Sludge Watch ==> Dentist Association Recommends Better Mercury Controls

[Maureen Reilly]

Sludgewatch Admin:

This is sure a step in the right direction. Here in Canada, sewage sludge 
land application is the second highest source of released mercury.

Much of the mercury in sewage sludge comes from dental offices.  Putting in 
fillings, taking out old fillings...much of the silver amalgam goes down the 
sink and into the sewers.  The heavy fillings can sit in the pipes emitting 
mercury into the sewage system for years.


Elemental mercury is turned into the more bioavailable and toxic methylated 
mercury during the sewage treatment process. When it is released on as 
sewage sludge spread on farmfields or at compost sites, that mercury 
vaporizes into the atmosphere...falling in rain and contaminating rivers, 
lakes, and ecosystems around the globe.  Animals that graze on sludged 
fields will take up the mercury since it is often top dressed on pasture 
land.

If the sewage sludge is incinerated without mercury pollution capture 
scrubbers, then the mercury will be released into the atmosphere.  The Peel 
sludge incinerators just west of Toronto are now being retrofitted with 
mercury scrubbers. This facility - when fully built- will have 4 fluidized 
beds, making it the largest sludge incinerator in North America.  The 
proposed Liberty Energy gasifier in Hamilton will have mercury 
capture/containment system.  The Lafarge Cement kiln in Bath has no mercury 
capture equipment - non of the cement kilns capture mercury.  In California  
The San Joaquin Compost facility is sending sludge into cement kilns  - no 
mercury containment.

http://www.mmc.co.jp/english/csr/csr2006-11.pdf
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ADA Recommends More Effective Methods for Handling Mercury-Containing Waste


By Brant McLaughlin


On Tuesday, The American Dental Association (ADA) updated its best 
management practices for the disposal of dental amalgam waste to include the 
use of separators, which are collection devices installed in dental office 
plumbing.

Dental amalgam is a silver-colored tooth filler made from an alloy of 
mercury, silver, copper, and tin which dentists have used for generations. 
Although it has been surpassed in frequency of usage by tooth-colored 
composites, amalgam remains a safe and valued treatment option for some 
patients, especially those who need large fillings put into their back teeth 
or who have some specialized need.

Having advocated for the public's health and promoted the art and science of 
dentistry since 1859, the not-for-profit ADA is the nation's largest dental 
association and represents over 155,000 members of the dental practices 
members. The ADA's state-of-the-art research facilities develop and test 
dental products and materials that have advanced the practice of dentistry 
and made the treating of patients more effective, less painful, and less 
frightening.

There has been concern about the potential health dangers of the mercury 
contained in amalgam for some time, although claims of tooth fillings 
causing acute, persistently returning symptoms of illness in those who have 
such fillings are, as Mark Twain said about reports of his own death, 
"greatly exaggerated".

Nevertheless, particles of amalgam that are rinsed down drains or that 
escape poorly maintained chair-side traps and vacuum pump filters in 
dentists' offices travel through the sewer system to local wastewater 
treatment facilities, from which the mercury within amalgam might enter the 
environment by being released directly into a waterway, being released into 
the air if a treatment facility's sludge is incinerated (burning causes a 
chemical reaction which releases mercury from amalgam) and then re-deposited 
into the ground or into a waterway, or it could spill directly into soil if 
treatment facility sludge is land-spread.

If a dentist's office's plumbing is connected directly to a septic system, 
amalgam particles become part of the sludge in the septic tank, eventually 
to be pumped out and transported to a wastewater treatment facility or local 
land spread, from which the mercury within the amalgam typically becomes 
soluble and gets into the local groundwater.

The recommended separators are designed to capture and remove at least 95 
percent of solid waste particles before they enter the sewer system. The use 
of separators permits reductions in the amount of mercury-containing amalgam 
that enters into wastewater treatment facilities.

"Dentists across the country have enthusiastically embraced ADAbest 
management practices since we introduced them in 2003, which clearly 
demonstrates that voluntary programs work. Since then, we have gained a lot 
of experience with separator technology, and even assisted the ISO in 
developing standards for the devices. We have learned that the systems work 
well, and we now feel comfortable including them in our best management 
practice recommendations," said ADA President Mark J. Feldman, DMD.

Source:
American Dental Association (PR Newswire), "ADA Updates Environmental 
Recommendations for Handling Waste"


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http://www.associatedcontent.com/article/401221/ada_recommends_more_effective_methods.html