Mercury  Fact Sheet  #3

Mercury is a unique element that has many uses in the health care industry. Historically, mercury has been used in thermometers, blood pressure gauges, dental amalgams, and various laboratory solutions such as fixatives, reagents, and solvents. 

But mercury is also very toxic to humans, even in small doses. It affects the central nervous system, kidneys, and liver. Once in the bloodstream, mercury remains in the system for long periods of time inflicting more damage. 
 
When a laboratory solution containing mercury is washed down the sink, the mercury travels with the wastewater and eventually ends up at a publicly owned treatment works (POTW). These wastewater treatment plants remove pollutants and debris before discharging wastewater into the environment. It is technically very difficult for a POTW to remove mercury from its waste stream, and inevitably mercury is released into the environment or collected in the biosolids produced during the wastewater treatment process, often at levels high enough to render them contaminated and unusable for land application. 

To prevent contamination of the aquatic environment and biosolids, many POTWs face stringent limitations on mercury, as well as requirements to identify and minimize contributions of mercury to their systems. Once in the aquatic environment, mercury 
becomes available to wildlife and accumulates in the food chain until it is eventually consumed by humans. State health departments have issued several fish consumption advisories due to the presence of mercury in fish tissue. 

Mercury in the waste stream of POTW's is of particular concern because bacteria inherent to the wastewater treatment process can methylate the available mercury. Mercury in the methylated form is more toxic to humans and wildlife than inorganic mercury. Discharge of methylmercury from POTW's has been recognized as a potential source of fish contamination in Minnesota. 

Hospitals and medical laboratories contribute mercury to POTW waste streams. Laboratories were the most frequently reported generators of mercury-bearing hazardous waste in the Great lakes region according to the 1991 Resource Conservation and Recovery Act Biennial Report. The second most frequently cited process generating mercury waste was the discard of out-of-date products or chemicals. Laboratories use mercury in products such as reagents, catalysts, as well as for calibration, scaling, and radioactive diagnosis. 

Dentists, who discharge dental amalgams to sewers, are another significant source of mercury to POTW's. According to a national study, the average filling must be replaced in 20 years. Dentists have estimated that roughly 20 percent of removed fillings end up going down the drain. 

Because there are currently no EPA regulations restricting the discharge of mercury down the drain at hospitals and laboratories like those for manufacturing or other industries, it is up to the individual facilities to be responsible and help to keep mercury out of the waste stream. To meet their own requirements, several POTW's have been working with hospitals, dental offices and other facilities on cooperative programs so that regulatory measures do not become necessary. 

The purpose of this fact sheet is to encourage all medical industry workers to keep mercury out of the POTW waste stream by: 

• handling products in a safe and proper manner, 
• selecting products that do not contain mercury, 
• recycling mercury-containing products, and 
• disposing of mercury-containing waste products in environmentally sound manner.

First, encourage your facility to buy products that do not contain mercury. There are now several products on the market that can be used as substitutes to mercury. By ordering mercury-free products, hospitals, nursing homes, clinics, and laboratories will encourage manufacturers to provide ecologically sound products. Medical professionals must ultimately balance the advantages of selecting mercury products against the risks that mercury poses in the environment. 
 
Proper Handling and Disposal of Mercury Products 

Mercury often ends up in the POTW waste stream because of improper handling and disposal of chemicals that contain mercury. 

Encourage all laboratory workers to read the material safety data sheets provided with each solution to determine not only the contents but also safe handling practices. Minnesota laws require sellers of mercury to provide buyers with a material safety data sheet and to have the buyer sign a statement regarding proper use and disposal. 
 

•      Label instruments containing mercury. 

•      Make sure the laboratory facility has a mercury spill cleanup kit on hand for accidental spills. 

•      Make sure personnel are familiar with the proper cleanup procedures for handling a spill involving mercury. 

•      Clean up spills promptly, placing soiled towels and rags in the plastic bags or other containers provided with the mercury spill kit and disposing of them in a hazardous waste receptacle. 

•      Do not place mercury-containing materials in waste receptacles for biohazardous waste because mercury will be released to the atmosphere when the biohazardous waste incinerated. 

•      When working with mercury solutions, make sure you are familiar with your laboratory policies on proper disposal practices for these solutions. 

•      Follow proper procedures when cleaning or refilling instruments that contain mercury. Instrument cleaning or refilling should take place in a well-ventilated area and, if possible, over a tray to contain any spills. 

•      Mercury should be handled in areas without tile flooring or carpeting to facilitate cleanup in the event of a spill. To minimize the risk of an accidental spill, never handle mercury over a sink. 

Several recycling companies accept mercury-containing waste. The companies differ in the type of mercury waste accepted and the transportation requirements.