish is in the food chain the lower it's likely level of mercury accumulation. The higher the fish is in the food chain the higher the potential mercury concentration may be. Shark, swordfish and kingfish are often cited as those having some of the highest concentrations of mercury. Of course, human consumption of these fish could increase one's exposure to mercury depending on the actual levels found in the fish.

So, we can see that although mercury is a naturally occurring element, over-exposure to it is not a good thing for humans.

The most notable way that mercury enters the cremation cycle, and therefore crematory emissions, is through silver amalgam dental fillings found in many dead human bodies.

Silver amalgam fillings contain mercury alloys that when introduced through dead humans into the cremation process of intense heat, often exceeding 180°F, results in the volatilization of mercury and its emissions into the atmosphere.

Silver amalgam tooth fillings containing mercury have been common for many years, but their use appears to be in significant decline. It is estimated that at one time silver amalgam represented the greatest majority of filling materials used, possibly as high as 90%. Within the last 10 years, the percentage of fillings containing mercury has already declined by 30%, a significant decrease.

Although concern for the environment has always been a priority for the dental industry, the primary driver of this trend is actually found in the mirror, appearance. Composite resins blend better with the color and appearance of natural teeth. Other materials, such as gold, porcelain and non-precious alloys are also used to restore teeth, but none of these contain mercury. All these changes in dental practices and consumer preferences have resulted in significantly less mercury entering the cremation stream and thereby reducing mercury emissions by reducing mercury input.

Mercury emissions from crematories today are in significant decline due primarily to changes in dental practices, but how bad were they actually before this recent trend?

One of the most detailed studies of mercury emissions impact was conducted in the United Kingdom where over 70% of dead humans are cremated. The study focused on a crematorium that had been in operation for over 40 years, processing more than 112,000 cremations at the time of the study.

The direction of the prevailing winds of the crematory exhaust was determined to identify the land surrounding the crematory where the highest concentrations of mercury could be found. Five soil samples were taken along this windward axis; three samples were taken on the downwind axis and two additional samples were taken on the upwind axis. All the samples were then analyzed.

As anticipated, the downwind samples contained a higher, though not significant, level of mercury. "Trigger concentrations" had been determined to evaluate level of soil contamination. These "trigger levels" ranged from low levels of 1mg/kg for human food producing soils to 20mg/kg levels that are deemed acceptable for children's playgrounds. The concentration of mercury found in the crematory soil samples averaged less than .15 mg/kg, almost 7 times lower than that allowed for food production and more than 100 times lower than that allowed for children's playgrounds. The soils were deemed uncontaminated even after 112,000 cremations and 40 years of operation.

Consider that typical North American crematories operate at only 20% of these production levels used in the analysis, and it becomes readily apparent the anticipated impact of mercury emissions from those crematories are even further diminished.

As an industry, we must be receptive to discussing environmental and performance issues whenever they come up. Proper training of crematory operators and managers must be continually encouraged and older cremation systems should be properly maintained and updated to keep them in prime operating condition.

Mercury use in the dental profession is significantly in decline. However we should always scrutinize the input of other materials into our crematories while looking for and encouraging alternative materials to be used in all areas of the death care profession, whenever possible.

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