It is emitted into the environment by a number of human activities. Coal-burning power plants have traditionally been the largest human-caused source of mercury emissions in the air in the United States.
Mercury released into the air eventually falls back to earth, where microorganisms in bodies of water convert it into methyl mercury. This type of mercury found in fish and wildlife, is highly toxic, and when eaten builds up in the body of animals and humans over time. It is especially harmful to fetuses, babies, and young children. Over two‐thirds of Minnesota lakes and streams evaluated by the Minnesota Pollution Control Agency (MPCA) are considered mercury-impaired.
Mercury in Dental Amalgam
The US Environmental Protection Agency (EPA) in their flow model for 2005-2010 estimated mercury emissions from crematoria at 3,000 kg (6,500 pounds) per year. This is a 350% increase from their 1990 flow model. The Mercury Policy Project predicts mercury emissions from crematoria will rise to 7,700 kg (17,000 pounds) by 2020. Implementation of reduction technologies and phase-out of mercury-containing products will lead to zero mercury emissions by 2025 for many industries. In contrast, emissions of mercury from cremation are steadily rising, and are projected to continue increasing to 2025 and beyond.
Implementation of reduction technologies and phase-out of mercury-containing products will lead to zero mercury emissions by 2025 for many industries. In contrast, emissions of mercury from cremation are steadily rising, and are projected to continue increasing to 2025 and beyond.
According to the Cremation Association of North America (CANA), there were 2,599,012 deaths and 1,214,146 cremations in the United States in 2014. These numbers are projected to grow to 2,694,489 deaths and 1,426,660 cremations by 2019. The trend is also observed in Minnesota, where the cremation rate grew from 52.6% in 2012 to 57% in 2014, and is projected to rise to 64.3% by 2019. The National Funeral Directors Association (NFDA) estimates that by 2030, 70.6% of all US consumers will choose cremation over burial.
Capturing mercury emissions - a tricky proposition
Outside of expensive smokestack scrubbers and resomators, there are no practical existing technologies in North America adapted for mercury capture during cremation. Proposed alternative solutions to control mercury in emissions from crematoria have included:
- Smokestack scrubbers - These are too costly for the majority of small crematoria, which perform low numbers of cremations. In addition, unwanted mercury ends up in a waste product that requires special processing to either recycle the mercury, or to contain and prevent its secondary escape into the environment.
- Resomation - This is a process of breaking down the human body chemically in an alkali and water solution, so called alkaline hydrolysis. The end product is a mixture of: a) liquid, which is returned to the water cycle where it is has also been touted as a fantastic natural fertilizer, and b) bone ash, which is pulverized and returned to the family. The process does not produce airborne emissions of mercury. However, alkaline hydrolysis requires a lot of water and the installation of an expensive set-up to contain and process the body. The cost of switching from cremation to resomation is prohibitive for the majority of small crematoria.
- Pre-cremation extraction of teeth - Extraction of teeth prior to cremation is problematic. Rigor mortis and/or embalming can totally restrict access to or viewing of the back teeth, where most dental amalgam fillings are located. Dental amalgam may be hidden from view under ceramic crowns, and dental records and x-rays may not be readily available to identify or exclude the presence of dental amalgam.