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Q: Finding Mercury in Fish at home ( Answered,   0 Comments )
Question  
Subject: Finding Mercury in Fish at home
Category: Science
Asked by: tina_oh_yeah-ga
List Price: $100.00
Posted: 27 Aug 2006 17:13 PDT
Expires: 26 Sep 2006 17:13 PDT
Question ID: 760020
Is there a way, at home, to test/measure fish for mercury levels?  If
she (7th grader) burns out everything else in a beaker, how can she
determine mercury levels since everything but metals should be
disappated?  How could she separate mercury from, say, lead? Is
there a simpler way to determine mercury in fish that is not apparent to me?
Answer  
Subject: Re: Finding Mercury in Fish at home
Answered By: crabcakes-ga on 27 Aug 2006 20:56 PDT
 
Hello Tina_oh_yeah,

   I?m afraid I must tell you that burning fish in a beaker will not
yield detectable levels of mercury. As you will learn further down in
my answer, the mercury found in fish is in an organic form, and in
minute quantities. Burning fish containing mercury will release the
mercury as a gas. If you had a way to capture all released gas, and
the proper instrumentation, you may be able to detect the presence of
mercury gas.

 I may be wrong, but your question reads as if you expected to see
metal mercury at the bottom of the beaker. This will not happen.
Mercury is a chemical heavy metal by definition, but it can exist in
many forms, and does not look like a metal to the eye. If you were to
dessicate a piece of fish tissue, using a vacuum drying method, in a
closed system, and ground up the fish, in a laboratory, one could
feasibly measure mercury in the sediment, and in the escaped vapors
and gases. This would require sophisticated laboratory equipment
however.

  I have included a link to a rapid home test (further down) that can
detect mercury in the fish tissue. This is a qualitative test, not a
quantitative test, meaning it will detect the presence of mercury, but
does not measure the quantity. I have also included some laboratories
you could contact. Your local Fish & Game Services could also direct
you to a lab that would measure mercury in a fish.


  ?Scientists test for methylmercury now using gas chromatography, a
method of separating and identifying chemicals in a sample carried
along by a gas pumped through the detection apparatus.

Preparation of the samples is laborious and prone to flaws that
require starting the testing procedure all over again, said Hudson and
Brian Vermillion and Wade Wimer, graduate students who work in
Hudson's lab.
"The analysis of methylmercury is really expensive," Hudson said.
"Typically, it's like $200 or more a sample."
http://www.news-gazette.com/news/local/2005/11/26/researchers_find_easier_test_for_mercury/


   This is what one University of North Dakota lab uses to test for mercury:
?Mobile sampling trailer for mercury field testing ? PSA Sir Galahad
mercury analyzer ? Tekran mercury analyzer ? BIOS gas flow calibrator
? Gilibrator gas flow calibrators ? Porter mass flow controllers ?
Bench-scale test cells ? TSI tri-jet aerosol generator ? TSI
aerodynamic particle sizers ? TSI condensation particle counters ?
Leeman PS200 automated mercury analyzer ? DMA 80 coal and ash mercury
analyzer ? Semtech mercury analyzers ? Ohio Lumex Mercury Spectrometer
? Nippon Mercury Vapor Analyzer ? Mercury speciation conversion
systems
http://www.undeerc.org/rnd/analyticallabs/mercurylab.asp



   The kind of mercury found in fish is a different type than the
mercury found in an older thermometer. ?Elemental or metallic mercury
is a shiny, silver-white metal and is liquid at room temperature. It
is used in thermometers, fluorescent light bulbs and some electrical
switches. When dropped, elemental mercury breaks into smaller droplets
which can go through small cracks or become strongly attached to
certain materials. At room temperature, exposed elemental mercury can
evaporate to become an invisible, odorless toxic vapor. People can be
exposed to elemental mercury vapor when products that contain mercury
break and expose mercury to the air, particularly in poorly-ventilated
spaces.

Inorganic mercury compounds take the form of mercury salts and are
generally white powder or crystals, with the exception of mercuric
sulfide (cinnabar) which is red. Inorganic mercury compounds have been
included in products such as fungicides, antiseptics or disinfectants.
Some skin lightening and freckle creams, as well as some traditional
medicines, can contain mercury compounds.
Organic mercury compounds, such as methylmercury, are formed when
mercury combines with carbon. Microscopic organisms convert inorganic
mercury into methylmercury, which is the most common organic mercury
compound found in the environment. Methylmercury accumulates up the
food chain.?
http://www.epa.gov/mercury/faq.htm 



   The mercury found in fish is an organic form, called
methylmercury.? There are two kinds of mercury. The simple one atom
(Hg is the chemical symbol) mercury is called "Inorganic Mercury". The
other type of mercury is called "Organic Mercury". The Organic mercury
is more dangerous since it can easily penetrate cell walls, is easily
absorbed in fatty tissues, and is easily absorbed into nerve and brain
cells. For this reason, some feel Organic mercury is 100 times more
dangerous than Inorganic mercury. The word "organic" refers to
something that connects well to life.?
http://www.beatcfsandfms.org/html/CheckForHg.html


 The way methylmercury accumulates in fish is interesting.
?Methylmercury in fish comes from mercury in the aquatic environment.
Mercury, a metal, is widely found in nature in rock and soil, and is
washed into surface waters during storms. Mercury evaporates from
rock, soil, and water into the air, and then falls back to the earth
in rain, often far from where it started. Human activities
redistribute mercury and can increase its concentration in the aquatic
environment.?

?Once mercury gets into water, much of it settles to the bottom where
bacteria in the mud or sand convert it to the organic form of
methylmercury. Fish absorb methylmercury when they eat smaller aquatic
organisms. Larger and older fish absorb more methylmercury as they eat
other fish. In this way, the amount of methylmercury builds up as it
passes through the food chain. Fish eliminate methylmercury slowly,
and so it builds up in fish in much greater concentrations than in the
surrounding water. Methylmercury generally reaches the highest levels
in predatory fish at the top of the aquatic food chain.?
http://www.oehha.ca.gov/fish/hg/index.html


   ?Mercury is a global pollutant with complex and unusual chemical
and physical properties. The major natural source of mercury is the
degassing of the Earth?s crust, emissions from volcanoes and
evaporation from natural bodies of water.
World-wide mining of the metal leads to indirect discharges into the
atmosphere. The usage of mercury is widespread in industrial processes
and in various products (e.g. batteries, lamps and thermometers). It
is also widely used in dentistry as an amalgam for fillings and by the
pharmaceutical industry. Concern over mercury in the environment
arises from the extremely toxic forms in which mercury can occur.

Mercury is mostly present in the atmosphere in a relatively unreactive
form as a gaseous element. The long atmospheric lifetime (of the order
of 1 year) of its gaseous form means the emission, transport and
deposition of mercury is a global issue.?
http://www.lenntech.com/heavy-metals.htm


   ?Nearly all fish contain trace amounts of methylmercury. How does
this element get into our fish supply? Mercury occurs both naturally
and from man-made sources. Some of it can be traced to coal-burning
power plants. Smokestacks release toxic mercury emissions which rain
down into rivers, lakes, and oceans. Bacteria convert the mercury to a
form that's easily absorbed by insects and other small organisms.
Mercury moves up the food chain as small fish eat the small organisms
and big fish eat the smaller fish. The highest concentrations
accumulate in large predators such as shark, swordfish and tuna...some
of America's favorite fish.


Around the world, there is concern about mercury contamination through
fish, but specific recommendations vary. For example, Health Canada
advises consumers to limit their consumption of swordfish, shark or
fresh and frozen tuna to one meal per week; for young children and
women of child-bearing age, the recommended limit is one meal per
month. Health Canada's guideline is 0.5ppm total mercury content ?
more stringent than in the U.S. Britain's Food Standards Agency is
advising pregnant and breastfeeding women and women who intend to
become pregnant to limit their consumption of tuna to no more than two
medium-size cans or one fresh tuna steak per week.

Even within the United States, women are hearing different advice from
different sources, especially where tuna is concerned. The EPA's
methylmercury guideline is a recommended limit on mercury consumption
based on bodyweight, also known as a "reference dose." EPA's
methylmercury reference dose is .1 micrograms/kg body weight per day.
In July 2000, the National Academy of Sciences found the EPA's
reference dose as "scientifically justifiable" for protecting most
Americans.
So exactly how much mercury a 45 lb. child would ingest by eating one
6 ounce can of tuna per week, and how does that compare to the EPA's
reference dose? Take a look at the following calculations:


Step 1  - DETERMINE EPA's RECOMMENDED LEVEL FOR A 45 LB CHILD 
?	Multiply child's body weight by EPA's reference dose. 
?	Convert 45 pounds to kilograms = 20.45 kilograms 
?	20.45 kilograms x .1 micrograms per kilogram per day 

EPA RECOMMENDED LEVEL = 2.05 micrograms per day = 14.35 micrograms per week. 

Step 2 - HOW MUCH MERCURY IS IN 6 OUNCES OF CHUNK WHITE TUNA? 
?	Multiply amount of fish by average mercury level for chunk white albacore. 
?	Convert 6 ounces to grams = 170 grams 170 grams X .31 ppm  (or
micrograms per gram)**

MERCURY INGESTED = 52.7 micrograms per gram   
Step 3 ? COMPARE MERCURY INGESTED WITH EPA'S RECOMMENDED LEVEL 
?	Divide 52.7 micrograms by 14.35 micrograms = 3.7 
BY EATING 6 OUNCES OF CHUNK WHITE TUNA A WEEK, THE CHILD IS INGESTING
ALMOST FOUR TIMES EPA'S RECOMMENDED DOSE.?
http://www.pbs.org/now/science/mercuryinfish.html

Here?s a nifty mercury calculator:
http://www.gotmercury.org/

Fact Sheet on mercury:
http://www.zeromercury.org/fact_sheet/index.htm


?Heavy metals are generally considered to be those whose density
exceeds 5 grams per cubic centimetre. A large number of elements fall
into this category, but the ones listed here are those of relevance in
the environmental context. Other heavy metals only rarely occur in
concentrations high enough to cause harmful effects. Arsenic is
usually regarded as a hazardous heavy metal even though it is actually
a semi-metal.?
http://www.internat.naturvardsverket.se/index.php3?main=/documents/pollutants/metall/tungmete.html




Tests for Mercury:
==================

Here is a simple home test kit for mercury:

?MercuryCheck Swabs are self-contained test units which provide a
rapid, easy to use, specific test for mercury on any surface.?

?There is a fiber tip at one end. Inside the barrel is a single glass
ampoule which contains the mercury reactive material. To activate the
swab, simply squeeze to crush the glass ampoule and shake well to mix
the reagents. Gently squeeze Swab and rub test surface. The tip will
turn violet (purple) in the presence of Mercury.?
http://www.leadcheck.com/MercuryCheckSwab.shtml


   ?In recent months, the Environmental Protection Agency (EPA) has
issued a warning to women who are pregnant or who are considering
becoming pregnant. The EPA cautions them to avoid eating the larger,
high-risk fish, such as swordfish, king mackerel and tilefish. The
Food and Drug Administration (FDA), which works with state regulators
and commercial fisheries to monitor methylmercury levels, also has
issued a warning in recent months. The agency has recommended a
mercury limit of no more than 1 part per million for human
consumption.

Janda's method uses a solution that changes color if there is even
half the recommended FDA limit on mercury levels in fish. Basically, a
tiny pellet of fish is placed in a tube with a few drops of an acid
and enzyme solution, which digests the tissue for a few hours, in a
way similar to human digestion. Then the mixture is stirred with a
special dipstick coated with a "chelating" resin. If there is any
mercury in the fish, it sticks to the resin. The dipstick is then
plunged into a second tube containing a mild acid, which pulls the
mercury off the resin, and then a few drops of lightly colored
detector solution is added.
This solution has a molecule that precipitates when it binds to the
mercury. If the fish is contaminated, the liquid changes color,
becoming clear. The addition of a drop of dye allows a quantitative
measure of the concentration of mercury in the fish.

Janda believes that the colorimetric assay could be a boon to field
environmentalists, since their current mercury detection procedures
demand that they catch whole fish and bring them into the laboratory
for slow, expensive and complicated testing.
"This method could be made field ready," he says. "Environmental
professionals could test the fish and then release them back into the
water."
http://www.sciencedaily.com/releases/2001/04/010415222727.htm


?A fluorescent sensor for detecting mercury in water has been
developed by US researchers.
The Mercury Sensor 4 (MS4), developed by Elizabeth Nolan and Stephen
Lippard at the Massachusetts Institute of Technology, is a
seminaphthofluorescein (SNAFL)-based dye that shows a change in
fluorescence intensity when mercury is present in solution.?
http://www.rsc.org/Publishing/ChemScience/Volume/2005/7/mercury_detection.asp


   ?We used an HP 5921A atomic emission detector coupled to an HP 5890
Series II gas chromatograph to determine the concentration and
speciation of mercury in various fish species caught and processed
locally. The AED was found to be a sensitive detector highly specific
to the atomic emission wavelength of 253.652 nanometers for mercury.
Using this wavelength, it is possible to detect Hg down to 0.1 pg/sec
peak width with the GC/AED. The specificity relative to carbon can be
as high as 100,000:1.
For fish tissue, it was possible to determine Hg down to about 1 g/kg
wet weight. An application of GC/ AED for the determination of
organomercurials using the 184.950 nm emission wavelength has been
reported (Carro-Diaz et al., 1994).

Converting Mercury Species
The speciation of Hg (II) present in fish tissue was determined by the
reaction with sodium tetraethyl borate (STEB) in aqueous solution
(Yong & Bayona, 1995 and Rapsomanikis & Craig, 1991), where ionic
mercury species are converted to their volatile ethyl derivatives.
Labile CH3HgX species react to form methylethyl mercury, and labile
HgX2 species form diethyl mercury. Nonionic forms such as dimethyl
mercury and elemental mercury do not react with the tetraethyl borate
anion, which makes it possible to determine the various forms of
mercury by GC separation.

A typical GC/AED chromatogram of an ethylated fish sample is shown in
Figure 1. This sample has a relatively low total Hg concentration of
0.05 mg/kg. Methyl mercury is the major form of mercury present in
fish. Upon ethylation with the tetraethyl borate anion, it reacts to
form methylethyl mercury.?
http://www.chem.agilent.com/cag/peak/peak2-96/fish_tissue.html



  Dickerson, La Clair, and Janda have begun to adapt their method for
field use by making small capillary tubes that are preloaded with the
ligand. When one of these capillaries is used to stab a piece of fish,
the precipitation reaction would take place and could be detected by
looking at the capillary under a field detector or microscope. This
method could be used to screen thousands of samples a day, the authors
say.

They also envision that it would not be difficult to develop a simple
consumer assay where a similar capillary could be placed in a
detection device plugged into a home computer, allowing consumers to
test their own fish and determine whether they are contaminated with
unsafe levels of mercury for perhaps as little as a few dollars per
test.
At the moment, the kit is still in development and is not available to the public.?
http://www.scripps.edu/news/press/112304.html



   ?Tiny pieces of gold and the properties of light can help
scientists find and remove mercury from polluted water, two University
of Central Florida chemistry professors have found.
Professors Florencio E. Hernandez and Andres Campiglia can quickly and
inexpensively detect even trace amounts of mercury in less than 10
minutes by mixing small amounts of gold with water. The gold absorbs
the mercury while the researchers monitor changes in the amount of
light through a hand-held device called an optical spectrometer. This
process can be used to create water filters and reclaim contaminated
water.?
http://www.research.ucf.edu/SponsoredPrograms/newsletter/IMPACT/2005Fall/ArticleMercury.htm

This lab performs mercury testing on seafood:
http://www.itscb.com/newsitetest/news/mercuryanalysis.shtml?gclid=CPOS3ruSgYcCFQpoDgodzT5JIg

This lab tests people for mercury, using a stool sample.
Doctor's Data
170 West Roosevelt Rd., West Chicago, IL 60185, Tel 800-323-2784
Email: inquiries@doctorsdata.com, http://www.DoctorsData.com/
Please email them for a doctor in your area that supports their tests.

?This approximately $100 test requires an Rx from your Doc, and is
purchased from Dr.'s Data Inc. They send you a test kit, you take a
stool sample, send the sample to the test lab, and then they send a
report to your doctor. It measures the micrograms (ug) of heavy metals
per kilogram (kg) of stool and shows how much metal you are exposed to
on a daily basis. This test is helpful at seeing metals that are not
seen in urine. An example of a metal that does not pass through liver
and kidney is organic mercury.?
http://www.beatcfsandfms.org/html/CheckForHg.html


?The best way to see mercury that was absorbed into the cells in the
past is a Porphyrin Analysis test. This involves sending a urine
sample to a lab.?
http://www.beatcfsandfms.org/html/CheckForHg.html



I hope this is the answer you were seeking. If not, if I have missed
the mark, please request an Answer Clarification, and allow me to
respond, before you rate. I will be happy to assist you further on
this question, before you rate it.

Sincerely, Crabcakes

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Mercury testing
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