Report on the
PROBLEM OF MERCURY EMISSIONS INTO
THE ENVIRONMENT OF THE
UNITED STATES
to the
WORKING PARTY ON MERCURY,
SECTOR GROUP ON UNINTENDED
OCCURRENCE OF CHEMICALS IN
THE ENVIRONMENT,
OECD
By
Victor W. Lambou
U.S. Environmental Protection Agency
January 27, 1972
-------
TABLE OF CONTENTS
I Introduction . 3
Purpose of Report 3
The Problem 3
II Production, Uses and Consumption of Mercury ... 5
III Hazards of Mercury ]k
Hazards to Man ]k
General 1*+
Methylmercury 1U
Organic Mercury Compounds Other Than Alkyl . 19
Inorganic Mercury 20
Hazards to Wildlife and Domestic Animals ... 23
Hazards to Aquatic Life 23
IV Sources of Mercury to the Environment 25
Man-Made Sources 25
General 25
Chlorine Industry 25
Pulp and Paper 25
Laboratories, Hospitals, and Dental Clinics. 26
Paint 26
Catalysts 27
Mining and Refining 27
Fossil Fuels 28
Sewage Treatment Plants . 29
Incineration 29
Phosphate Rock Industry . .;. .'' 30
Raw Materials and Basic Chemicals 30
Agricultural Use of Pesticides 30
Use of Pesticides in Water Systems 31
Containers 31
Miscellaneous Sources 31
Natural Sources 31
V Environmental Data From North America 33
Poisonings 33
Man 33
Domestic Animals 33
Wildlife 3^
Fish 3^
Environmental Levels 35
Air 35
Water 37
Land 37
-------
Residue Levels 38
Man 38
Aquatic Life 39
Aquatic Birds 40
Other Birds 41
Food 42
Fishing and Hunting Restrictions 44
Fishing 44
Hunting 44
Removal of Fish from the Market 46
VI Movement of Mercury in the Environment 47
Air 47
Land 48
Soils 48
Biota 49
Water 50
Waterways 50
Transformations 51
Accumulation by Fish 53
Decontamination . . . .• 55
Environmental Budget 57
VII Policies and Standards 58
General 58
Residues in Aquatic Life ...... 59
Drinking Water A 63
Residues in Bottom Sediments of waterways ... 63
Discharges to the Total Environment ...... 63
Discharges to the Atmosphere 64
Waste Water Discharges to Public Waters .... 64
VIII Actions Taken 66
Pesticides 66
Water 6?
Background 67
Water Supplies 67
Industrial Discharges 68
Wastewater Treatment Plants 70
Air 70
Literature Cited 72
-------
I. INTRODUCTION
Purpose of Report
At its second meeting in October 1971, the Sector Group on Unintended
Occurrence of Chemicals in the Environment decided to investigate
the problem of mercury emissions. A Working Party on Mercury was
formed with representation from Canada, Japan, Sweden and the United
States, the countries with experience in mercury control methods;
Representatives from each country were requested to prepare a report
on the environmental problems of mercury emissions in their country.
From these submissions the Working Party is to prepare a single
paper on the nature of the mercury problem and the consequence of
present or anticipated actions to control mercury emissions. This
report is the United States' Working Party member's contribution.
The Problem
Over the years mercury and its compounds have become useful to society in
a host of applications. They have also developed a notorious reputation
as .toxic substances in the workplace, the home and the environment, with a
long record of disabling sickness and fatality.
Mercury metal is a liquid at ordinary temperatures which expands uniformly,
is a good electrical conductor, amalgamates readily with most other metals,
and is quite volatile. It combines with many other elements to form a larcje
vaiety of inorganic and organic compounds with a wide range of useful
properties.
Metallic mercury is used in a variety of electrical and mechanical devices
such as switches, light bulbs, batteries, flow meters, thermometers, and
barometers. It is extensively used as an electrode in the manufacture of
chlorine and caustic soda and as a catalyst in the production of vinyl
chloride. An amalgam of mercury with tin/silver is widely used in the
filling of teeth. Mercury compounds are used as biocides and preservatives
in many industrial and agricultural applications. Mercury is also used in
a variety of Pharmaceuticals and cosmetics. In 1969 almost 80,000 flasks
(a flask is 76 pounds) of mercury were consumed in the United States in all
applications.
The primary source of mercury for industrial use is from the red sulfide
ore, cinnabar. The ratio of domestic production to annual consumption is
highly variable. U. S. producers have virtually no control over the price
of mercury, and mines open and close frequently as the price changes. The
-------
price of mercury is presently below $270 per flask and the number of
operating mines has decreased from 109 in 1969 to less than 10 today.
As an environmental contaminant mercury comes from nany types of man-made
and natural sources and enters the environment through direct discharges to
the air, water and soil. The principal man-made discharges are through the
various applications of pesticides, chlor-alkali production, fuel burning,
catalytic processes, ore refining, sewage treatment waste incineration,
phosphate rock processing, paint manufacture and use, and breakage of
mercury-containing devices. Recent concern has focused on pesticides
applications and water discharges from chlor-alkali plants since these
sources have been closely associated with contamination of the food chain.
A limited amount of mercury may be emitted from natural ore bodies, thus
causing contamination of the local air and aquatic environment.
Because mercury can be introduced into the environment in many fornis--
some volatile, some water soluble, some stable, some unstable—it is
readily transported throughout the environment. In addition it is
easily trans formed from one physical or chemical state to another de-
pending on the environmental conditions. It also has a strong tendency
to accumulate in sediments and in organisms, depending on its form.
In the air mercury may fall out or be rained out and be entrained in
soil and water. It may also be transported great, distances in the-
atmosphere. In soil and water, it may be transformed to a volatile or
soluble form, taken up by organisms, deposited in bottom sediments or
released to the air. The cycle is dynamic, but once mercury enters
the environment its removal becomes a complex long-term problem.
Long before the present concern over methylmercury contamination in fish
and poisonings due to treated seed, there were many documented cases of
mercurial ism, both acute and chronic, from a variety of industrial and
domestic exposures. The mercury problem is not new, only society's
awareness of it is. The forms of mercury vary in their relative toxicity
to man and animals. The alkyl (methyl and ethyl) compounds are believed
to be the most toxic followed by metal mercury vapor, which is more toxic
than the Inorganic salts and organic compounds other than alkyl. The
affinity of the mercury alkyl compounds and metal vapor for nervous tissue,
especially the brain, explains the rather bizarre neurological synjptons
seen in man and other mammals suffering severe nercury intoxication.
Although effects at these high levels are striking, the United States is
just as concerned about the more subtle phychological effects at low
levels. i-Je are also very concerned over the likely terctogenic and
mutagenic effects which may impact on future generations of nen and
arrivals.
-------
Although present emphasis is on protecting the human peculation fron
ingesting excessive levels of nethylmercury in diet, the concentrations
of mercury recently observed in the air and water convince us that there
must now be an effort to drastically reduce the human intake of r.iercury
from all routes of entry.
The problem of mercury in the environment boils down to tliesa salient
features:
1. There are diverse and widespread "an-ioade sources emitting
mercury into the environment.
2. The many physical and chemical forns of mercury are such that
it moves readily fror.i one environmental medium to another, it is easily
transformed physically and chemically, it tends to accumulate in sedi-
ment, soil and living organisms, and once in the environment, it ;n?.y bo
impossible to remove.
3. Although methlylmercury in the diet is believed to oresent
the greatest environmental hazard to human health at present, due
consideration must be given to the potential hazard now and to future.
generations from the intake of other forns of mercury through other
routes such as metallic vapor from air. Our concern for the future
reflects the as yet unknown, but likely teratogenic or mutacjonic effects
of mercury compounds
4. Even if all discharges to the environment were suddenly (and
miraculously) stopped, the residual already, produced by past activities,
(e.g. the current accumulation in fish and the aquatic sediment), if not
removed or permanently stabilized, will present a mercury problem for
years to come.
-------
II. PRODUCTION, USES AilD CONSUMPTION OF MERCURY
The chief source of mercury is the red sulfide ore, cinnabar. Commercial
deposits of cinnabar are located in the U.S., China, Italy, Mexico, the
Phillipines, Peru, Spain, the U.S.S.R. and Yugoslovia. During 1969, there
were 109 operating mercury mines in the U.S. which produced 29,360 flasks
of mercury (West, 1970). An additional 31,924 flasks were imported into
the United States (Hest, 1970). The ratio of domestic to annual consump-
tion is higly variable. U. S. producers have virtually no control over
the price of mercury, and mines open and close frequently as the price
changes. The price of mercury is presently below $270 per flask and the
number of operating mines has decreased from 109 in 1969 to less than 10
today. World production of mercury during 1969 amounted to 285,343 flasks
(West, 1970).
Mercury is used in a variety of ways, including electrolytic preparation
of chlorine and caustic soda, paints, industrial and control instruments,
Pharmaceuticals and agriculture.
The mercury cell electrolytic method of producing chlorine and caustic
soda and/or caustic potash requires large quantities of mercury for startun
and to replace what is lost during operation. Mercury cells in the United
States accounted for 27.9 percent of the total installed chlorine caoacity
in 1969 (West, 1970). The diaphragm-type cell electrolytic method, which
utilizes no mercury, accounted for the rest of the installed capacity.
Approximately 0.5 Ib. of mercury is lost for each ton of chlorine produced
(National Materials Advisory Board, 1970). The national Materials Advisory
Board (1970) predicted that by 1975 the average loss of mercury per ton of
chlorine produced would be reduced to about 1/4 Ib.
There are a number of reasons why the use of mercury cells has become
increasingly popular. The national Materials Advisory Board (1970)
states that purity of products from these cells is superior to that
available from diaphragm cells, an important consideration for certain
markets. Mercury cells have higher power consumption than diaphragm
types; however, mercury cell derived caustic requires no steam for evapo-
ration, a necessity for diaphragm liquor (National Materials Advisory
Board, 1970). Although economics have historically favored diaphragm cells,
this increment has gradually narrowed and may be incidental within the near
future (National Materials Advisory Board, 1970). A new dimensionably
stable anode made of specially coated titanium has been devised that may
increase the attractiveness of the use of the diaphragm-type cells (West,
1970).
All metals except iron can be amalgamated with mercury. Before the
development of the cyanide process for gold and silver, mercury was widely
used in the "patio" process to form amalgams for recovering silver and
gold. Potassium, sodium and zinc amalgams are used as reducing agents.
Sodium amalgam has been used in production of tetraethyl and tetramethyl
-------
lead; however, a continuous electrolytic process suitable for their
production threatens to curtail the use of sodium amalgam (national
Materials Advisory Board, 1970).
One of the more important uses of mercury as a catalyst is in the production
of vinyl chloride. However, the trend has been toward the use of etnylene,
a less expensive feedstock than acetylene (National Materials Advisory
Board, 1970). Approximately 0.074 Ib. of mercury is lost per 1000 Ibs. of
vinyl chloride monomer in the acetylene process (National Materials
Advisory Board, 1970). Mercury in the form of a mercuric oxide catalyst is
used with sulfonated anthraquinone products as raw materials to make vat
dyes and is expected to retain its place in the industry without rivalry
from any replacement catalyst (National Materials Advisory Board, 1970).
Organic mercurial salts are used in urethane elastomers for casting,
sheeting and sealant applications. The National Materials Advisory Board,
(1970) estimated that there would be an increase in the use of mercury for
this purpose from 600 flasks in 1963 to 1,570 flasks in 1975. Mercury
based catalysts in the production of vinyl acetate monomer and acetaldehyde
have been replaced by other catalysts (National Materials Advisory Board,
1970).
During World War II considerable quantities of mercury were used in
fulminate for munitions and blasting caps (including mercuric chloride
for tracers as munitions other than fulminate). An average of 4,-100 flasks
was used annually for this purpose during V/orld Mar II; however, this
decreased to 420 flasks in the postwar period (Pennington, 1959).
An amalgam of mercury with a silver/tin alloy is used extensively for the
filling of dental cavities. Under normal economic conditions there are no
substitutes for the mercury amalgam; but if mercury were in short supply
its use in dental amalgams could be sharply curtailed to practically zero
(National Materials Advisory Board, 1970). Current substitutes would produce
satisfactory restorations even though they would not be as permanent (national
Materials Advisory Board, 1970).
Considerable amounts of mercury are used in electrical aoparatus, instruments
and for laboratories. Such uses include batteries, lamps, electron tubes,
pressure sensory devices, thermometers, guages, barometers, valves, pump
seals, meters, electrical switches and relays.
An unusual use for mercury was the utilization of 290 flasks for a pool
of the metal to provide a frictionless support for floating the ontical
assembly of a telescope (West, 1970).
-------
8
Mercury is used in a variety of Pharmaceuticals including diuretics, anti-
septics, skin preparations and preservatives for cosmetics and soap.
Substitutes are available in each of these areas of mercury use (National
Materials Advisory Board, 1970).
A relatively unique application for mercury is its use for frozen mercury
precision castings. Owing to its smooth surface and low uniform expansion,
mercury is superior to wax or plastic pattern materials.
Possible new industrial uses of mercury include a technique for purifying
aluminum. Mercury is added to form aluminum mercury crystals which are
melted in a molten salt bath, the mercury vaporized and condensed and the
purified aluminum separated from the bath (Uest, 1970). An electrolytic
process for recovery of zinc from drosses or other by-products involves
precipitation of elemental zinc at the cathode and alloying with mercury.
Zinc of high purity can be recovered (National Materials Acivisorv Board,
1970).
Mercury is used as ballast as part of the emergency flotation system in
some research and rescue submersibles. One such vehicle v/ould jettison
approximately 2500 Ibs. of mercury into the water"in case of an emergency
in order to provide flotation or trimming capability.
Mercury based pesticides have been used in paints, paner and pulp manu-
facture, and agriculture. -During 1970 there were". 380 mercury based
pesticides registered under the Federal Insecticide, Fungicide and
Rodenticide Act (Table I).
The use of mercury based slimicides fell sharply in 1965 consequent to
a U.S. Food and Drug Administration ruling that paner or cartons which cane
in contact with food must be free of mercury. In order to conform with
the Food, Drug and Cosmetic Act of the United States where a large per-
centage of the Canadian pulp and paper products are being sold most of
the Canadian companies have discontinued the use of mercury slimicides in
the last 10 years (Fimreite 1970). Fimreite (1P70) found only 9 mills in
Canada recently using phenylmercury slimicides. Regardless, there was,
at least until recently, some use of mercurv based slimicides in the
United States.
Mercury based pesticides are used in the paint industry for three general
purposes: (1) preservation of interior paint formulations in the can
(2) mildewproofing both oil and water based exterior paints and (3) as
an antifoul ing agent in marine paints. Mercury based compounds have been
or are being used as biocides in laundry products, industrial water systems
cooling towers, air conditioner filters, adhesives, starches, glues, floor
waxes, sanitizing or disinfecting rinses, fabrics, textiles, fibers, logs,
lumber, paper, broom corn, cellulose sponges, etc.
-------
Table 1 Number of mercury based pesticides registered under the Federal Insecticide,
Fungicide and Rodenticide Act during 1970*
USE
Trees
Flowers
Ornamentals and
Turf
Humans
Home
Wood
preservatives
Anti foul ing
paints
Hospital
Industrial
maintenance
Crop
Restaurants
Others
Hhenyl
Mercury
6
1
.39
1
21
20.
13
36
59
14
6
10
Other Mercury
Alkyl Organo- as Mercurous Mercuric
Mercury Mercury Elemental Chloride Chloride
1 -
3
16 2 - 25 23
13
3 - -
3 - 1
1 2 3 2
1 -
2 - -
6 1
_
1 - 2
Other
Inorganic
Salts
-
-
-
3
2
1
39
2
-
-
-
-
Total
7
-------
10
The primary agricultural use of mercury based pesticides is for the
fungicidal treatment of cereal grains. Secondary agricultural uses are
for the treatment of diseases of turf, fruits and trees.
U. S. consumption of mercury steadily increased from approximately 30,000
flasks per year from 1930 to 1939 to almost 80,000 flasks in 1969 (Table
2). However, the U. S. consumption of mercury decreased to approximately
60,000 flasks in 1970. In 1969 the primary consumers of mercury in order
of importance were the electrolytic preparation of chlorine, electrical
apparatus, paint, industrial and control instruments, dental preparations,
and catalysts (Table 3). In 1970, the primary consumers in order of
importance were electrical apparatus, electrolytic preparation of chlorine,
paint, industrial and control instruments, catalysts, and agriculture.
The chlorine industry consumed approximately 4,000 flasks of mercury
annually during the period 1955-59. Consumption increased steadily until
1969 when 20,720 flasks were consumed. However, in 1970, consumption
decreased to 14,977 flasks. The consumption of mercury by the paper and
pulp industrv decreased from approximately 3000 flasks annually in the
period 1960-64 to 316 flasks in 1970 (Table 3).
The National Materials Advisory Board (1970) estimated that there would
be an increasing trend in the United States consumption of mercury from
73,855 flasks in 1968 to 84,544 flasks in 1975 (Table 4). The Board also
estimated trends in consumption by uses (Table 4). These estimates were
made before attention was called to environmental problems associated
with mercury in the United States during 1970.
-------
11
Table 2 Mercury consumed in United States.
Flasks
1928 . 34,482
1933-37 29,900
1938-42 32,400
1943-47 45,400
1948-52 46,900
1953-57 51,900
1955-59 54,346
1960-64 66,564
1965 73,560
1966 71,509
1967 69,517
1968 75,422
1969 79,104
1970 61,490
JL/ Represents total consumption for indicated year or average yearly
consumption for indicated years.
2/ Preliminary estimates.
3/ Source US Bureau of Mines.
-------
Table 3
Mercury consumed in the United States by uses. Z/
(Flasks)
1955-59 1960-64
(overage) (overage) 1965
1966
1967
1968
<. 1969
1970
Agriculture (includes fungicides and bacterlcides
for industrial purposes) 7,500 3,096 3,116
Amalgamation-------------------—----—---—-—- 243 ' ' 361 268
Catalysts — 848 773 924
Denial preparations I/ 1,489 2,186 1,619
Electrical apparatus \J 9,285 10,540 16,097
Electrolytic preparation of chlorine and caustic
noda 4,172 7,430 8,753
General laboratory usei
Commercial 986 1,459 1,119
Industrial and control instruments I/ 5,998 5,450 4,628
Painti
Antifouling 1,213 639 . 255
Mildew proofing-------------------------------- 5/ 4,772 8,211
Paper and pulp manufacture-----------—--------- 6/ 2,831 619
Pharmaceuticals 1.615 3,350 418
Redistilled \J— - 9,509 9,662 12,131
Other 3/ - 11.488 9.807 15.402
Total known uses----------------------- 54,346
Total uses unknown----------------------- --
Grand Total — 54,346
2,374
248
1,932
1,334
16,257
11,541
1,563
4,097
140
8,280
612
232
7,267
15.632
3,732
219
2,489
1,359
14,610
1,133
3,865
154
7,026
446
283
7,334
12.563
3,430
267
1,914
2,089
17,484
14,306 17,453
1,246
3,935
392
10,174
417
424
8,252
7.945
66,564 73,560
71,509
69,517 75,422
2,689
195
2,958
3,053
18,650
20,720
2,041
. 6,981
244
9,486
558
724
V
9.689
77,988
1,116
66,564 73,560
71,509
69,517 75,422
79,104
1,812
216
2,641
1,799
15,789
14,977
1,513
4,035
193
8,771
316
571
6,521
59,154
1.100
61,490
I/ A breakdown of the "redistilled" classification showed averages of 47 percent for instruments, 13 percent for dental preparations,
23 percent for elcctrizal apparatus, 10 percent for general laboratory, and 7 percent for all other uses in 1965-68.
2/ In 1969-70 "redistilled" mercury is broken down and included in the categories for which it is used.
3/ Includes mercury used for installation and expansion of chlorine caustic soda.plants.
4/ Preliminary estimates
5_/ Unavailable
6/ Included with agriculture
Tj Source U. S. Bureau of Mines
-------
Table 4 Estimates of trends in consumption of mercury made
by the National Materials Advisory Board (1970).
Estimated Mercury
Consumption flasks
Use
1968
1974-75
Agriculture
Amalgams
Catalysts :
Urethanes
Vinyl Chloride Monomer
Anthraquinone Derivatives
Miscellaneous
Dental Applications
Electrical Apparatus
Electrolytic Preparation of Chlo-
rine £> Soda
General Laboratory Use
Industrial £» Control Instruments:
Switches & Relays
Other Instruments
Paints
Paper &. Pulp
Pharmaceuticals
Others**
Total
3,480
259
800
500
175
230
3,500*
17 , 200
;7,424
2,075*
2,500
6,400*
10,588
375
600
7,815
73,855
2,650
250
1,580
250
220
340
3,800*
22,700
22,884
2,075*
2,650
6,000*
10,725
250
650
5,960
84,544
* Includes some redistilled mercury.
** Includes mercury requirements for start-up of new chlorine cells,
-------
14
III. HAZARDS OF MERCURY
Hazards to Man
General
Mercury in many forms is toxic to nan and other living things. In terms
of toxicity mercury and its compounds may be divided into three categories:
(1) alkyl (methyl and ethyl) mercury salts; (2) elemental mercury vapor;
and (3) inorganic mercury salts and phenyl and methoxyethyl mercury
compounds (Report of an International Committee, 1969).
Alkyl forms of mercury are generally considered to be the most toxic
of the three categories, probably because of their relatively slow excre-
tion rate and their tendency to concentrate in the brain and other central
nervous system tissues. Elemental mercury vapor ranks second in toxicity.
It concentrates in nervous tissue to a greater extent than the inorganic
salts and non-alky! organic compounds although it is excreted more rapidly
than alkyl mercury.
It should be pointed out that no definitive studies have been conducted
to compare the relative toxicities of the various forms of mercury during
chronic exposure. During acute exposures there does not appear to be any
great difference among the various forms (Berglund, e_t al_., 1971).
In non-occupational exposures to mercury, the routes of entry into the
human system are quite different for the different forms. The organic
forms are more likely to be taken in from food and water (an exception
is dimethy!mercury which may occur as vapor in the air) while elemental
mercury is mostly absorbed through inhalation of the vapor. The inorganic
salts of mercury may be inhaled or ingested in environmental exposures.
Methylmercury
Mercury in many different forms can be toxic; however, methy!mercury is
one of the most hazardous to man. It is easily transported and persists
in the natural environment. It is formed by the rnethylation process
from any type of mercury in the aquatic habitat and is accumulated by
organisms common in the human diet. It has a long retention time within
the human body, has serious effects on the human nervous system and damages
developing human tissue.
The extent of exposure of the general population to methylmercury aonears
to be chiefly through fish and possibly other foods and not directly
through water or air (Study Group on Mercury Hazards, 1970). Me thy line re ury
may be absorbed through the skin, respiratory tract and the alimentary
-------
15
canal (Berglund et al.. 1971). Data fron rats and nan indicate that more
than 90 percent bT the methylinercury in food is absorbed (Berglund and
Berlin, 1969). Berglund and Berlin" (196D) state that methyl mercury salts
if applied on the skin, e_.£. dissolved in an ointment, nay give rise to
clinical toxicity in man. There is considerable risk of absorption of
methy!mercury in the respiratory tract in connection with the occupational
handling of seed dressings.
Approximately 10 percent of the total body burden of methyl mercury in man
is found in the head, presumably most of it in the brain (Berglund, et al.,
1971). Also, particularly high levels of methyl mercury are found in liver
and kidneys (Berglund e_t al., 1971). Methylmercury accumulates in red blood
cells, and in man these cells contain over 90 percent of the methylmercury
in the blood stream (Report of an International Committee, 1969). A direct
relationship between levels of mercury in blood and hair was found
for Swedish individuals who were considered to have reached an equilibrium
state between dietary intake and body burden of mercury (Study Group on
Mercury Hazards, 1970). In fatal cases of Minimata Disease, the ratio
of mercury in brain, liver and kidney was of the order of 10:40:50
(Study Group on Mercury Hazards, 1971).
According to Berglund et_ al_. (1971) the following can be stated relative
to methylmercury poisoning. Methylmercury in organisms is relatively stable.
• 1ethy1mercury administered to animals is present almost entirely as methyl-
mercury in the brain and blood. The main route of excretion in man is by
the feces, which is about ten times higher than the urine. Elimination
from the body can be described as a monophased exponential course. The
half life of methylmercury in nan ranges from 70 to 90 days for the whole
body; however, limited data indicate that it is somewhat shorter in the
blood and somewhat longer in the brain than in the body as a whole. Because
of the slow elimination rate in man the steady state between uptake and
elimination is reached approximately one year after exposure has started.
The organ which first shows injurious functional disorders from exposure
to methy!mercury is the nervous system. Postnatal poisoning has a symptom
free latent period of about one month from the time of exposure to the
onset of symptoms. Symptoms are sensory disorders, ataxia and concentric
constrictions of the visual fields. The diagnosis is difficult to establish
in the case of only mild or atypical symotoms. Besides raised mercury
levels in blood and hair, no clinical laboratory investigations have given
any clear and common positive finding. Blood levels in Japanese cases of
methylmercury poisoning at Niigata were estimated to be in excess of 0.2 ug/g
whole blood at the onset of the disease. Hair levels in all cases except
one was about or exceeded 200 ug/g. The Japanese cases at Minamata who
died all had levels of methylmercury in the brain equal to or more than
5 ug/g.
-------
16
Methylmercury can effect genetic material. Methylmercury added to a medium
in which plant cells are growing causes disturbances in the mechanisms of
cells division and chromosome breakage (Berglund e_t aJL , 1971). It also
causes disturbances in the mechanism of cell division in fruit flies and
in tissue culture of mice and man (Uerglund et^ al_., 1971). In persons who
have been exposed to methylmercury from the consumption of fish, a correla-
tion has been found between the mercury levels of blood cells with the
frequency of chromosome breakage in circulating lynphocytes cultured vn_
vitro (Berglund et^ al_., 1971; Larsson, 1970). There are grounds for assum-
ing that the effects on genetic material in man are of the same character
as those in lower animals. Berglund e_t al_. (1971) states it must be assumed
that exposure to methylmercury involves certain genetic risks; however, it
is not possible with presently available data to estimate the extent of such
risks and the relationship to different exposures of methylmercury.
In experiments with animals, methylmercury has been shown to cause
teratogenic effects. There is also a risk that methylmercury accumulations
in the fetus could cause disturbances in chromosome segregation during
fetal development (Ramel, 1969). According to the Renort of an International
Committee (1969) data from the Minamato cases presented by Murakami indicate
teratogenic effects occurring at an earlier stage of development than would
be the case of central nervous system damage from inethylmercury intoxication.
This report states "Because of the experimental evidence of strong effects
of methylmercury compounds on cell division and chromosome segregation it
is conceivable that this early effect may have resulted from induced
chromosomial alterations of humans". ' . " •
Methylmercury readily crosses the placental barrier. Tejning (1970) found
a 30 percent higher concentration in fetal red blood cells than in maternal
red blood cells; however, the fetal plasma had a lower concentration than
did the maternal plasma. The Report of an International Committee (1969)
states "Studies in animals and man indicated that methylmercury easily
penetrates to the fetus via the placenta. The concentration of mercury in
the fetal blood is about 20 percent higher than in the mother and the same
statement should apply to the brain of the fetus as well." In the ilinimata
Japan incident, 22 children (5.8 percent) born between 1955-5G had cerebral
palsy. The expected frequency of cerebral palsy was 0.1-0.6 percent (3enjlund
ejt al_., 1971). None of the mothers had clinical syriotoms of inethy 1 mercury
poisoning. However, an examination of 15 of the mothers several years after
their pregnancy revealed that 11 of the 15 had neurological abnormalities
consistent with methy!mercury poisoning. The Study Group on Mercury Hazards
(1970) states that the affected children did not eat contaminated fish or
shellfish and the mothers apparently were not affected. They further state
that the clinical symptoms were more difficult to elicit and more varied than
in the case of methylmercury poisoning in adults and children without fetal
exposure. Also, the disease in prenatally exposed children varied in
severity; sane children having mild to moderate spasticity and ataxia, and,
-------
17
others, having severe intellectual retardation, seizures, and evidence of
more generalized brain damage. Prenatal methylrnercury poisoning cannot be
distinguished from other types of cerebral palsy and diagnosis would have
to be done epidemiologically with the support of mercury levels in blood
and hair (Berglund et. a]_., 1971).
Berglund et_ al_. (1971) concluded that of 230 cases of known methylrnercury
poisoning slightly over 20 were prenatal. A total of 20 cases were due to
occupational exposures, three cases were from skin preparations containing
methylmercury, and the rest were due to consumption of food containing
methylmercury of which 150 were from eating fish and shellfish, while the-
rest were from eating seed treated with methylmercury or neat from animals
that had been fed such seed. In the Japanese methylmercury poisoning in-
cident at Minimata, one-third of the cases were lethal (Berglund et al.,
1971). In serious cases of methylmercury poisoning a degree of disability
persists for a considerable period of time. Hunter (1955) reoorted a
sixteen year old boy exposed for only a few months to methylmercury compounds
was unable to work after 20 years because of persistent ataxia tremors and
inability to recognize objects by touch. In Minimata Japan, brain damage
was largely accomplished by the time methylmercury poisoning diagnosis had
been made and although chelating agents increased the rate of excretion of
mercury in the urine they were clinically ineffectual (Study Group on
Mercury Hazards, 1970). The Study Group on Mercury Hazards (1970) states
that because of the delay in recognition of these outbreaks in Japan, it is
likely that the number of persons who were truly effected was appreciably
greater than reported. Furthermore, relatively early cases with less neurologic
deterioration were recognized in Niigata, Japan suggesting that many mild
cases were missed in Minimata. It appears that compensatory mechanisms
of the nervous system can delay clinical recognition of uethylmercury
poisoning, even though the patient has partial brain damage (Study Group
of Mercury Hazards, 1970).
Forty families in Minimata Japan affected with methylmercury poisoning had
61 cats of which 50 percent were affected with methylmercury poisoning
(Kurland, 1960). A commonly observed syndrome in cats from the affected
households included unsteadiness, frequent falls, circling movements and
convulsions. The sensitivity of human beings to methylmercury is presumably
higher than in the case of cats which is higher than in the case of rats
(Takeuchi, 1970).
The mercury blood levels of a few individuals in Sweden who consumed high
levels of methylmercury contaminated fish exceeded the low levels of the
toxic cases reported in Japan. The Study Group on Mercury Hazards (197H)
believes this is due to individual variation and sensitivity to methyl mercury.
-------
18
Berglund et^ al_. (1971) made calculations of the degree of exposure which
May cause intoxication in adults with the aid of data on radioactive trace
doses of methylmercury in man. The lowest reported level in the brain of
persons who had died of methylmercury poisoning was estimated to be about
5ug Hg/g at onset of the disease. Based on these data, they estimated the
total body burden in cases of fatal poisoning to be about 80 ng mercury.
Using a daily elimination rate of one percent of the total body burden,
they calculated that the body burden of GO mn is reached after prolonged
exposure corresponding to 0.3 mg mercury per day. Berglund e_t al_. (1071)
state that uncertain trace doses data indicate that about one oercent of
the total body burden is found in 1,000 ml of whole blood and for a body
burden of SO mg this would correspond to about 0.8 ug/g mercury in whole
blood. They further state that on the basis of available material it
would appear justifiable to assume that clinically manifest poisoning of
adults sensitive to methylmercury may occur for a level in whole blood of
0.2 ug/g mercury, which is reached on exposure to about 0.3 nig mercury per
day or about 4 ug/kg body weight per day.
According to Berglund et_ al_. (1971): "A safety factor must be applied
between the lowest mercury level and the exposure that may be assumed to
cause clinically manifest intoxication with neurologic.synptoms in adults
and an acceptable mercury level and exposure for the population." They
were of the opinion that a factor of 10 gives a sufficient safety margin.
Thus, acceptable levels of mercury would be as follows:
(1) whole blood - 0.02 ug/g,
(2) red blood - 0.04 ug/g, and
(3) hair - 6 ug/g.
Based on the above levels, the acceptable daily intake of methylmercury
would correspond to 0.03 mg mercury or approximately 0.4 ug/kg body weight
(Berglund et_ al_. 1971).
In view of the large number of persons exposed to a varying extent in the
Japanese instances of methylmercury poisoning, it seems likely there was
an overrepresentation of individuals especially sensitive among those who
fell ill (Serglund et_ al_., 1971). Levels of mercury have been found in
Sweden and Finland higher than 0.2 ug/g in blood cells in some 20 persons
and levels exceeding 0.4 ug/g in 4 persons; while levels have been found
in hair of at least 130 persons in Japan exceeding 50 ug/g without clinical
symptoms of methylnercury poisoning (Berglund e_t aK , 1971).
-------
13
The diagnosis of methylmercury poisoning is based on neurologic symptoms
and theoretically it is conceivable that brain lesions nay occur at lower
exposures and levels than which cause neurologic symptoms and which could
not be diagnosed by available methods (Berglund ejt a_l_., 1971). Lofroth
(1969) noted that: "One of the observable effects of methylmercury
poisoning in man is the impairment of the coordination of muscle movement,
etc., resulting from damage to certain brain cells. Thus, Lofroth raises
the question: "whether these effects are brought about only at and above
some threshold value of methylmercury intake." He further states: "as to
the gross clinical symptoms one can state that a threshold mechanisrr, is
operating. This threshold mechanism is, however, not due to a methy!mercury
threshold, but to a threshold in the number of damaged brain cells. After
damage of one or a few cells, other cells may take over the net result
showing up as no effect in the clinical investigation. Uhen too many cells
have been damaged during a short time, the clinical results do show up early.
This type of mechanism can erroneously be classified as a methylmercury
threshold mechanism." He also states: "however, even a low frequency of
brain cell damage, above the natural inactivation rate of these cells, during
a long time has an effect on the organism as the number of available cells
for each brain function is limited. Such a damage nay then, have serious
effects in later stages of life."
The possible synergistic effects of nethylmercury in combination with other
neurotoxic chemicals, e.g_. DDT, PC3s, lead, which are also found in food
are not known. ChernoTf and Courtney (1970) found that a combination of
MTA and methylmercury resulted in a slight enhanced fetal toxicity and
teratogencity of methylmercury in rats.
iJo known drugs are. effective for the treatment of methylmercury poisoning;
however, the work of Dr. Clarkson of the University of Rochester School of
Medicine and Dentistry, using non-absorbable polymer sulfhydryl-containing
resins possessing a high affinity for r.ie thyl mercury to increase fecal
excretion offers promise.
Organic Mercury Compounds Other Than Alkyl
Organic mercury compounds may enter the body by inhalation, skin absorption
or oral ingestion (Report of an International Cotmittee, 1069). Golcwater
(1964) states that in studying occupational exposure to mercurials it is
virtually impossible to evaluate the role of skin absorption, since inhala-
tion and possibly ingestion also occurs when skin absorption is taking place.
The Report of an International Committee (I960) states that the efficiency
of absorption by the respiratory tract is unknown but should be high. The
Committee notes that when mercury is as aerosols, it is likely to dissolve
quickly in body fluids and be distributed to the blond. Furthermore, the
-------
Committee notes that exposure to mercury vapor is more dangerous than dust.
Phenylmercurials are readily absorbed through the intact skin and measurable
quantities of nhenylmercurials can be absorbed through the skin from clothes
(Golciwater 1964).
Phenylmercury and methoxyethylmercury show a distribution pattern in the
body similar to inorganic mercury comnounds, except that a higher concentra-
tion may be present in the liver, alimentary tract and red blood cells and
a lower concentration in the renal cortex (Report of an International
Committee, 1969).
Phenylmercury and nethoxyethylmercury are degraded in the body to inorganic
mercury (Report of an International Committee, 1969). Excretion is through
the urine and as inorganic mercury in feces. Golciwater (1964) states that
absorbed phenylniercury compounds leaves the blood in a matter of hours
and much is excreted in the urine.
Phenylmercury has been shown to affect genetic material in a manner similar
to methylmercuryi however, since it is excreted more rapidly and is degraded
in the body to inorganic mercury the genetic risk to man would seem to be
much less than in the case of methylmercury. Compared to methylmercury,
relatively little phenylmercury crosses the placental barrier (Berlin and
Ulberg, 1963).
The toxicity of-organic mercury coninounds (including nhenyl-and r.iethoxyethyl-
mercury) which degrade to inorganic mercury is similar to that of mercuric
salts (Report of an International Committee, 1969). vlo conclusive evidence
of toxic effects have been shown from long-term exposure to phenylmercury
salts (Report of an International Coirnittee, 1969). The Report of an
International Committee (1969) recommended a limit at which the average
concentration in air should not be exceeded during the working day on a
continuing basis of 0.10 mo Hg/nr for inorganic mercury salts and phenyl
and methoxyethylriiercury salts.
Inorganic Mercury
Absorotion of inorganic mercury is mainly through inhalation of elemental
mercury vapor or aerosols of mercury salts. Mercury also enters the body
via the skin; however, the rate of penetration is slow (Report of an
International Committee, 1969). Contamination of skin or workclothes with
mercury could cause heavy exposure to mercury vapor by inhalation (Reoort
of an International Committee, 1969). Furthermore, mercuric salts are
absorbed in the gastrointestinal tract, so that either by direct absorption
in the lungs or by clearance of the alimentary tract, aerosols or mercuric
salts can be taken into the body. Man will absorb via the respiratory
-------
tract 75 to 35 percent of the mercury vapor at concentrations ranging from
50 ug to 350 ug/rn3 (Report of an International Committee, 1969). Magos
(1967) exposed mice to different concentrations of elemental mercury vaoors
and found that the percent uptake of inhaled mercury was inversely related
to the air concentration. At concentrations below 100 ug/m uptake exceeded
98 percent.
After acute administration of inorganic salts to animals and nan, the highest
levels of inorganic mercury are found in the kidneys and the second highest
in the liver (Report of an International Committee, 1969). The brain
accumulates mercury to a greater extent when man is exposed to vannr than
when he is exposed to inorganic mercury salts (Holmstedt, 1967; Renort of
an International Committee, 1969).
Elemental mercury vapor nroduces its toxic effect after being oxidized to
mercuric ions in the body and this oxidation occurs partly in the blood and
tissues, but mainly in the erythrocytes (Report of an International
Committee, 1969). After being inhaled, mercury occurs in blood, partly
unchanged and partly oxidized. In man the placenta constitutes a barrier
to the absorption of inorganic mercury by the fetus (Berlin and Ullberg, 1963)
In man excretion of inorganic mercury is by the kidney, by the liver in
the bile, by the intestinal mucosa, by the sweat glands, and by the salivary
glands; however, urinary and fecal routes of excretion are the most important
(Report of an International Committee, 1C59). Elimination from the brain,
thyroid and testes is slow; thus, accumulation of mercury in these organs
is possible (Report of an International Committee, 19G9).
Intoxication from mercury vapor or from the absorption of mercuric salts is
due to the action of mercuric ions (Renort of an International Comnittee,
1959). The kidney is the critical organ after acute exposure to inorganic
mercury salts; however, the central nervous system is the critical organ
in long-term exposure to mercury vapor (Report of an International Comittee,
1969). In the case of chronic exposure to mercury vapor it is not clear
whether mercury levels in the brain or testes reach toxic concentrations
before severe renal damage occurs (Report of an International Committee,
1969).
Symptoms of acute poisoning from inorganic salts or nercury vapor are acute
gastroenteritis, with abdominal pains, nausea, vomiting, an'i sometip.es bloody
diarrhea and severe kidney injury leading to anuria with uremia (P.eport of
an International Committee, 1969). In cases of chronic cxnosure to mercury
vapor, symptoms involving the central nervous systavi are nost cournorsly sec-n,
the principal features being tremor and psycholoniccl disturbances (Report
of an International Canr.ri ttee, 1969).
-------
The Report of an International Cci-wi ttee (13G9) states that evidence fron
USSR indicates that increased excitability of the central and autonomic
nervous system, together with increased frequency of slight anemia and .,
hyperthyroidisin occurred among workers exposed to 0.01 to 0.03 ro per m"1
of mercury vapor, mere is a positive correlation between the degree of
exposure to inorganic mercury and mercury concentration in urine; however,
this conclusion is valid only on a group basis and does not consistently
apply to individual cases (Goldwater, 1963). Furthermore, there is a
narked variation in urinary excretion of mercury in urine among similarly
exposed persons and a lack of correlation between mercury In urine and
clinical manifestations of poisoning. Evidence indicates that on a grouo
basis mercury concentrations of 0.1 ing/ni in air will correspond to 100
to 300 ug/1 of urine and a decrease in exposure to 0.05 mn/m should result
in a decrease of the concentration of mercury in the urine to about 50
percent of these levels (Report of an International Committee, 1960).
The Threshold Limit Value (TLV) for non-alky! forms of mercury, including
metal vapor has been 0.1 ng/rnj for an 8-hour occupational exposure over a
5-day work week. In 1970 the American Conference of Governmental Industrial
Hygienists issued a notice of intended changes to reduce the TLV to 0.05
mg/m3 (AGGIri, 1970) in conformance with the recommendations of the Report
of an International Committee (1969). It should be understood that these
limits are for occupational exposures only and do not apply to environmental
or general population exposures which would require .much lower limits to
protect the public health. The Environmental Protection Agency, in develop-
ing its National Emission Standards for mercury under Section 112 of the
Clean Air Act, is using an allowable ambient concentration of 1.0 ug/m^
(0.011 mg/m3) for a 30 day average exposure as a working number for
calculating emission standards for sources emitting mercury to the air.
This number includes an allowance for continuous as opposed to occupational
exposure and an ample margin of safety as required by law.
The Report of an International Committee (1969) recommended a limit for
mercury vapor in which the average concentration in air should notnbe
exceeded during the working day on a continuing basis of 0.05 mq/m°. The
FAO/UHO guidelines for permissible concentration of mercury in foodstuffs
other than fish is 0.05 ppm. A study of 642 workers from 21 chloralkali
plants in the United States and Canada showed a strong correlation between
mercury vapor concentrations in the workplace and nervous system symptoms
such as loss of appetite, weight loss, tranors, and insomnia (Smith, et al..
1970). Timeweighted exposure concentrations ranged from near zero to 270
ug/m3 with approximately 85 percent of the workers exposed to 100 ug/m or
less.
-------
23
Hazards to Wildlife and Domestic Animals
Vlildlife and domestic animals can absorb toxic doses of mercury from their
food. The acute toxicity of methylmercury to birds is in the same order as
that for laboratory animals, !..§_., 12 to 20 nig/kg (Study Group on Mercury
Hazards, 1970). According to the Study Group on Mercury Hazards (1970)
mercury residues in liver-kidney composites of birds experimentally
killed from eating methylmercury treated seeds ranged from 30 to 130 ppr.i
for pheasants, 70 to 115 ppm for jackdaws and 50 to 200 ppm for magpies.
They conclude that liver-kidney residues of 30 npm in birds indicate
critical exposure and that normal levels are less than 1 ppn mercury.
Hov/ever, Firnreite and Karstad (1971) found that the tolerance level to
mercury may be lower in hawks than in pheasants and chickens. They
found that hawks which died after experimental exposure to methylmercury
had mercury residues in their livers of 17 to 20 ppm. Furthermore, they
found that a steady diet of chicks containing 7 to 10 ppm in their liver
was fatal to hawks. The signs of poisoning orior to death of the hawks
were essentially neurological, consisting of weakness in the extremities,
difficulty in walking and standing, and inability to control muscle
movements.
Hens with mercury liver levels of 3 - 13 ppm were found to lay eggs with
significantly lowered hatchability than controls (Fimerite, 1970). Birds
excrete considerable amounts of mercury through molting and egg laying.
Cats which had been fed fish and shellfish naturally contaminated with
5.7 ppm mercury were killed (Study Group on Mercury Hazards, 1070). A
variety of wild and domestic animals are susceptible to methylmercury
poisoning from eating seafood. Takeuchi (1970) reports that in the Japanese
methylmercury poisoning of humans at Minamata caused by consumption of sea
food-, cats, crows and sea birds also fell ill presenting such symptoms as
unsteadiness, frequent falling down to the ground and abnormal movement.
Takeuchi also states that dogs and pigs were affected.
Hazards to Aquatic Life
Mc.Kee and Wolf (1963) have summarized the effects of mercuric chloride,
mercuric cyanide, mercuric nitrate, mercurial - organic compounds and
mercury on aquatic life and it will not be repeated here.
In natural waters it is methylmercury which is of orimary concern from an
environmental standpoint. It appears, that in most cases, levels of methyl -
mercury in water, v/hich will not result in unacceptable level of residues
of mercury in fish from a human health standpoint, will protect aquatic life
from acute toxic affects. For example, fish are believed to be able to
concentrate mercury from water by a factor of 3000 or more. Thus, at a
concentration factor of 3000, a level of mercury in water of 0.17 ppb would
correspond to a residue level of 0.5 ppm in fish, while a level in water of
0.07 ppb would correspond to a residue level of 0.2 ppm mercury in fish.
-------
The more subtle effects of mercury on fish e_.g_., effects upon reproduction
and behavior have not been adequately evaluated. The Study Group on Mercury
Hazards (1970) reports, that they were informed by Swedish investigators
that when pike were reared for a season in water containing 0.1 ppb of
methylmercury and then placed in clean water they underwent continuing
mortality. Such low rates of mortality undoubtedly would not be detected
in nature. They also reported that Swedish workers saiJ that a population
of fish from below a source of mercury pollution definitely weighed less
at each age than those taken upstream from the source. They further
reported that a Swedish worker had shown them data which showed behavior
inadequacy of fish exposed to methy!mercury, and that this effect increased
with treatment level and with length of exposure.
Mercury compounds have been shown to interfere with primary nroduction and
to be toxic to phyto and zooplankton. Harris, White, and MacFarlane (1970)
reported a significant reduction in photosynthesis and growth in marine
and fresh water phytoplankton exposed to 1 ppb methylmercury compounds. At
levels of 50 ppb photosynthesis was stopped. Ekeles (1962) found that methyl
mercury phosphate was lethal to species of marine phytoplankton at levels
of 60 ppb.
-------
IV. SOURCES OF MERCURY TO THE ENVIRONMENT
Man-Made Sources
General
No complete list of man-made sources of mercury to the environment exists.
This is especially true for sources to the atmosphere. For example,
emissions from cement plants have been detected by the Environmental Pro-
tection Agency source sampling teams. All extractive metallurgy may be
suspected of emitting mercury to the atmosphere. Emission inventories
published up to this time do not list all sources of mercury, thus the
weight of mercury emitted to the atmosphere is substantially higher than
tested in these inventories.
Chlorine Industry
The electrolytic preparation of chlorine and caustic soda and/or caustic
potash utilizing the mercury cell process consumed during I960 approximately
0.5 of mercury per ton of chlorine produced (National Materials Advisory
Board, 1970). In 1967 the discharge from the mercury cell process in Sweden
amounted to 51 to 85 g per ton of chlorine produced resulting in a discharge
of 30 to 40 g to water; 5 to 10 g to hydrogen gas; 1 to 10 g to the caustic
and 15 to 25 g to ventilation (Study Group on Mercury Hazards, 1970). In
1970 it was technically possible for the Swedish industry to reduce their
total discharge of mercury to about 0.53 to 1.11 g per ton of chlorine pro-
duced consisting of a discharge of 0.01 to 0.1 g to water; 0.01 g to
hydrogen gas; 0.01 to 0.5 g to caustic; and 0.5 g to ventilation (Study Grot
on Mercury Hazards, 1970). Fimrite (1970) reported a loss of 0.5 Ib. per ton
of chlorine produced in Canada by the mercury cell process. There has been
a drastic reduction by the U. S. chlorine industry in the quantity of mercury
discharged to the environment as evidenced by a reduction in the consumption
of mercury by the industry from 20,770 flasks in 19G9 to 14,977 flasks in
1970.
Caustic soda and potash produced by the mercury cell process may contain
from 4 to 5 ppm mercury (Study Group on Mercury Hazards, 1970) and since it
is used extensively in other industrial processes and products it is a
potential source of mercury to the environment. Likewise, chlorine produced
by the mercury cell process is a potential source of mercury to the environ-
ment. Also, the hydrogen gas produced during the preparation of chlorine
by the mercury cell process contains mercury. Hithout controls, as much as
50 Ibs. of mercury per 100 tons of chlorine produced would be emitted to the
atmosphere. End box and cell room ventilation air could emit an additional
5 to 25 Ibs. of mercury per 100 tons of chlorine produced. Controls are
being applied which drastically reduce these emissions.
Pulp and Paper
Prior to 1965, organic mercury compounds (mainly phenylnercury) were used
extensively in the pulp and paper industry for impregnating mechanical
pulp and for slime control. At the present, the use of mercury compounds
-------
26
by the pulp and paper industry is at a minimum. Registrations of iv.ercury
compounds under the Federal Insecticide, Fungicide and P.odenticide Act
for pulp and paper were cancelled in 1970. Boureng (19E7) found that
approximately 5 to 20 percent of the nercury usea is discharged to water-
ways, the rest remaining in the product. However, the mercury contained
in the product would eventually be discharged to the environment e_.£_. , by
incineration of paper in trash.
The pulp and paper industry is a major consumer of caustic soda. Caustic
soda produced by the mercury cell process nay contain significant quantities
of mercury which may result in contamination of paper products and/or
result in wastewater discharges.
Laboratories, Hospitals, and Dental Clinics
Mercury is used in commercial laboratories, hospitals, and dental clinics
for variety of purposes, including drugs, reagents and dental preparations,
disinfectants and sterilizing solutions. These uses undoubtedly result in
discharges to municipal sewage treatment plants; however, no accurate
estimates of the total contribution of mercury from these sources are
available.
The Bureau of Foods, Food and Drug Administration, Department of Health
Education and Helfare has estimated that 25 percent of an approximate
200,000 pounds of mercury per year used in dental preparations or 50,000
pounds is lost in particles of amalgam which are scraped off-t!ie tooth
or fall into the mouth and which are'then spit out into dental bowls and"
hence to sewers (Mercurical Pesticides Registration Review Panel, 1971).
The Bureau of Foods estimated that approximately 50 percent or 100,000
pounds of the total annual use of mercury in dental preparations is
actually put into teeth. The Bureau of Foods states that this is not
available for absorption to the blood stream until decay sets in and, as
a rule, by this time the amalgam has been subject to leaching and has
reached a state of disintegration. They further state that a substantial
part of such a filling is inevitably swallowed and thus contributes inorganic
mercury to the body load. Some of this mercury in fillings would eventually
reach sewage treatment plants after being excreted by the body.
Paint
Mercury may be discharged to the environment from the manufacture and use
of paints containing mercury by: (1) wastewater discharges from manu-
facturing, (2) volatilization of mercury from painted surfaces, (3) dis-
charges to sewers or drains from the washing of paint brushes, rollers,
containers, etc., used to apply paint, mainly latex, water-thinned paints,
(4) the slow release to water of mercury in anti-fouling paints on ship
bottoms and (5) the discharge to waterways of anti-fouling paints removed
from ships. Data are not available to accurately estimate the amount of
mercury discharge to the environment from these sources; however, essen-
tially all mercury used in paint could enter the environment.
-------
The slow release of mercury from anti-fouling paints to the water can be
of significance in localized areas as evident by fish stored in cages in
small boat harbors showing increased mercury levels (Hanson, 1971). In-
creased concentrations of mercury have been found in sediments in the
vicinity of shipyards reconditioning ships previously painted with mercury
based anti-fouling paints. For example, in the vicinity of a Dry Dock in
Hampton Harbor, James River, Virginia, the Environmental Protection Agency
has measured up to 5.2 ppm mercury, dry weight, in bottom sediments.. The
Massachusetts Department of Public Health (1971) found mercury levels UP
to 83 and 17 ppm in the sediments of Quisset Harbor, Falnouth and Sippican
Harbor, Marin, Massachusetts, respectively. Their investigations indicated
that the most probable source of contamination was the mercurial anti-fouling
paint used in boatyards and marinas.
Catalysts
Industrial use of mercury catalysts can result in significant discharges of
mercury to the environment, e_.g_., the source of mercury to the environment
resulting in the Japanese instances of methylrnercury poisoning was from the
uses of mercury catalyst in the production of vinylchloride (Kurland et al.,
1960). The Study Group on Mercury Hazards (1971) reported a Swedish vinyl-
chloride plant discharged 300 kg per year. Hanson (1971) reports that
prior to 1964, several tons of spent mercury catalysts were dumped in the
sea off the Swedish East Coast. Kurland et al. (I960) found 12.5 ppr.i mercury
in muds of Galveston Cay adjacent to a hoTcfing basin where spent catalyst
used in the production vinylchloride had been dunned. They also reported
the mercury lost from the reactors in the Texas vinylchloride plant was
flared or incinerated and dissipated into the atmosphere. The Environmental
Protection Agency has found a considerable number of discharges of mercury
to waterways from manufactures using mercuric oxicie catalysts with sulfonated
anthraquinone products as raw materials to make vat dyas.
Mining and Refining
Considerable quantities of mercury were used in the early days of gold and
silver mining to recover free gold and silver from placer and lode ores.
Undoubtedly, large quantities were introduced into waterways which may still
be present in some instances. The discharge of tailings from the mining
of cinnabar and other metals sulfide ores, are a potential source of mercury
to waterways. Johnasson (1970) reported that base metal deposits around the
Great Lakes contain as much as several hundred ppm mercury.
Refining of sulfide ores where the ores are heated in retorts or furnaces
can result in significant discharges of mercury to the air. Stahl (1969)
states that in refining of mercury ores, stack losses of nercury should not
exceed 2 or 3 percent, although ;nucn higher losses have recurred. He
estimated that with a stack loss of only 3 percent in the United States
mercury smelting would emit 50,000 Ibs. of mercury into the atmosphere
annually. Furthermore, Stahl points out that the refining of other sulfide
ores emit mercury vapor into the atmosphere.
-------
28
Fossil Fuels
The Environment Magazine (1971) reported that nine power olants in Illinois
and the St. Louis area discharge large quantities of mercury into the
atmosphere, presumably resulting from the burning of fossil fuels. A
Springfield, Illinois power plant was cited as discharging 5,300 pounds
of mercury into the air annually.
Petroleum, natural gas, and oil field brines all have been reported to
contain significant quantities of mercury. White et_ al_. , (1970) reports
that crude oils from the Cymric Oil Field, California contain from 1,900
to 21,000 ppb mercury and that the natural gases from the field are
saturated with mercury vapor. Mercury vapor during transport of these
gases in pipelines combines with hydrogen sulfide from "sour" gases of
other oil fields and is precipitated in the pipelines (I'hite e_t al_., 1970).
According to White et_ al_., (1970) mercury separates from the crude oil at
the local pumping station in the Cymric Oil Field and the yield may be in
the order of hundreds of tons. They report that light petroleum of the
Abbott Mine California contain 100,000 ppb mercury and tarry petroleum from
the mine contain 500,000 ppb. Tar fron a Wilbur Spring District, California
oil test was reported to contain 1,000 ppb mercury (White e_t aj_., 1970).
Oil field brines from the Cymric Oil Field contain up to 200 ppb mercury
(White et_al_., 1970). Hanson (1970) reports that Swedish fuel oil may "
contain 2-4 ppn mercury while gasoline may contain 2-17 ppm mercury.
According to Larson (1970) Swedish fuel oils havs an average content of 3
ppm mercury. There are insufficient data to evaluate the amount discharged
into the environment from the mining and use of petroleum and natural gss;
however, discharges to waterways of oil, oil field brines, the flaring of
waste gas, and the use of natural gas, fuel oil and gasoline as a source
of power and heat, may be emitting large quantities of Mercury to the
environment.
The Study Group on ['ercury liazards (1971) states that based on presently
available information, coals in the United States nay contain from a few
ppb to several ppm mercury and that it is reasonable to estimate that the
average concentration is at least 1 ppn. The Study Group further states that
based on an annual consumption of 500 million tons of coal per year, one
million pounds of mercury per year would be released to the environment.
However, this estimate may be high, as Ruch et_ aj_. (1971) found fiat 55 rav.1
coal samples from 10 coal seams in Illinois had a mean mercury concentration
of 0.18 ppm and eleven coal samples from states other than Illinois had
mercury concentrations within the range or slightly lower than Illinois
coals. The United States Geological Survey report "Mercury in the
Environment" (1970) states that typical samples of bituminous coal from the
United States contain from 1 to 25 ppb and many anthracite coals contain
from 1,200 to 2,700 ppb. Pit coals in Sweden have a mercury content ranging
from 60 ppb to 400 ppb (Larsson, 1970). Presumably, when coal is burned,
the mercury which it contains would be distilled off into the atmosphere.
-------
.29
Sewage Treatnent Plants
The mercury content of sludge from sewage treatment nlants give a good
picture of mercury emission from urban areas. Larsson (1970) found
that sludge fror.i some 30 towns in Sweden had mercury concentrations rang-
ing from 0.3 to 40 rag/Kg dry weight. The high levels were found in strongly
urbanized areas with richly differentiated industry. Larsson (1970) states
that purification of the sewage water may lead to a reduction of mercury up
to 97 percent. One treatment plant in Stockholm, serving 500,000 inhabitants
discharged to the receiving water about 350 kgs per year of mercury (Hanson,
1971). The Environmental Protection Agency measured piercury being discharged
at the rate of approximately 2,700 Ibs per year in the effluent of the Vlhites
Point District, Los Angeles Sanitation Sewage Treatnent Plant outfall based
on a 24 hour composite sample taken during the fall of 1970. Also, mercury
was measured being discharged at the rate of approximately 2.HOO pounds per
year from the Hyperion, Los Angeles City Sewage Treatment Plant outfall based
on a 24 hour composite sample. The sludge produced by this plant, which is
deposited at sea, was estimated to contain during a years time approximately
1100 pounds of mercury. The incineration of sewage sludge containing mercury
can result in discharges of mercury to the atmosphere, e_.g_., the Environment
Magazine (1971) reported 570 Ibs. of mercury per year being emitted from
Chicago's Stickney Sludge Oryer Incinerator.
Uses of mercury at waste water treatment plants which may rc-sult in mercury
being released to the system are: (1) mechanical shredders (comminutor)
utilizing mercury seals, (2) flow meters and rate of flow controllers and
(3) rotary sewage flow distributors utilizing mercury seals. The Environ-
mental Protection Agency estimated that during 1971 approximately 2.5 tons
of mercury were lost to the environment from rotary sewage flow distributors
at municipal sewage treatment plants.
Mercury contained in the effluents of wastev.-ater treatment plants, as well
as the common practice in same places of disposing of sewage sludge at sea,
will result in discharge of mercury to the aquatic environment. Incineration
of sewage sludge will result in discharges of mercury to the atmosphere.
Incineration
Incineration of materials containing mercury, such as wood, paper, trash,
batteries and used containers, will result in discharges of mercury to the
atmosphere. During 1970 the Environmental Protection Agency measured an
average of 2.4 ppm mercury in 11 samples of refuse collected from 6 different
incinerators. The Environment Magazine (1971) reoorts that 5,400 pounds of
mercury per year is being discharged to the air from Chicago's Calumet
Incinerator.
-------
30
Phosphate Rock Industry
The United States Geological Surveys' unpublished preliminary analysis of
natural phosphate deposits reveals that Wyoming ohosphate deposits contain
from 90 to 2700 ppb mercury while Florida deposits rancje from 10 to 110 ppb
mercury. Phosphate rock is utilized for the production of phosphorous and
fertilizers. In the production of phosphorous by electrolytic furnaces, it
is assumed that mercury contained in the phosphate rock would be volatilized
and emitted to the atmosphere. In the production of fertilizers, waste
water discharges could be a source of mercury to the water environment.
Manson (1970) found that in Sweden a fertilizer factory with a production
rate of 50,000 tons of phosphorous pentoxide resulted in a loss of 220 kgs
of mercury per year to the water.
Raw Materials and Basic Chenicals
As mercury is found as a trace element in rocks, sands, etc. it is possible
that significant amounts of mercury are entering the air and water environ-
ment from the processing of raw materials. Hanson (1970) found significant
amounts entering the environment from such sources in Sweden; however, such
data are not available from the United States. He also found significant
amounts, up to and exceeding 0.5 ppin in the basic chemical, sulphuric acid.
Agricultural Use of Pesticides
Agricultural use of mercury based pesticides can be a significant source of
mercury to environment. The use of mercury based fungicides to treat seed
grain flooded after planting (e_.n_. rice) can be a direct source of mercury
to the water environment. The Environmental Protection Agency estimated
that 9,550 pounds of mercury were applied to the rice growing area in
Louisiana during 1969, including 1,560 pounds in the Calcasieu River water-
shed. Seed grain treated with mercury based fungicides can be a significant
source of mercury to wildlife feeding on such grain. The drainage of vats
used for the dipping of bulbs, corms, broom corn, logs and lumber in mercury
based pesticides, is a potential source of mercury to soil and water/ays.
Considerable quantities of mercury based fungicides are used on turf, in-
cluding golf greens and tees fairways, parks, cemeteries and house lawns.
It is expected that runoff from such areas under some conditions could result
in the discharge of mercury to waterways; however, little data are available
to determine how significant of a source this is. Frequent use of turf
fungicides may lead to significant accumulation of mercury in soils, since
as much as 15 Ibs. of mercury is added to each acre in a single application
(Boer, 1944). Considerable quantities of raw logs and lumber are treated
with mercury based pesticides. After treatment, lumber is dressed prior to
use and the shavings may be used in the manufacture of paper, wall board, or
as fuel which when burned would be a direct source of mercury to the atmosphere.
The use of a mercury based preservative to treat downed timber after a
hurricane has been reported as a possible source of mercury contamination of
remote New England lakes and ponds.
-------
31
Use of Pesticides in '.-later Systems
The use of mercury based biocides in water systems, with the subsequent
drainage or spillage of such water can result in significant discharges
of nercury to the water environment. Mercury based biocides have been
used extensively in swimming pools, industrial water systems, cooling
towers, heat exchangers, air conditioners, laundry systems, etc. Billings
(1970) reported that discharges fron a laundry using approximately 5 Ibs.
of PMAS-30 (phenylmercuric acetate) per day as a mildew inhibitor was
sufficient to cause serious nercury contamination of fish in the Iron
River, Michigan.
Containers
The disposal of empty containers previously used for the holding of nercury
products are a potential source of nercury to the environment. Used
phenylmercuric acetate drums were a source of mercury to Doon-3 Reservoir,
Tennessee, resulting in fish kills. During the period July 0-13, IDS",
over 500,000 fish were killed, while during tiie period May 3-13, 1C-3S, over
2,300,000 fish were killed (F'r.'PCA, 19G9). The drums were used as flotation
devices at boat docks or were floating derelictts.
?!iscellaneous Sources
The manufacture and formulation of nercury compounds (§_.;]_. pesticides),
mercury reclaiming, broken clinical thermometers, disposal of electrical
apparatus containing mercury, etc., all are potential sources of mercury
to the environment; however, data are not available as to how significant
these sources are.
iiatural Sources
Some geological formations contain significant quantities of mercury.
Mercury from such sources can be emitted to the environment by leaching and
volatilization, and this may account for high concentration of mercury in
bodies of waters v/ith no known man-made sources of mercury pollution (Study
Group on Mercury Hazards, 1970). According to Jonasson (1970) it is highly
probable that lake areas overlying mineralized clay sediments, or black
shales which may contain up to 2 ppm of mercury will contain considerable
mercury in their waters.
Areas naturally high in nercury are believed to be associated with areas
of volcanic activity. Klein and Goldberg (1970) reports that Costrom and
Fisher (1969) found between 1-2 and 400 ppb mercury in pelagic sediments
(on a calcium carbonate-free basis) on a traverse across the East Pacific
3ise. The highest values occurred on the crest of the ridge in a zone of
high heat flow and it was suggested that a degasing of the mantle through
volcanic activity governs the mercury distribution pattern. '.Jhite e_t a]_.,
(1970) reports water condensed from volcanic fumaroles have been found to
-------
contain 0.3 to 6 ppb mercury. They also reported mercury content of
thermal and mineral waters from the northern California coast range up
to about 5 ppb and 20 ppb mercury. In the Aqua defley Spring of Siskiyou
County, California, the mercury content of precim'tates of thermal
springs range up to 500,000 ppb (White e_t al_., 1970). Shacklette (1970)
points out that anomalous concentrations of mercury a,re found in air
over mercury rock mineral deposits (ur> to 1,500 ng/nj at ground level
and 55 ng/m° at 400 feet above ground) and that snail amounts are found
in air over nonniineralized areas.
-------
33
V. ENVIRONMENTAL DATA FROM MORTH AMERICA
Poisonings
Man
Curley et_ al_., (1971) has described the Alamogordo, New Mexico tragedy
where a family was poisoned from eating meat from a hog fed mercury
treated seed. In August of 1969, Mr. Huckleby and five of his neigh-
bors obtained waste seed from a local granary which they used for hog
feed. The grain had been treated with an alkylmercury fungicide, either
Panogen or Ceres an. Mr. Huckleby began feeding his hogs the grain in
late August or early September. After 2 to 3 weeks, one hog was
slaughtered and the family ate the meat for the next 3 to 5 months.
Three of the feeder pigs developed blindness, lack of coordination,
and posterior paralysis by mid October and 12 of the 14 pigs died in
the next three weeks.
During December three of Mr. Huckleby's children became seriously ill
and mercury poisoning was suspected. They showed symptoms of e.texia,
incoordi nation, blindness, and loss of consciousness. A level of 23.4 pp;n
mercury was measured in the muscle of the hon which :'r. Huckleby fed his
family, while 32.8 porn mercury was found in the grain feed to the hog.
Urine samples obtained from Mr. liuckleby's children on January 0, 1570 had
levels of mercury of 0.16, 0.21,0.20 and O.OG ppn. At the Urns the children
became ill, Mrs. Huckleby was pregnant and three months later the baby was
born. Or, January 3, Mrs. Huckleby's urine contained 0.09 ppm r.ercury and
on February 11, it contained 0.18 ppm. Concentrations of mercury in the
newborn baby's urine ranged from 2.70 pnm at delivery to 1.56 ppn several
days later, indicating placenta! transfer to the fetus.
Curley e_t al_., (1971) states; "these data clearly show that mercury accu-
mulated in animal tissues and human body fluids and confirm that compounds
containing organic mercury were, in fact, the causative agents in the
poisoning incident." Curley et_ aJL (1?71) states that details of the
epidemiology, symptomatology and diagnoses, and the clinical history and
treatment of the patients for mercury poisoning will be reported by the
Center for Disease Control in a report which is now in preparation.
Recently, at a Congressional hearing, Dr. Roger Herdr-ian, Deputy Commissioner
of the i-iew York State Department of Health testified that a dieting woman
who ate swordfish twice a day for more than a year had been diagnosed as a
victim of mercury poisoning.
Domestic Animals
There are a few reported instances of poisoning of livestock from the
misuse of mercury-treated seed. Most of a herd of 44 adult sv/ine and
5 litters of pigs fed several weeks on a diet, one half of which consisted
of seed grain treated with a melthymercuric compound, died within a three
month period (Kahrs, 195S).
-------
34
In June of 1970, a resident of the Hashington, D. C. area, reported to
the Federal VJater Quality Administration, U.S. department of Interior
(now part of the Environmental Protection Agency) that his cat was showing
symptoms of mercury poisoning. His description of the symptoms were
almost identical to those which Kurland (1960) reported for methyl mercury
poisoned cats from Minimata, Japan, i. e., unsteadiness, frequent falls,
circling movements and convulsions. "Tin's v/as of interest, as Pakeuchi
(1970) has pointed out, the sensitivity of human beings to methylmercury
is presumed to be higher than in the case of cats. The owner of the cat
reported that he had been feeding the animal an. almost exclusive diet of
smelt, which he purchased from a local food store and stored in his home
freezer. The packages of Si7ielt which he currently had on hand were marked
as being from the town of Erie, Michigan which is in the vicinity of the
Detroit River, Lake St. Glair and St. Clair River, all known to have
mercury pollution problems.
The cat subsequently died and kidney and liver tissue samples were
analysed for rnercury by the United State Air Force Environmental iiealt'i
Laboratory, Kelly Air Force Base, Texas. The lab report contained the
notation that the samples were treated in a lev/ temperature asher and a
possibility exists that at one time during the process the temperature
might have gone higher causing a loss of mercury and, that if error exists,
the reported results are low. The mercury residues neasured_iri liver and
kidney tissue samples were 63 ppm and 7 ppm, respectively. Takeuchi (1973)
reported that cats affected with methyl mercury poisoning from ilinanata,
Japan had mercury levels in liver samples ranging frori 37.0 to 145.5
ppm for 15 cats, while mercury levels in kidney samples ranged frori 12.2
to 36.1 ppm for 7 cats, lie also reported those cats not affected with
methylmercury poisoning had mercury levels in liver sannles ranging from
0.6 ppm to 6.6 ppm for 13 cats while mercury levels in kidney samples
ranged from 0.1 to 0.8 ppm for 10 cats. Based on these :!ata, the cat is
definitely suspect of being a victim of methy!mercury ooisoning.
Wildlife
According to the United States Fish and Mildlife Service (1?71) two bald
eagles found dead in Minnesota during 1970 had lethal amounts of nercury
in their kidneys. Residues levels in their kirineys were renortei.i to be
130 and 117 ppm mercury. Tha Study Group on ''arcury Hazards (Ir70) con-
cluded that liver-kidney residues of 30 ppr.i in birds indicate critical
exposure. The Fish and '/ildlife Service (197.?) stated that they believed
the eagles were picking up the mercury through ingestion of fish.
Fish
Fish kills due to inercury, even though not common, are not unknown. In
Soone Reservoir, Tennessee over 500,000 fish were killed Juring the period
from July 9-13, 1958, while over 2,300,000 fish were killed during che
period from Hay 9-13, 1969 by phenylmercuric acetate (F'./PCA, ISCD).
-------
35
Environmental Levels
Air
Very little is known about the quantitive or qualitative aspects of mercury
in the atmosphere. The Study Group on Mercury iiazards (1970) points out
that mercury nay occur in the atmosphere as a vapor or as an aerosol or
both, and r.iay be present as organic or inorganic mercury. Since dimethyl -
mercury is volatile it is likely that some of the atmosoheric mercury is
in that form.
VII 11 1s ton (1963) found that in the San Francisco Bay area (Los Altos) ,
concentrations of mercury in the atmosphere iqange from over 0.5 to 23 ng/m°
curing the winter and from over 1 to 50 ng/mj during the suiter. Fie
found that concentrations depended upon v/ind direction, win-J spaed, and
seasonal temperature variations. High levels v/ere found alv/ays to coin-
cide with high smog levels. According to Fleischer (1070) unpolluted
air contains 1 to perhaps 10 ng/mj mercury while in the case of "natyral
pollution" over mineralized areas t!ie air will contain up to 62 ng/n^
mercury. McCarthy et_ al_. (1970) concluded that the naturally occurring
mercury content of air is highest over areas where the rocks are richest
2,000 to 20,000 ng/m3 at ths surface and fran 29
state that the maximum
lesser amounts in the
morning and evening; and minimum amounts near nidnight. McCarthy °t al .
(1970) found that the background concentrations of mercury in air at
400 feet above ground in the Southwestern U.S. range fron 3 to 9 n-g/vi-.
in mercury,, ranging from 2,000 to 20,000 ng/m3 a
to 103 ng/m"' at 400 feet above ground. They sta
content of mercury in air is found near midday;
A recent study of airborne mercury concentrations by ';he Environment:-!
Protection Agency in seven urban areas showed maximum 2':-':our levels
ranging from less than 30 ^j ng/m° (the minimum Jetecta-:le vaUii) in .Mtocna,
Pennsylvania, to 310 ng/m° in Mew York City. The report of this study
has not yet been published, but should be in pri.it in the near future.
s
te
of i'iew York has measured airborne concentrations as high ss 2300 ng/m-
for 24 hours in a non-industrial urban area (Personal communications ,
liew York Department of Environmental Conservation, 1?71).
Dr. D. J. Sibbet of Geomet, Inc. ran a test of mercury levels in a room
after painting with an interior latex paint. The roo;;; had not bears
painted for over "r years prior to the, tast. 'Jith doors and windows
closed, he found a level of 0.3 mg/mj before appji cation of paint. After
painting the initial readings v/ere about 4 mg/m°; after 200 hours readings
ranged from 1.3 to 1.7 r.ig/n3. The readings decreased rapidly the first
few hours. Readings were decreasing very slowly the time the test
-------
'i J6
Table 5 Summary of total mercury measured in water samples from U.S.
rivers and lakes obtained during October and November, 1970.ir
Kumbor of samples with ug/1
State
Alabama
Alaska
Arizona
Arkansas
California
Colorado
Connecticut
Delaware
District of Columbia
Florida
Georgia
Hawaii
Idaho
Illinois
Indiana
Iowa
Kansas
Kentucky
Louisiana
Maine
Maryland
Massachusetts
Michigan
Minnesota
Mississippi
Missouri
Montana
Nebraska
Nevada
New Hampshire
New Jersey
New Mexico
New York
North Carolina
North Dakota
Ohio
Oklahoma
Oregon
Pennsylvania
Rhode Island
South Carolina
South Dakota
Tennessee
Texas
Utah
Veraont
Virginia
Washington
West Virginia
Wisconsin
Wyoraing
Puerto Rico
Total
<.<"
18
8
10
10
6
17
24
3
1
8
17
4
5
13
19
8
3
11
6
13
8
15
12
8
9
8
7
3
3
18
15
27
21
5
9
9
13
42
4
16
5
10
27
8
3
11
13
12
15
9
10
579
.5-. 9
.
.
.
3
11
2
1
.
.
4
-
2
1
2
2
1
3
1
1
.
6
4
1
.
-
.
2
4
1
-
-
6
-
1
8
2
.
1
_
•
1
2
2
_
_
.
.
.
~
79
1.0-1.9
.
1
'
.
10
-
-
-
-
3
-
2
1
1
-
I
1
. 1
.
-
-
-
.
-
2
'
1
1
-
-
.
.
-'
.
7
T
.
-
_
.
_
•
3
1
_
.
1
. _
1
-
44
2.0-2.9
.
.
1
.
3
-
.
-
-
1
-
_
_
.
-
2.
-
.
'
.
'
-
.
1
1
. •
.
.
_
-
-
.
-
1
_
_
.
'
_
_
.
.
_
_
_
_
.
_
•
.
-
10
3.0-3.9
.
-
-
.
-
.
-
-
-
.
.
-
.
.
.
1 -
-
.
.
.
. .
-
.
1
1
. .
.
.
.
-
-
.
-
.
_
_
•
.
—
.
_
—
—
•
.
„
_
.
_
_
-
3
4.0-4.9 5.0-5.9 6.0-6.9
.
...
...
.
1 - 1
_
...
...
_ . -
...
_
...
1
...
...
ill
...
. . -
. ' -
...
...
...
_ - -
...
r.
- .
_
...
...
...
- . -
. . - _
...
• • V
• — •
• • V
- • .
— •> .
•• • •
• • _
- • .
-
— — _
• « •
« — •
• • •
• • •
•• • •
-
• • .
-
2 0 2
I/ Summarized from Durum e_t aj_, (1970).
21 Below detection limit.
-------
was discontinued after 200 hours. The room was occasionally ventilate:.!
and the readings dropped to about .3 mg/m^. llhen the room was again close:
the reading approached the before ventilation readings after approximately
three hours.
Water
The United States Geological Survey, Department of Interior analyzed water
samples obtained during October and November 1970 from 'J.S. rivers and la!:es
for both dissolved and total mercury (Durum et_ al_., 1971). Sampling sites
were: (1) surface water sources of public water supplies for cities of more
than 100,000 population, or for some States, the largest city in the State,
(2) water sources downstream from major municipal and/or industrial complexes
in each State, and (3) U.S. Geological Survey bench nark stations established
for measuring long-tern natural trends in stream flow and water quality.
Dissolved mercury was found to range from below the lower limit of detection
of 0.1 to 4.3 ug/1 and was found in 7 percent of the samples. Concentration
of total mercury above the detection limit of 0.5 ug/1 were measured in 140
out of 719 samples (Table 5). Concentrations of mercury ranging from 0.5 to
0.9 ug/1 were measured in 79 samples while concentrations from 1.^-1.9 un/l ;
2.0-2.9 ug/1; 3.0-3.9 ug/1; 4.0-4.9 ug/1; 5.0-5.9 ug/1; and 6.0 to 6.9 ug
were measured in 44, 10, 3, 2, 0, and 2 samples, respectively (Table 5).
Vlershav/ (1970) reported that 73 samples from Um'tad St.= tcs w?.ters analyzed
for dissolved mercury during May - July 1970, ranged in concentration from
less than 0.1 to 17 ppb. Of the total, 34 were below the detection limit
of 0.1 ppb while of the remainder, 27 were from 0.1 to 1.1 ppb; 10 were frr
1.0 to 5.0 ppb and two were over 5.0 ppb. !!e concluded that the mercury
content in unpolluted rivers or where mercury deposits are not known are
less than 0.1 ppb. Jenne (1971) also concluded that mercury concentrations
in major U.S. streams are commonly less than 0.1 pnb but msy reach 0.5 ppb
or more below sources of contamination. Pierce §_t al_., (1970) tabulated
statistics on the mercury content of stream sediments. From these data he
concluded that any stream sediment containing ncre than 1 ppm mercury is
possibly from mercury mineralization or surface conta:;/!nation by mercury-
bearing wastes. Klein and Goldberg (1970) reported that concentrations of
mercury in dried sediments off the coast of California varied from .02 to
1.0 ppm with the highest levels close to sewer outfalls.
Hammond (1970), states that measurements of the oceans made 3G years ago
indicate a range in mercury content of 0.03 to 2.0 ppb, but recent
measurements with modern techniques see:", to average close to 0.1 ppb.
The form in which mercury is found in the oceans is unknown.
Land
Green (1959) estimates that the average abundance of mercury in the e?.rth's
-------
38
crust is 50 nob. Mercury content of rocks in the earth's crust range from
10 ppb to 20',000 ppb (U.S. Geological Survey, 1970). Igneous rocks j_.e_.,
those formed by melting and cooling, are the- basic source of ^-ercury and
these contain less than 200 ppb mercury and average 100 ppb (U.S. Geological
Survey, 1970). The United States Geological Survey (1?70) reports Liiat soil
averages 100 ppb mercury and varies within relatively narrow limits; while
sedimentary rocks average less than 100 ppb r^srcury and seldom exceed 200
ppb except for certain organic-rock shales which may contain 10,000 ppb
or more-mercury (U.S. Geological Survey, 1970). A more recent United States
Geological Survey report (Shacklette e_t al_., 1971) reported that the average
concentration of nercury in soils throughout the United States is 71 ppb,
with the average in the western States being 55 ppb and the average in the
eastern States being 9G ppb. The maximum concentration found was 4,600 ppb.
'//eiss et_al. (1971) measured the mercury content of glacial ice fron Antartica
and Greenland. Samples of ice deposited prior to 1952 had an average mercury
concentration of 60 ng/kg ranging from 30 to 75 n-j/ko while samples of ice
deposited between 1952 and 1955 had an average mercury concentration of 125
ng/kg ranging from 37 to 230 ng/kg.
Residue Levels
Man
Goldwater (1964) reported ranges of mercury concentration in blood for f-
States in the United States. !-!e reported that mercury in all of IT1 samples
from California were below the detectable limits of .005 ppm, while 34 out
of 40 blood samples from Ohio, 5 out of 14 blood samples from Missouri, and
38 out of 55 blood samples from ;;ew York were below detectable limits.
Mercury concentration in the blood samples from Ohio ranged up to 0.009 pn:ii,
while blood samples from Missouri and :'lew York ranged up to 0.07 and 0.045
ppni, respectively. Thus, at least some of the blood levels were above the
0.02 ug/g (approximately 0.02 ppm) considered ?.s an acceptable lave! in
whole blood by Berglund et_ al_. (1971). Goldwater (19G4) docs not present
data as to what form of mercury was present in the blood samples; however,
he did state the few high values, strongly suggest some unrecognized unusual
exposure to mercury.
Jervis et_ a_l_. (1970) analysed hair samples from residents of the \enora-
Dryden District and the Lake St. Clair area in Canada which had a known
history on the frequency of fish consumption fro/n contaminated water. They
state that nearly 75 percent of the persons tested had abnormal levels
in their hair and several had concentrations of 50 to 100 ppn corresponding
bo their practice of having one to five meals per week of fish during the
previous 10 months, while those who had less than 1 meal per two weeks
during this period had essentially normal concentrations of mercury in the-
-------
hair. An examination of the data they presented in their report showed
that 25 out of 37 hair measurements exceeded the 5 ug/g lavs! of mercury
in hair considered as acceptable by Berglund et_ a]_. (1971).
Martz e_t al_. (1971) reported on the mercury content of hair from residents
of AngwTn, California. They found that concentration of mercury in hair
of approximately half of the local elementary school students was hi'jh.
Serial analyses of the hair established that mercury concentration in t.'ie
hair of the high school subjects reflected an exposure dating back approxi-
mately eighteen months earlier. They subsequently traced the exposure of
the children with high mercury levels to swimming in an institutional pool
treated with a phenylmercuric acetate algicidc. On January 11, In71 , they
measured 270 npb of r,:ercury in the pool, after a regular schedule of treat-
ment with the algici'Je for 10 weeks. An average of 39.5 nnn mercury was
found in the hair of 22 children which had been exposed tc mercury in !;he
pool. Since some of the hair in the children had grown since the chil'jrsn
were exposed to mercury from sv/imrnng, the- hair v/as not subjects:1 directly
to the mercury in tvj v/ater. Since such hair still co^tai'vc.; •^rc'.iry, the
riiithors concluded that it must reflect an intemil exposure to marcury.
Aquatic Life
residues lias been widespread.
uuhler §t_ al_. (1971) found that the mercury content of muscle tissue-
exceeded tiie 0.5 ppm maximum guidelines set by the Food and Drug Adminis-
tration for approximately C5 percent of the brown bullhead fro;.; various
rivers, lakes, and bays in Californinia, Idaiio, Oregon, ar.J V.'asliin-jton.
The guideline was exceeded in 74 percent of the northern squawfish, 3-"
percent of the channel catfish, 47 percent of the largsnoutii bass, and
11 percent of the white sturgeon. Duhler et_ aj_. (1C71) also reported tiiat
crayfish from the Columbia P.iver downstream from Long view, '.Jasiiinrton con-
tained an average mercury concentration of 2.10 pom. Gebhards (1971)
found that of the 160 fish samples analyzed for mercury content fron- Idaho
waters, 19.3 percent were at or exceeded the 0.5 ppm Food and Drue Adminis-
tration guideline. Me also reported that tiie mercury content of 45 percent
of the channel catfish and 39 percent of the yellow perch exceeded the 0.5
ppin guideline, i-lenderson and Shanks (1971) found mercury concentrations
above a detectable limit of 0.05 pom in 15 of 143 composite sarolss of fish
collected by the Bureau of Sport Fisheries and IMldlife in the fill of
1959 as part of the National Pesticide I'onitoring Program. Values re-ngsci
from 0.06 ppm to 1.25 ppm mercury net weight whole fish.
Anas (1971) measured mercury in fur seals collected on the Pribilof Island,
Alaska and off i-Jasln'ngton in 1970 and found all s21:10las contained mercury.
He found mean mercury values for liver tissue to be 0.20 ppm for 10 puos,
-------
40
10.3 ppr.i for 29 two and three year old males end 67.2 ppm for 29 females
in ages 5-10. The highest value obtained was 172 ppr: mercury in the
liver of a 19-year-old female.
In August of 1970, the Federal Hater Quality Administration (1070) neda
a survey of State Directors of Fish, Game and Conservation Departments
for information on the mercury problem as it is related to the natural
resources under their jurisdiction. Eighteen out of the 48 states respond-
ing reported that residues of mercury in excess cf 0.5 pnn v.«ere present in
fish in their States; however, a considerable number of the States reported
that they were only getting started in a mercury testing program. Texas
also reported that in Lavaca Bay oysters they found up to 5 nnni mercury in
an oyster bed below an industrial discharge of mercury containing wastes.
Low mercury levels, were found in oysters from beds in the outer estuary.
Aquatic Birds
Following the Canadian discovery of high nercury levels in the fish of Lake
St. Clair, the Bureau of Sport Fisheries and Wildlife, 'J.S. Den«rtr.:ent of
Interior undertook a preliminary assessment of mercury residues in birds
and their eggs collected on the St. Clair Flats Public Hunting Grounds
during the period of May 21 to 23, 1370 (Dustman e_t a_l_., 1970). Mercury
residues were found in liver of great blue herons up to 175 npr.i v.'hile 23 ppm
v/ere found in their carcasses. They also found mercury residues in liver of
common terns up to 39 ppm while 75 ppm were found in their carcasses.
Dustman zt_ al_. (1970) pointed out that these residues are comparable- to
those in birds from Sweden that died under experimental dosages with methy1-
mercury and in birds that died under field conditions in several Scandinavian
countries.
Dustman et_ al_. (1970) also reported that nercury residues in the eggs of ? of
5 terns, a grebe and a mallard range;.! from 1.3 tc 2.0 ppm. i'erc'jry in breast
muscle of 4 out of G mallards, one out of 4 blue-wings:! teal, and in all of
four lesser scaup exceeded 0.5 ppr. Also mercury in tiie breast muscle cf one
bird of each species exceeded 1.0 ppr.:. The maximum morcury concentration in
the liver of each species was 5 to G ppm. Dustman et_ al. (1070) concluded
that many birds which depended upon water areas in tieTake St. Clair region
have high residues of mercury in their tissue and eggs, demonstrating the
extension of the water pollution problem into the marshland environment.
Gaskett (1970) reported that mercury residues in fulvous tree
-------
41
in their breast Muscle ranging from 0.17 to 2.26 ppni. Baskatt (1?70) also
statad that 39 scaup taken at Lake St. Glair in the winter by the Michigan
Department of iiatural Resources averaged 0.6 pnr.1 in breast muscle.
Vermeer (1971) reported on a survey of nercury residues in conposite 23-3
samples of aquatic bird species collected from Alberta, Saskatchewan and
Manitoba, Canada. Mercury residues were reported for California gull
ranging from 0.1 to 0.4 ppn while ring-billed gull ranged fron 0.1 to 0.5
ppn; Franklin's gull ranged from 0.10 to 0.13 ppn, iierring gull ranged 0.3
to 1.0 ppr.i; common tern ranged from 0.1 to 0.73 pon; double-crested cor-
morant ranged from 0.3 to 0.7 pom; white pelican ranged from 0.1 to 0.4 ppi-i;
great blue heron ranged fron 0.2 to 0.4 ppr.r, Western grsbe ranged fron 0.03
to 0.17 ppi;r, American avocet ranged from 0.15 to 0.15; Canada goose- ranged
from 0.03 to 0.05 ppn; mallard ranged from 0.02 to 0.06 ppn; gadvvall ranged
from 0.1 to 0.3 porn; and lesser scaup ranged fron 0.03 to 0.2 ppn. The
highest mercury levels were found in herring gulls which nay ba related to
its fish eating habits. !1ercury residues in livers of California gull
females were reported to average 5.5 tines higher than in their eggs.
Other Birds
Dale (1970) reported that pheasant tissues collected in 1?6G at five loca-
tions in California had mercury levels ranging up to G.GO ppn. Of the
23 pheasant tissue samples analyzed 1C were above 0.13 pnm. In 1^50, 13
pheasa.it tissue samples collected in the Tule Lake arsr», California ranged
frota 1.6 to 6.76 ppm, while Montana pheasant and Muricjsrian partridge ha-ii
mercury residues in tissue ranging fron 0.05 to 0.38 ppm and fro;.! 0.07 to
0.3 ppm, respectively. Buhler et al. (1971 ) reported on nercury residue
of 137 ring-necked pheasants coTTected from agricultural arc-as of Oregon
during 1970. They found mercury residues exceeding 0.5 ppm in br~ast
muscle in 2 out of 59 birds from Unatilla County, 5 out of C4 birds fron
Willamette Valley and 7 out of 64 birds fron "alheur County. A majority
of mercury present in the tissue was in the form of netliylnecury. Also,
they found that the concentration of mercury in pheasant liver was
normally about 2 1/2 tines as great as that found in muscle. Griffith
(1971) reported that laboratory findings revealed that virtually all of
the mercury in California pheasants was in the form of methyl mercury.
The August 1970 survey of State Directors of Fish, "ana and Conservation,
Departments conducted by the Federal ',,'atar Quality Administration reveale-J:
(1) that California had found up to 4.7 ppn morcury in pheasant flesh,-
(2) Colorado had found from 0.04 to 0.6 nercury in pheasants, 0.4 to 2 pp:.:
in pheasant eggs, 0.04 to 1C ppn in sage grouse- asvJ 0.05 to 0.4 pp-.i in bar.:;
tailed pigeons, (3) Idaho had found fron 0 to 7 ppn nercury in pheasants,
and (4) Oregon had found that 3 of 94 pheasants analyzed contained mercury
levels in breast tissue in excess of 0.5 pnr.
-------
The Alberta Interdepartmental Comittee on Pesticides (li?70) reported
that pheasants and Hungarian partridge collected fro™ southern Alberta in
1052 contained, an average conceritr5.ti_cn of ;.:erciiry in tho Hash 0* 0.<"5
ppi.:, ranging fro;;-; 0.24 to 0.7? ppir;. The Co::;::ri ttse stctc-'.! l:h?.t background
levels in biological material appears to be fro:.: 0.00" to 0.1.1-3 ppr; nercury
and, persunably higher concentrations in tissue ssr.iplos ^ra fro:;: so:ne kind
of contamination. Fureite et_ al_. (1070) reported on mercury residues in
birds collected fror.i southern Alberta and Southern Saskatchewan during
136G and 1069. They found elevated mercury residues levels in tha livers
of ring-necked pheasant and gray partridge. The ring-necked pheasant
livers had a nean of 2.3 ppm mercury ranging fron 0.4 to 5.9 op;.' v-/hile
the gray partridge livers had a mean of 1.1 ppi.i r.:ercury rang in-:; fro:: 0.4
to 2.7 ppm. These v/ere the two species of resident upland gone birds nost
frequently associate with far:-i yards, roadsides and cultivated fields where
r.isrcury treated seed grain could be found. Lower levels v/ere found i;i
other species of birds except for the Horned Lark winch had a i-.ea'ii of 1.5
ppm in their livers ranging from 0.02 to 10.2 npn. Elevated mercury residue
levels v/ere found in the egg contents of the majority of the predatory birds
samples and were nost pronounced in the eggs of the great horned ov/1 and
red-tailed hawk. The eggs of the Great Horned Owl had a :'.:c-an r.iercury con-
centration of 1.0 ppr.i while the rr.ean in the eggs of the red-tailed hav/l:
had a mean mercury concentration of 0.3 ppn, ranging fro:~.i 0.03 to l.i; ppi.i.
Food
There are only lir.ited data on mercury residues in food. The Food and Drug
Adr.rini strati on conducted a limited study of mercury residues in foods as
part of their Pesticide Total Diet Study and this indicated background
levels of mercury in order of 0.002 to 0.005 ppr;. Jervis et al_."(1070)
reported on the nercury content of selected Canadian foodsTTable 5). They
found levels of snercury averaging 254 pob in wheat; 250 pnb in flour; ?5 pnb
in milk powder, 113 ppb in beef-muscle, 102 pp'j in beef liver, 23£ pnb in
perch, 275 ppb in pike, and 415 ppb in walleye. However, the Mercurial
Pesticide Registration Review Panel (1?71) points out that at the Inter-
national Conference on Mercury, held in Ann Arbor, Mi tin gars, September 30
to October 2, 1970, questions v/ere raised as to the validity of thu results.
The Mercurical Pesticide Registration Review Panel (1971) states that studies
should be repeated to confirm their potential significance fron ?. hu^an
health hazard.
The misuse of nercury treated seed is a potential rncchanisn by which
grain containing e/ccessive levels of residues of nsrcury could show up
in the human food supply. The Food and Drug Administration reoorted that
140 cars of grain at 100,000 Ibs. each and one hundred fifty thousand pounds
of potatoes v/ere seized during 1970 because of r.isrcury contamination
(Mercurial Pesticide Registration Review Panel, 1071). Also, during the
period July 1967 through February 1970, the Food and Drug Afj-:ini strati on
obtained 12 judgments for voluntary destruction of nercury contaminate-.!
-------
43
Table 6 Summary of mercury content of selected food products in Canada.
I/
Commodity
Wheat
Flour
Milk Powder
Tea
Beef - Muscle
- liver
-kidney
Pork
Turkey - muscle
Chicken - muscle
- liver
Salmon
Halibut
Cod
Flounder
Scallops
Pickerel
Perch
Pike
Whitefish
Walleye
Sucker
Hungarian Partridge
Pheasant - muscle
- liver
No. of Samples
5
6
5
8
3
5
3
3
3
14
4
2
2
4
2
3
3
6
6
5
26
3
18
38
5
Range, ppb
79-400
140-380
60-180
10-110
10-310
14-220
22-130
18-170
12- 33
25- 61
22- 59
8- 32
14- 31
27- 80
62-170
9- 68
150-420
200-260
62-630
11-400
80-1540
50- 50
20- 75
6-460
5-220
Average
254
260
95
64
118
102
70
96
22
37
46
20
23
54
116
30
152
236
275
189
415
33
43
55
From Jervis e_t al_. (1970).
-------
grain. An additional party voluntarily followed suit bring the quam'ty of
destroyed grain to about 14 Million Ibs. (Mercurial Pesticide Registration
Review Panel, 1971).
Fishing and Hunting Restrictions
Fishing
A survey of State Fish and Game Departments conducted by the :j:ii £eci States
Bureau of Sport Fisheries and Wildlife revealed that 17 states had inposed
state fishing restrictions or wciming of soi-e type because of excessive
levels of mercury in aquatic life as of September 1, 1P70 (Table 7). The
August 1970 survey of State Directors of Fish, Gare and Conservation Depart-
ments conducted by the Federal Mater Quality ,V.hini strati on listed one-
additional State which had imposed fishing restrictions, i_.a_., ;!ev/ Mexico.
Since these surveys there have been additional States issuing fishing
restrictions or warnings of soire tyoe e_.g_., California issuer! * v/arnincj
that large stripec! bass and catfish fror*~the Sacramento-San Joaqin'n Delta
and San Francisco Bay area should not bo eaten more then o:ice a week and
pregnant women should not eat then: at all (Griffith, l::'7"i). Curre.it .!'?.ta
on State fishing restrictions or warning currently in sffcict sra not
available.
There has been no consistency in the type of.fishing restriction or warning
issued by the various states or for that matter the criteria on which the
restrictions or v/arnings are based. For exar.ple, actions have varied
fror.i a warning by California for people not to eat fish :.:ore than once a
week and pregnant worsen not to eat them at all, to complete closures of
certain commercial and sport fisheries by Michigan (F'.IOA, 1P70). Otlier
examples of the types of actions taken by States arc-: (1) Mississippi:
warnings to sport fisherman to release fish caught fror.i certain waters,
(2) Hew iiampshirs: advise to fishermen not to eat large quantities of
yellow perch, chain pickerel, and sr-iall:-:outh bass, (3) '.le.-i Mexico:
advise to fisherman not to eat more than two pounds per wee!-: of brown
trout or black bullhead fron a particular reservoir, (4) VJi scons in:
warnings to fishermen not to sat more than 1 meal per weak from the
'..'isconsin River, and (5) Tennessee: a public statement by a Tas:; Force
that citizens wanting to take a very conservative approach to the con-
sumption of bass species from certain areas night temporarily li;:vit tlier;-
selves to no more than 3 meals of bass per week.
Hunting
In Canada all adult pheasants and Hungarian partridge collected in Southern
Alberta in June and July of 1969 showed levels of r;ercury in their tissues
above the 0.1 ppm tolerance level established by the Canadian Federal Food
and Drug Directorate for food products. Therefore, the 1969 hunting season
in Alberta on these two snecies was closed by Alberta authorities with the
-------
Table 7 State fishing restrictions because of aicrcury « September 1, 1970.
Stale
Texas
Michigan
Wisconsin
Ohio
New York
New Hampshire
Vermont
Pennsylvania
West Virginia
Alabama
Georgia
Louisiana
Mississippi
North Carolina
South Carolina
Tennessee
Virginia
Closure of
sport fishery
So. L. Huron, West L. Erie
take no walleye, drier,,
white bass
L. Onondsgo
Savannah R., New Savannah
Dam to Hichway 12 closed
Brunswick Estuary, closed
Savannah P.. , Augusta tc
coast, closed
Closure of
CPnr.ercial fishery
Oysters, 19,900 acres
Lavoca Bay
Detroit R..L. St. Clair,
St. CUir R. closed
So', L. Huron, West L.
Erie closed to walleye,
dru.-n, white bass
L. Cric, close? to
walleye
Tombigbee R. closed.
Kobile R. , Tensaw P.. ,
Kobile-Tensaw system,
Tennessee R. and
ta'.paundnents, closed
Brunswick Estuary, closed
Pickwick L., closed
Savannah R. , Augusta to
coast, closed
Tennessee R., Pickwick L.
closed
Warning or catch and
release for snort fishery
Detroit R. , L. St. Clair.
St. Clair R. catch and
release only
Wisconsin R. , catch and
release recor.riended ; no
more than 1 r.eal per week
Lake Eric - warning
released via news
L. Champlain, Erie, Ontario
Oswego R. , Niagara R. ,
St. Lawrence R. , danger
warninis
Kerrimac R. , Connecticut R.
danger warninos for
pickerel, yellow perch,
seal Imouth bass
L. Char.plain, L. Mer.pnre-
magog, danger warr.ing
L. Eric, danger warning
for walleye, drun, snail -
nouth boss, white bass
Ohio R., danger warning
Tombigbec R. up to Jacksor.
Clan, warn inn
Mobile R. , Tensev: R. ,
I'obilc-Tensaw oysteo,
Tennessee P.. and
impoundments, warnina
Calcasieu R., warning
Pickwick L. , warning
Danger warning (general)
Tennessee P.. , PicLwick L.,
warning, catch and release
!i. rork Moisten P.. belCW
S^ltvlllc, Wirniiiij
Embargo or warning
to cn-:r;ercial fishery
Embargo on species other
than walleye, drum,
white bass
Embargo on whfie bass
L. Char.pl e in, L.
Cierr.phrcmagoij , cnbargo
on sales
Ohio R., request to stop
•Operations
-------
statement that the closure would renain in effect until Jata indicates
r;ercury residues have dropped to a safe level in the birds (Alberta Inter-
departmental Conriittee on Pesticides, 1970).
On September 23, 1970, the Idaho Fish and Gane Department (1970) announced
that about one fourth of 300 wild pheasants tasted contained over 1 ppr.i
mercury and recommended that: (1) persons not eat more than one neal per
week of pheasant, (2) pregnant women avoid food with a known or suspected
nercury content and (3) the backs and all giblets of pheasant be discarded.
Tiie announcement further stated that the hunting season would go on as
scheduled.
Removal of Fish fror.i the Market
The Food and Drug Acininistrati on found that during the period fron
December 1970 through February 1971 almost 4 percent of the canned tuna
on the wholesale market contained residues of rsercury over the Food and
Drug Adrnini strati on guideline of 0.5 ppr.i, ranging up to approximately
1 ppm. Species of tuna primarily involved v/ere yallov.-fin, albacorc,
bigeye and bluefin. Approximately 12,500,000 cans of domestic tun.3; were
voluntarily removed from the United States narket. On 'lay 5, 1971, the
Food and Drug Administration announced that a three-r.iorit!i study shov/ad
that all but 42 of G53 samples of sworjfish contained Mercury at or above
their guideline of 0.5 ppm. The announcement also stated that the average
'level was -double the guideline and soiie ser.iples were 2 tii::5s tlie accent-
able levels. The Food and Drug Administration advised the public to ston
eating sv/ordfish. Previous to this, approximately £,"!00,">on Ibs. of sword-
fish had been seized by Food and Drug Aurnini strati on or voluntarily
withheld from the market because of excessive levels of :"£rcury.
t -
-------
vi MOVEMENT OF MERCURY i;i THE Eiiyir:o'!ME:!T
Ai r
Significant quantities of mercury are emitted to the atmosphere from the
manufacture of chlorine, industrial use of catalysts, mining and bum in-::
of fossil fuels, joining and refininy of ores, incineration of sewage sludge,
incineration of trash (including paper, wood, containers etc.), arid the
processing of phosphate rock (See Chapter IV, Sources of Mercury tc tha
Environnont). Mercury is also emitted into tha stmosphera fro:: soil
and mineralized land areas and by volcanic activity (See Copter IV,
Sources of Mercury to the Environment). The for:.; of mercury ir. emissions
from industrial sources has not been quantified to any extent; however,
undoubtedly much of it is in the elemental form, as a veinor cr aerosol
(Study Group on Mercury Hazards, T370). Some of the atmospheric mercury
is probably in the form of vaporized dimethylm-ercury v.'hich reaches tha
air prinarily through evaporation froi.i soil or v/atsr (Study Group on
Mercury Hazards, 1?70). Jonasson (1970) states that ;iost mercury co;,>
pounds v/ill degrade to nercury r.;etal under the c-ctior; of sunlight.
The vaporization rate of mercury v/ill approximately double for every 1"!°C
increase in temperature (Stahl, 19GD). Likowise, the saturation levsl of
mercury in air in equilibrium v/ith metallic mercury, increases logarit;ii:;ic^lly
with increasing temperatura (Vaughn, 19G7). These ciio.ractoristies :iay explain
the correlation of r.iercury atmospheric levels v/ith season and ii;.i£ of dsy.
For exasriple, during 1969 and 1070 th-a monthly concentrations of total :;Ljrc- '
in precipitation sanples at Stropserdt in Ceiitral Sv;eden shov/eJ seascrsal
changes relating to evaporation during wan'.: summer :':ont!is (Study Proup on
Mercury Hazards, 1970). A low or 0.03 ug/1 mercury v.'-ns r-=asjrad in tlia
sar.iples during December while a high of 1.45 un/1 v/as measured in July.
••Mlliston (1953) found that atmospheric mercury concentrations v/ere the
highest in the Sen Francisco Bay Area in the sui.-imer. He also found that
prolonged cool wet weather v/ould lov/er the averaqe readings v/hile prolonged
warn dry temperature v/ould increase the mininu;:: readings.
'.•Jilliston (1968) states that because of the ability of v,ercury to adsorb
on any and all surfaces, dust particles in air will nornally carry nore than
the expected amount of nercury and that mercury evaporated intc thi air v/i 11
tend to concentrate on dust particles. He found that high atmospheric
mercury levels always coincided with high smog levels in the San Francisco
Bay area, 'ii'lliston (19-33) states that it is merely speculative whsther
the high mercury content of smog is merely coincidental or v/hsther mercury
vapor's catalytic effects under the influence of ultra-viol-st light ri.iy be
contributory to the siv.og.
-------
'18
Air currents will transport mercury in the atmosphere as evidenced by the
fact that l/illiston (1953) found that the mercury content over the San
Francisco area was dependent primarily on wind direction and speed. In
still air, inasmuch as metallic mercury vapor is approximately 3 to 9 tines
heavier tiian air, irercury './ill tend to collect near the surface of the
ground (Stahl, 1959).
Mercury is removed fron the atmosphere by dry fallout as well as by precipi-
tation. Jenne (1970) states that r\ore nercury nay possibly be deposited by
dry fallout than by rainfall during dry seasons. In an industrial area of
Chicago, 4.8 ng/:n3 or two and 1/2 tiires as nuch participate mercury was.,
found as was found in a rural area where the concentration was 1.0
(Jenne, 1970).
Rainfall riay re:nove most if not all cf^ths nercury in the at'/.cs^h^rc-.
McCarthy e_t al_. (1970) measured 20 nj/n- of nercury in ths air nen.r a
the day before a raiti-storn while several hours after tie rain no rx-rcury
was detected in the air. Snow also removes nercury fros-.i tho atinsnhera
as evident by tha neasurement of nercurv in tie per.iansnt snow fields
of Greenland by '.,'eiss eL al. (1371).
Land
Soils
Significant quantities of nercury can enter soils fro:.: the disposal of
sewage sludge; agricultural use of nercury based pesticides; dry fallout
from tie atmosphere; and rainfall (see Chapter IV, Sources of Mercury to
tils Environment). Jonasson (1970) states that a considerable amount of
nercury in soils is present as elemental vapor, probably adsorber!.
Jarren (196G) found that soil horizons with either a high clay ccnte-nt or
a high organic content carried a significantly greater quantity cf nercury
than did the soil profile as a whole. Jonasson (1970) quotes Anderson
(1967) as finding that a high hunus content is needed in soils for the i-ercury
content to exceed 150 pnb, assuming no previous pollution, say fro:.; sued
dressing. The affinity of certain soils for mercury is illustrated by Ross
and Stewart (1962) finding that phenyl,.iercuric acetate applied as an orchard
spray failed to migrate below the surface 2 inches which contained 500 to
1,000 pnb mercury, depending on the number of sorays applied. According to
Jonasson (1970), clays can play a key role in the collection and retention
of mercury ions and at a pii of 5 the adsorption of nercury by the cl?.ys
tested was at a Maximum.
Leaching or soil erosion can move :nercury fror. soils to waterways. The
ability of certain soils to retain mercury close to their surfaces should
-------
facilitate the movement of nercury from such soils by erosion, "arcury
is "lore easily washed frae from mineral soils than fro;:', soils contairmY/j
humus matter (Jonasson, 1071}. Hunates contain sulphur sites upon which
mercury nay absorb very strongly (Jonasson, 1071).
A slow breakdown of piienylnercuric acetate, ethylmercuric compounds and
metiiylnercuric compounds to nercury ion and nercury vapor in soils has
been demonstrated (Kir-iura and Miller, 13C4). Jonasson (1070) states that
nost mercury cor.-.pouncls wi 11 degrade to nercury netal under the action of
sunlight.
Tono;,iura, iiakagami, e_t al_. (19GT.) have isolated a bacterial strain of
Pseudoiiionas froi.i soil heavily contaminated with phenylnercuric acetate-,
which was found to be very resistant to nercury compounds. Its growth \/as
inhibited only at concentrations of nercury 1003 times that inhibiting the
growth of Eschericin'a coli and P_. aeroginpsa. The organism w,-:.s also found
to be capable of splitting tiie linkage between nercury and carbon in organic
mercurials, including phenylnercuric acetate, ethylnercuric nhosphate and
nethylinecuric chloride, to form metallic nercury (Furuknwa e_t 2_1_., 1PS5).
Furthermore, tiie organ ism was able to stimulate vaporization of nheriyli'iorcuric
acetate and mercuric chloride fron the nedia in which it was cuUured and the
evidence suggested that the vaporized compounds were different fro:.; tie
original coinpcund (Tono:nura, ''aeda e_t aj_., IP^O; Tonor-iur?., Maeda, and
Futai, 1963).
1/hat significance such organises play in the ncver.ient of nercury compounds
from soil to air is not known. Regardless, significant quantities of nercu'
are enn'tted fron soil to the atmosphere as is indicated by tiie presence of
high mercury concentrations in the air over mercury enriched soils.
'.,'eiss et al. (1971) states that permanent snow fields record the
introduction of matter into that atmosphere. They were able to show an
increase in the content of glacial ice from Antartica and Greenland.
Samples of ice deposited prior to 1052 had an average mercury concen-
tration of GO ng/kg ranging from 30 to 75 ng/kg while samples of ice-
deposited between 1952 and 1965 had an average mercury concentration of
125 ng/kg ranging from C7 to 230 ng/kg. They concluded that t:ic increased
fluxes of mercury to the atmosphere was due to the activities of nor,
causing greater exposure of terrestrial surfaces which allowed more mercury
vapor and gaseous compounds to enter the atmosphere.
Si ota
Some mercury is translocated to fruits, tubers or seeds in plants following
the foliar applications of nercury fungicides (Smart, 195C). Foliar
applications of phenylroercuric acetate to rice resulted in the transloca-
tion of mercury to the grain (Lindberg, 1061). There is some trans location
of mercury fro;n treated seed to the plant and harvested seed; however, the
amount is relatively small (Mercurial Pesticide Registration Re vie.-/ Panel,
1971).
-------
50
Terrestrial aninals accumulate mercury mainly from their food (Johnels and
Hestermark, 1959). Man is also occunationelly exposed to nercury. Girds
accumulate mercury mainly fror.i eating nercury treated seed or nercury con-
taminated fish (Johnels and vlestermark, 1939).
As a rule, mercury compounds are not methylated in higher anirials (Larson,
1970); however, ilestoo (1959) reported that there was a very srall con-
version of nercury compounds to methylnercury in hens. The eggs o* hens
fed rriCthylmercury contained only nethylnercury in their eggs ('.Jostoo, 1953).
Buhler, Claeys and Rayner (1971) reported that the majority of mercury pre-
sent in wild Oregon pheasant tissue was methylmercury and Griffith (1971)
reported that the same was true for California pheasants.
The tendency for mercury to be deposited in growing feathers, claws, and
beaks of birds is so strong that feathers and other ksratir.ous strucLures
will eventually contain all the whole body load of nercury (Study Group on
Mercury Hazards, 197T). Since birds molt once or twice D year, large anounts
of nercury will be excreted. Hi Id pheasants show rapid ssnscnal changes
in mercury level, depending on the availability of nercury treate-J seed:
however, the fish eating osprey loses methylmercury nuch slower. The half
life of nsthy!mercury in the osnrey is in the order of 2 to j norths (Study
Group on Mercury Hazards, 1971).
'.Jatsr
!fatarv/ays
Significant qualtiti-ss. of nercury are aisdurrsd to v/sLsrvays fro:". ;.:?.;)•;.!l^cturs
of chlorine, manufacture of pulp and paner, laboratories, hospitals, -Jc-ntal
clinics, manufacture and use of pciiit, industrial use of catalysts, r.imYig
and refining or ores, disposal of us£d p'jrcury containers, sewage- treot.ieni
plants, processing of phosphate rock, industrial utilization of r^.v: materials
and basic chemicals, and the use of nercury based pesticides (soe Chapter IV,
Sources of Mercury to the Environment). In some areas, natural waters over-
lying geological formations naturally enriched in mercury nay nick up mercury
by Teachings or volatilization (See Chanter IV, Sources of Mercury to the
Environment). Mercury enters waterways directly from dry fallout and
precipitation. Soils, especially those rich in organic natter, absorb much
of the ,-ercury contained in rainfall, lloivevar, in urban areas where much
of land surface consists of roofs, pavement and other nonsoil surfaces,
there is a likelihood that a considerable portion of the mercury contained
in precipitation would enter waterways directly or indirectly through
sewage treatment plants. Erosion of mercury enriched soils would con-
tribute mercury to waterways.
uecausa nercury is strongly sorbed on particulate matter and forms
complexes with particulate organic matter, nercury entering into strains
-------
51
will quickly be rei.ioved freer, the water itsalf. iiannerz (lOGD) found that
suspended solids in pond water act as scavengers of nsrcury carrying ths
absorbed Mercury to the bottom. Tie ability of mercury to become absorbed
is shown by the fact tiiat water solutions at a nil of 5 to 3 and containing
less than 500 ppb mercury, lose :;iercury to '.-/alls of glass or nolyetiiylerie
containers to the extent of about 70 percent after 5 to 10 days (Jonasson,
1970). According to Jonasson (1970), ir.arcury v/i 11 probably be very tightly
bound and concentrated by sediments containing high concentrations of metal
oxides. Jenne (1970) states that the available evidence indicate that stream
sediments and related fine grained materials rer.iove a high percentage of any
slugs of mercury introduced into streams, within a distance of few to several
miles. The water movement of bottom sediments would transport any r-iercury
in association with such sediments.
Transformations
It is necessary to understand the'transformation reactions between the
different compounds of mercury in nature if the ecological effects of the
different kinds of discharges and risk involved are to be evaluated (Jernelov,
1969). Mercury is usually discharged to the water environment in one of the
following forms:
(1) As inorganic divalent mercury, Hg?+
(2) As netallic mercury, Mg°
(3) As phenylmercury, Cgii^g*
(4) As nethylmercury, Cihr!g+ and
(5) As alkoxiyalkymercury, CH-jO-CI^-Ci^-iig*
Jernelov (1969) presented the following diagram showin-j some of the steps
by which mercury and its compounds are converted to -lethylnercury:
(Siphenyliiierc'jry) icsH5)2Hg icH3)2HQ (Dime thy Ir.-.arciiry)
CH3o-cH2 -CHZ—Hg-^fe Hg^^rcHjHg* (; loiionethy Inercury)
ililuly reducing conditions, which occur in many lake and stream sadi'mants,
can cause mercury to precipitate as the sulfide cinnabar which has an
extremely low solubility; however, very strong reducing conditions may in-
crease the solubility somewhat by converting the mercuric ion to free r,etal
(Hem, 1970). Cinnabar can be slowly oxidized in ferric ion charged watar
derived from pyrite freeing the mercury i.'ito solution (Jcnasson, 1?7T).
Oxygen deficient bottoms are often rich in hydrogen sulfide. Under such
conditions hydrogen sulfide will react with inorganic mercury ions tc for.':
-------
nercury sulfide (Study Group on Mercury Hazards, 1P70)'. Jemelov
found that v/hen r.iercury was added to nud as a sulfida it was net ne thy In tec!
under permanent anaerobic conditions. iiov:cver, he found that nercury bound
to organic substances and subsequently subjected to anerobic conditions co;ild
be methylated in the presence of hydrogen sulfide and the process under such
conditions could be very fast.
If the water bottoms becor.ie aerobic the mercury sulfide can be oxidized to
the sulfate and the nethylation process can proceed (Jernclov, 1969).
Thus, if waters which have anoxic bottoms are oxygenated through decreased
supply of nutrients, !•§_., by decreasing the SOD load from pollution,
or by other efforts at reversing eutro^hication, the nethylation process
can proceed and methylnercury can be released to the water (Larsson,
1970; Study Group on Mercury Hazards, 197"}; Mercurial Pesticide Re
-------
53
Although methylation will occur anaerobically, the process appears to be
more efficient in aerobic systems (Study Group on "ercury Hazards, 1070).
Jernelov (1969) states that the speed of the nethylation is higher when tic
bottom sediments contain r.iorc organic matter and conversion rates can be
h i gh i n sewage trea tnien t p 1 an ts .
Jernelov (1970) found that the mucus on pikj is able to convert inorganic
divalent mercury almost completely into nethylnercury within a short period
of time of 2 to 4 hours. However, in later tests he did not find the riatnyl-
ation rates to be as fast. At the International Conference on Environmental
Mercury Contamination at Ann Arbor, 'lichigan, September .33-October 2, 1370,
Jernelov indicated that subsequent tests shov/ed that there was a seasonal
trend in the nethylation rate by mucus and that this trend was associated
with microorganisms occuring in the fish mucus during the winter.
Jornelov (19G9) raised the question as to whether or not the methylation
of mercury would be faster for certain concentrations of inorganic mercury.
He found that in aquarium experiments that there was a steep increase in the
amount of monomethylmercury observed as the concentration of added
inorganic mercury in mud readied 1 to 10 on;,!, iiov/ever, Jcrnc-lov noints
out that in the experiments con-ducted there arc several other possibilities
other than a threshold value to explain the observed relationship.
Jernelov (1059) states that the conversion of nhenylmorcury to i-at'iyl-
rnercury has been studied and"shewn to occur in nature, lie further states
chat it see::is plausible that the formation of mono and -dimethyImercury froi.:
phenylmercury proceeds along more tlian one synthetic nathway. Observations
in nature repeatedly indicate that discharge of ohenylnercury has a stronger
and faster effect on the mercury concentration in fish than the discharge
of a similar amount of inorganic mercury (Jernelov, l!?3").
Jonasson (1970) states that most mercury compounds will degrade to mercury
metal under the action of sunlight whether in soil or v/ater surfaces or in
the atmosphere. According to Jernelov (1!?^), the conversion of alkoxi-
alkylmercury to inorganic divalent mercury is well known to occur.
In summary, it appears that no matter what form mercury is introduced into
the aquatic environment, it eventually can be converted to methylmercury.
Accumulation by Fish
Fish accumulate mercury directly from the water as well as their fond.
However, available data indicates that probably they obtain most of it
•directly from tiie water. Jernelov (1971) found that by comparing mercury
concentration in predatory fish and food fish that the nredstory fish CCL;!::
absorb no more than 20 percent of the nercury present in the food fish.
Johnels e_t al. (13G7) demonstrated that the concentration factor from
water to nilce" is in the order of 3,000 or mere. A linear relation bo-.vson
-------
.p.je or weight of pike arrJ the ; sercury content in axial rvjscjl.;.t::ro or
other organs w?,s demonstrated by Johiisls and '..'esterMEirk (19o~). For lev/
levels of nercury in fish (belo1./ 0.2 np:.:) no increase or a very s-.r-Jsrate
increase in nercury content vns found to occjr with increasing wei-jht
of the fish. As the nean level of nercury increased they f auric that the
,.:ercury level in relation to weight increased noticeably. For excr-a:iely
high levels of mercury, caused by Manifest contamination, they ^ound no.
relation to age or weight. Wallace 2_t_ a]_. (1C-71) interprets this to
indicate that there is a threshold level of r.ercury in the eiwiron;.:^!:,
above which fish cannot eliminate Mercury from their nuscular tissues
faster than it is incorporated and above which accumulation tiius occurs.
Lofroth (1959) states that this relationsiiip is an .indication that fish
are adapted to a riercury concentration of less than 1.2 ppr.i. AccorJing
to Lofrotii (1369) all data v/hich have accuMulated regardiiij tiie nntjral
concentration of nercury in fish indicate that the r-axi::iu;.! natural con-
centration is 0.2 ppr.i fresh weight or less.
Larsson (1970) states because of the relation bctv/een size and nercury
level in fish, conclusions of the mercury content of the "standard m'ke"
should only be drawn fros.i fish with a weight lying between "00-1500 g.
Sweden, when conparing residues of nercury in fisli sannles for restricting
fishing, adjusts tiie level of mercury neasured in pike to fit a size fish
weighing 1 kg or about 2.2 Ibs. (Study Group on "ercury Hazards, 1070).
Hannerz (10S3) found that in brackish water uptake of ;iGthyl:-;c?rc.!ry by
pike is less 'than in fresh water; however, he found that in saltwater, cod- •-'
concentrate nethylinercury faster than in brackish water. /\ccorJi:iy to
Larsson (1970), cod in seawater accumulate nercury to higher levels than
in brackish water, presumably because cod in 100 percent ssawatar swollen
;.iore v/ater tiian they do in brackish water.
ilannerz (19GG) found that in exposing pike to r.ietiiylmercury for 70 to ?0
days, that the concentration factors were the greatest in kidneys follov.'Gc!
by liver, spleen, stomach, heart, gills, brain, fins, gonaJs, nuscles,
scales, eyes and bone. Salmon retained in cages in rivers for un to t.vo
r.ionths first showed an increase in the nercury content of the blood cor-
puscles followed by the liver, while tiie increase in -uscular tissue oro-
gressed considerably r^ore slowly (Masselrot, 105?.). Jernelov (1070) states
that according to experiments the ratio between tiie rvercury content of liver
and body r.uscles varies between approximately 0.1 to 50 and that with a ratio
greater than 1 (liver content/:;uscle content) the content in the fish muscle
will rise; while if on the other hand the ratio is clearly lower than 1(0.?)
then the content in the fish muscles can bs expected to dscrcrise or at least
remain constant.
Miettinen and his associates of the Institute of riadiochosM'stry, Helsinki
University, Finland, have shown in a series of unnublishac! nepers, that tho
-------
55
loss of methylmercury from fishes has tv/o components, fast and slo-.; (Study
Group on Mercury Hazards, 1970). The fast loss occurs early and lasts only
a few v/eeks while mercury is being redistributed through the body. The sub-
sequent loss from established binding sites follows slowly: indeed, the
half life estinated from this component is in hundreds of days—on the order
of 2 years. They also have shown extrenely low rates of loss from aquatic
nollusks and crayfish, and they have noted distinct snecies differences.
Mercury is present in Swedish fish almost entirely as nethvlrercurv ("erjlund
et_al_. , 1971). This is further substantiated by Lofroth (I?'??) who in his
review of the health hazards and side effects associated with the em'ssion
of mercury compounds states that mercury is almost 1^0 nercent in the form
of nethylmercury in all types of fish investigate.'- fros'i water, Baltic,
and Atlantic. The fact that practically all ^srcury in fish is -c-tliyl-
mercury is also substantiated by Horen and '.Jestoo (197"!}; Johnels and
'..'esternark (1969); and '.'festoo (19G3). Fjrcher.icrG jt^ublishe..! an.Tlysis
of a variety of salt and fresh water fish by the 'Jit i ted States Food and
Jrug Admim strati on have showed that practically all •iorcury in fish fro;i
the United States is methylmercury. This is not surnrisiii-j in li-j-it of
the fact that all for.is of r.:ercury introduced into the aquatic dr,viro:i,ioiit
can be converted into "letiiylriercury.
TillarvJer et a1. (1070) found that excretion rates of :::ethyl:Torc-jry in
a species oT seal (Pusa hispida) was slov/er than any oLhsr iia:.1.;!?.! anc
about like fish.
Decoiitaninati on
The continuincj supply of nercury fron bottor.i sedinents to t:ie water ar.'J
the slow rates of excretion of nercury by fish give little hope for quid;
improvement in levels of nercury residue in fish. The Swedish experience
confirms this. In Sweden nercury i;i pi:;e in r:ost lakes has drooped
little if at all since Miercury bans became effective in early ID'G. Tliese
lakes where the fish residues have not dronned tend to be biologically poor
and acid. Only about three lakes apoarently have had r.icrcury levels in
pike drop to a demonstrable extent. ?.ivers have a better chance -due to
continual flushing action (Study Group on Mercury Hazards, 127?}.
Jernelov (1953) calculated that it would take fron 10 to 100 years for
the methylation process to remove the ::;ercury from the bottoi.i of lakes.
These calculations were based on the yield over a period lasting fron .
1 week to 2 months of mono and dimethyl mercury from jotton sediments
taken from contaminated lakes and rivers and kept under natural conditions.
In iiina::iata 3ay, Japan, once the cause of the pollution was dstarrined
and eliminated, nercury levels in shellfish drconed fron 35 no;;-, to 11
ppin over a two year period and remained constant for at l^ast a five
-------
56
year period (Irukayama, 1D56). Rivars should have a better chance of
being decontaminated because of the flushing action of currents moving
sediments downstream. Mercury levels of salmon placed in cages below
former sources of mercury in some Swedish rivers shewed considerable
improvement within 3 years (Study Group on Mercury Hazards, 1070).
Swedish workers have considered the following approach-as to the decontam-
ination of nercury contaminated waterv.-ays: (1) introduce oxygen-consuming
materials to create continuous anaerobic conditions in tiie sediments,
thereby reducing methylation, (2) increase the pH of tiie sediments to
favor uimethylation and increased volatilization, (3) cover tiie sediments
with fresh finely -divided materials with high adsorotive affinity (e_.g_.,
quartz and silicates), (4) cover the sediments with inorganic inert
materials of any type, i_.e_., bury them, and (5) remove merc-jry-bearing
sediments by dredging or pumping (Study Group on Mercury Hazards, WO).
The first two approaches appear to be impractical, however Sweden is
evaluating tiie other approaches (Study Group on Mercury Hazards, 1070).
Experiments have been conducted in Sweden to evaluate covering sediments
by layers of inorganic sediment of varying thicknesses (0-2? cm), with
and without Tubificidae (oligochaete worms) and Anodonta (a bivalve) (Study
Group on Mercury Hazards, 1970). These studies have- revealed that: (1) in
the absence of Tubi fici-Jae, methylmercury accumulated in fish only when
the sediments were uncovered, (.2) in the presence of large populations of
these worms, fish accumulated methylmercury when tiie covering-layer w?.s
less than 2 cm, and (3) in the presence of Anodonta, v;hich stirs tiie
sediments, leakage of me thy! mercury occurred if tiie covering layer was
less than D cm.
Swedish workers have conducted tests to evaluate the effectiveness of
ground silicate, on the uptake of mercury by fish from sediments contami-
nated with metallic mercury, ionic mercury, an:! oh2nylmercury (-tudy flrcum
on Mercury Hazards, 1070). These tests have- reverie--:' th.Tt there v:.:i.s n--.
reduction in uptJiki when the oolluton;; wr.s phony riai
decrease in uptake by n factor of t.;c occurred v/h':-n
j.i-,,
wl'c
The removal of mercury contaminated se.!i,:ents by Jrc-dgin.j
some serious shortcomings. For one tiling, the cost to •.redg; any j.'xtsnsi•/•;
area may be excessive. The dredging of a Finnish nort increased the
soluble mercury concentration in the water from z. level of i..v to approxi-
mately 10 ug/1 (Stephen, 1971). This increase took "some weeks" to roach
a peak; however, it returned to background in a "fe1..1 more weeks" (Stc-nhan,
1071). Swedish workers v/ere of the opinion that by dreJging t-i-ira v:£s •?.
considerable risk of increasing the rate of methylation o-c mercury in the
sediments (Stephan, 1071). Measurements taken on sludges jredgec frcm
mercury sludge banks in Sweden indicated that while some 05 nerr.ent o^ the
suspended solids can be retained in tiie sludge, only 50-60 Darccnt of t.:i2
-------
57
mercury will renain in the sludge, t!ie re:.iaim'nrj /n-4!- percent oaing -Jis-
charged with the supernatant (Stenhans, 1371).
Environi.iental Gadget
In order to fully evaluate the ecological consequences of -nercury in
tiie total environment and to insure the identification of nil .-Jiscliarjes
of mercury to the environnant, there should be available a total budget
for the environmental distribution of mercury, including sources,
transfer, transportation, deposition and fate. Sufficient -.-atn are
not presently available to produce n :-iodel of the flov/ of mercury fron
origin to disposal.
-------
58
VII. FORMULATION OF POLICIES AND STANDARDS
General
In the formulation of policies and standards to control the introduction
of mercury into the environment, the United States Environmental Protection
Agency is using a total environmental approach. Historically monitoring
and research has been inadequate in tracing the environmental dangers
of ultra-deleterious elements in small quantities. Moreover, normally
abatement has been sought only after the pollutant has gotten into the
environment, damage has occurred, and can be conclusively shown. Typically,
only one source or effect of a pollutant has been traced, rather than
considering the effects on the total environment. We believe that
regulatory actions should be focused upon prohibiting, restricting,
and preventing the introduction of toxic substances before damages to
human health and welfare have occurred.
The United States Environmental Protection Agency in determining the
need to control the introduction of all toxic substances into the
environment weighs the following general considerations: (1) the nature
and magnitude of the foreseeable hazards associated with use of a
particular substance and (2) concurrently, the nature of the benefit
conferred by the direct and indirect use of a given substance.
In approaching the problem of taking regulatory action to abate pollution
for toxic substances, such as mercury, the United States Environmental
Protection Agency proceeds in as far as is practical, by:
1. Identifying all significant sources and applying equitable
reduction requirements to them,
2. Bringing in other State and Federal agencies and utilizing
all information available to them,
3. Keeping the public informed, and
4. Giving the dischargers a reasonable ooportunity to state
their point-of-view and being sure of the most current infor-
mation relating to each discharge and the sources program for
abatement before regulatory action is commenced.
However, it must be recognized that because of statuatory limitations,
some sources of pollution are not controllable, while others may not at
this particular time be identifiable. Therefore, the United States
Environmental Proection Agency does not permit the facts that it is
not possible for us to abate all sources of pollution or that it has
not identified every significant source of a pollutant to be used as
justification for not taking regulatory action against known and
controllable sources. It is obvious, that v/here the total amount of
-------
59
a toxic substance being introduced into the environment must be reduced,
first consideration must be given to restricting the most significant
and controllable sources when taking regulatory actions.
Residues in Aquatic Life
Standards for allowable quantities of mercury in aquatic life are
primarily for the protection of human health. All residues of
mercury in fish must be considered to be methylnercury (See Chapter
VI, Movement of Mercury in the Environment). Furthermore, as
Westoo (1969) has pointed out, broiling, boiling or frying fish
does not remove methy!mercury. In fact, since fish lose water by
these processes, a corresponding increase in the concentration of
methylmercury in fish is observed (Hestoo, 1969). Also, for the most
part, concentrations of mercury in the aquatic habitat, which will
result in acceptable residue levels of mercury in fish, will also be
acceptable for the protection of aquatic life (See Chapter III, Hazards
of Mercury). Thus, in formulating standards for allowable quantities
of mercury in fish, the prime consideration is the toxicity of
methylmercury to man.
The following salient points relative to the toxicity of metfiylnercury
to man are summarized from Chapter III, Hazards of Mercury:
1. Man absorbs from ingested food practically all of the
methylmercury present,
2. Methylmercury in man is relatively stable, i_.e_.,
it remains in man as methy1 mercury,
3. The half life of methy!mercury in man is from 70 to
90 days;
4. Because of the slow elimination rate in man the steady
state between uptake and elimination is readied aooroxi-
nately one year after exposure has started,
5. Methylmercury has a propensity for the human nervous
system and about 10 percent of the total body burden
is in the head, presumably most of it in the brain,
6. Methylmercury is neurotoxic,
7. Postnatal methylmercury poisoning is not easy to
diagnose, especially in the case of only mild or
atypical symptoms,
-------
60
8. Besides raised mercury levels in blood and hair, no
clinical laboratory investigations have given any clear
and common positive findings for methylmercury poisoning,
9. Diagnosis of methylmercury poisoning is based on neurological
symptoms and it is conceivable that brain lesions may occur
at lower exposures and levels than those which cause neuro-
logic symptoms and which could not be diagnosed by available
methods,
10. It is not possible, with presently available data, to
estimate what the long term effects of subclinical methyl-
mercury poisoning are on man,
11. In non-fatal cases of methylmercury poisoning disability
can persist for an extended period of time,
12. Compensatory mechanisms of the nervous system can delay
clinical recognition of methylmercury poisoning, even
though brain damage has already occurred,
13. There are presently no known drugs effective for the
treatment of methylmercury poisoning,
14. There probably are individual variations in sensitivity to
methylmercury,
15. Methylmercury is teratogenic,
16. Prenatal methylmercury poisoning cannot be distinguished
from other types of cerebral palsy and diagnosis would
have to be done epidemiologically with the sunoort of
mercury levels in blood and hair,
17. In man, concentrations of methylmercury in fetal blood
are about 20 percent higher than in the mothers blood,
18. There is a greater risk of methylmercury poisoning
to the fetus than to the mother and affected children
can be born to mothers showing no clinical symptoms of
methylmercury poisoning,
19. Methylmercury has been shown to be mutagenic to test
organisms,
20. A correlation in man between the frequency of chromosone
breakage in lymphocytes and mercury level in blood cells
has been shown,
-------
61
21. It nust be assumed that exposure to methylmercury by man
Involves certain genetic risks; however, it is not
possible with presently available data to estimate the
extent of such risks,
22. An intake by man of 0.8 mg per day of mercury (as methyl-
mercury) corresponding to a level of 0.8 ug/g of mercury
(as methylmercury) in whole blood may be fatal,
23. Clinically manifest poisoning of adults sensitive to
methylmercury may occur at a level in whole blood of
0.2 ug/g mercury (as methylmercury) which can be reached
on exposure to about 0.3 mg mercury (as methylmercury) per
day,
24. Based on item 23 and using a safety factor of 10, accep-
table levels of mercury (as methylmercury) v/ould be 0.02 ug/g
in whole blood and 6 ug/g in hair, and
25. Based on item 24, an acceptable daily intake of mercury
(as methylmercury) would be 0.03 mg per day.
The conclusion that an acceptable level of mercury (as methylmercury) in
human blood is 0.02 ug/g, corresponding to a daily intake of mercury (as
methylmercury) of 0.03 mg, was reached by a prestigious Expert Group
appointed by the Swedish Board of the National Institute of Public Health,
in consultation with the Swedish National Board of Health and Welfare and
the Swedish National Veterinary Board to make a toxicologic-epidemiologic
evaluation of the risks involved in the presence of mercury in fish intended
for consumption (Berglund e_t al_., 1971). The United States has no basis at
present to disagree with their conclusion. However, in light of the
susceptibility of the human fetus to methylmercury and our inability
to fully evaluate possible unmeasured effects of exposure to methylmercury,
we are of the opinion that it is desirable to minimize the intake of
methylmercury by man to as low a level as possible.
The Study Group on Mercury Hazards (1970) asserts that the human intake
of mercury appears to be mainly through fish. If all drinking water
contained the maximum recommended allowable concentration of 5 ppb and
with an average daily intake of 2 liters of v/ater, a person would ingest
0.01 mg of mercury per day. However, it appears that mercury in water
supplies for the most part are much below this level. Also, present
indications are that mercury in most other foods, with the exception
of contaminated wildlife, grain, etc., are at a relatively low level.
Thus, in formulating an acceptable level of mercury in fish, the assumntion
has been made that fish is the only significant source of human intake of
mercury. Hov/ever, recent measurements of mercury in anbient air suggest
that intake of mercury from inhalation may be significant.
-------
In order to evaluate the risks of mercury in fish, it is necessary
to know how much fish people eat. If all fish contained 0.5 nnm mercury,
the daily limit of 0.03 mg mercury intake could be reached by eating GO gn
of fish per day. If all fish contained 1.0 pnn, the daily limit could
be reached by eating 30 gm of fish. Kolbye (1970) states that the average
daily intake of fish in the United States is 40 gm per day. However,
according to a survey of household food consumption by the Agriculture
Research Service, United States Department of Agriculture (1965), the
average daily intake of fish is approximately 24 gms. The Food and Drug
Administration, United States Department of Health, Education and Welfare
has established a "0.5 ppm mercury interim guideline for fish" (Kolbye,
1970). Based on the United States average daily consumption of fish,
the daily intake of methylmercury by persons in this country should
be below 0.03 mg.
According to Berglund (1971), the average consumption of fish in Sweden
is about 30 g of fish flesh per day; however, consumption varies con-
siderably, with a few percent of the population never eating fish, whereas
some individuals may consume up to 500 g per day. Likewise, fish consump-
tion in the. United States varies according to personal preferences, as
well as regional, ethnic and cultural patterns.
Sweden has adopted a limit of 1 ppm mercury in fish; however, this is
combined with the recommendation that fish from non-banned waters be
eaten only once a week (Lofroth, 1969). Berglund et_ al_. (1970) states
relative to the Swedish situation that a level of 1 nnm in fish might
result in some high consumers reaching the lowest level assumed to be
present in persons sensitive to methylmercury poisoning, with clinically
manifest poisoning and neurologic symptoms. They further state that with
this level in fish, one third of the population could reach levels above
the acceptable level; with a level in fish corresponding to 0.5 ppm some
persons with extremely high fish-consumption might reach the lowest toxic
level, and about one tenth of the population might reach the highest
acceptable level; with a level of 0.2 opm with free consumption, or 1 ppm
in combination with a restriction of the consumption of contaminated fish
to one meal a week, exposure would be within the acceptable level.
Tejning (1967) estimates that the average meal of fish in Sweden consists
of 150 gm, ranging from 100 to 200 gm. It is believed that in the United
States very few people on the average eat more than 2 or 3 meals of fish per
week. Assuming, that the average meal of fish in the United States is
150 gm containing 0.5 ppm of mercury, then an average weekly intake of
0.22 mg would be reached by eating 450 gm of fish per week. Taken on a
daily basis, this would mean an average daily intake of 0.032 mg of mercury.
However, all fish eaten would not necessarily contain residues of mercury
at or near the 0.5 ppm level. Therefore, assuming no other intake of
mercury the Food and Drug Administration interim guideline of 0.5 pon
mercury in fish is a reasonable basis for the protection of public health.
-------
63
However, it is recognized that as recommended by the Study Group on Mercury
Hazards (1970), the normal and extreme patterns of fish consumption
in this country need better documentation.
A Food and Drug Administration Ad Hoc Committee of Scientific and Medical
Experts from this country and Canada expressed consensus support
for the 0.5 guideline (Food and Drug Administration, 1971). Likewise, the
Study Group on Mercury Hazards (1970) concluded "on the basis of their
examination of their experience in Sweden and Finland that the interim
Food and Drug Administration guideline of 0.5 ppm in fish is, for the
present, a sound basis for the protection of public health. However, the
margin of safety may not be large, and residual uncertainties remain in
regard to oossible hazards where large amounts of contaminated fish are
eaten."
The purpose of the Food and Drug Administration guidelines of 0.5 pom
for the maximum level of mercury in fish is to remove from the narket
or prevent fish from reaching the market with excessive levels of
mercury. However, we are also faced with another problem, i_.e_.,
levels of mercury in fish which are indicative of pollution. '.Je
consider that when a range of fish species in an inland or estuarine
body of water have residue levels of mercury equal to or greater than 0.5
ppm that there is an indication of gross mercury pollution. Background
levels of mercury in fish would normally be below 0.2 ppm. Therefore,
when a range of fish species in an inland or estuarine body of water
contain between 0.2 and 0.5 ppn: mercury, while consumption night not
represent a hazard, it is indicative of mercury pollution, and should
lead to investigative activities to find the mercury source.
Drinking Hater
The Bureau of Water Hygiene of the United States Public Health Service
(now part of the United States Environmental Protection Agency) has
proposed a standard of 0.005 ppm for mercury in drinking water (Bureau
of Water Hygiene, 1970).
Residues in Bottom Sediments of Waterways
The presently available data indicate under many conditions, a total
mercury content of at least 1 ppm dry weight in bottom sediments of waterways
can result in gross contamination of aquatic life (See Chapter VI-Movement
of Mercury in the Environment).
Discharges to the Total Environment
As mercury moves from soil to both the atmosphere and water, as it also
moves from the atmosphere to both land and water; and since all forms of
-------
84
mercury in the aquatic environment can be converted to methyl mercury, it
is the policy of the United States Environmental Protection Agency that
the discharge of mercury to all environmental media should be reduced
to the lowest levels possible.
Discharges to the Atmosphere
Emissions of mercury to the atmosphere, and the effects of this mercury,
are not well documented. Neither the sources of mercury emissions, nor
the effects of these emissions on human health or welfare, has been
studied in sufficient detail to form final conclusions as to their
hazard to man's environment. It is believed that annual emissions to
the United States atmosphere approach 1000 tons, and without control
will increase at least 5 percent a year.
Much of the earth's mercury is in the sulfide form and buried in the earth.
Very little of this mercury can enter the environment through natural
processes. Man, by removing fossil fuels and metallic ores from under-
ground, and burning or heating them breaks down the sulfide compound and
introduces elemental mercury to the environment. Relatively little is
known about the movement of mercury through the environment. However,
it is certain that mercury once released to the environment may move
between air, water, land and living organisms. Emissions of mercury to
the atmosphere contribute to methylmercury contamination of the aquatic
environment. ...
Recent limited measurements by the United States Environmental Protection
Agency of mercury levels in the ambient air of a few large cities
showed 24 hour average mercury levels of 110 to 810 ng/m3. The Department
of Environmental Conservation in N&fi York found mercury concentrations
in non-industrial urban areas ambient air as high as 2300
Techniques and devices to control emissions of mercury into the atmosphere
are not available at the present time for most sources. An immediate
attempt to control all sources of mercury emissions to the United States
atmosphere could have a severe impact on our way of life. A comprehensive
program to identify sources of mercury emissions to the atmosphere,
mercury's movement through the environment once edited, and means to
control these emissions if necessary, is essential. As knov/ledge of
sources and control technology becomes available it is believed that all
man-made emissions of mercury should be controlled.
Waste '.-later Discharges to Public Waters
It is the policy of the United States Environmental Protection Agency
that all man made discharges of mercury to public waters should be prohibited.
This policy is based on the facts that: (1) all forms of mercury in
the aquatic environment can be converted to methyl mercury , (2) fish
-------
and other aquatic life concentrate methyl mercury from the aquatic environment,
(3) the health of man is adversely affected by eating mercury contaminated
aquatic life, (4) mercury contaminated waterways .-nay remain contaminated
for a period of possibly up to 100 years, (5) there are no proven methods
of decontaminating mercury polluted waterways, (6) there are many mercury
polluted waterways in this country, and, (7) the imposition of fishing
restrictions, because of mercury pollution, has had a significant economic
impact on recreational and commercial fishing industries.
-------
VIII. ACTIONS TAKEN
Pesticides
Un-Jer authority of the United States Federal Insecticide, Fungicide, and
Rodenticide Act (FIFRA) all pesticides used in interstate commerce must
be registered with the Administrator of the Environmental Protection
Agency. Under FIFP.A two procedures are available for v/ith drawing regis-
tration, cancellation and suspension.
Cancellation is the milder of the two procedures and is used when there
is substantial question as to safety of the product. Cancellation is
effective thirty days from receipt of official notice unless challenged
by the registrant. If the cancellation is challenged then either a
statutory scientific advisory committee is convened or a public hearing
is held, or both, in order to decide whether or not to affirm the cancel-
lation. Meanwhile the registrant is allowed to market the product in
interstate commerce until a decision is reached.
Suspension is a more drastic procedure and is warranted whenever the
Administrator determines that continued use of the product presents an
"imminent hazard to the public." Immediately upon notice of suspension
of registration the registrant must cease all interstate shipments of
the product.
During the period 1969-1970 four notices of cancellation were issued:
1. February 1, 1969 - Cancellation of phenylmercuric nonoethanol
ammonium acetate compounds for use on apples, and straw-
berries; phenylmercury nitrate compounds for use on
almonds and prunes; and phenylmercury urea compounds
for use on barley, corn, cottonseed, flax, oats, peas,
rice, rye, sorghum, and wheat,
2. February 26, 1970 - Cancellation of phenylmercuric
acetate or phenylmercuric ammonium acetate compounds
for use on millet, rye, and sugarcane, and
3. March 12, 1971 - Cancellation of hydroxynercurichlorophenol
compounds for use on snap beans, sweet corn, cowpeas, flax,
peanuts, peas, potatoes, seedlings (transplant bed),
soybeans, sweet potatoes, and velvet beans; hydroxy-
mercuri ni tropheno1-hydroxymercuri ch1oropheno1 compounds
for use on potatoes and sweet potatoes; nethy1mercury
8-quinolinolate compounds for use on apples; and phenyl-
mercuric acetate or phenylmercuric ammonium acetate com-
pounds for use on apples, cherries, peaches, strawberries and
sugarcane.
4. On August 8, 1970, all mercury products bearing claims and/or
directions for use as slimicides or algicides, and for use
-------
67
in laundering were cancelled. This action was taken because
the use of mercury compound v/hich results in water contamination
is potentially injurious to man and his environment.
On March 9, 1970 all pesticide products containing alkyl mercury for use
as seed treatments v/ere suspended, while on October 7, 1971, algicides
for use in swimming and wading pools and for industrial uses were
suspended.
Water
Background
On April 2, 1970, the American Embassy at Ottawa, Canada transmitted to
the Secretary of State a telegram which contained the text of a note
drawing attention to mercury contamination in certain boundary waters,
principally Lake Saint Clair. The Federal Hater Quality Administration,
Great Lakes Regional Office, U. S. Department of the Interior (now part of the
Environmental Protection Agency) immediately initiated an investigation
of mercury contamination in the Saint Clair River, Lake Saint Clair,
Detroit River, and western Lake Erie.
During April of 1970, it became evident that the mercury pollution problem
was not limited to the Great Lakes area, but was of national scope.
Therefore, on May 1, 1970, the Regional Directors of the Federal Water
Quality Administration were directed to identify and measure the existing
and potential threat from mercury contamination on a top priority basis.
Work was immediately initiated and concentrations of mercury in effluents
sediments and biological materials were measured. Known users of mercury
were systematically checked to ascertain if they discharged mercury to tie
aquatic environment. Also natural waters, where suspect, were checked to
determine if they v/ere contaminated with mercury. Priority was given to
the determination of (1) the extent and intensity of the contamination,
(2) whether unacceptable residues in fish might be present, and (3)
whether water supplies might be endangered.
Vlater Supplies
During the period, May 1970 through June 1971, the Division of Hater
Hygiene of the Environmental Protection Agency, analyzed G9C
samples of raw and finished waters collected from the sources and/or
treated waters of 273 community, recreational area, and Federal
installation water supplies in 31 States, the Virgin Islands, and
Puerto Rico. Over ninety percent of the water supplies analyzed
were surface or combined surface and ground water supplies.
-------
Table 8 Summary of findings of mercury discharges to waters as of April 26, 1971.
Number of Dischargers or Users
Effective Date
Analysis Positive Discharges greater than
sampled for which most recent 1.0 Ib/day . . .
analysis indicates the pros- 0.5-1-0 Ib/day .
da l,i shov/n as wcl 1 as compar- less than
olive findings where there •'• 0-.25 Ib/day. . .
have been reductions in the
discharge of mercury.
Analysis iterative Discharges
Suciplcs Tor vjhicii most recent
analysis did not detect the
presence of mercury above the
concentration of 1 part per
b i 1 1 i on .
Mercury useru (or potential
users) determined not to be
discharging mercury on the
basis of an on-sitc inspection.
Tol.il An.ily/.cd (I t II)
TO:J| Invut-.tin.iiod (1, II 6 III)
Sept. 3
26. . .
. . .36
. . .1.3
07
130
Sept. 17
... 52
o .
27. • .
... 36
-
... 86
83
17s*
Oct. 1
• • 53
9. .
2 .
28. .
. . 36
. .111.
89
203
Oct. IS
. . .53
9. . .
28. . .
. . ;36
• • 153
89
21.2
Oct. 29
. . .51.
Hi '
9. . .
3. . .
28. . .
. . .36
. . 173
SO
263
Nov. 12
. . .60
i*
15 ...
30 . . .
. . .1.3
. . 183
103
2do
Nov. 25
... 62
8. . .
38. . .
... 48
. . .183
•110
-2yj
Dec Ifl 70
. . . 61.
i •>
i j. . .
7. • •
6. . .
38. . .
• . . 57
. . .192
121
3'3
Anr 2n 71
... • 73
10
9. . .
7- . .
l|7- • •
. . ..6<.
. . .61.7
137
88:*
-------
"68
Of the 273 community, recreational area, and Federal installation
water supplies examined, 261 showed either no detectable quantities
of mercury present or concentrations of less than 0.001 ppm in the
raw and finished waters. In 11 of the water supplies examined, the
mercury concentration ranged from 0.0010 ppm to 0.0048 ppm. One
of several samples collected from a large community water supply
exceeded the tentative drinking water standard of 0.005 ppm.
Industrial Discharges
In previous programs of the Federal Water Quality Administration of the
United States Department of Interior top priority on compiling a list
of potential mercury uses and systematically checking them to ascertain
if they were discharging mercury into public waters. Investigations and
sampling of the potentially serious discharges were initiated in early
Hay of 1970, and by the end of June and in early July, sound evidence had
been developed to support regulatory actions. On July 14, 1970, the
Secretary of the Interior acting under authorities of the Federal Hater
Pollution Act forwarded telegrams to the Governors of 17 States in which
mercury pollution was suspected and urged the Governors to act vigorously
in eliminating known discharges of the metal. The Secretary also announced
that he would notify all industries across the nation which are shown by
investigations and data to be responsible for mercury pollution and that
court action will be sought in any confirmed cases of mercury pollution
if corrected measures are not taken swiftly on local levels. On July 22, 1970
the Secretary of the Interior announced that he was submitting the names
of United States industrial firms to the Justice Department for possible
prosecution on the charge of discharging mercury into the Nation's waterways
in sufficient quantitites to constitute a serious hazard to public health.
On July 24, 1970, it was announced that the Justice Department was filing
charges against 10 United States industrial plants which are discharging
mercury into the Nation's waterways. Subsequently, stipulations to reduce
mercury discharges to less than 1/2 Ibs per day and requiring plans for
further reductions by December 1, 1970 were entered in the courts in
9 cases.
In August of 1970, the Federal Water Quality Administration, Department
of the Interior, (now part of the Environmental Protection Agency)
initiated a series of administrative meetings with mercury discharges at
both the Headquarters and Regional level to establish abatement programs.
Most of these meetings have produced agreements at least equivalent
to those achieved by the Justice Department in. the courts. High intensity
investigation of newly discovered potential discharges and a continuing
process of resurvey of known discharges have continued to the present.
As of April 26, 1971 the Environmental Protection Agency has investigated
834 potential mercury discharges (Table 8). The most recent analyses
-------
•• '-"i* \
A)
available indicates that 73 sources were discharging mercury to the
aquatic environment while 64 sources the presence of mercury above the
concentration of 1 ppb were not detected (Table 3). On the basis of an
on-site inspection, 647 potential mercury discharges were determined not
to be discharging mercury to the aquatic environment. These investigations
clearly show that one of the major sources of mercury to the aquatic
environment is the chlorine industry. Of the 73 sources presently discharging
mercury to waterways, 31 are from chlorine manufacture (Table 9). Other
major sources of mercury to the aquatic environment are chemical and
pesticide manufacture, dye manufacture, and mercury reclaming (Table 9).
••Jastewater Treatment Plants
Because it was determined that mercury seals on rotary-type trickling
filters could be a source of mercury to wastewater treatment plants,
the United States Environmental Protection Agency initiated a program
on October 29, 1970, in cooperation with State v/ater pollution control
agencies to achieve the total replacement of such seals in municipal
and industrial sewage plants. The Federal Agency also notified state water
pollution control agencies that the use of mercury seals in trickling
filters was no longer considered acceptable for any reason. In order
to eliminate this hazard at Federal installations, the United States
Environmental Protection Agency requested on February 26, 1971 that
each Federal agency conduct a survey of its sewage treatment plants
to identify rotary distributor trickling filters equipped with mercury
seals and develop a schedule for early elimination of these seals in
both Federal and State agencies.
Air
Pursuant to the authority contained in the Clean Air Act, the United
States Environmental Protection Agency on March 31, 1971, designated
mercury as a hazardous pollutant for which hazardous emissions standards
will be promulgated. Proposed emission standards for chlorine production
and primary processing of mercury - bearing materials were published
on December 7, 1971 and are scheduled for promulgation within 130 days
thereafter. The proposed regulations would limit mercury emissions
to 5 Ibs. per days.
In order to intelligently reduce the emissions of mercury to air
under the United States Clean Air Act the Environmental Protection Agency
will take the following actions; 1) conduct a more thorough and detailed
identification of emission sources; 2) develop accurate emission factors
for each source category based on actual source sampling :.:ieasurements;
and 3) adapt or develop control systems adequate to reduce emissions
below a level which would be hazardous.
-------
'7:1
Table 9 Types of industrial discharges to the aquatic environment
for which the most recent analyses indicates the presence
of mercury as of April 26, 1971-
Source of discharge
Number
Chlorine manufacture
Chemical & pesticide manufacture
Dye manufacture
Mercury reclaiming
Pulp and paper manufacture
Instrument manufacture
Laboratories
Aluminum industry
Lamp &.light bulb manufacture
Plastic manufacture
Paint manufacture
Gold mining
Manufacture of switches
Manufacture of meters & pumps
Pulp and paperboard manufacture
Manufacture of catalysts
Manufacture of batteries
Manufacture of ammunition
Manufacture of magnets
Plastic fabrication
Sugar mi 11
31
6
5
k
3
3
3
2
2
2
2
Total
73
-------
'72
I TTTDrtTMr)" ,"TTr'
L 1 I L. . .r', I Jf kl_ U i I - U
Agricultural Research Service. 1235. Dietary Levels of Households
in the United States, Spring 19G5. U.S. Dept. of Agriculture,
Household Food Consumption Survey 1-355-t'G, Report lie. G.
Alberta Interdepartmental Committee on Pesticides. 1?70. "ercury
Residues in l/ildlife in Alberta. Report prepared for Minister,
Alberta Dept. or Agriculture, Edmonton, Alberta. Jan. 13, 197:3.
American Conference of Governmental Industrial Hygiem'sts. 1070.
Threshold Limit Value of Airborne Contaminants. ACGI.i, Cincinnati.
Anas, R.E. 1971. Mercury in Fjr Seals. Abstract of Panar Presented
at '/lorkshop on Mercury in tiie '.Jestern Environ;lent, Portland,
Oregon, Feb. 25-2S, 1971.
Anderson, A. 1057. Mercury in Soil. Grur.dforbatring, Vol. 20,
.'los. 3-4, pp 95-105, Dept. Sec. State. Trsnsl. Bureau .'!o. 5433 (
Caskett, T.S. 1970. Mercury - '.later Problei.-.s. Presented at
'..'aterfov.'l Advisory Cor.mnttee ileetinc], V/aslnngtcn, D. C., Aug. 12, 1?70.
Barylund,-F. and '!. Derlin. 1363. Human Risk Evaluation for
Various Populations in Sweden due to f'ethylnercury in .Fisli. In
Che::iical Fallout, Charles C. Thonas, Springfield, Illinois.
Serglund, F. and ;•!. Serlin. IQGOa. A Risk of Methykiercury Cumulation
in Man and Mar.snals and the Relation between Cody Burden of
Methykiercury and Toxic Effects. In Chemical Fallout, Charles
C. Thomas, Springfield, Illinois, 25G-273.
Jerglund, F. '.'. Berlin, G. Dirks, V. Von Euler, L. Friberg,
3. lionstedt, E. Jonsson, C. Rar.el, S. Skcrfvin-j, A Sv.-ensson
and S. Tejning. 1971. ''ethylmercury in Fish, A Toxicoloci c-
Epidniiologic Evaluation of Risks, Report from an Expert flrouo,
Chapter 1, Abstract, .'iordisk llygienisk Tidskrift, Supnlementu.''.
3arlin, '!. ii. and Ullberg S. 1963. Accumulation and detention of
Mercury in 'Mouse II. An Autoradiouranhic Conocirison of
Plienylmercuric Acetate with Inoraanic Mercury. Arc!1,. Environ, liealtli
Vol. 6.
Billings, :!. 1970. Letter of July 22, 1370 to Mr. 5. Soninick,
Commissioner, Federal '/later Quality Administration from "r.
Ii. Billings, Assistant Executive Secretary, State of Michigan
Dept. of Natural Resources.
3oor, J. R. 19'--4. Tlie Behavior of Mercury Compounds in Soils.
Ann. Appl. 3iol., 31, 340-53.
-------
73
Borg K., H. Wanntorp, K. Erne, e_t al_. 1969. Alkylmercury Poisoning
1n Terrestrial Swedish Wildlife, Viltrevy, 6:301-377.
Bouveng, H. 0. 1967. Organo-mercurials in Pulp and Paper Industry.
Oikos Suppl. 9.
Bouveng, H. 0. and P. Ullman. 1969. Reduction of Mercury in Waste
Waters From Chlorine Plants. Swedish Water and Air Pollution
Research Laboratory, Stockholm. Pul. No. 4-46.
Buhler, D. R., R. R. Claeys and John Rayner. 1971. The Mercury
Content of Oregon Pheasants. Abstract of Paper Presented
at Workshop on Mercury in the Western Environment, Portland,
Oregon, Feb. 25-26, 1971.
Buhler, D. R., R. R. Claeys and W. E. Shank. 1971.
Mercury in Aquatic Species from the Pacific Northwest.
Abstract of Paper Presented at Workshop on Mercury in the
Western Environment, Portland, Oregon, Feb. 25-26, 1971.
Bureau of Water Hygiene, 1970. Mercury in Water Supplies.
Journal Amer. Waterworks Association, Vol. 62(5): 285.
Chernoff, N. and K. D. Courtney. 1970. Maternal and Fetal Effects
of NTA, NTA and Cadmium, NTA and Mercury, NTA and Nutritional
Imbalance in Mice and Rats. Progress Report. National
Institutes of Environmental Health Sciences.
Commission on Pesticides and their Relationship to Environmental
Health. 1969. Report of the Secretary's Commission on Pesticides
and their Relationship to Environmental Health. U.S. Dept. of
Health Education and Welfare.
Curley, A., V. A. Sedlak, E. F. Girling, R. E. Hawk, W. F. Barthel,
P. E. Pierce, and W. H. Likosky. 1971. Organic Mercury
Identified as the Cause of Poisoning in Humans and Hogs.
Science, Vol. 172 (3978):65-67.
Dale, F. H. 1970. Letter to H. W. Hayes, Pesticide Regulation
Division, U.S. Agricultural Research Service, March 3, 1970.
Dams, R., J. A. Robbins, K. A. Rahn, and J. W. Winchester. 1970.
Non-destructive Neutron Activation Analyses of Air Pollution
Particulates. Anal. Chemistry. Vol. 42(8): 861-067.
Durum, W. H., J. D. Hem and S. G. Heidel. 1971. Reconnaissance
of Selected Minor Elements in Surface Waters of the U.S.,
October 1970. U.S. Geological Survey Circular, 643.
Dustman, E. H., L. F. Stickel and J. B. Elder. 1970. Mercury
in Wild Animals, Lake St. Clair, 1970. Presented at the
International Conference on Environmental Mercury Contamination,
Ann Arbor, Michigan, Sept. 30-Oct. 2, 1970.
-------
'74
Environmental Protection Agency. 1971. Reasons Underlying the
Registrations Decisions Concerning Products Containing
DDT, 2,4,5-T, Aldrin and Dieldrin, March 18, 1971.
Fish and Wildlife Service. 1970. Mercury Found to be Another
Environmental Menace for Bald Eagles. Bureau of Sport Fisheries
and Wildlife, Fish and Wildlife Service, Dept. of Interior,
News Release, July 2, 1970.
Environment Magazine. 1971. Mercury in the Air, An Environment
Staff Report. Environment, May 1971.
Federal Water Pollution Control Administration. 1969. Report on
Boon Reservoir Fish Kill, May 9-11, 1969. Southeast Region,
Atlanta, Georgia.
Federal Water Quality Administration. 1970. Initial State Report
on Mercury Pollution in Water, Fish and Wildlife.
Fleischer, M. 1970. Summary of the Literature on the Inorganic
Geochemistry of Mercury. In Mercury in the Environment,
Geological Survey Professional paper 713.
Fimreite, N. 1970. Mercury Uses in Canada and their Possible
Hazards as Sources of Mercury Contamination. Environ. Pollut.
(1): 119-131.
Fimreite, N. 1970a. Effects of Dietery Methylmercury on Ring-necked
Pheasants, with Special Reference to Reproduction. Canadian
Wildlife Service Occassional Paper.
Fimreite, il. and L. Karstad. 1971. Effects of Dietery Methylmercury
on Red-tailed hawks. The Jour, of Wildlife Management, Vol. 35
(2): 293-300.
Fimreite, N., R. W. Fyfe, and J. A. Keith. 1970. Mercury
Contamination of Canadian Prairie Seed Eaters and their
Avian Predators. The Canadian Field-Naturalist Vol. 04: 269-276.
Food and Drug Administration. 1971. HEW, May 6, 1971.
Furukawak, T. Suzuki and K. Tonomura. 1969. Decomposition
of Organic Mercurial Compounds by Mercury-resistant Bacteria.
Agr. Biol. Chem., Vol. 33 (1); 128-130.
Gebhards, Stacy V. 1971. Mercury Residue in Idaho Fishes-1970.
Abstract of Paper Presented at Workshop Mercury in the Western
Environment, Portland, Oregon, Feb. 25-26, 1971.
Goldwater, L. J. 1964. Occupational Exposure to Mercury, the Harbel
Lectures. 1964. The Royal Institute of Public Health and Hygiene,
27:279-301.
-------
'75
Green, J. 1959. Geochemical Table of the Elements for 1959. Geo.
Soc. Amer. Bull. Vol. 70(9): 1127-1183.
Griffith, W. H. 1971. Mercury Contamination in California's Fish
and Wildlife. Abstract of Paper Presented at Workshop on
Mercury in the Western Environment, Portland, Oregon, Feb. 25-26, 1971.
Hag, F. U. 1963. Agrosem Poisoning in Man. British Medical Journal.
1:1579.
Hammond, A. L. 1970. Mercury in the Environment: Natural and Human
Factors. Science Vol. 171: 788-789.
Hannerz, Lennart. 1963. Experimental Investigations on the
Accumulation of Mercury in Water Organisms. Fishery Board of
Sweden, Institute of Fresh Water Research, Drottningholm,
Report Ho. 48:120-176.
Hanson, A. 1971. Man-made Sources of Mercury. Presented at Mercury
Symposium in Ottawa, Canada, 15-17 Feb., 1971.
Harriss, R. C., D. B. White and R. B. MacFarlane. 1970. Mercury
Compounds Reduce Photosynthesis by Plankton. Science, Vol. 170:
736-737.
Hasselrot, T. B. 1968. Report on Current Field Investigations
Concerning the Mercury Content in Fish, Bottom Sediment, and
Water. Fishery Research Board of Sv/eden, Institute of Freshwater
Research, Drottningholm, Report ilo. 48:102-111.
Hem, J. D. 1970. Chemical Behavior of Mercury in Aqueous Media. In
Mercury in the Environment, U.S. Geological Survey Professional
Paper 713.
Henderson, Y. and H. W. Haggard. 1943. Noxious Gases, 2nd ed.,
Reinhold, Mew York.
Henderson, C. and W. E. Shanks. 1971. Mercury Concentrations in Fish.
Abstract of Paper Presented at Workshop on Mercury in the Western
Environment, Portland, Oregon. Feb. 25-26, 1971.
Holmstedt, B. 1967. The Toxicology and Metabolism of the Different
Mercury Compounds. In Oikos Supplementum 9:25-27.
Holmstedt, B. 1967a. The Toxicology and Metabolism of the Different
Mercury Compounds, a Short Historical Survey. In Oikos,
Supplementum 9:25.
Hunter, D. 1955. Mercury in Diseases of Occuoations. Boston:
Little, Brown.
-------
76
Idaho Fish and Game Dept. 1970. Mercury Test Clear Pheasant Hunts.
New Release, Sept. 23, 1970.
Jalili, M. A. and A. H. Abbasi. 1961. Poisoning by Ethyl Mercury
Toluene Sulphonamilide. Brish. Journal of Industrial Medicine
18:303-308.
Jeanne, E. A. 1970. Atmospheric and Fluvial Transport of Mercury.
In Mercury in the Environment, Geological Survey Professional
Paper 713.
Jeanne, E. A. 1971. Mercury Concentrations in Waters of the U.S.
Abstract of paper presented at Workshop on Mercury in the Western
Environment, Portland, Oregon, Feb. 25-26, 1971.
Jensen, S. and A. Jernelov. 1969. Biological Methylation of Mercury
in Aquatic Organisms. Nature, Vol. 223:753-754.
Jernolov, H. 1969. Convertion of Mercury Compounds. In Chemical
Fallout, Charles C. Thomas, Springfield, Illinois, 75-93.
Jernolov, A. 1970. Laboratory Experiments on the Change of
Mercury Compounds from One Into Another. Fisheries Research
Board of Canada, Translation Series No. 1352 [From: Vatter, 24 (4):
360-362, 1968] 6 pp.
Jernolov, A. 1971. Aquatic Ecosystem for the Laboratory. Fisheries
Research Board of Canada, Translation Series No. 1676,
Translated from Vatter, 26(3):262-272, 1970.
Jervis, R. E., D. Debrun, W. LePage and B. Trefenback. 1970. Mercury
Residues in Canadian Foods, Fish, Wildlife. Dent, of Chemical
Engineering and Applied Chemistry, University of Toronto,
Canada.
Johnels, A. G., and T. Westermark. 1969. Mercury Contamination of the
Environment in Sweden. In Chemical Fallout, Charles C. Thomas,
Springfield, Illinois. 221-241.
Johnels, A. G., T. Westermark, W. Berg, P. I. Persson, and B. Sjostrand.
1967. Pike (Esox lucius L.) and some other Aquatic Organisms
in Sweden as Indicators of Mercury Contamination of the Environment.
Oikos, 18: 323-333.
Jonasson, I. R., 1970. Mercury in the Natural Environment, A. Review
of Recent Work. Geological Survey of Canada.
Kahrs, F. R., 1968. Chronic Mercurial Poisoning in Swine. Cornell
Vet. Vol. 58:67.
-------
77
Kimura, Y. and V. L. Miller. 1964. Degradation of Phenylmercuric
Acetate to Mercury in Soils. Agri. Food Chem. Vol. 12:253-257.
Klein, D. H., 1971. Sources and Present Status of the Mercury Problem.
Abstract of Paper Presented at Workshop on Mercury in the Western
Environment, Portland, Oregon, Feb. 25-25, 1971.
Klein, D. H., and E. D. Goldberg. 1970. Mercury in the Marine
Environment. Envir. Sci. and Tech. Vol. 4 (9): 765-767.
Kolbye, A. C., 1970. Statement of Dr. Kolbye of FDA at Hearing
before the Subcommittee on Energy, Natural Resources and the
Environment of the Committee on Commerce, U. S. Senate on
the Effects of Mercury on Man and the Environment, May 8, 1970.
Kurland, L., and L. N. Firo. 1960. Minamata Disease. World Neurology
Vol. 1 (5): 320-395.
Larsson, J. E., 1970. Environmental Mercury Research in Sweden.
Swedish Environmental Protection Board Research Secretariat.
Libett, D. J., 1971. Unpublished report of Dr. Sibbett of Geomet, Inc.
Linberg, G. D., 1961. Mercury Residues on Rice Treated with Phenylmercuric
Acetate. 53rd Annual Progress Report, Rice Experiment Station,.
Crowley, la. •• •
Lofroth, Goran. 1969. Methy!mercury. Working Group on Environmental
Toxicology, Ecological Research Committee of the Swedish Natural
Science Research Council, Stockholm, Sweden. 38 pp.
Magos, L., 1967. Mercury Blood Interaction and Mercury Uptake by
the Brain After Vapor Exposure. Environmental Research 1, 323-337.
Mann, A., 1971. Mercurial Biocides: Paint's Problem Material. Paint
and Varnish Production, March 1971.
Martz, D. E., and J. Larsen. 1971. Mercury Concentrations in Human
Hair from Residents of Angwin, California. Presented at Workshop
on Mercury in the Western Environment, Portland, Oregon,
Feb. 25-26, 1971, 12 pp.
Massachusetts Department of Public Health, 1971. Mercury Levels in
Marine Life and Sediment. The New England Jour, of Medicine,
Vol. 285(18): 1031-1032.
McCarthy, J. H., J. L. Meuschke, W. H. Ficklin, and R. E. Learned.
1970. Mercury in the Atmosphere. In Mercury in the Environment,
U.S. Geological Survey, Professional Paper 713.
McKee, J. E., and Wolf, H. W. 1963. Water Quality Criteria. The
Resources Agency of California State Water Quality Control Board,
Sacremento, California, Publication No. 3-A, XIV + 547 pp.
-------
"78
Mercurial Pesticide Registration Review Panel.. 1971. A Report on
Mercury Hazards in the Environment.
National Materials Advisory Board. 1970. Trends in Usage of
Mercury, Report of the Panel on Mercury. Jour of Metals,
(May): 28-38.
New York State Department of Environmental Conservation. 1971.
Letter from Mr. Alfred Rhim of Division of Air Pollution
control.
Noren, K., and G. Westoo. 1970. Methylmercury in Fish. Fisheries
Board of Canada, Translation Series No. 135. From: Var Foda
(Our Food), (2): 13-19, 1967 9 pp.
Ordones, J. V. Carillo,. J. A. Meranda, C. M. and J. L. Gale. 1966.
Epidemeolgic Study of an Illness in the Guatemala Highlands
though to be Encephalitis. Pol of San Pan 60:18.
Pennington, J. W., 1959. Mercury A Materials Survey. Bureau of -
Mines Information Circular 7941, IX + 91 pp.
Pierce, A. P., J. M. Botbol and R. E. Learned. 1970. Mercury
Content of Rocks, Soils, and Stream Sediments in Mercury in the
Environment. U. S. Geological Survey Professional Paper 713.
Porter, D. H., and J. D. Watts. 1971. Economic Aspects of Converting
a Chloralkali Plant from Mercury Cells to Diaphragm Cells.
Presented at the AIChE. National Meeting, Houston, Texas,
March 3, 1971.
Purdy, R. W., 1970. Statement of Mr. Purdy, Executive Secretary,
Michigan Water Resources Commission before the Subcommittee
on Energy, Natural Resources and the Environment of the Committee
on Commerce, U.S. Senate on the Effects of Mercury on Man and the
Environment, May 8, 1970.
Ramel, E., 1969. Methylmercury as a Mitosis Disturbing Agent.
Japan Medical Association Journal, 61.
Report of an International Committee. 1969. Maximum Allowable
Concentrations of Mercury Compounds. Arch. Environ. Health
19:891-905.
Ross, R. G. and K. K. R. Stewart. 1962. Movement and Accumulation
of Mercury in Apple Trees and Soil. Canadian Jour. Plant Sci.,
Vol. 42: 280-285.
-------
79
Ruch, R. R., H. J. Bluskoter and E. J. Kennedy. 1971. Mercury
Content of Illinois Coals. Environmental Geology Notes., Illinois
State Geological Survey, No. 43.
Shacklettle, H., J. G. Boerngen and R. L. Turner. 1971. Mercury
in the Environment - Surficial Materials of the Conterminous
United States. Geological Survey Circular 644.
Skerfving S., K. Hasson and J. Lindsten. 1970. Chromosome Breakage
in Humans Exposed to Methylmercury through Fish Comsumption.
Arch. Environ. Health 21:153-139.
Smart, fl. A., 1968. Use and Residues of Mercury Compounds in Agriculture
Pesticide Reviews, 23:1-36.
Smith, R. G., A. J. Vorwald, L. S. Path, and T. F. Mooney, Jr. 1970.
Effects of Exposure to Mercury in the Manufacture of Chlorine.
American Industrial Hygiene Association Journal, Nov.-Dec. 1970.
Spear, R. C., E. Wei. 1971. Methylmercury Toxicity: A Probabilistic
Assessment. Presented at Workshop on Mercury in the Western
Environment, Feb. 26, 1971, Portland, Oregon.
Stahl, Q. R., 1969. Preliminary Air Pollution Survey of Mercury and
its Compounds, A Literature Review. U.S. Dept. of Health and
Welfare, Public Health Service, National Air Pollution Control
Administration.
Stephan, D. G. 1971. Trip Report-Finland and Sweden, Feb. 21-25,
1971. Assistant Commissioner, Research and Development,
Water Quality Office, Environmental Protection Agency.
Study Group on Mercury Hazards. 1970. Hazards of Mercury. Special
Report to the Secretary's Pesticide Advisory Committee, Dept.
of Health, Education, and Welfare and Environmental Protection
Agency.
Takeuchi, T. 1970. Biological Reactions and Pathological Changes of
Human Beings and Animals under the Conditions of Organic
Mercury Contamination. Presented at International Conference
on Environmental Mercury Contamination in Ann Arbor, Michigan,
Sept. 30-Oct. 2, 1970.
Tejning, S. 1967. Translation Series Mo. 1362. Fisheries Research
Board of Canada, 1970.
-------
'SO
Tejning S. 1967a. Mercury Control in the Blood System, Blood Plasma
and in Heavy Fish Eaters from Different Regions and the Connections
between Mercury Content in Fish together with a Proposal on
International Food Hygienic Limits on Mercury Applicable to Fish
and Fish Products. Report 670731, Clinic of Occupational Medicine,
Univ. Hosp. Jund, Sweden.
Til lander, M., Miettinen, J. K., and Koivisto, I. 1970. Excretion
Rate of Methyl Mercury in the Seal (Pusa hispida). Presented at
FAO Technical Conf. on Marine Pollution and its Effect on Living
Resources and Fishing, Rome, Dec. 1970.
Tonomura K., K. Maeda and F. Futal. 1968. Studies on the Action of
Mercury-Resistant Microorganism on Mercurials (ii) the Vaporization
of Mercurials Stimulated by Mercury-resistant Bacterium. Jour, of
Fermentation Technology, Vol. 46(9): 635-692.
Tomomura K., K. Maeda, F. Futal, T. Nakagami and M. Yamada. 1963.
Stimulative Vaporization of Phenylmercuric Acetate by Mercury-
Resistant Bacteria. Nature, Vol. 217 (5129):644-646.
Tomomura K., T. Nakagami, F. Futal and K. Maeda. 1968. Studies on
the Action of Mercury-Resistant Microorganisms on Mercurials
(1) The Isolation of Mercury-Resistant Bacterium and the Binding
of Mercurials to the Cells. Jour of Fermentation Technology
Vol. 46(6): 506-512.
Trukayama, K. 1966. The Pollution of Minamata Bay and Minamata Disease.
Adv. Water Pollution Research, Proc. Int. conf., 3rd Vol:3 153-180.
Ukleles R. 1962. Growth of Pure Cultures of Marine Phytoplankton in
the Presence of Toxicants. Appl. Microbial. 10: 532-537.
U.S. Geological Survey. 1970. Mercury in the Environment. Professional
Paper 713.
Vaughn, W.W. 1976. A Simple Mercury Vapor Detector for Geochemical
Prospecting. U.S. Geological Survey Circ. 540.
Vermeer, K. 1971. A Survey of Mercury Residues in Aquatic Bird Eggs
in the Canadian Prairie Provinces, Presented at 36th N. Amer.
Wildlife and Natural Resources Conference, Portland, Oreg,
March 7-10, 1971.
Wallace, R.A., W. Fulkerson, W.D. Sholts and W.S. Lyon. 1971.
Mercury in the Environment The Human Element. Oak Ridge
National Laboratory.
-------
'81
Warren, H.V., R.E. Delavult and J. Barakso. 1966. Some Observations .
on the Geochemistry of Mercury as Applied to Prospecting. Econ.
Geol. Vol. 61: 1010-1028.
Weiss, H. V., M. Koide and E. D. Goldberg, 1971.
Mercury in a Greenland Ice Sheet: Evidence of Recent Input
by Man. Science, Vol. 174: 692-174.
Wershaw, R.L. 1971. Sources and Behavior of Mercury in Surface
Waters. In Mercury in the Environment, U.S. Geological Survey
Professional Paper 713.
West, J.M. 1971. Mercury. In 1969 Bureau of Mines Minerals
Yearbook, ppl-11.
Westoo, G. 1969. Methylmercury Compounds in Animal Foods. In
Chemical Pallet, Charles C. Thomas, Springfield, Illinois, 75093.
White, D.E., M.E. Hinkle and 1. Barnes. 1971. Mercury Contents
of Natural Thermal and Mineral Fluids. In Mercury in the
Environmental, U.S. Geological Survey Professional Paper 713.
Williston, S.H. 1968. Mercury in the Atmosphere. Journal of Geophysical
Research, Vol. 73(22): 7051-7055.
Wisconsin, State of, 1971. Public Intervenor's Report on Mercury
Air Pollution.
Wood, J.M., F.S.Kennedy and C.C. Vosen. 1968. Synthesis of
Methylmercury Compounds by Extracts of a Methanogenic Bacteriuim.
Nature, 220 (5173): 174-174.
World Health Organization. 1967. Pesticide Residues in Food.
Technical Report Mo. 370.
------- |