A human body contains on average 3 grams of Mercury (Hg), in the form of dental amalgam. Cremation releases the material to the atmosphere in the form of gaseous elemental Mercury. As Mercury is a well known toxin, should there be concern over its release to the environment via cremation?
Currently there are over a million cremations a year in the United States, resulting in the release of about three tons of Mercury. That is a lot of Mercury but it pales in comparison to the Mercury released from burning coal – over 50 tons per year.
Just how dangerous Mercury exposure is depends on two important variables, the chemical form and the amount of the exposure (dose). In the elemental form, for example the liquid in older thermometers, it has a relatively low acute toxicity. If inhaled in the gaseous form or absorbed through the skin in the liquid form it is poorly metabolized and rapidly excreted unchanged. We are all exposed to trace amounts of elemental mercury from airborne sources, but in this form it presents little hazard.
Even children on a playground near a crematorium are at little to no risk from this type of Mercury. This doesn’t mean that the Mercury from a crematorium is of no consequence, but the explanation is more complex.
Mercury in the form of a salt is much more toxic. Lewis Carroll’s Mad Hatter of Alice in Wonderland was a parody of the real life risk of hatters of the 19th century. Exposure to certain Mercury salts caused tremors and a form of dementia.
Hat makers in Central Asia used felt which was obtained by separating the fir from the skin of small animals. Traditionally camel urine was used to help form the felt. When felt preparation moved to Europe, hatters substituted their own urine. It was soon discovered that hatters who had syphilis and were being treated with Mercury salts made better felt! Thenceforth, solutions of Mercury salts were substituted for urine for hat making.
The most toxic form of Mercury comes in the form of certain organomercurials, specifically Methylmercury. In this form it is easily absorbed, where it binds to and destroys nervous tissue. This is the form of Mercury found in both fresh and saltwater fish.
The first recognition of the toxicity (principally nerve damage) of Methylmercury occurred in Japan in 1956 and was referred to eponymously as Minamata Disease. Chisso Chemical Company on Minamata Bay manufactured industrial chemicals and disposed of their wastes in the bay. A component of the waste was Methylmercury which was absorbed by fish and shellfish. Consumption of the sea food resulted in chronic poisoning and thousands of deaths.
This brings us back to the crematorium and the release of the relatively non-toxic elemental Mercury. When this mercury is deposited on soil or in water, it makes its way to the benthic layer – basically the mud at the bottom – of streams and lakes. There, anaerobic bacteria convert it to the much more toxic Methylmercury. It bioaccumulates in the smallest organisms, then up the food chain to fish.
The long and short of it is that it is not a good idea to allow release Mercury to the environment. The problem is easily solved however by simply removing the Mercury amalgam from teeth before cremation, as has been proposed by Humphrey Funeral Service. They are currently seeking a permit to construct a crematorium near Center Valley here in Pope County. If so they will be the first in the nation to take this simple but environmentally important step. Occam’s razor, don’t operate a crematorium without it.