| Mercury in Healthcare Facilities  Healthcare
facilities are under increasing pressure to eliminate
mercury. Good alternatives exist for virtually every
mercury containing medical product.
On this
page, you will find information that will help you understand
why hospitals have acquired so much mercury, why this has
become a problem, and what your options are.
Consult
the H2E Ten Step Mercury
Guide to learn how to get mercury out of your facility.
Properties
Mercury
is the only common liquid metal. Its usefulness stems
from its unique combination of weight, ability to flow,
electrical conductivity, chemical stability, and its high
boiling point and relatively low vapor pressure.
- For
centuries, mercury was the ideal choice for devices to
measure temperature and pressure:
- For
temperature, the high boiling point of mercury
means it can measure a wider range of temperatures
than most other liquids.
- For
pressure, the high density of mercury means a conveniently
short column can measure a wide range of pressures. The
measurement is simple: the pressure is proportional
to the length of the column, and it is hard (though
not impossible) to go wrong when simply measuring
a length.
- Other
medical applications take advantage of mercury's density. For
example, esophageal
dilators (bougie tubes) and similar devices use flexible
tubes inserted into partially blocked passages that can
apply expansion pressure when the tube is filled. From
a mechanical standpoint, mercury's weight makes it a
good choice as a filling fluid.
- Mercury's
electrical conductivity combined with its ability to
flow motivated its use in electrical switches that respond
to tilt, such as devices to turn on a light when a cover
is opened, and silent wall switches.
For these
and many other applications, mercury containing devices
and materials have been an integral part of healthcare
facility operations for decades. A typical large
hospital might easily have over one
hundred pounds of mercury onsite, incorporated into
hundreds of different devices in dozens of separate locations,
unless it has undertaken a conscious and sustained effort
to eliminate mercury.
Risks
Health
risks
Mercury
is typically encountered in one of three forms:
- metallic
liquid mercury, also called "elemental" mercury,
found in thermometers and sphygmomanometers, and in dental
fillings (mixed or "amalgamated" with silver
and other metals)
- inorganic
mercury salts, found in mercury batteries
- organic
mercury compounds, such as methyl mercury, produced by
microorganisms such as soil bacteria, and found in fish
and other foods
The forms
have different properties, and therefore present different
types of exposure risks:
Metallic
liquid mercury,
like any other liquid, evaporates. Once in the
vapor state, it passes very efficiently into the lungs
(about
80% of what is inhaled stays in the body). Some
of it is then converted to inorganic salts. The
rest dissolves in fatty tissue, and can enter the central
nervous system, where it can cause neurological problems
ranging from subtle to severe. In contrast, metallic
liquid mercury does not pass very readily though skin,
nor is it absorbed well from the digestive tract.
Inorganic
mercury salts are highly toxic. If ingested, about
10% will pass into the body through the digestive
tract lining. Much of that will collect in the
kidneys and can cause severe damage there. But
inorganic mercury salts do not dissolve well in fat,
and are not absorbed easily into cells.
Organic
mercury compounds are fat-soluble, and pass
easily into the body (90
- 95% in the case of methyl mercury) from the digestive
tract. They will be distributed throughout the
body, and will cross the placental barrier, passing
from mother to unborn child.
The EPA
website provides a concise
summary of health effects from exposure to each form of
mercury, with links to more detailed references.
Risks
to the environment
Any emission
of mercury into the environment, even at very small concentrations,
can pose a threat to human health because of mercury's
tendency to become concentrated in animal tissue as it
moves up the food chain. The phenomenon is known
as bioaccumulation. It is a remarkable
natural process that is able to produce concentrations
of certain compounds in fish tissue that are millions of
times higher than the water they are swimming in.
In
the case of mercury, bioaccumulation begins when
certain common bacteria convert mercury into an organic
form, methylmercury. Mercury in this form can pass
through the lipid membranes of various microorganisms. This
is true of other forms of mercury as well, but many of
them tend to diffuse out again just as rapidly. But
once a few of the forms, like methylmercury and mercuric
ion have entered a microorganism, they stay there. The
microorganisms are eaten by copepods,
tiny shrimp-like animals that have been called "the
base of the marine food web". The copepods
tend to excrete the membranes of the cells they eat,
and the mercuric ion tends to stick to the membranes,
so that form does not bioaccumulate. But the methylmercury
builds up throughout the life of the copepod. The
process continues as the copepods are eaten by organisms
higher up the chain, with the methylmercury concentrations
increasing at every step. As this case history
indicates, it takes a set of special circumstances for
bioaccumulation to occur; most forms of mercury
do not bioaccumulate. But methylmercury hits the
jackpot.
The problem
is particularly acute for fish consumption. In 2003,
there were 3,089 fish advisories in the 48 contiguous states. This
actually undercounts the number of bodies of water affected,
since some advisories cover large geographic areas. In
all, fish advisories in 2003 covered 35% of the total lake
acreage, and 24% of the total river miles in the country. Mercury
contamination was involved in 76% of these advisories. These
and much additional data are available in an August
2004 publication from EPA's Office of Water.
It is
a global, not just a local problem. Mercury at levels
exceeding the recommended maximum for consumption (1 part
per million in fish tissue) has been detected even in remote
locations in Canada and the U.S. One reason is
that mercury can remain in the air for a long time in the
elemental form. It slowly oxidizes through the action
of ozone and other reactive pollutants, and can then settle
back to the earth in rain or snow. But it may remain
in the atmosphere for a year before this happens, giving
it plenty of time to travel far from its source.
The transport
and bioaccumulation of mercury is discussed in an informative
and readable article (Annu. Rev. Ecol. Syst.,
1998. 29:54366) available on the website of the Department
of Civil and Environmental Engineering, Northwestern University.
Liability
Along
with health and environmental risks, the presence of mercury-containing
devices in a healthcare facility presents a substantial
business risk associated with a growing area of
litigation.
Compliance
with federal and
state [link to state locator] workplace standards
for mercury is necessary, but may not be sufficient to
protect a facility from future liability claims. Mercury
poisoning involves a very broad, and not very well defined,
range of symptoms that can overlap with a wide variety
of other causes. The appearance of the symptoms can
occur some time after the exposure.
Under
the circumstances, it is not surprising that law firms
specializing in personal injury cases are aggressively
seeking clients with perceived symptoms of mercury
poisoning. The focus is currently on thimerosal,
an ethyl mercury compound used as a preservative in vaccines.
But if history is any guide, a few well-publicized damage
awards would soon engender litigation involving other mercury
exposure routes.
Mercury
liability is a wild card. Healthcare facilities are
exposing themselves needlessly to substantial future liability
risks if they continue to use mercury-containing devices
in applications where practical
alternatives exist.
Compliance
requirements
Hazardous
waste and universal waste
The presence
of mercury can cause a waste material to become classified
as a hazardous waste. If
so, the waste must be handled and disposed of in compliance
with a very detailed set of regulations under the Resource
Conservation and Recovery Act, or RCRA. See the HERC
Managing Hazardous (RCRA) Wastes [link] page for
more information.
To determine
whether the mercury in a sample triggers a hazardous waste
classification, the rules specify a test called the Toxicity
Characteristic Leaching Procedure, or TCLP (EPA
Method 1311). The test is designed to give some
indication of how readily a material would tend to leach
into groundwater if the waste were placed in a landfill. The
standard test involves subjecting the waste to a mild acetic
acid solution (about the strength of household vinegar)
at room temperature for 18 hours. If the extract
contains more than 0.2 mg per liter mercury, the waste
is considered hazardous. Thus the classification
will depend on both the concentration and the form of the
mercury in the waste.
See the
HERC Hazardous Waste Determination page
for more information on how wastes become classified as
hazardous.
EPA has
established a special category called "Universal Waste" to
encourage recycling of certain common items. An item
that is eligible for classification as a universal waste
is exempt from many of the cumbersome aspects of hazardous
waste regulation that might otherwise make recycling impractical. Mercury-containing
items that qualify include:
- fluorescent
bulbs and other mercury-containing lamps
- mercury
batteries
- thermostats
- pesticides
But note
that universal waste rules can vary from state to state. See
the Mercury
State Resources Tool for state-specific information
on regulations covering the disposal of mercury containing
wastes.
More RCRA-related
information on mercury is available from the Safe
Mercury Management program of EPA's Office of Solid
Waste.
Air
emissions
At one
time, many healthcare facilities operated medical waste
incinerators. Enough mercury found its way into the
medical waste stream that hospital incinerators had become
the fourth largest source of mercury emissions to the atmosphere.
Increasing
public awareness of the magnitude of mercury emissions
from medical waste incinerators was a major factor in the
drive to shut them down. In 1997, EPA finalized a
National Environmental Standard for Hazardous Air Pollutants
(NESHAP) for Hospital/Medical/Infectious Waste Incinerators
(HMIWI). The new standard set strict limits on emissions
for several compounds, including mercury.
The number
of medical waste incinerators had already been declining
before the HMIWI NESHAP, but its effect was even more dramatic
than anticipated. In 1997, there were approximately 2,400
incinerators burning medical waste nationwide, accounting
for 8% of
the national total of mercury emitted to the air. By
2004, the number of incinerators had declined to 111.
The emission
limit for mercury specified in the Hospital/Medical/Infectious
Waste Incinerators (HMIWI) NESHAP for all cases (new
or existing sources of any size) is 0.55 mg per dry standard
cubic meter, or 85% reduction. You can find additional
background and technical information on the HMIWI NESHAP
on a summary
page on the EPA Air Toxics website.
Wastewater
In general,
facilities that discharge wastewater are regulated in two
different ways, depending on whether they release their
wastewater directly to the environment ("direct discharge")
or indirectly, through a municipal sewer system, known
in the jargon as a Publicly Owned Treatment Works, or POTW
("indirect discharge")
Direct
dischargers are required to obtain permits under the National
Pollutant Discharge Elimination System (NPDES) program. An
individual facility's permit will specify limits for various
compounds of concern, including mercury. The value
of the limits will depend on site-specific factors.
Effluent
limits for indirect dischargers are set by their POTW. In
determining the limits, the POTW has to take its own requirements
into account. POTWs are themselves direct dischargers,
and will therefore have to operate under their own NPDES
permits, which will include site-specific mercury limits. In
addition, POTWs generate sludges from their biological
wastewater treatment systems, and many POTWs dispose of
the sludges by land application. These sludges must
also meet mercury concentration limits. POTWs will
restrict the allowable concentration of mercury in wastewater
discharged to their systems in order to ensure that their
requirements can be met.
Additional
background is available on a website
maintained by the Masco-MWRA mercury workgroup.
Workplace
rules, hazard communications
Taking
the different health effects into account, OSHA has developed different
workplace standards for each of the three forms of
mercury discussed above. The
OSHA website provides summary sheets listing exposure limits
and linking to additional references for each form.
In addition
to workplace exposure standards, OSHA requires compliance
with its Hazard
Communication Standards. Any workplace in which
employees may be exposed to hazardous chemicals must have
a HAZCOM
Program in place that includes a written plan, labeling
of hazards, access to Material Data Safety Sheets (MSDSs),
and appropriate training.
The OSHA
website provides a compliance-oriented
page with a formidable list of standards that may apply
to mercury. The links on the page tend to be nonspecific,
making the page of somewhat limited utility to the general
reader, but that sinking feeling you will experience as
you scan through the list should serve as a useful incentive
to minimize the presence of mercury in your facility wherever
possible.
Other
regulations involving mercury
Mercury
is also regulated under a bewildering variety of federal,
state, and local statutes and agencies. For example,
special regulations exist for mercury contained in many
common products, including:
- pesticides
(now mostly phased out)
- cosmetics
(as a preservative)
- dental
products (regulated under medical device rules)
- food
(as a trace contaminant)
For background,
a detailed
discussion of mercury regulation nationwide, provided
on the EPA website, is a good place to start. The
discussion contains links to several useful summary tables,
including:
Mercury-free
alternatives
Most
of mercury's unique advantages have become obsolete with
developments in solid state electronics and materials science. Mercury-free
products that are equivalent to or better in performance
than the old mercury devices are now readily available
for virtually all applications in healthcare facilities.
The
following table lists the mercury-containing devices that
typically account for a substantial fraction of the mercury
in healthcare facilities. For each device, the table
indicates the properties of mercury that have made it the
material of choice for those devices in the past, and the
alternatives that have since become available to perform
the same functions without the use of mercury.
| Device |
Properties |
Alternatives |
| Thermometers |
Flow,
thermal expansion coefficient, high boiling point |
Galinstan (uses
a gallium-indium-tin alloy, otherwise similar in appearance
and operation to the mercury version). A recent
study finds Galinstan thermometers an "appropriate
replacement" for mercury.
Digital
(now available with comparable accuracy to mercury). Generally
requires a battery, but solar cell models are available.
[Infrared
type, RATE "instant thermometer" type,
liquid crystal "dot" type -- are these
mainly for home use, or would they be of interest
to hospitals?] |
| Sphygmo-manometers,
barometers |
Flow,
density, low vapor pressure |
Aneroid (No
liquid: uses motion of bellows.)
Electronic
(No liquid: uses solid state pressure sensor.)
Note: Calibration
issues exist for all types of sphygmos, including
mercury. |
| Esophageal
dilators |
Flow,
density |
Tungsten
powder in gel (tungsten is dense, more inert
than mercury, and flows when dispersed in a gel) |
| Electrical
switches |
Flow,
conductivity |
Mechanical
and optical devices |
A few
of these alternatives, such as the aneroid sphygmomanometer,
have been around for decades, but have recently been improved
to address issues such as durability, stability, and ease
of calibration. Some were simply not available until
very recently. But in all cases, there is no longer
any technological barrier to phasing mercury out of healthcare
applications.
Today,
the main obstacle to moving to a fully mercury-free facility
is short-term cost. But when liability considerations
and compliance costs are included in the assessment, it
is hard to make the case for postponing the switchover. The
presence of mercury exposes your facility to
- immediate
costs, including cleanup costs from spills, and citations
from regulatory and accrediting organizations
- long
term costs, such as legal actions by workers, patients,
or members of the surrounding community thought to have
been exposed to mercury used on site or found in your
facility's waste stream
The
cost of mercury spills is documented in a fact
sheet from the Sustainable Hospitals project. In
several actual cases, spill costs for relatively minor
incidents have generally amounted to several thousand dollars,
and larger spills commonly involve tens of thousands.
Because
the situation is still developing, no good liability cost
projections appear to be available. In case you missed
it above, this
link may help provide a qualitative appreciation of
the potential.
Disposal
of mercury-containing wastes
Mercury-containing
materials that are hazardous wastes must be disposed of
in compliance with RCRA regulations, and discussed on the
HERC page Disposal and Recycling -- Hazardous Waste [link]. Some
mercury-containing items may qualify as Universal Wastes [link].
A good
overview of disposal issues specific to mercury can be
accessed from the EPA Office of Solid Waste's Safe
Mercury Management Program home page. Resources
include:
Cleanup
of mercury spills
There
are several good reference sources available on the web
that deal with mercury spill management. A sampling
includes:
An article
on mercury spills in New York State provides a good
overview of the frequency and consequences of mercury
spills in that state, which is presumably typical of
the rest of the country. You may be surprised by
the number of the spills documented, and the number of
people inconvenienced by them.
More
resources
EPA
CDC
The Centers
for Disease Control provides a series of detailed toxicological
profiles for various hazardous substances. The profile
for mercury, which includes environmental fate information
as well as extensive health effects data, is at http://www.atsdr.cdc.gov/toxprofiles/tp46.html
Mercury
products and alternatives
- A
comprehensive list
of alternatives to mercury-containing products is
maintained on the Sustainable Hospitals website, at http://www.sustainablehospitals.org
- A
table of mercury products and alternatives, with links
to product and recycling resources, is available from
Inform, Inc., at http://www.informinc.org/fsmercalts.pdf
- A
more detailed fact sheet on specific mercury-containing
products, including thermometers, pressure gauges, thermostats,
and switches is also available from Inform, at http://www.informinc.org/fact_P3industrialmeters.php
Information
on Galinstan is not easy to come by on the
web, but a page
offered by thefreedictionary.com contains an interesting
insight. Apparently Galinstan, unlike mercury, wets
glass, and would therefore tend to creep up a glass capillary
tube through the action of surface tension. This
may explain why Galinstan thermometers haven't been available
until recently, and what enabling technology was required
to develop the alloy as a mercury replacement in glass
thermometers: for a thermometer, you need to have
the length of the liquid column be determined solely by
thermal expansion. The fix is to coat the inside
of the capillary tube with gallium oxide.
|
We
recommend:
Mercury
toxicity:
A
very readable and detailed article summarizing
what is known about mercury toxicity (eMedicine).
A summary
and links page with an emphasis on workplace health
standards (OSHA)
A summary
of risks and regulations, with an emphasis on effects
on unborn children
(National Institutes of Health)
|
