&EPA
United States
Environmental Protection
Agency
Environmental Monitoring
and Support Laboratory
P.O. Box 15027
Las Vegas NV 89114
EPA-600 4-78-051
August 1978
Research and Development
Environmental
Monitoring Series
Mercury, Lead,
Arsenic, and Cadmium
in Biological Tissue
The Need For Adequate
Standard Reference
Materials
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been grouped into nine series. These nine broad categories
were established to facilitate further development and application of environmental
technology. Elimination of traditional grouping was consciously planned to foster
technology transfer and a maximum interface in related fields. The nine series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
6. Scientific and Technical Assessment Reports (STAR)
7. Interagency Energy-Environment Research and Development
8. "Special" Reports
9. Miscellaneous Reports
This report has been assigned to the ENVIRONMENTAL MONITORING series.This series
describes research conducted to develop new or improved methods and instrumentation
for the identification and quantification of environmental pollutants at the lowest
conceivably significant concentrations. It also includes studies to determine the ambient
concentrations of pollutants in the environment arid/or the variance of pollutants as a
function of time or meteorological factors.
This document is available to the public through the National Technical Information
Service, Springfield, Virginia 22161
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EPA-600/4-78-051
August 1978
MERCURY, LEAD, ARSENIC, AND CADMIUM
IN BIOLOGICAL TISSUE
The Need For Adequate Standard
Reference Materials
by
Werner F. Beckert
Monitoring Systems Research and Development Division
Environmental Monitoring and Support Laboratory
Las Vegas, Nevada 89114
U.S. ENVIRONMENTAL PROTECTION AGENCY
OFFICE OF RESEARCH AND DEVELOPMENT
ENVIRONMENTAL MONITORING AND SUPPORT LABORATORY
LAS VEGAS, NEVADA 89114
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DISCLAIMER
This report has been reviewed by the Environmental Monitoring and
Support Laboratory, Las Vegas, U.S. Environmental Protection Agency, and
approved for publication. Mention of trade names or commercial products
does not constitute endorsement or recommendation for use.
ii
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FOREWORD
«
Protection of the environment requires effective regulatory actions
which are based on sound technical and scientific information. This informa-
tion must include the quantitative description and linking of pollutant
sources, transport mechanisms, interactions, and resulting effects on man
and his environment. Because of the complexities involved, assessment of
specific pollutants in the environment requires a total systems approach
which transcends the media of air, water, and land. The Environmental
Monitoring and Support Laboratory-Las Vegas contributes to the formation and
enhancement of a sound monitoring data base for exposure assessment through
programs designed to:
• develop and optimize systems and strategies for monitoring
pollutants and their impact on the environment
• demonstrate new monitoring systems and technologies by
applying them to fulfill special monitoring needs of the
Agency's operating programs
A prerequisite for the generation of reliable analytical data is a
sound quality assurance program which in turn depends to a large degree on
the skillful use and the availability of appropriate reference materials.
This report reviews the present scarcity of standard reference materials
consisting of biological tissues and the need for the preparation of additional
materials. A cross section of published data is presented demonstrating the
wide concentration ranges of mercury, lead, arsenic and cadmium encountered
in biological samples. The parameters of importance are identified for the
cost—effective preparation of biological reference materials containing
elevated levels of toxic elements. This information will be of value to
everybody involved in analyzing biological tissues for toxic elements. For
further information, the Quality Assurance Branch, Monitoring Systems Research
and Development Division, should be contacted.
'
/
George B. Morgan
Director
Environmental Monitoring and Support Laboratory
Las Vegas
iii
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ABSTRACT
The present situation of standard reference materials consisting of
plant and animal tissues is examined. A brief literature review presents a
cross section of published data on the incorporation of mercury, lead,
arsenic and cadmium into plant and animal tissues. It points out the wide
concentration ranges of these elements that are encountered in biological
tissue samples under environmental and experimental conditions. These
concentration ranges are compared with the individual values of the corres-
ponding elements as determined for the biological standard reference materials
presently available from the National Bureau of Standards.
The conclusion is reached that there is a need for the preparation of
additional biological reference materials encompassing wide concentration
ranges of the elements of interest. The parameters of importance for the
cost-effective preparation of biological tissue reference materials are
discussed. Some plant and animal species are identified which could advan-
tageously be used to prepare this kind of reference material. In an appendix,
the concentrations of mercury in plant and animal tissue samples, as presented
in the literature, are listed.
iv
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CONTENTS
Foreword lii
Abstract lv
Acknowledgement vi
Introduction 1
The Standard Reference Material Situation 3
Mercury, Lead, Arsenic, and Cadmium in Plant Tissue 6
Mercury 6
Lead 7
Arsenic 8
Cadmium 10
Considerations for the Preparation of Plant Tissue SRM's ... 12
Mercury, Lead, Arsenic, and Cadmium in Animal Tissue 15
Mercury 15
Lead 18
Arsenic 21
Cadmium 23
Considerations for the Preparation of Animal Tissue SRM's ... 26
References 28
Appendix A:
Mercury Content of Selected Plant and Animal Tissues 44
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ACKNOWLEDGEMENT
Permission by Dr. C. C. Patterson, California Institute of Technology,
to include data from an as yet unpublished report is gratefully acknowledged.
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INTRODUCTION
In the years ahead, increasing amounts of toxic stable and radioactive
pollutants will be introduced into the environment. A major part of this
increase will come from the combustion and conversion of fossil fuels,
including oil shale, and from relatively new energy sources such as nuclear
and geothermal. In addition, waste disposal via incineration will contribute
significant amounts of pollutants such as cadmium and zinc.
In order to determine the patterns and the extent of environmental
pollution, pollutant levels in a variety of environmental matrices must be
monitored. Valid laboratory analyses and associated quality assurance proce-
dures attendant to the monitoring of pollutants depend on the availability
and the use of standard reference materials.
Standard reference materials (SRM's) are generally materials which have
been certified for one or more (physical or chemical) parameters. Examples
are alloys, ores, radioactivity standards, polymers and biological tissues.
The major uses of SRM's are as control materials (to be analyzed periodically
along with unknown samples), as bases for the calibration of instruments, and
as materials for technique and instrument development and evaluation.
Additional uses of SRM's are in methods standardization and equivalency
determinations, cross-check programs, and laboratory performance evaluations.
There is an important limitation to the use of SRM's, which is particularly
true for-biological material. It has been found that, for certain constituents,
the matrices* of materials analyzed can influence the validity of the analy-
tical results (Zief and Mitchell, 1976). Therefore, to minimize the occurrence
of matrix effects, both the SRM's used to produce the calibration curves and
the samples to be analyzed must have similar matrices to assure that the
instrument responses are similar for the interferences from the matrix (Cali
et al., 1975). This is of utmost importance since the analytical data must
be scientifically acceptable and legally defensible.
There is presently a scarcity of adequately characterized biological
SRM's that contain pollutants of current interest at varying levels. In this
report the present SRM situation with respect to biological tissues is discussed.
A cross-section of published data demonstrating the wide concentration ranges
* Matrix in this context means the combination of chemical composition and
physical structure of the sample material.
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of mercury, lead, arsenic and cadmium encountered in biological tissues is
presented, and the parameters of importance for the cost-effective preparation of
biological SRM's containing elevated levels of mercury, lead, arsenic, and
cadmium are identified.
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THE STANDARD REFERENCE MATERIAL SITUATION
The National Bureau of Standards (NBS), the world's leading producer of
SRM's, has approximately 900 SRM's presently available (National Bureau of
Standards, 1975a, 1975b) with approximately another 100 in preparation.
Because of the rapidly increasing demand, the NBS can only partially fulfill
the requests for new SRM's (Cali et al., 1975).
The NBS has recognized the need for biological SRM's which are certified
for in vivo incorporated elements and has started a program for their production
which began several years ago. The biological SRM's presently available from
the NBS include the following:
SRM 1569 - Brewers Yeast, certified for chromium;
SRM 1570 - Trace Elements in Spinach, certified for 16 elements;
SRM 1571 - Orchard Leaves, certified for 19 elements;
SRM 1573 - Tomato Leaves, certified for 14 elements;
SRM 1575 - Pine Needles, certified for 15 elements;
SRM 1577 - Bovine Liver, certified for 12 elements.
Biological SRM's presently under preparation or consideration by the
NBS include wheat flour, rice flour, and oyster meal. All of the SRM's listed
above contain environmental levels of the certified elements (National Bureau
of Standards, 1975b). Table 1 reports the certified values of these SRM's
for mercury, lead, arsenic, and cadmium. The preparation of the plant tissue
SRM1 s involved handpicking the plant material, removing the stems and other
undesirable parts, and freeze-drying, grinding, sieving, blending, sterilizing
(with radiation), and analyzing the material (Taylor, 1976).
The preparation and certification of SRM's are time-consuming and
expensive (Cali et al., 1975), because SRM's must satisfy a number of impor-
tant requirements. Solid SRM's to be used for chemical analyses must be of a
small particle size because there is usually no guarantee that the starting
material is microuniform. A high degree of uniformity is required to keep
the minimum reproducible sample size as small as possible (the NBS usually
specifies the minimum sample size which will still guarantee reproducible
results). Certified SRM's must be stable for extended periods of time under
the proper storage conditions. The material must be analyzed and certified
by at least two independent methods. In order to exclude errors caused by
matrix effects, the matrix of a SRM should ideally be similar to the matrix
of the sample to be analyzed with the constituents of interest incorporated
in an identical manner in both the SRM and the sample. Furthermore, because
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TABLE 1. CERTIFIED VALUES FOR MERCURY, LEAD, ARSENIC AND CADMIUM IN SRM's
OFFERED BY THE NBS (yg/g)
Hg Pb As Cd
Orchard Leaves
Tomato Leaves
Spinach
Pine Needles
Bovine Liver
0.155
(0.1)
0.030
0.15
0.016
452
6.3
1.2
10.8
0.34
142
0.27
0.15
0.21
(0.055)
0.11
(3)3
(1.5)3
(<0.5)3
0.27
Values in parentheses are not certified but are given by the NBS for
information only.
2
The lead and arsenic values in the orchard leaves are relatively high
because of past applications of lead- and arsenic-containing pesticides
to the orchard.
3
Cadmium was not sufficiently homogeneous for certification.
one-point calibration may be unreliable and extrapolation may result in
erroneous conclusions, calibration curves should be prepared using two or
more SRM' s containing different levels of the element or elements in question
to closely bracket the unknown value for interpolation from the calibration
curve.
With increasing emphasis on the use of biological monitors, an increasing
number of environmental samples will consist of various plant or animal
tissues. This, in turn, will require the availability of a larger variety of
biological SRM1s so that the influence of matrix effects on analytical data
can be minimized.
To meet the requirement for varying quantities of given pollutants in
the reference material, it is practical to select a single or a few plant and
animal species into which the desired pollutants can be systemically incor-
porated. In order to minimize the cost per sample unit, it is further desir-
able to prepare and certify as large a batch of material at one time as is
feasible. In addition, it would be very expensive to prepare a series of
biological SRM's for each pollutant which differ only in concentration.
Therefore, the exploration of alternate approaches is justified.
A program has been initiated at EMSL-LV to prepare biological SRM's
containing a variety of in vivo incorporated pollutants. These SRM's will
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be useful in the analysis of biological samples obtained by monitoring activities
in the vicinity of fossil fuel extraction and utilization plants, geothermal
sites, etc. The first set of pollutants to be incorporated under this program
into plant and animal tissue consists of mercury, lead, arsenic, and cadmium
which are of particular interest and ever-growing concern. The measurement
methodology for these elements is fairly well established, but there is
presently only a small number of biological reference materials available.
Other pollutants of present and future concern to the Agency will be incorpor-
ated into plant and animal tissue at a later date and processed to form SEM's.
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MERCURY, LEAD, ARSENIC, AND CADMIUM IN PLANT TISSUE
The chemical analysis of plant tissue usually does not indicate whether
the elements found have been taken up by the plant and have become incorpo-
rated into the plant tissue, or whether they have merely been deposited on
the plant surface as a result of air pollution (Shaklette, 1970). Yet, this
distinction is of interest because materials that have been deposited on
aerial plant parts often consist of oxides or other relatively insoluble
chemical compounds. But elements that have been incorporated into plant
tissue allegedly exhibit a higher biological availability. It is also proba-
ble that the volatility of incorporated substances is in many instances
different from that of surface-deposited substances. This is an important
consideration which will directly affect the stability and shelflife of
SRM's.
Many different species of plants have been investigated to determine the
uptake and incorporation of mercury, lead, arsenic, cadmium and many other
pollutants into their tissue, as evidenced by numerous original and review
articles. It would be redundant to list and discuss all of them; however,
examples of data on the uptake of mercury by plants are listed in Appendix A,
Tables 1 through 8. These data have been obtained from analyses of plant
tissues grown under a variety of environmental and experimental conditions,
and their ranges should be indicative of the mercury levels which might be
expected for environmental samples collected from the clean to the highly
polluted areas. Additional uptake data for mercury as well as lead, arsenic,
and cadmium will be discussed in the following pages.
MERCURY
Mercury enters the environment through natural weathering processes and
through a number of man-related activities. It has been said that natural
weathering processes and man-caused processes contribute approximately
equally to the global mercury contamination (Klein, 1972). However, mercury
entering the environment via natural processes usually results in low concen-
trations over wide areas whereas mercury as a contaminant enters the environ-
ment in few locations but at high discharge rates and concentrations. Mercury
uses which result in significant losses to the environment are in the chloralkali
industry, in the electrical apparatus and industrial control instrument
industries, in general laboratories using mercury, in the paint industry and,
at least in the past, in mercury-containing pesticides (D'ltri, 1972a). Some
of these uses and the resulting losses to the environment have been sharply
curtailed during the last few years. Other important environmental mercury
sources are the combustion of fossil fuels and smelter emissions and effluents.
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Discharges of volatile mercury into the environment can be deposited on
aerial plant parts or in soil and can eventually enter plants via the root
system. Translocation of mercury occurs within plants. Lindberg (1961) has
shown that foliar application of phenylmercuric acetate to rice plants resulted
in the translocation of mercury to the grain, and Smart (1968) showed that
mercury was translocated to fruits, tubers, and seeds after foliar application
of mercury fungicides. D'ltri (1972b), in his review summarizing data on
mercury translocation in plants, reported that translocation occurred for
apples, potatoes, tomatoes, grains, and other crop plants.
Foliar absorption can be an important entryway for mercury into plants
even when the mercury compounds have been applied only to the soil or, in the
case of aquatic plants and hydroponic cultures, to the water. A variety of
inorganic and organic mercury compounds can be reduced in an aquatic or
terrestrial environment to the metallic or even the methylated state (Tonomura
et al., 1968; Wood et al., 1968; Beckert et al., 1974). These volatile forms
of mercury can easily evaporate from the soil and water surfaces and at least
be partially deposited on nearby plant surfaces, thus becoming available for
foliar absorption. Obviously, because of these reduction and methylation
processes, the roots of edaphic and aquatic plants are exposed not only to
the chemical form of mercury as applied to the soil or water but also to
methylmercury and elemental mercury, and possibly other chemical forms.
LEAD
Lead is of high environmental priority because it is being continuously
introduced into the environment in large amounts. The most important source
of environmental lead pollution is automotive exhaust which comprises the
combustion products of automobile fuels containing lead compounds for pre-
ignition prevention (according to Hall (1972), approximately 20 percent of
the U.S. total consumption of lead in 1969 was used for gasoline additive
production). During the combustion process, most of the organic lead is
converted to inorganic compounds and is emitted as hydroxide, halide, and
oxide, together with smaller amounts of carbonate and sulfate (Habibi, 1970;
Ter Haar and Bayard, 1971). An important source of lead (as well as arsenic)
to the environment was the application of lead arsenate as an insecticide.
This use has now been largely discontinued. However, in certain agricultural
areas, large amounts of lead arsenate have been added to the soil over several
decades, and both accumulated lead and arsenic will present a problem for
some time. Further lead sources of environmental concern are inorganic
fertilizers containing lead as impurities. Lead deposition from fertilizers
may even account for the high lead levels in certain agricultural soils
(Schuck and Locke, 1970) which have been reported to range up to 200 ppm
(Swaine and Mitchell, 1960). Smelter emissions and sewage sludge, as well as
lead-based paint pigments and storage batteries, also contribute to lead
pollution.
Plants can absorb and translocate lead. This fact has been considered
for lead prospecting^(Cannon 1960, 1971). Root uptake is an important pathway
of lead uptake in plants in the field as has been demonstrated by a number of
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researchers (for additional references see Zimdahl and Arvik, 1973). Ter
Haar et al. (1969), for example, found that 46 percent of the lead content of
perennial rye grass blades and all of the lead found in radish roots came
from the soil rather than from the air. Lead levels in the edible parts of
crop plants are usually well below 1 ppm (Schuck and Locke, 1970) and are
lower than those of the other vegetative plant parts (Aarkrog and Lippert,
1971). For a variety of plants, an average lead content of 10 ppm (dry
weight) was reported with a high of 45 ppm in potato tops (Warren and Delavault,
1962). Gamble (1963) reported that the leaves of various plant species in
wooded areas contained from less than 0.3 ppm to as much as 30 ppm (dry
weight) of lead, and Prince (1957) found 10-25 ppm (dry weight) in corn
leaves.
Aerial contamination, however, occurs to some extent in almost all cases
and becomes the dominating factor especially in areas close to heavily traveled
highways or to smelters (Zimdahl and Arvik, 1973). Hay contains normally
2 to 3 ppm (dry weight) of lead, but in areas near smelters values up to
284 ppm (dry weight) have been determined (Hammond and Aronson, 1964). In
one study it was shown that 40-50 percent of the total lead associated with
plants could be removed by one washing with distilled water, whereas two washings
removed between 60 and 70 percent (Page et al., 1971).
Only three years ago it was believed that the methylation of inorganic
and organic forms of lead could not occur in the environment (Wood, 1974).
Recently, however, methylation of lead has been shown to occur but under
conditions which are unlikely to make it a problem similar to the methylation
of mercury (Wong et al., 1975).
ARSENIC
Arsenic is suspected of being carcinogenic to humans and being related
to arteriosclerosis and chronic liver diseases (Hueper, 1963; Wagner, 1973).
There still remains some doubt as to these allegations, but the potential
hazard to man makes it necessary to monitor the distribution and the fate of
arsenic in the environment.
Arsenic is ubiquitous in nature, with concentrations in uncontaminated
soils ranging from 0.2 to 40 ppm (Olson et al., 1940) with an average of
about 5 to 6 ppm. It is concentrated in a variety of minerals including many
sulfides and phosphates; coal reportedly can contain up to 2000 ppm (Onishi,
1969; Bowen, 1966; Boyle and Jonasson, 1973). Large amounts of arsenic can
be distributed over areas adjacent to facilities engaged in processing arsenic-
containing ores so that arsenic levels can be reached that are directly
injurious to humans (Oyanguren and Perez, 1966; Birmingham et al., 1965).
Inorganic and organic arsenicals are still being used as pesticides; extensive
applications in the past gave rise to very high arsenic levels in some soils,
especially those in orchards. The burning of coal constitutes another major
source of arsenic. It was reported that fly ash from a coal-burning power
plant contained as much as 139 ppm of arsenic (Furr et al., 1976a).
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-t
Arsenic emission to the environment was reduced considerably during
recent years, mainly by abatement procedures applied to industrial sources of
arsenic. Probably the most important factor was the replacement of arsenical
pesticides, especially sodium arsenite, which was banned (Fed. Reg., 1968)
and lead arsenate which was largely replaced by organic pesticides.
Arsenic compounds can be methylated leading to a number of very toxic
compounds (Wood, 1974), but it is unlikely that these transformations will
pose a serious problem in the environment.
The literature on arsenic uptake by plants is much less voluminous than
that on mercury or lead. Plants vary in their tolerance, and in a few instances,
very high levels of arsenic have been reported for certain plants. Warren et
al. (1968) reported 10,000 ppm in the ash of Douglas Fir needles which would
correspond to a value of nearly 1,000 ppm on a dry weight basis. Even higher
values were reported for native vegetation collected from arsenic-enriched
sites (mine wastes), namely 6,640 ppm (dry weight) for Jasione montana L. and
4,130 ppm (dry weight) for Calluna Vulgaris CL. ) Hull (Porter and Peterson,
1975). Fortunately, however, the edible parts of plants usually do not
accumulate hazardous levels of arsenic and contain considerably less than the
permissible limit of 2.6 ppm (U.S. Dept. of Agric., Pestic. Reg. Div., 1968).
Furr et al. (1976a) found 0.2 ppm of arsenic (dry weight) in the edible parts
of beans, cabbage and carrots, and lower values in a number of other vegetables
when grown on fly-ash-amended soil with an average arsenic content of 16 ppm.
Steevens et al. (1972) grew potatoes in fields where the potato vine defoliant
sodium arsenite had been used extensively in the past. The soil contained
2.7 to 25.7 ppm of arsenic while from the harvested potatoes the tuber peeling
contained 0.2 to 2.6 ppm (dry weight) and the tuber flesh only up to 0.6 ppm
(dry weight). Chisholm (1972) conducted similar experiments with vegetables
grown in soil which had been heavily treated with lead arsenate and contained,
at the time of the experiment, 122.5 ppm of arsenic. None of the arsenic
levels which he reported were above 1.1 ppm (dry weight) in the edible parts
of the plants. This is in line with older observations by McLean et al.
(1944) who reported that vegetables grown on soils treated with high levels
of lead arsenate seldom contained more than 1 ppm of arsenic in the edible
parts.
The surface of aerial portions of plants may be contaminated with
resuspended material when soils nearby had been treated with substantial
quantities of arsenic. Jones and Hatch (1945) found 3.1 ppm of arsenic in
the aerial growth of vegetable plants which were growing in untreated soil
adjacent to arsenic-treated fields whereas the roots of the plants from the
untreated soil contained only 1.1 ppm of arsenic. Obviously, the aerial
portions must have been contaminated by arsenic-containing dust particles
since roots usually accumulate more arsenic than the aerial plant parts.
Some of the data in the literature on plant uptake of arsenic might therefore
be questionable unless the plant tissues were washed carefully prior to
analysis to remove adsorbed soil particles.
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CADMIUM
Cadmium is of concern as an environmental pollutant mainly because of
its relatively high toxicity to animals and humans. The kidneys are the
critical organ with respect to prolonged low-level exposure to cadmium
(Friberg et al., 1973). An association seems to exist between cadmium
exposure and the incidence of cancer in man (Friberg et al., 1971). In
animal experiments, cadmium salt injections resulted in malignant tumors.
Cadmium has also been shown to be teratogenic in animals (Friberg et al.,
1973; Mulvihill et al., 1970; Chernoff, 1973), as well as mutagenic (Doyle et
al., 1974; Shiraishi and Yosida, 1972); however, the mechanism is unknown.
Cadmium is closely related chemically to zinc and is always found in
zinc ores. While zinc is an essential trace element in living cells, cadmium
is very toxic. Cadmium is also contained as an impurity in phosphate rock
with concentrations ranging as high as 100 ppm (Williams and David, 1976), in
coal from 0.02 to 10 ppm (Hiatt and Huff, 1975) with values as high as 28 ppm
(Gluskoter and Lindahl, 1973), and from 0.42 to 0.53 ppm in heating oil
(Hiatt and Huff, 1975).
Most of the commercially produced cadmium is recovered as a by-product
during the refining of zinc and other metals. The principal uses are in
electroplating, which accounts for approximately 50 percent of the total
cadmium production, as a component of stabilizers for plastics, in pigments
and alloys, and in cadmium batteries.
The recycling of cadmium is difficult, if not impossible, for most of
the cadmium-containing products; therefore, the amount of cadmium released to
the environment from the disposal of these products is an important considera-
tion. Other factors in environmental cadmium pollution are the use of phos-
phate fertilizers, the combustion of fossil fuels, and the processing of many
metal ores, especially those of zinc, lead, and copper which contain small
amounts of cadmium. A source of growing concern is sewage sludge which
reportedly has cadmium levels as high as 200 ppm (Furr et al., 1976b), and
geothermal sites, a largely unknown factor in environmental pollution.
Airborne and waterborne cadmium as well as fertilizer and sewage sludge
can substantially increase cadmium concentrations in soil. Plants take up
cadmium via roots and foliage, but little is known about the uptake mechanism.
In experiments with culture solutions containing cadmium chloride, it was
found that the cadmium concentrations were always greater in the roots than
in the shoots. It was concluded that the roots can take up large quantities
of cadmium from culture solutions, but that there are apparently mechanisms
which restrict the movement of cadmium through plants (Jarvis et al., 1976).
As much as 14.95 yg/g of cadmium were reported for corn plants (excluding
roots) which were grown on soil amended with cadmium sulfate to a level of
5.0 ugCd/g soil (Street et al., 1977). Similar accumulations were reported
by John et al. (1972), who studied cadmium uptake by radish and lettuce plants
grown on a variety of soils amended with cadmium chloride to a level of
100 ppm. They found that the edible portions of the radishes and lettuce
harvested from 30 different soils averaged 387 ppm and 138 ppm (dry weight),
10
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respectively, and concluded that potentially hazardous accumulations of
cadmium in plant tissues may occur when soils are contaminated.
Williams and David (1976) reported that fertilizer impurities had
increased the original levels of hydrochloric acid-soluble cadmium by more
than an order of magnitude in several soils and that this resulted in most
cases in considerable increases in the cadmium content of plants grown on
such soil. Furr et al. (1976a) in their study on the effects of fly-ash
amendments to soils on the uptake of certain elements by vegetable plants
reported that the cadmium content of the plant tissues did not increase. The
plant values of cadmium on a dry weight basis from the control and amended
soils containing 0.1 ppm and 0.14 ppm of cadmium, respectively, were as
follows (reported in ppm): beans 0.1/0.1, cabbage 0.2/0.2, carrots 1.1/0.6,
millet 0.2/0.2, onions 0.6/0.4, potatoes 0.4/0.2 and tomatoes 0.1/0.1. The
results are not surprising when one considers that there was only a slightly
higher cadmium level in the amended soil. These authors reported in another
study (Furr et al., 1976c) that the same vegetable plants took up high amounts
of cadmium from soil amended with 10 percent of municipal sludge containing
112 ppm cadmium. For the control soil with <0.9 ppm and the amended soil
with 11.3 ppm cadmium, the plant values of cadmium on a dry weight basis were
as follows (in ppm): beans 0.1/1.8, cabbage 0.2/37.5, carrots 1.1/3.9,
millet 0.2/24.5, onions 0.6/9.2, potatoes 0.3/2.0, and tomatoes 0.1/2.4.
Mushrooms can accumulate relatively high amounts of cadmium from soil.
Stijve and Besson (1976) reported that Agar-Lcns edul'ls grown on soil contain-
ing 0.16 ppm cadmium contained 2.1-7.5 ppm cadmium (dry weight) which corre-
sponds to a concentration factor of 13 to 47- Other mushrooms of the same
genus which were collected from various areas in Europe and analyzed by these
investigators contained from 0.1 to 75 ppm cadmium.
Aerial contamination was shown to occur by Little (1973) who analyzed
elm leaves collected in an area with heavy cadmium fallout. He reported that
more than 60 percent of the total cadmium in the elm leaves could be removed
by washing with deionized water, and more than 98 percent with 1 percent
HN03.
Methylation of cadmium will not be a problem as cadmium alkyIs hydrolyze
under environmental conditions.
11
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CONSIDERATIONS FOR THE PREPARATION OF PLANT TISSUE SRM's
The concentrations of toxic elements in plant material which will be
encountered by the analyst comprise a wide range, from low levels in samples
from certain pristine areas to very high levels in plants grown in highly
contaminated or experimentally enriched soils. Figure 1 shows graphically
the concentration ranges of mercury, lead, arsenic and cadmium in plant
tissues, as discussed in this report. Included are, for comparison, the
concentrations of the same elements in the plant tissue SRM's available from
the NBS.
Cd—
As—
Pb-
Hg-
ppb
0.1
I I I I I I I I T
1 10 100 1000 10« 105 106 107 108
The marks denote certified values in SRMs from the NBS:
* Orchard leaves
*Pine needles
• Tomato leaves
• Spinach
Figure 1. Ranges of mercury, lead, arsenic, and cadmium levels
as reported in the literature for plant tissues.
It is apparent that especially .for mercury and arsenic, concentration
ranges extending over several orders of magnitude are not covered by SRM's.
In order to fill these gaps, a series of SRM's with varying pollutant concen-
trations must be prepared. It seems that the most cost-effective way of
achieving this would be to prepare batches of highly contaminated and uncontam-
inated (except for background levels) plant tissue of the same kind and,
after separate processing, blend them to the desired pollutant concentrations.
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A plant species suitable for cost-effective in vivo incorporation of
pollutants and processing to form a SRM should fulfill certain requirements.
It should tolerate and incorporate as many of the projected pollutants as
possible because the experience gained during early studies may directly
apply to the incorporation of additional pollutants into the same kind of
plant. The plant should grow fast because large quantities of fresh plant
tissue will be needed to prepare enough material to justify the certification
cost. Harvesting should preferably be a continuous operation because of the
logistics involved in picking and processing of the plant material. In order
to obtain a homogeneous SRM, a uniform starting material is necessary. Large
leaves with few veins would therefore make a suitable starting material since
only the stems and large veins will have to be removed. It must be possible
to easily monitor and eventually modify the pollutant levels in the growth
medium; this makes the use of hydroponic culture techniques almost imperative.
Obviously, a plant species is required which grows well and is easy to handle
in large quantities under these production conditions.
The above criteria eliminate the vast majority of plants from considera-
tion as suitable matrices for SRM's containing in vivo incorporated pollutants.
Algae and other submerged plants or plant parts may adsorb rather than incorpo-
rate the pollutants. Certain fungi accumulate heavy metals and other pollutants,
but their growing conditions are uncertain and are, in general, not sufficiently
defined. Mosses are slow growers, and it would be difficult to avoid cross-
contamination from spiked growth media. Tree leaves have been used as a SRM,
but picking and processing were found to be extremely labor-intensive processes.
Fruit, grain, and plant parts such as tubers and roots are not representative
of the plant tissue likely to be encountered in future monitoring activities.
Some of the plants often used in research, such as alfalfa, peas, and barley,
are impractical since extensive manual labor is necessary to isolate the
usable leaf parts.
Plants which meet many of the above requirements are leafy vegetables
such as cabbage, lettuce and spinach. These can be grown under controlled
conditions with the planting staggered for continuous harvesting. Even more
promising are leafy water plants such as water hyacinths that are self-
propagating, require very little care, and produce leaves which are relatively
easy to process since only the major veins must be removed.
The water hyacinth (Eichhornia opassipes) is basically an undesirable
aquatic weed which thrives in water bodies of tropical and subtropical
regions. Its growth aspects have been well documented, and the interest in
water hyacinths is evidenced by the number of articles published in the Hya-
cinth Control Journal, a research publication which is devoted exclusively to
aquatic weed research. The prolific growth of water hyacinths in water
bodies is only limited by the availability of nitrogen and phosphorus (Wahlquist,
1972). Their growth rate under optimum conditions is high. Boyd (1976)
reported from a series of experiments an average growth rate of 194 kg/ha/day
over a 5-month period; however, values as high as 540 kg/ha/day have been
reported for growth in a eutrophic lake (Yount and Grossman, 1970).
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A number of uses for water hyacinths have been recently considered. To
reduce the nutrient levels of water bodies the cultivation of water hyacinths
followed by their periodic removal has been proposed for eutrophic lakes
which have high concentrations of nitrogen and phosphorus (Boyd, 1976). The
potential of water hyacinths for the removal of pollutants from sewage was
investigated by Wolverton and McDonald (1975a), and Wooten and Dodd (1976).
The recovered plant material could possibly be used as animal feed (Hentges
et al., 1972; Wooten and Dodd, 1976) or it could be used for the production
of methane (Wolverton et al., 1975).
The growth of water hyacinths under laboratory and field conditions in
the presence of a variety of pollutants has been studied by Woxverton and his
group (for references see Wolverton and McDonald, 1975a)- They found that
mercury, lead, cadmium and several other metals, as well as phenols and cer-
tain pesticides, were efficiently removed from solution. Approximately
10 percent of the removed metals were transported to the aerial parts of the
plants (Wolverton and McDonald, 1976).
Water hyacinths are easy to grow in hydroponic solution. Their large
leaves, which are above the water surface, could be harvested periodically and
processed to form a uniform powder that is suitable as a SRM. These and
other advantages mentioned earlier make water hyacinths grown under hydroponic
culture conditions a very desirable plant species for the in vivo incorpora-
tion of toxic elements into plant tissues. Time and additional studies will
show if one kind of plant tissue SRM which contains pollutant levels above
ambient will be sufficient for future analytical tasks, or if a variety of
plant tissue SRM's will have to be developed.
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MERCURY, LEAD, ARSENIC, AND CADMIUM IN ANIMAL TISSUE
Standard reference materials consisting of animal tissues containing
in vivo incorporated toxicants are needed for a variety of tasks. It was
pointed out earlier that the use of biological receptors as investigative
tools is increasing in environmental pollution monitoring studies. As a
consequence, an increased number of tissue samples from indigenous and
domestic animals must be collected and analyzed for a variety of pollutants.
In addition, tissue samples from domestic animals raised in highly polluted
areas, such as the vicinity of smelters or heavily traveled highways, which
may have excessive amounts of toxic elements incorporated into their tissues
will have to be analyzed.
A variety of different organ tissues is desirable as SRM's since in
many routine cases only one kind of tissue might be obtained, because it is
either easily accessible or is part of a target organ for a particular pollutant.
Examples of target organs or tissues which are frequently sampled for analysis
are liver, kidneys, blood, and muscle. Some of these tissues, such as blood,
might even be routinely used to screen humans. A special case is hair, a
metabolic end product that can be painlessly collected and easily handled,
stored, and analyzed. Hair can be considered as a minor organ for the elimina-
tion of certain elements. Although its use in monitoring exposure to and
accumulation of toxic elements is still controversial, it might become feasible
in special problem areas.
Animals take up varying amounts of toxic elements with their food and
with air, as well as by licking and grooming, soil ingestion, and other
activities. Usually only a relatively small percentage of the ingested toxic
elements is incorporated into the animal body organs while the remainder is
excreted. The amount retained depends on the animal, its age and health, the
feed, the chemical forms of the toxic elements, and other factors. Different
tissues accumulate different levels of the toxicants; these levels are dependent
on the nature of the toxic elements and, in some cases, on their chemical
form and the mode of entry.
MERCURY
Essentially all animal tissues contain low levels of mercury. A large
number of epidemiological studies have been carried out, and vast amounts of
data have been published on the mercury content of various animal tissues.
It was found that, in general, animals higher up in the food chain accumulate
comparatively higher amounts of mercury. Tables 9 through 12 list a cross
section of data on mercury levels reported for fish, birds, and mammals from
15
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a variety of studies; these values illustrate the range which might be
encountered in future experimental and monitoring studies.
The rates of absorption, distribution, excretion, and toxicity of
mercury in animals can be influenced drastically by the chemical form of the
applied mercury. Experiments with mice showed that only about one percent of
ingested inorganic mercuric compounds but up to 98 percent of methylmercury
were absorbed via gastrointestinal tract (Hartung and Dinman, 1972). It has
been discussed that inorganic mercury might be converted to organic mercury
in man by the intestinal flora or by biochemical processes, but no methyl-
mercury has been detected thus far in mammals following ingestion of inorganic
mercury (Hartung and Dinman, 1972). Organomercurials are generally more
likely than inorganic mercurials to cause genetic, teratogenic, and carcinogenic
effects. Phenyl- and methylmercury are 200 times more effective as c-mitotic
agents than inorganic mercurials and 1000 times more effective than colchicine,
the classic inducer of c-mitosis (D'ltri, 1972a). Treatment of human leucocytes
in culture with 1 to 2.0 * 10 6 M methylmercuric chloride solution resulted
in c-mitosis (D'ltri 1972b). Results of animal experiments indicated that
organic mercury compounds directly affect either the genetic material, causing
chromosome breakage (Ramel, 1969), or meiosis (Ramel, 1967; Ramel and Magnusson,
1969), and even produce mutagenic (Ramel, 1969) or teratogenic effects (WHO, 1966)
or sarcomas (Druckery et al., 1957).
The mercury content of fish has been of major concern since Canada
announced in March of 1974 that 12,000 Ibs of commercially caught walleye
from Lake St. Clair were to be destroyed because of mercury contamination.
This triggered a chain reaction of fishing closures and restrictions in North
America and marked the beginning of the "mercury scare" for the United States.
The mercury in fish muscle is present primarily as methylmercury, thus
making it a serious hazard to man. The methylmercury levels depend, as
expected, on the mercury concentration of the water. Predatory fish such as
tuna and swordfish have generally higher levels. For mercuric chloride in
water, the lethal concentrations for fish range from 0.02 ppm for guppy to
9.2 ppm for rainbow trout (U.S. Environmental Protection Agency, 1973).
However, even in heavily polluted bodies of water, the mercury concentration
is usually not high enough to be lethal to fish. Mercury levels reported for
freshwater fish vary from 0.08 ppm for brown trout (Byrne et al., 1971) to
27.8 ppm for northern pike (Fimreite and Reynolds, 1973). For marine fish
the values ranged from 0.02 ± 0.01 ppm for sardines (average of 104 FDA
analyses, reported by Simpson et al., 1974) to 14.0 ppm for Pacific blue
marlin (Rivers et al., 1972). Fish and shellfish from the highly polluted
Minamata area contained 9-24 ppm of mercury (Holden, 1973).
The mercury levels found in birds reflect their dietary habits. As
expected, birds eating fish from polluted water, or grain and seeds from
agricultural areas where mercury-containing pesticides have been used, contain
higher mercury levels than birds living in areas of low mercury concentra-
tions. This is documented in a paper by Spronk and Hartog (1970) who reported
that mercury levels in flight feathers of goshawks and buzzards in the Nether-
lands varied from 26 to 72 ppm and 2 to 23 ppm, respectively. The high
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levels in the feathers of-4zhe goshawk were related to their diet, one third
of which was seed-eating pigeons, whereas buzzards prey mainly on sprout- and
root-eating mice. Martin and Nickerson (1973) found that starlings which
were collected in the United States from 50 sites had mercury levels below
0.50 ppm with 76 percent of the birds containing 0.05 ppm or less. Kreitzer
(1974) sampled mourning doves in the Eastern United States and found that the
breast muscles of 93 percent of the birds contained less than 0.05 ppm of
mercury. Analyses of different bird organs generally showed mercury concentra-
tions decreasing in the order of liver-kidney-muscle-brain (Westermark, 1967;
Stoewsand et al., 1971). Gardiner et al. (1971) found in chickens which were
fed 203Hg-methylmercuric dicyandiamide that the radioactive isotope was
concentrated in the liver and kidneys.
The mercury levels in mammalian tissues vary widely (Appendix A, Table 12)
and reflect to a great extent the dietary habits of the animals. In areas of
mercury contamination the levels of mercury increase upward with the food
chain which makes predators quite suitable for environmental monitoring
purposes. As a food source for man, wild mammals are only of very minor
importance in the United States.
The mercury intake by domestic animals can be largely controlled via
their feed, and their mercury levels should normally be around background
levels. The isolated incidents reported of humans being poisoned through the
consumption of mercury-containing meats resulted from accidents or ignorance.
Such a tragic case happened in New Mexico and resulted in death or blindness
to members of a family that had consumed the meat of hogs which were fed
waste seed grain treated with the fungicide methyImercurie dicyandiamide
(Curley et al., 1971).
The distribution of mercury in mammalian tissue depends on a number of
factors such as route of entry and chemical form of the mercury compound,
dietary content of certain other elements like selenium (Ganther et al.,
1972), and age of the animal. Experimental studies with mercury-203 showed
that the mercury level was higher in liver and kidney than in other tissues
for a variety of mammals including cows, calves and goats, and that the level
was independent of the chemical form or the route of dose administration
(Ansari et al., 1973; Friberg and Vostal, 1972; Potter et al., 1972; Sell and
Davison, 1973; Stake et al., 1975). However, the relative distribution among
the tissues may vary with the chemical form used and the route of entry. In
calf muscle, the ratio of methylmercury to mercuric chloride was 594 when the
compounds were administered orally, and only 6 when introduced intravenously
(Ansari et al., 1973; Stake et al., 1975).
It has been claimed that hair analysis is a good technique for monitoring
mercury levels in the human population (Hartung and Dinman, 1972). Hair has
been used in recent studies as an index of mercury exposure for fish consumers
in Ontario (Jervis et al., 1970), and Takeuchi (1972) quoted a Japanese
publication which reported that a close relationship existed between mercury
concentration in hair and the onset of the Minamata disease. Eads and Lambdin
(1973) determined mercury and six other elements in selected human hair
samples from an area with refineries and petrochemical plants. A wide range
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in content for both males and females was observed for mercury, lead, and
zinc. The average mercury concentration was found to be 5.4 ppm for males
and 5.5 ppm for females.
Before hair samples can be used as a reliable exposure monitor for
mercury, several important parameters must be more clearly defined. The
reliability of removal of surface contamination, and the establishment of a
hair-blood ratio relationship are particularly important.
LEAD
Lead contamination is more widespread than mercury contamination, but
fewer spectacular cases of acute poisoning or contamination have been reported.
The presence of lead in the environment must nevertheless be monitored primarily
for its persistence and its long-term effects. Lead is present in all animals,
and as for all heavy elements, animals higher up in the food chain accumulate
higher amounts of lead in their bodies. Organic lead compounds are generally
more toxic than inorganic ones (but the difference is not as pronounced as in
mercury compounds). This higher toxicity seems to be important because of
the addition of organic lead compounds to gasoline. However, less than
10 percent of the organic lead compounds added to gasoline are emitted in the
exhaust as the organic form (Bryce-Smith and Waldron, 1974).
Most freshwater fish contain at least about 0.5 ppm of lead, with
values reported as high as 16.0 ppm in green sunfish (.Lepomis ayane'ilus')
(Illinois, 1972). No spectacular lead values or events involving lead in
fish have been reported. However, freshwater fish might possibly be of use
as biological monitors. Saltwater fish contain on the average less lead than
do freshwater fish; reported values range from lows around 0.1 ppm (Vinogradov,
1953; Stapleton, 1968) to highs of several ppm. Examples are Atlantic cod
(Gadus moTfhua) which contains (based on dry weight) 1-2 ppm in muscle, and
3.0 ppm in liver, and sand dab (Fieuponectes timanda) containing 14.0 ppm in
muscle (Stenner and Nickless, 1974).
A recent detailed study of lead contamination of tuna (albacore -
Thunnus alalunga) has revealed some interesting facts. Patterson (1977) and
his coworkers sampled and analyzed albacore under ultra-clean laboratory
conditions to avoid secondary contamination. Using the highly sensitive
analytical method of stable isotopic dilution they were able to show that
albacore muscle contained only 0.0003 ppm of lead, while commercially processed
and canned tuna, analyzed by the same group, contained 0.007 ppm of lead for
samples taken from non-soldered cans and 1.6 ppm for samples taken from
soldered cans. Similarly, whole anchovies removed from albacore stomach
contained 0.021 ppm of lead whereas commercially processed anchovies taken
from soldered cans contained 4.2 ppm. The author uses these data to demonstrate
the extent of lead contamination of food during processing and to emphasize
that present lead levels in the biosphere are already several orders of
magnitude higher than they were before man-caused lead pollution started.
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The lead content of' birds covers a wide range. Of specific concern is
waterfowl which ingest dispersed lead shot. It has been estimated (Stickel,
1969) that over 1 million geese, ducks and swans die per year due to lead
shot poisoning. Lead values reported for waterfowl liver tissue range from
0.4 to 1.5 ppm (wet weight) in ducks (Bagley and Locke, 1967) to 45 ppm for
mallards in Sweden (Erne and Borg, 1969). Similarly, lead values based on
wet weight vary for muscle from 2.2 to 55.8 ppm in mallards (Benson et al.,
1974), for bone from 2 to 19 ppm in American scoter (Bagley and Locke, 1967),
and for kidney from 4 to 99 ppm for mallards and up-to 350 ppm for swans
(Erne and Borg, 1969).
The lead values found in the tissues of terrestrial birds are, in general,
lower although some high values have been reported. In ring-necked pheasant,
lead in liver and kidney ranged from 0.09 to 0.84 ppm and 0.11 to 0.27 ppm
(wet weight), respectively, while for a dying pheasant the values amounted to
169 ppm for the liver and 42 ppm for the muscle (Natl. Acad. Sci., 1972).
Lead values determined for tissues of birds of prey do not differ much from
their prey. Liver values for horned owl, bald eagle and osprey ranged from
0.6 to 2.8 ppm (wet) (Benson et al., 1974; Bagley and Locke, 1967) and
17.4 ppm (wet) for prairie falcon; bone values were from 1.5 ppm for osprey
up to 36.0 ppm (wet) for falcon (Benson et al., 1974; Bagley and Locke,
1967).
Lead levels in mammals generally reflect their dietary habits and,
naturally, the degree of environmental contamination. The influence of the
traffic patterns from nearby highways on the lead content of various rodents
was determined in a study conducted in Illinois (Illinois, 1974). It was
found that for short-tailed shrews, least shrews, and prairie voles the
relative lead values were approximately 4:2:1 for heavy, medium and low
traffic areas. The values for heavy traffic areas ranged from 8.2 ppm (dry
weight) for voles to 15.2 ppm (dry weight) for short-tailed shrews. In mice,
white-footed mice, and deer mice, the influence of the traffic conditions was
less pronounced.
Lead poisoning is one of the most frequently reported causes of poisoning
in farm animals. Of major concern is the acute form of lead poisoning. It
has been discussed earlier that translocation of lead from soil to plants
does take place, and there is the possibility of lead entering the feed from
soil. However, the bulk of the lead contamination of feed seems to result
from deposition of particulates on plant surfaces.
Ruminants are more often affected by lead poisoning (Ammerman et al.,
1973) than horses, poultry and swine (Blood and Henderson, 1968). The
susceptibility of individual animals depends on the type of lead compound
(mainly if inorganic or organic), kind of animal, age, health, etc. As
little as. 6 mg lead/kg of body weight given daily over 60 days has been fatal
for cattle (Hammond and Aronson, 1964). Approximately 0.2 to 0.4 g/kg body
weight of lead on any one day, ingested as acetate, basic carbonate or oxide
caused death in calves up to 4 months of age (Allcroft, 1951). Older cattle
can tolerate twice this dose (Buck, 1970). Marshall et al. (1963), in their
studies on lead transfer to bovine milk, fed lactating cows up to 13 mg of
lead/kg body weight for 126 days, apparently without serious effects. Adult
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sheep survived single doses of up to 0.6 g/kg while abortions and death
occurred at these levels with pregnant ewes (Allcroft and Blaxter, 1950).
Ewes receiving up to 4.5 mg lead/kg as finely divided metallic lead for
27 weeks including 22 weeks of gestation, showed no signs of clinical lead
poisoning (Carson et al., 1973). Horses grazing near lead smelters may also
be subject to lead poisoning because, in addition to the aerial plant parts,
they ingest the roots and the adhering lead-contaminated soil particles, both
often containing much more lead than the plant tops (Schmitt et al., 1971).
Lead distribution in mammalian tissue depends on the chemical form of
the lead ingested, the animal species and the administrative route (Natl.
Acad. Sci.. 1972; Blaxter, 1950a, 1950b). Lead absorbed from the gut goes
mainly to bone and kidney while injected lead goes to bone marrow, spleen and
liver. Apparently orally ingested lead is primarily deposited in the skeleton
until the threshold value is attained and then it is deposited in other
tissues, particularly the kidneys (Cantarow and Trumper, 1944; Natl. Acad.
Sci. 1972). Schroeder and Balassa (1961a) reported lead content in cow
muscles (wet weight) of 0.20 ppm, with 0.67 and 0.51 ppm present in liver and
kidney, respectively. Allcroft (1950) found up to 126.0 and 297.0 ppm of
lead in the kidney and liver, respectively, from cows that had ingested lead-
containing materials. In sheep muscle 0.15 ppm (wet weight) of lead was
found, and values reported for pigs were 0.16 ppm for muscle, 0.26-0.82 ppm
for liver and 0.26-0.98 ppm for kidney (Schroeder and Balassa, 1961a).
Horses that ate contaminated grass near a smelter had lead concentrations
(controls in parentheses) in kidney of 40.4 (3.1) ppm, liver 12.0 (9.0) ppm
and lung 1.6 (1.3) ppm (Goodman and Roberts, 1971). In experimental studies
it was demonstrated that lead in guinea pigs crossed the placental barrier.
The maternal femur of guinea pigs fed a diet containing 2,000 ppm of lead
contained 626 ppm of lead while the fetal femur contained 5700 ppm (Illinois,
1974).
The determination of lead in hair and teeth has received special attention
in recent years as a possible screening method for lead accumulation in
animals and humans. Kopito and Shwachman (1975) investigated the accumulation
of lead in human scalp hair in male and female children and adults from
various locations in several countries. They concluded that the most signifi-
cant variables which influenced the concentration of lead in hair were ingestion
of lead-containing substances, exposure to lead of environmental origin,
place of residence, location of sample along the hair shaft relative to its
distance from the scalp, and age. Hair clippings have also been used to test
300 animals for lead (Bazell, 1971). A major problem in the use of hair
samples for determining lead exposure is the tendency of hair to accumulate
surface lead from the atmosphere. This and other uncertainties mentioned
earlier require that more work be done before hair can be used as a reliable
screening and monitoring tool for lead. Altshuler et al. (1962) analyzed
deciduous teeth from children who died from lead poisoning, teeth from lead-
poisoned but surviving children, and shed teeth from control children. The
mean levels found were 160 ppm for fatal cases, 116 ppm for poisoned but
surviving children, and 15 ppm for the control children. Needleman et al.
(1972) analyzed deciduous teeth of children who lived in the "Lead Belt" of
urban Philadelphia and from Philadelphia suburbs, and found that the lead
content of the teeth of the former was 51.1 ± 109.0 ppm and 11.1 ± 14.8 ppm
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for the suburban controls. The authors claim that deciduous teeth can be
used to identify past exposure, as a possible means to measure hidden deficits
caused by lead ingestion. Wilkinson and Palmer (1975) found in a study that
the amount of lead contained in human teeth increased at a fairly uniform
rate with age up to about 50 years at which time a sharp increase was noted.
Human teeth collected from people living in a rural area in Delaware showed a
lower accumulation of lead than teeth collected from people living in the
inner city area of Baltimore. The above results appear encouraging but more
research is required before teeth can be used as a reliable monitoring means
for lead exposure.
ARSENIC
Arsenic is ubiquitous in the environment. The most important man-
related sources of arsenic pollution are smelters which emit arsenic compounds
from their stacks, and the use of arsenic compounds as pesticides and herbicides.
The latter practice has been largely discontinued but very high arsenic
levels in the soil have accumulated in areas of earlier high applications of
arsenic pesticides (Woolson et al., 1971).
Plants can take up arsenic from soil but there appears to be little
danger of poisoning to the animals which consume these plants; however,
animals grazing on plants contaminated externally by arsenic trioxide have
died (Haywood, 1907). Also, injuries to humans living in communities exposed
to industrial arsenic contamination have been reported (Oyanguren and Perez,
1966; Birmingham et al., 1965). Perhaps the most important aspect of concern
with arsenic in the environment is the potential carcinogenicity of arsenical
compounds to humans.
Freshwater concentrations of arsenic are usually in the ppb range,
but values in the ppm range have been reported (EPA, 1976). Arsenic concen-
trations reported for freshwater fish are usually below 1 ppm (wet weight)
with 0.09 ppm reported for freshwater drum fish (Pillay et al., 1974), 0.52 ppm
for bluegills (Gilderhus, 1966), 0.069-0.149 ppm for trout (Pratt et al.,
1972), 0.055-0.51 ppm for carp (Ellis et al., 1941; Pratt et al., 1972) and
0.8 ppm for pike (Chapmann, 1926). Values as high as 2.75 ppm have been
reported for small-mouthed buffalo fish and up to 77.31 ppm for the liver oil
of the large-mouth black bass (Ellis et al., 1941).
Seawater contains several ppm of arsenic (EPA, 1976). The arsenic
content of marine fish is generally higher than that of freshwater fish.
Arsenic values (based on wet weight) for anchovies ranged from 7.1 to 10.7 ppm
(Lunde, 1973), for tuna from 0.71 to 4.6 ppm (Cardiff, 1937; Orvini et al.,
1974); sole contained 5.2 ppm (Chapman, 1926) and herring fillet 3.8 ppm
(Lunde, 1970). Lunde (1970) analyzed extracts of fish muscle and found that
the aqueous fraction contained most of the arsenic. His reported values
ranged from 0.9 ppm (based on dry weight) of arsenic for whale extract to
37 ppm for cod liver extract. A standard reference material which is avail-
able from the International Atomic Energy Agency ("Fish Solubles A-6, 1974")
is certified for 14.5 -ppm of arsenic.
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Some marine organisms tend to accumulate arsenic. Schrenk and Schreiheis
(1958) reported arsenic values of 3-10 ppm for oysters, 70 ppm for lobster,
up to 120 ppm for mussels, and 170 ppm for prawns. The same authors note
that the arsenic content of urine in humans is generally higher following the
consumption of seafood.
Relatively few data are available on the arsenic content of wild birds.
Andren et al. (1973) reported arsenic levels, based on dry weight, of 0.05 ppm
for owl, 0.1 ppm for crow, 0.2 ppm for sparrow, and 0.4 ppm for hawk. Domestic
birds, mainly chicken, can be fed growth-promoting drugs which contain arsenic,
so that maximum permissible levels of arsenic have been established for
poultry which are 0.5 mg/kg for fresh, uncooked muscle, and 2.0 mg/kg for
fresh, uncooked by-products (Woolson, 1975). Obviously, the levels found in
usable poultry tissue must be lower than the maximum permissible amount.
However, since there is an increasing interest in the use of dried poultry
excreta as cattle feed supplement, the levels of the arsenic contents of
poultry wastes as well as the effect of arsenic on ruminants are of special
interest. The FDA has not granted approval of the use of arsenicals in the
feed for ruminants.
Andren et al. (.1973) determined arsenic levels, based on dry tissue
weight, for wild mammals. They reported 0.2 ppm of arsenic for opossum,
0.8 ppm for squirrel and fox, and 1.0 ppm for mice. Arsenic values reported
for domestic mammal tissue include 0.063 ppm for beef liver (Orvini et al.,
1974), 0.22-0.32 ppm for swine muscle (Barela and Pezzeri, 1966; Pezzeri,
1970), and 0.52 for calf muscle (Pezzeri, 1970). Swine can be fed growth-
promoting arsenic-containing drugs; studies have shown that the bulk of the
ingested arsenicals was rapidly eliminated, once administration of the drugs
was stopped (Woolson, 1975).
In a number of studies, the distribution of arsenic in animals has been
investigated using radioisotopes of arsenic. It was found that in most
animals arsenic was present in all tissues, with the highest accumulation in
the muscles (EPA, 1976). Only in rats was arsenic concentrated in the red
blood cells, which makes rats rather undesirable as a model for studies with
arsenic (Hunter et al., 1942; Ducoff et al., 1948; Lanz et al., 1950).
Arsenic concentrations in washed hair ranged from 1 to 5.5 ppm (Perkons
and Jervis, 1966; Dubois et al., 1965). The question of whether the arsenic
content of hair is indicative of previous arsenic ingestion received widespread
publicity when the hair of Napoleon was analyzed via neutron activation and
was found to contain arsenic. It was determined that there was a good correla-
tion between the distribution of arsenic along the length of the hair shaft
and the ups and downs of Napoleon's health (Forshufvud et al., 1961; Smith et
al., 1962; Forshufvud et al., 1964). Arsenic is transferred to animal and
human hair, but it must be remembered that external contamination of hair by
atmospheric dust can readily occur. Dubois et al. (1965) found arsenic
values in hair of up to 243 ppm, but after washing the hair in detergent, all
values were reduced to 3.0 ± 1.0 ppm. Contrary to this it was also reported
that arsenic in the environment reacts with the keratin of the hair and
cannot be removed by repeated washings (Lerner, 1954). When hair from cases
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of arsenic poisoning was examined, a concentration of 3.0 to 26.0 ppm was
found shortly after arsenic exposure (Lander et al. , 1965). The concentra-
tions near the hair tips were often similar to those near the scalp, a fact
which the authors attributed to arsenic-deposition from sweat. It is obvious
that a number of problems need to be addressed before hair can be used to
monitor the previous arsenic exposure of individuals.
CADMIUM
The cadmium accumulation and distribution in animal tissue have been
investigated to a lesser extent than those of mercury, lead and arsenic.
Cadmium is an accumulative poison, and its long-term biological effects are
not well understood (Hiatt and Huff, 1975). However, cadmium is suspected of
being carcinogenic to man as well as teratogenic and mutagenic, as has been
stated earlier. This fact combined with the fairly wide distribution of
cadmium makes it necessary to monitor its concentration levels in the environ-
ment.
In nature, cadmium is usually associated with zinc. Zinc and cadmium
are known to be antagonistic to each other in humans (Bunn and Matrone, 1966;
Underwood, 1971); however, the protective action of zinc does not reduce
absorption of cadmium and its transfer to tissues. Some of the toxic effects
of cadmium can be reduced by selenium, cobalt, and certain sulfur compounds
CFlick et al., 1971; Friberg et al., 1971).
The cadmium levels reported for freshwater fish tissue are generally
low. Values ranged from less than 0.01 ppm (wet weight) for carp and white
bass to 0.142 ppm for goldfish collected from the Hudson River (Lovett et
al., 1972) and 0.14 ± 0.06 ppm for trout-perch (Lucas et al., 1970). Values
as high as 23 ppm were reported for brook trout (Lovett et al., 1972).
Cadmium levels in freshwater fish livers are somewhat higher, ranging for
lake trout liver from a low of 0.06 ± 0.02 ppm to a high of 3.0 ppm (Lucas et
al., 1970). A study using bluegill showed that exposure to varying cadmium
concentrations resulted in corresponding similar cadmium variations in the
fish tissue (mg Cd/1 vs ppm Cd in tissue): 0.008 vs 0.03, 0.08 vs 0.1, and
0.85 vs 1.1 (Cearley and Coleman, 1974). A value of 1300 ppm* (dry weight)
of cadmium was reported for channel catfish exposed to sub-lethal amounts of
cadmium (Mount and Stephan, 1967). Saltwater fish contain levels of cadmium
similar to freshwater fish. Herring, sea trout and haddock muscle contained
0.06 ppm, 0.01 to 0.015 ppm, and 0.003 to 0.014 ppm (wet weight), respectively
(Havre et al., 1973), whereas sand eel, swordfish and lanternfish contained,
on a dry weight basis, 0.4 ppm, 0.9 ppm, and 1.6 ppm, respectively (Stevens
and Brown, 1974; Gibbs et al., 1974). Again, cadmium accumulates in the fish
liver: angler and whiting contained 0.023 ppm and 0.003 to 0.032 ppm of
cadmium in .the muscle, but 2.5 ppm and 0.17 ppm, respectively, in the liver
(Havre et al., 1973).
* It has been cautioned (Friberg et al., 1971) that certain salts, especially
sodium chloride, can"interfere with the cadmium determination via atomic
absorption spectrophotometry.
23
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Few values have been reported for the cadmium content of bird tissue.
Martin and Nickerson (1973) analyzed starlings and found that in 46 areas of
the United States the cadmium concentrations in starling muscle were below
0.1 ppm (wet weight) with most cases even below 0.005 ppm. Only in certain
city areas did the cadmium level go as high as 0.24 ppm. Liver and kidney
concentrations are generally considerably higher than corresponding muscle
values. Ruffed grouse liver contained, on a wet weight basis, 0.88 to 2.04 ppm
of cadmium (Schroeder et al., 1967; Schroeder and Balassa, 1961b), and pheasant,
starling and robin liver contained 0.9 ppm, 0.57 ppm, and 0.55 ppm, respectively
(Schroeder and Balassa, 1961b). Starling and robin kidneys contained 1.0 ppm
and 2.03 ppm, respectively (Schroeder and Balassa, 196Ib).
Cadmium absorption from the GI tract in mammals is low. Rats, mice and
monkeys absorb approximately 2 to 3 percent of ingested cadmium while humans
seem to absorb nearly 6 percent (Friberg et al., 1971; Friberg and Vostal,
1972). In experiments with goats it was found that the percentage of dietary
radioactive cadmium which was absorbed and retained was the same even when
the dose was increased about 400-fold (Miller et al., 1969). However, many
of the cadmium absorption data reported in the literature are derived from
the difference between intake and fecal excretion. Obviously when this
difference is small, there is room for large errors (Miller, 1975).
The quantity of dietary cadmium which is toxic to mammals depends on
such variables as animal species, dose, and method of administration (Ammerman
et al., 1973; Friberg et al., 1971; Underwood, 1971). Four calves which
received 2,560 ppm of dietary cadmium died after 2, 3, 5 and 8 weeks (Powell et
al., 1964). Other calves survived 640 ppm of cadmium in the feed. In rats,
500 ppm of cadmium was lethal (Wilson et al., 1941). The highest cadmium
concentrations are usually found in the kidney, followed by the liver. When
radioactive cadmium was administered to goats, 50 percent of the total body
burden was found in the liver and 23 percent in the kidneys (Miller et al.,
1969). Under similar conditions, lactating cows accumulated 32 percent in
the liver and 10 percent in the kidneys (Neathery et al., 1974).
The administration route has a profound influence on the relative
distribution in the tissue. This was demonstrated by Miller and his associates
(1968) who administered radioactive cadmium to young goats and found that
two weeks after oral administration, the cadmium concentration in the muscle
was 7.4 percent of that in the liver while 2 weeks after an intravenous dose,
the muscle tissue contained only 0.4 percent of that in the liver. In general,
dietary cadmium seems to preferentially accumulate in the kidney, and intrave-
nously administered cadmium concentrates in the liver.
Cadmium levels in blood and muscle tissue are low, independent of the
mode of administration (Neathery and Miller, 1975). Thus, muscle, the most
important tissue for human consumption, is well protected from ingested
cadmium.
Some values for cadmium levels in the liver and kidney of wild land
mammals have been published. Schroeder et al. (1967) found 0.36 ppm (wet
weight) in coyote liver and 0.73 ppm (wet weight) in red squirrel liver, and
Schroeder and Balassa (1961b) reported 0.3 ppm for rabbit liver. Published
kidney values are generally higher. Schroeder et al. (1967) reported 2.07 ppm
24
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of cadmium for deer kidney, and Schroeder and Balassa (1961b) found 3.62 ppm
in gray squirrel kidney, 7.97-17.35 ppm in red squirrel kidney and 3.58 ppm
in rabbit kidney.
Cadmium levels in the liver and kidneys of domestic mammals are similar.
Schroeder et al. (1967) found 0.28 ppm of cadmium in cow liver and 0.52 ppm
in cow kidney. Schroeder and Balassa (1961b) reported 0 ppm which means
below the detection limit for pig liver, 0.15-0.6 ppm for pig kidney, and
0.14 for sheep kidney, Goodman and Roberts (1971) reported 1.6 ppm for horse
liver and 35.0 ppm for horse kidney, and Doyle et al. (1974) found up to
769 ppm in sheep kidney and 276 ppm in sheep liver after feeding sheep high
cadmium doses.
Small amounts of cadmium are found in hair. Hammer et al. (1971)
determined cadmium levels in the hair of fourth-grade boys in several cities
and concluded that mean hair cadmium levels reflect community exposure.
However, they cautioned that it is not fully known how well hair reflects the
body burden of the metal. The arithmetic means of cadmium content of the
boys' hair ranged from 0.8 to 2.1 ppm, depending on the city. Petering et
al. (1973) concluded from experimental studies that the cadmium content of
hair of the general population not exposed occupationally ranges between 0.5
and 2.5 ppm, regardless of sex and age above 2 years. Eads and Lambdin
(1973) analyzed human hair samples collected in an industrial city and reported
mean cadmium concentrations of 2.2 and 1.0 ppm for hair of males and females,
respectively. The latter studies support the hypothesis that age influences
the cadmium content of human hair.
25
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CONSIDERATIONS FOR THE PREPARATION OF ANIMAL TISSUE SRM's
A wide range of toxic element concentrations occur in animal tissues.
This is illustrated in Figure 2 where the ranges of mercury, lead, arsenic
and cadmium found in animal tissues, as discussed in this report, are presented.
Included are the corresponding analytical values for these elements as certified
for the Bovine Liver SRM available from the NBS.
Cd-
As-
Pb—
Hg
ppb
I I I I I I I I I
0.1 1 10 100 1000 10* 10s 10s 107 108
The •denote certified values in Bovine Liver SRM from the NBS.
Figure 2. Ranges of mercury, lead, arsenic, and cadmium levels as
reported in the literature for animal tissues.
It is obvious that a need exists to prepare a series of SRM's that vary
in the concentrations of the toxic elements under consideration to more
closely cover the concentration ranges encountered in the samples. The low
value reported for lead in albacore was determined under very special conditions
that cannot usually be achieved in analytical laboratories. Therefore, no
need exists at present to prepare SRM's that cover this extremely low lead
level. However, it should be understood that relatively high levels of lead
and other toxic elements in SRM's do not imply that these levels are environ-
mentally acceptable. Rather, these levels are essential for the usefulness
of SRM's in conjunction with contaminated samples that might even contain
toxic levels of pollutants.
It has been discussed earlier that different pollutants administered to
animals may accumulate in different target tissues. This makes it desirable
26
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to collect and process a variety of animal tissues to be used as SRM's, such
as liver, kidney, muscle, and bone. Liver and kidney concentrate a wide
variety of pollutants, bone accumulates specific pollutants such as lead, and
muscle is the most important tissue for human consumption. It is desirable
to also prepare SRM's from other animal tissues which can easily be collected
in the environment for screening and monitoring purposes. Such tissues
include blood, hair, and possibly brain, teeth, and hoof.
In order to get a relatively fast accumulation of toxicants in certain
tissues such as bone or teeth, young animals which are still in the active
growth phase should be used, with the toxicants administered over prolonged
periods of time. It has been discussed earlier that the metabolic fate and
the tissue distribution of toxicants may vary with the mode of dose applica-
tion. Since in the environment most pollutants enter the animal body via the
digestive tract, it is reasonable to apply the toxicants orally rather than
intravenously. Animals used for the in vivo incorporation of toxicants
should have at the least average resistance to the toxicants to be administered,
they should be easy to handle and maintain, and they should not be expensive.
These requirements narrow the selection to domestic or experimental
mammals. Experimental animals commonly used in laboratories, such as mice,
rats, guinea pigs and rabbits, are small in size and a large number would be
required to produce an adequate amount of processible tissue. Furthermore,
the dosing of the animals as well as cleaning the small organs following
sacrifice are cumbersome and labor-intensive and thus costly. The attractive
feature for the use of animals such as bovine or horse is their large size.
Dose administration would be relatively simple, sufficient tissue could be
recovered from just one or a few animals at the most, and tissue preparation
would pose no problem. However, because of the animals' size, facilities
would be required which might not be readily available. In addition to this,
the small number of animals needed to obtain the required amount of tissue
may become a disadvantage should an illness or injury occur among the animals
during the experiment. A compromise of sizes might be the most suitable and
cost-effective solution. Several intermediate sizes of domestic animals are
available such as sheep, goats, and large and miniature pigs. Pigs are poor
hair-growers and can pose an odor and handling problem. Goats and sheep seem
equally suitable with goats having a slight advantage, because of their
better resistance to disease, and because they grow hair instead of wool.
27
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43
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APPENDIX A:
MERCURY CONTENT OF SELECTED PLANT AND ANIMAL TISSUES
44
-------
TABLE 1. MERCURY CONTENT OF ALGAE
Species
(a)
ppm, D/W
(b)
Reference
Ascophyllwn nodoswn
Caldophora rupestris
CeTamium rubrum
Enteromorpha compressa
Fuous serratus
Fucus vesiculosus
Laminaria digi.ta.ta
Polysiphonia lanosa
Porphyra urribilicaL-ls
Ascophyllwn nodosum
Fucus vesiculosus
Ulva pertusa
Phytoplarikton, Great Lakes
0.319
0.826
3.031
1.007
1.153
D
D
D
D
D
0.083-0.206 D
0.794 D
0.612 D
2.353 D
0.05-1.2 D
0.018-0.023 W
5.3- 14.00 D
0.44 W
2.2 D
Jones et al. (1972)
it
Stenner and Nickless (1974)
Stock and Cucuel (1934)
Matida and Kumada (1969)
Copeland (1972)
(a)
(b)
As named by authors
Based on dry (D) or wet (W) weight of the plant material
45
-------
TABLE 2. MERCURY CONTENT OF FUNGI
Species
(a)
ppm, Dry Weight
Reference
Agari,eus arvensis
Boletus edulis
Clavaria sp.
Hypholoma sp.
Kuehnevomyces mutabi,1i,s
Lactcnrius sp.
Lysoperdon p&rlakwn
Polporus sp.
Russula sp.
Seleroderma vulgare
Boletus subtomentosus
Collybia butyracea
Collybia oonfluens
CoTt-incanus odorifer
Laetarius delitiosus
Lactapius sarobiculatus
Lepista nuda
Lyeopefdon gemmatum
Lyooperdon p-ir-iformi,
Mycena pura
Ramca"ia tuval-ia
Rusulla integra
Tricholoma sealpturatum
0.4 - 1.1
2.2 - 2.4
6.6 -16.4
15.5 -20.2
0.35- 0.92
80.5
32.2 -74.0
0.4
23.9 -36.0
0.01- 0.02
0.24- 4.0
1.90-62.5
3.39-73.6
1.90-19.5
0.68- 7.9
0.14- 3.0
1.50- 5.2
5.54-64.3
2.60- 5.9
4.20-44.8
0.14- 2.2
0.04- 1.8
5.6 -86.5
Stegnar et al. (1973)
Rantes (1975)
(b)
(a)
As named by authors
High values derived from samples collected within 1 km of chloralkali
plant
46
-------
TABLE 3. MERCURY CONTENT OF MOSSES
Species
(a)
ppm, Dry Weight
Reference
Fonbinal-Ls sp.
Ewchynohi-ian hians
Brachytheeium riimlare
Sharp-Leila strLate'lla
Dicranum sp.
Polytriehum
3.70
0.012-0.080
0.012-0.080
0.012-0.080
0.118
0.092
Wallace et al. (1971)
Huckabee (1973)
Huckabee and Blaylock (1973)
(a)
As named by authors
47
-------
TABLE 4. MERCURY CONTENT OF AQUATIC VASCULAR PLANTS
Species
Alligator weeds
Elodea densa
"
Soirpus oyperinus
(in .04 yg Hg/1
» H20)
Sagittaria lati folia
"
"
Water hyacinth
"
Ceratophyllwn demerswn
Elodea aanad&nesis
Water lily
Plant Part
Whole
Whole
10 ppm CH3Hg
in H20
Whole
10 ppm Hg2
in H20
Submerged stem
Root
Leaf
Stem
Root
Whole
Leaves
ppm,
149
1000
400
1.02
0.23
0.3
0.49
0.04
151
'vlS
£ 6.95
<. 9.35
0.52
D/W(b)
D (max. )
W
W
W
W
W
W
W
D
D
D
D
D
Reference
Wolverton and McDonald (1975a)
Mortimer and Kudo (1975)
ii it
Eriksson and Mortimer (1975)
ti ii
ii it
it ii
it ti
Wolverton and McDonald (1975a)
Wolverton and McDonald (1976)
Fang (1973)
it
it
(a)
(b)
As named by authors
Based on dry (D) or wet (W) weight of the plant material
-------
TABLE 5. MERCURY CONTENT OF TREE LEAVES
Species^
Sugar maple
Norway spruce
Australian pine
London plane
Pin oak
Basswood
Red cedar
Black spruce
Rosa sp.
Orchard leaves
ppm, Dry Weight
0.81
0.22
0.17
0.71
0.76
1.10
<0.5
1.0-1.5
1.3-808.0
0.155
Reference
Smith (1972)
IT
"
"
"
"
Shaklette (1970)
11
Stahl (1969)
NBS (1975)
(a)
As named by authors
49
-------
TABLE 6. MERCURY CONTENT OF FRUIT
Species (a)
Apple, red
Apple, yellow
Banana
Cherry
Grape
Lemon
Lime
Melon
Nectarine
Orange
Peach
Pear
Plum
Strawberry
ppm, Wet Weight Reference
0.007-0.025 Gerdes et al. (1974)
0.083-0.092 "
0.032-0.147 "
0.004-0.014
0.028-0.034
0.087-0.135 "
0.075-0.158
0.006-0.013 "
0.094-0.1 "
0.074-0.102
0.053-0.057
0 -0.092 "
0.047-0.282
0.043-0.053
(a)
As named by authors
50
-------
TABLE 7. MERCURY CONTENT OF VEGETABLE PLANTS
(a)
Species v '
String beans
Broccoli (head)
Cabbage (head)
Carrot (root)
Cauliflower (head)
Celery (stalks)
Cucumber (fruit)
Eggplant (fruit)
Lettuce (leaves)
Okra (pod)
Onion, white (tuber)
Pepper, green
Potato (tuber)
Radish (root)
Squash (fruit)
Sweet potato (tuber)
Tomato (fruit)
ppm, Wet Weight Reference
0.046-0.057 Gerdes et al. (1974)
0.024-0.027 "
0.027-0.123
0.004-0.006 "
0.020-0.046 "
0.007-0.023
0.002-0.019
0.045-0.048 "
0.019-0.021 "
0.057-0.097
0.033-0.049 "
0.001-0.1
0.026-0.042
0.001-0.007 "
0.001-0.005
0.019-0.036 "
0.02 -0.036
(a)
As named by authors
51
-------
TABLE 8. MERCURY CONTENT OF GRAIN CROPS
Species^ ppm, D/VT ' Reference
Barley <0.02 D Smart (1968)
" 0.03 D D'ltri (1972)
Corn 0.006-0.033 W Gerdes et al. (1974)
Rice - Japan 0.23 -1.0 D Smart (1968)
" Texas 0.08 -0.092 W Gerdes et al. (1974)
Wheat 0.008-0.012 D Smart (1968)
" 0.005-0.040 D Saha (1972)
(a)
As named by authors
Based on dry (D) or wet (W) weight of the plant material
52
-------
TABLE 9. MERCURY CONTENT OF FRESHWATER FISH
Species
(a)
Location
Tissue
ppm
(b)
Reference
Ul
U)
Rock bass
Amblop'Lites rupestris
American eel
Anguilla rostrata
White fish
Covegonus clupeaformis
Northern pike
Esox "Lucius
Bluegill
Lepomis maorookivus
Smallmouth bass
Miaropterus dolomieui
Largemouth black bass
Miavopterue salmo-Ldes
Yellow perch
Peraa flavesaens
Brown trout
Salmo fario
Rainbow trout
Salmo
Michigan
muscle
Chesapeake Bay muscle
Lake Huron edibles
Ontario muscle
E. Canada "
Michigan
edibles
New York whole fish
Utah muscle
Utah "
near cinnabar muscle
refinery
experiment
exposed to Hg blood
phosphate kidney
liver
" brain
(1.14-10.90) Fimreite and Reynolds (1973)
6.22
(0.02-0.12)0.06 Bender et al. (1972)
0.05-0.15 Rottschafer et al. (1971)
1.61-27.8 Fimreite and Reynolds (1973)
1.40 Fimreite et al. (1971)
0.40 Rottschafer et al. (1971)
0.55 Bache et al. (1971)
(0.17-7.3)1.94 Smith (1973)
(0.13-0.43)0.29
0.08-9.6
22.8
17.3
16.7
10.1
Byrne et al. (1971)
Rucker and Amend (1969)
(Continued)
-------
TABLE 9. MERCURY CONTENT OF FRESHWATER FISH (Continued)
Species
(a)
Location
Tissue
ppm
(b)
Reference
Lake trout
Salvelinus nconayoush
Walleye pike
Stizostedion vitreum
E. Canada muscle
New York whole fish
Ontario(normal) muscle
Ontario(polluted) "
1.07-10.5(5.78) Fimreite et al. (1971)
0.14-0.16 Bache et al. (1971)
0,24- 1.12
0.28-19.6
Fimreite and Reynolds (1973)
(a)
(b)
As named by authors
Based on wet tissue weight
-------
TABLE 10. MERCURY CONTENT OF MARINE FISH
Ln
Species (a)
American shad
Alosa sapidissima
Atlantic herring
Clupea harengua
Haddock
Gadus aeglefinus
Common cod
Gadus morrhua
Halibut
Hippoglossus hippoglossus
Pacific blue marlin
Makaira ampla
White perch
Morone americana
Striped bass
Morone saxatilis
Flounder
Pleuroneates flesus
Sardine
Sardinia pilahardus
Atlantic mackerel
Scomber scombrus
Location
Virginia
Atlantic
"
Sweden
Atlantic
Hawaii
Chesapeake
Bay
n
Atlantic
n
Tissue
flesh
muscle
muscle
muscle
muscle
it
muscle
liver
muscle
n
muscle
n
m(b)
0.10
0.07+0.01
0.04+0.01
0.09+0.04
0.026-0.036
0.1410.03
(0.35-14.0)4.78
(0.39-36.0)7.57
(0.02-2.0)0.1
(0.08-0.22)0.13
0.0810.03
0.0210.01
0.1210.11
Reference
Boyle (.1970)
Simpson et al.
(1974)
n
n
Westoo (1967)
Simpson et al. (1974)
Rivers et al.
(1972)
Bender et al.
(1972)
ii
Simpson et al.
(1974)
n
(Continued)
-------
TABLE 10. MERCURY CONTENT OF-MARINE FISH (Continued)
Species
Albacore tuna
Thurmus albaoova
Swordfish
Xiphias gladius
Location Tissue
(domestic) canned tuna
California muscle
(b)
ppmv
0.2510.1
0.23-1.27
Reference
Simpson et al.
(1974)
Miller et al.
(1972)
(a)
(b)
As named by authors
Based on wet tissue weight
-------
TABLE 11. MERCURY CONTENT OF BIRDS
(a)
Species
(A) Water birds:
Spotted sand piper
Aotitis maaularia
Mallard
Anas platyrhynahos
Great blue heron
Ardea herodius
Common egret
Casmerodius albus
Common eider
Somateria molHssima
(B) Birds of prey
Goshawk
Accipiter gent-ilis
Buzzard
Buteo buteo
Bald eagle
Haliaeetus leuoooephalus
Location Tissue
United States carcass
" liver
" liver
" kidney
muscle
liver
carcass
" liver
carcass
Finland liver
kidney
ii ,
muscle
Sweden liver
Norway kidney
United States carcass
" brain
(b)
Ppm
0.55
2.8
0.23- 4.8
0.1 - 3.5
0.1 - 1.15
14.6 -175.0
5.3 - 23.0
6.3
0.74
12.9
1.6
3.9
6.0 - 53.0
0.3
59.0
130.0
Reference
Dustman et al.
(1972)
ii
ii
M
II
It
II
Henriksson et al.
(1966)
M
,
Borg et al. (1966)
Holt (1969)
Mulhern et al.
(1970)
(Continued)
-------
TABLE 11. MERCURY CONTENT OF BIRDS (Continued)
Ul
oo
Species
(C) Terrestrial birds
Hooded crow
Corvus aorone
comix
"
Gambels quail
Lophovtyx gambel'i'i
Black grouse
Lyrwcus tetvix
Ring-necked pheasant
Phasianus ooldhieus
»
Starling
Stwrnus vulgaris
Location
Sweden
it
"
Arizona
ii
Norway
California
Colorado
Idaho
Idaho
Indiana
Oregon
Utah
Canada
Denmark
Finland
Sweden
Tissue
liver
kidney
muscle
brain
liver
muscle
kidney
muscle
it
ii
it
it
it
ii
liver
kidney
muscle
brain
».<"
35.0
28.0
.18.0
12.5
over 0.5
below 0.2
0.68
1.6 - 4.7
0.04 - 0.6
0 -15
0.16
0.058
to 0.5
0.01 - 2.08
0.006- 0.46
0.01
0 -13.4
2.2 -21.0
2.4 -24.3
0.6 - 5.7
1.0 - 9.2
Reference
Westermark (1967)
"
Montague (1971)
M
Holt (1969)
Benson et al. (1971)
Montague (1971)
it
Benson et al. (1971)
Montague (1971)
ti
Smith et al. (1974)
Jervis (1970)
Berg et al. (1966)
Karppanen et al. (1970)
Westermark (1967)
it
it
(a)
As named by authors
-------
TABLE 12. MERCURY CONTENT OF MAMMALS
Ul
10
Species (a)
Northern fur seal
Callovhinus uvs-inus
n
Harbor seal
ti
it
n
n
n
it
ii
Coyote
Can-is latrans
Red-backed mice
CletlwLonomys gapperi.
Amer. mink (normal diet)
Mustela visan
ii
n
n
Black bear
Uvsus ameviaanua
ti
Location
Washington
n
n
Calif.
Oregon.
Wash.
Pribilof Island
Nova Scotia
n
n
n
Wyoming
ii
United States
n
n
n
M
Idaho
M
n
Tissue
liver
kidney
muscle
liver
n
n
n
fur
liver
kidney
muscle
hair
hair
liver
kidney
muscle
spleen
brain
hair
muscle
fat
(b)
ppmv
7.1 -172.0
0.6 - 1.6
0.2 - 0.4
81.0 -700.0
0.3 - 68.0
1.3 - 60.0
0.6 - 8.9
1.8
0.99
0.67
0.55
to 0.6
to 0.6
0.28±0.06
0.6810.14
0.0510.03
0.24±0.22
0.2210.14
0.11- 0.275
0.04- 0.171
0.05- 0.12
Reference
Anas (1974)
M
n
n
M
n
ti
Freeman and
Home (1974)
M
n
Huckabee et al.
(1973)
it
Aulerich et al.
(1974)
n
M
n
Benson et al.
(1974)
II
(Continued)
-------
•vl
00
vj
00
^
to
TABLE 12. MERCURY CONTENT OF MAMMALS (Continued)
Species
(a)
Location
Tissue
Reference
a
3
i
o
Reindeer
Rangifer tarandus
Sweden
"
"
liver
kidney
muscle
0.004-0.27
0.002
0.005-0.023
Westoo (1969)
-------
TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA-600/4-78-051
2.
3. RECIPIENT'S ACCESSION NO.
4. TITLE AND SUBTITLE
MERCURY, LEAD, ARSENIC, AND CADMIUM IN BIOLOGICAL
TISSUE The Need for Adequate Standard Reference
Materials
5. REPORT DATE
August 1978
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
Werner F. Beckert
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Environmental Monitoring and Support Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Las Vegas, Nevada 89114
10. PROGRAM ELEMENT NO.
1HD621/1HD621A
11. CONTRACT/GRANT NO.
12. SPONSORING AGENCY NAME AND ADDRESS
U.S. Environmental Protection Agency - Las Vegas, NV
Office of Research and Development
Environmental Monitoring and Support Laboratory
Las Vegas, Nevada 89114
13. TYPE OF REPORT AND PERIOD COVERED
Interim Report
14. SPONSORING AGENCY CODE
EPA/600/07
15. SUPPLEMENTARY NOTES
16. ABSTRACT
The present situation of standard reference materials consisting of
plant and animal tissues is examined. A brief literature review presents a
cross-section of published data on the incorporation of mercury, lead,
arsenic and cadmium into plant and animal tissues. It points out the wide
concentration ranges of these elements that are encountered in biological
tissue samples under environmental and experimental conditions. These
concentration ranges are compared with the individual values of the corres-
ponding elements as determined for the biological standard reference materials
presently available from the National Bureau of Standards.
The conclusion is reached that there is a need for the preparation of
additional biological reference materials encompassing wide concentration
ranges of the elements of interest. The parameters of importance for the
cost-effective preparation of biological tissue reference materials are
discussed. Some plant and animal species are identified which could advan-
tageously be used to prepare this kind of reference material. In an appendix,
the concentrations of mercury in plant and animal tissue samples, as presented
in the literature, are listed.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS
COSATI Field/Group
Biological accumulation
Mercury
Lead
Arsenic
Cadmium
Quality assurance
Quality control
Standard reference materi
Biological reference mate
Biological sample analysi
Biological tissue analysi
Matrix effects
Plant tissue samples
Animal tissue samples
Is
ials
06A,C,F,H,T
07B,C
18. DISTRIBUTION STATEMENT
RELEASE TO PUBLIC
19. SECURITY CLASS (ThisReport)
UNCLASSIFIED
21. NO. OF PAGES
68
20. SECURITY CLASS (Thispage)
UNCLASSIFIED
22. PRICE
A04
EPA Form 2220-1 (Rev. 4-77) PREVIOUS EDITION is OBSOLETE
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