Number

052-EN

Section

General Section

Use

Abstract

The report presents six case studies with examples on the substitution of mercury and mercury compounds in USA health care units.
Alternatives include substitution by other chemicals (tungsten for mercury in dilators, zinc chloride for mercury chloride in B-5 fixative, alcohol for mercury in thermometers), but also substitution by other products that do not need mercury (mercury-free vaccines, mercury pressure devices replaced with aneroid units) or situations where the use of mercury-containing parts are no longer required by regulations (switches for automatic collimation of X-Ray tubes).

Substituted substances

Alternative Substances

Reliability of information

Evidence of implementation: there is evidence that the solution was implemented and in use at time of publication

Reason substitution

neurotoxicant
other toxic effects

Other type of alternative

Aneroide barometer instead of mercury barometers

Hazard Assessment

- Tungsten filled dilators: Tungsten is a neurotoxicant and does not pass SUBSPORT screening criteria.  Tungsten hazards like flammability and neurotoxicity are less relevant for the application described here.
- Zinc chloride has lower acute and specific organ toxicity than mercury chloride. Both are however of the same category of toxicity for aquatic organisms, which is important for the use described (are rinsed with water). Mercury and its compounds are known to bioaccumulate in aquatic organisms (bioaccumulation factor 5000 for inorganic mercury), while for zinc and its compounds there is less concern (and fewer studies).
- Thimerosal free vaccines are safer but are less stable and need to be stored properly, because they do not contain preservatives (see Further reading).
- Aneroide barometers are safe to use and instead of mercury they use a flexible alloy sensitive to pressure changes.
- Discontinuation of the use of mercury switches for the X ray machine for the Positive Beam Limitation does not generate hazards.
- Thermometers with ethanol are much safer to use than the one wirh mercury.

Description of Substitution

The U. S. Environmental Protection Agency (EPA) and the American Hospital Association (AHA) signed a Memorandum of Understanding (MOU) in 1998 on implementing pollution prevention in hospitals. One of the goals was to virtually eliminate mercury-containing waste from hospital waste streams by 2005.
As part of the Mercury Elimination Project six Californian health care units provided data regarding identification of internal sources of mercury pollution and measures to reduce mercury wastes. Substitution was considered one of the measures.
- Esophageal dilators (bougies) are made of thick rubber/latex tubes filled with mercury that makes them heavy yet flexible.
Alternative, mercury free dilators are made of silicon tube filled with tungsten gel.
- Gastro/esophageal tubes (Blakemore tube) have a mercury-weighted tube that has been replaced by a solid rubber weight in newer, mercury-free devices.
- Intraocular pressure devices use mercury weight to lower the eye pressure before surgery. In newer micro-surgical procedures pressure reduction is not always necessary.
- Pressure measuring devices (e.g. sphygmomanometers, barometers) contain mercury in glass tubes. They may be replaced with aneroid units that do not need mercury.
- Thermometers containing mercury can be replaced by other types using alcohol or other chemicals, depending on the range of temperatures they are meant to measure.
- B-5 fixative (or Zenker?s solution) is one of the compounds widely used in laboratories for tissue preparation. B5 contains mercury II chloride but several brands of B-5 fixative have been developed using zinc chloride instead.
- Vaccines containing thimerosal as preservative in multi-dose vials are more stable but alternatives are also available as single-dose vials requiring no preservative, which are preferred by some of the patients.
- Mercury leveling switches typically contained by X-ray machines are intended to assure that the X-ray beam is perpendicular to the film, operation called the Positive Beam Limitation (automatic collimation). Since this operation is no longer required by Federal US legislation, switchers may be removed and need not be replaced.

The report states that most of the alternatives to mercury were not more expensive. However, the cost for a tungsten-silicone bougie may be almost twice the one for the mercury- containing version.
For thimerosal free vaccines stock should be minimized by applying ?just-in-time? inventory. Single-dose vials require a much larger refrigerated storage space as well as greatly increased shelf space and transportation. This costs more.

Experience during the project showed that identification of mercury sources is done better by smaller teams (three persons) and when there is a very open and sincere atmosphere.
The report underlines the importance of maintaining the good practices once implemented. Instructing the purchasing department, as well as the rest of the employees is important, as well as scrutinizing vendor agreements.
Other sources of mercury have been identified during the project (like barostats, fluorescent lights, cleaners, etc) and measures have been proposed. The report notes that ??rarely, resistance for these changes from professional staff has been observed??.

Case/substitution evaluation

Alternative solutions to mercury in hospitals are available and do not pose special problems for implementation.
The cost of alternatives is not much higher (although there are exceptions) and part of the expenditures are balanced by the reduction for the taxes and for the transport and disposal of hazardous mercury wastes.
Some alternatives are easily transferable to SU99 and activities (e.g. thermometers, barometers) or to similar activities (e.g. the reactive for histological laboratories in research or academic sectors).

Tungsten used in dilator does not pass SUBSPORT screening criteria. However,  being contained in the dilator tube provides acceptable protection of  health care worker and patients. It is less volatile and is a solid not a liquid as mercury under the  conditions of use. Tungsten powder in gel is less likely to generate significant leaks when tube ruptures occur, like in the case of mercury.

State of implementation

In use

Date and place of implementation

1999-2000 in USA

Enterprise using the alternative

Health care units in California USA

Availability ofAlternative

The substitutes are available on the market. The report states that rarely the mercury free alternatives are more expensive than the one with mercury.

Type of information supplier

Authority

Contact

The Department of Care Health Services, State of California, USA, https://www.dhcs.ca.gov/Pages/default.aspx

Further information

ATSDR report on tungsten: click here
WHO statement on thiomersal: click here
Thimerosal: click here
EU mercury strategy and legislation: click here
X ray mercury switch: click here
Bioaccumulation of zinc chloride (o): click here
Thimerosal MSDS Sigma Aldrich: click here
Mercury-Containing Products and Alternatives in the Health Care Setting, 2002
www.informinc.org/fsmerchealth.pdf
Lowell Center for Sustainable Production: Mercury Reduction in Healthcare
Eliminating Mercury in Health Care: A Workbook to Identify Safer Alternatives, 2012

Type of publication and availability

Full text report freely available on internet

Publication source: author, company, institute, year

The Department of Health Services, State of California, USA

Publication source

Type of publication and availability

http://www.dtsc.ca.gov/pollutionprevention/upload/guide-to-mercury-assessment-in-healthcare-facilities.pdf

Date, reviewed

February 27, 2020