HANDBOOK OFCHEMICAL RISK ASSESSMENT Health Hazards to Humans, Plants, and Animals ( VOLUME 1 ) - PART 7 (end ) potx

CHAPTER

31
Selenium

31.1 INTRODUCTION

Selenium poisoning is an ancient and well-documented disease (Rosenfeld and Beath 1964).
Signs of it were reported among domestic livestock by Marco Polo in western China near the
borders of Turkestan and Tibet in about the year 1295; among livestock, chickens, and children in
Colombia, South America, by Father Pedro Simon in 1560; among human adults in Irapuato,
Mexico, in about 1764; and among horses of the U.S. Cavalry in South Dakota in 1857 and again
in 1893 (Rosenfeld and Beath 1964). In 1907/08, more than 15,000 sheep died in a region north
of Medicine Bow, Wyoming, after grazing on seleniferous plants. The incidents have continued,
and recent technical literature abounds with isolated examples of selenosis among domestic animals
and wildlife.
Selenium (Se) was first identified as an element in 1817 by the Swedish chemist Berzelius. It
is now firmly established that selenium is beneficial or essential in amounts from trace to µg/kg
(ppb) concentrations for humans and some plants and animals, but toxic at some concentrations
present in the environment (Rosenfeld and Beath 1964). Selenium deficiency was reported among
cattle grazing in the Florida Everglades, which showed evidence of anemia, slow growth, and
reduced fertility (Morris et al. 1984). Selenium deficiency has been demonstrated in Atlantic salmon,

Salmo



salar

(Lorentzen et al. 1994), in various species of deer in Florida and Washington (Hein

et al. 1994; McDowell et al. 1995), and in free-ranging ungulates in Washington state, including
moose (

Alces



alces

) and bighorn sheep (

Ovis



canadensis

) (Hein et al. 1994). Conversely, calves of
Indian buffaloes died of selenium poisoning after eating rice husks grown in naturally seleniferous
soils (Prasad et al. 1982). Adverse effects of excess selenium are reported on reproduction of cattle,
monkeys, sheep, swine, rats, and hamsters, including fetal and maternal death, and a dramatic
increase in developmental abnormalities (Domingo 1994). Severe reproductive and developmental
abnormalities were observed in aquatic birds nesting at selenium-contaminated irrigation drainwater
ponds in the San Joaquin Valley, California (Ohlendorf et al. 1986, 1986a, 1987, 1989, 1990;
Hoffman et al. 1988; Schuler et al. 1990; Besser et al. 1993; Lemly 1996b). Accumulation of more
than 8 mg Se/kg dry weight in fish gonads is the probable cause of reduced reproduction and
subsequent species disappearances in Belews Lake, North Carolina, and the endangered razorback
sucker (

Xyrauchen

texanus

) from the Green River, Utah, in 1991 (Cumbie and Van Horn 1978;
Hamilton and Waddell 1994; Waddell and May 1995).
Selenium has been the subject of many reviews (Rosenfeld and Beath 1964; Frost 1972;
Sandholm 1973; Zingaro and Cooper 1974; Frost and Ingvoldstad 1975; Anonymous 1975; National
Academy of Sciences [NAS] 1976; Harr 1978; U.S. Environmental Protection Agency [USEPA]
1980, 1987; Lo and Sandi 1980; Shamberger 1981; Wilber 1980, 1983; Fishbein 1977, 1983;
National Research Council [NRC] 1983; Reddy and Massaro 1983; Eisler 1985; Lemly and Smith
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1987; Ohlendorf 1989; Hodson 1990; Goede 1993; Lemly 1993, 1996a, 1996b; Heinz 1996; U.S.
Public Health Service [USPHS] 1996). These authorities agree that selenium is widely distributed
in nature, being especially abundant with sulfide minerals of various metals, such as iron, lead, and
copper. The major source of environmental selenium is the weathering of natural rock. The amount
of selenium entering the atmosphere as a result of anthropogenic activities is estimated to be 3500
metric tons annually, of which most is attributed to combustion of coal and the irrigation of high-
selenium soils for crop production. However, aside from highly localized contamination, the
contribution of selenium by human activities is small in comparison with that attributable to natural
sources. Collectively, all authorities agree that selenium may favorably or adversely affect growth,
survival, and reproduction of algae and higher plants, bacteria and yeasts, crustaceans, molluscs,
insects, fish, birds, and mammals (including humans). Most acknowledge that sensitivity to selenium
and its compounds is extremely variable in all classes of organisms and, except for some instances
of selenium deficiency or of selenosis, metabolic pathways and modes of action are imperfectly
understood. For example, selenium indicator plants can accumulate selenium to concentrations of
thousands of parts per million (mg/kg) without ill effects. In these plants, selenium promotes growth;
whereas in crop plants, accumulations as low as 25 to 50 mg/kg may be toxic. Thus, plants and

waters high in selenium are considered potentially hazardous to livestock and to aquatic life and
other natural resources in seleniferous zones.

31.2 ENVIRONMENTAL CHEMISTRY

Selenium is characterized by an atomic weight of 78.96, an atomic number of 34, a melting
point of 271°C, a boiling point of 685°C, and a density of 4.26 to 4.79. Chemical properties, uses,
and environmental persistence of selenium were documented by a number of researchers whose
works constitute the major source material for this section: Rosenfeld and Beath (1964); Bowen
(1966); Lakin (1973); Stadtman (1974, 1977); Frost and Ingvoldstad (1975); Chau et al. (1976);
Harr (1978); Wilber (1980, 1983); Zieve and Peterson (1981); Robberecht and Von Grieken (1982);
Cappon and Smith (1982); Nriagu and Wong (1983); Eisler (1985); USPHS (1996).
There was general agreement on four points.

1. Selenium chemistry is complex, and additional research is warranted on chemical and biochemical
transformations among valence states, allotropic forms, and isomers of selenium.
2. Selenium metabolism and degradation are significantly modified by interaction with heavy metals,
agricultural chemicals, microorganisms, and a variety of physicochemical factors.
3. Anthropogenic activities (including fossil fuel combustion and metal smelting) and naturally selenif-
erous areas pose the greatest hazards to fish and wildlife.
4. Selenium deficiency is not as well documented as selenium poisoning, but may be equally significant.

Selenium chemistry is complex (Rosenfeld and Beath 1964; Harr 1978; Wilber 1983; Porcella
et al. 1991; Wiedmeyer and May 1993; Besser et al. 1994; USPHS 1996). In nature, selenium
exists: as six stable isotopes (Se-74, -76, -77, -78, -80, and -82), of which Se-80 and -78 are the
most common, accounting for 50% and 23.5%, respectively; in three allotropic forms; and in five
valence states. Changes in the valence state of selenium from –2 (hydrogen selenide) through 0
(elemental selenium), +2 (selenium dioxide), +4 (selenite), and +6 (selenate) are associated with
its geologic distribution, redistribution, and use. Soluble selenates occur in alkaline soils, are slowly
reduced to selenites, and are then readily taken up by plants and converted into organoselenium

compounds, including selenomethionine, selenocysteine, dimethyl selenide, and dimethyl dise-
lenide. In drinking water, selenates represent the dominant chemical species. Selenites are less
soluble than the corresponding selenates and are easily reduced to elemental selenium. In seawater,
selenites are the dominant chemical species under some conditions (Cappon and Smith 1981).
Selenium dioxide is formed by combustion of elemental selenium present in fossil fuels or rubbish.
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Selenium is the most strongly enriched element in coal, being present as an organoselenium
compound, a chelated species, or as an adsorbed element. On combustion of fossil fuels, the sulfur
dioxide formed reduces the selenium to elemental selenium. Elemental selenium is insoluble and
largely unavailable to the biosphere, although it is still capable of satisfying metabolic nutritional
requirements. Hydrogen selenide is highly toxic (at 1 to 4 µg/L in air), unstable, acidic, and irritative.
Selenides of mercury, silver, copper, and cadmium are very insoluble, although their insolubility
may be the basis for the reported detoxification of methylmercury by dietary selenite, and for the
decreased heavy metal toxicity associated with selenite. Metallic selenides are thus biologically
important in sequestering both Se and heavy metals in a largely unavailable form.
In areas of acid or neutral soils, the amount of biologically available selenium should steadily
decline. The decline may be accelerated by active agricultural or industrial practices. In dry areas,
with alkaline soils and oxidizing conditions, elemental selenium and selenides in rocks and volcanic
soils may oxidize sufficiently to maintain the availability of biologically active selenium. Concen-
trations of selenium in water are a function of selenium levels in the drainage system and of water
pH. In Colorado, for example, streams with pH 6.1 to 6.9 usually contain <1 µg Se/L, but those
with pH 7.8 to 8.2 may contain 270 to 400 µg/L (Lakin 1973). Selenium volatilizes from soils at
rates that are modified by temperature, moisture, time, season of year, concentration of water-
soluble selenium, and microbiological activity. Conversion of inorganic and organic selenium
compounds to volatile selenium compounds (such as dimethyl selenide, dimethyl diselenide, and
an unidentified compound) by microorganisms has been observed in lake sediments of the Sudbury
area of Ontario. This conversion may have been effected by pure cultures of

Aeromonas

,

Flavobac-
terium

,

Pseudomonas

, or an unidentified fungus, all of which are found in methylated lake sedi-
ments. Production of volatile selenium is temperature dependent. Compared with the amount of
(CH

3

)

2

Se produced at an incubation temperature of 20°C, 25% less was produced at 10°C and 90%
less at 4°C. Details of selenium reduction and oxidation by microorganisms are not clear. One
suggested mechanism for selenite reduction in certain microorganisms involves attachment to a
carrier protein and transformation from selenite to elemental selenium, which in turn may be
oxidized to selenite by the action of

Bacillus

spp., as one example. It is apparent that much additional
research on this problem is warranted. It now appears that selenates and selenites are absorbed by

plants, reduced, and then incorporated in amino acid synthesis. The biological availability of
selenium is higher in plant foods than in foods of animal origin (Lo and Sandi 1980). The net effect
of soil, plant, and animal metabolism is to convert selenium to inert and insoluble forms such as
elemental selenium, metallic selenides, and complexes of selenite with ferric oxides.
Selenium was used in the early 1900s as a pesticide to control plant pests, and is still used
sparingly to control pests of greenhouse chrysanthemums and carnations (Rosenfeld and Beath
1964). It has been used to control cotton pests (in Trinidad), mites and spiders that attack citrus, and
mites that damage apples. Although no insect-resistant strains have developed, the use of selenium
pesticides has been discontinued, owing to their stability in soils and resultant contamination of food
crops, their high price, and their proven toxicity to mammals and birds (Rosenfeld and Beath 1964;
Eisler 1985). In Canada and France, sodium selenite applied to the soil to discourage deer from
browsing conifer seedlings when deer numbers were high was unsuccessful and should be avoided
(Jobidon and Prevost 1994). Selenium shampoos, which contain about 1% selenium sulfide, are still
used to control dandruff in humans and dermatitis and mange in dogs. Selenium is used extensively
in the manufacture and production of glass, pigments, rubber, metal alloys, textiles, petroleum
products, medical therapeutic agents, and photographic emulsions (Eisler 1985).
Domestic consumption of selenium in 1981 exceeded 453,000 kg. About 50% was used in
electronic and copier components, 22% in glass manufacturing, 20% in chemicals and pigments,
and 8% miscellaneous (Cleveland et al. 1993). In 1987, world production of selenium was about
1.4 million kg (USPHS 1996). In 1986, 46% of the global selenium produced was used in the
semiconductor and photoelectric industries; 27% in the glass industry to counter coloration impu-
rities from iron; 14% in pigments; and 13% in medicine, in antidandruff shampoos, as catalysts in
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pharmaceutical preparations, in nutritional feed additives for poultry and livestock, and in pesticide
formulations (USPHS 1996).
Air and surface waters generally contain nonhazardous concentrations of selenium. Significant
increases of selenium in specific areas are attributed exclusively to industrial sources, and to leaching
of groundwater from seleniferous soils. In the United States, about 4.6 million kg selenium are released
annually into the environment: 33% from combustion of fossil fuels, 59% from industrial losses, and

8% from municipal wastes. Of the total, about 25% is in the form of atmospheric emissions, and the
rest in ash. Mining and smelting of copper–nickel ores at Sudbury, Ontario, Canada, alone releases
about 2 metric tons selenium to the environment daily, and probably represents the greatest point
source of selenium release in the world. In 1977, 680,000 kg selenium was produced at Sudbury, but
only about 10% was recovered, suggesting that about 90% was lost to the environment. Of the amount
lost, perhaps 50 metric tons were dispensed into the atmosphere, probably as selenium dioxide
(airborne Se levels 1 to 3 km from Sudbury were as high as 6.0 µg/m

3

). The rest was probably
associated with mine tailings, wastewater, and scoria, and is a local source of selenium contamination,
most notably in lakes. The present annual rates of selenium accumulation in lake sediments in the
Sudbury area range from 0.3 to 12.0 mg/m

2

. These deposition rates exceed those of pre-colonial times
by factors of 3 to 18, and are among the highest recorded in North America (Nriagu and Wong 1983).
Selenium is a serious hazard to livestock and probably to people in a wide semiarid belt that
extends from inside Canada southward across the United States into Mexico (NRC 1983). Selenium
tends to be present in large amounts in areas where the soils have been derived from Cretaceous
rocks. Total selenium in such soils averages about 5 mg/kg, but is sometimes as high as 80 mg/kg.
Lack of rainfall has prevented the solution of the selenium minerals and the removal of their salts
in drainage waters. In some areas, modern fertilization practices and the buildup of sulfates in the
soil due to acid precipitation partly lessen the availability of selenium to plants and forage crops.
In the United States, highly seleniferous natural areas (200 to 300 µg/kg in forage) are most
abundant in the Rocky Mountain and High Central Plains areas. Areas with lower concentrations
(20 to 30 µg/kg) in forage are typical in the Pacific Northwest and the Southeast. However, huge
variations are not uncommon from one specific location to another. Among plants, primary and

secondary selenium accumulators are almost always implicated in cases of acute or chronic selenium
poisoning of livestock. Primary selenium accumulator plants, such as various species of

Astragalus

,

Oonopsis

,

Stanelya

,

Zylorhiza

, and

Machaeranthera

, may require 1 to 50 mg Se/kg in either soil
or water for growth, and may contain 100 to 10,000 mg Se/kg as a glutamyl dipeptide or seleno-
cystanthionine. Secondary accumulator plants (representative genera:

Aster

,

Gutierrezia

,

Atriplex

,

Grindelia

,

Castillaja

, and

Comandra

) grow in either seleniferous or nonseleniferous soils and may
contain 25 to 100 mg Se/kg. Nonaccumulator plants growing on seleniferous soils contain 1 to
25 mg Se/kg fresh weight. Meat and eggs of domestic animals may contain 8 to 9 mg Se/kg in
seleniferous areas, compared with 0.01 to 1.0 mg/kg in nonseleniferous areas. Tissues from animals
maintained on high-Se feeds generally contain 3 to 5 mg Se/kg fresh weight vs. up to 20 mg/kg
in animals dying of selenium poisoning (Harr 1978).
Selenium is nutritionally important as an essential trace element, but is harmful at slightly
higher concentrations. Although normal selenium dietary levels required to ensure human health
range from 0.04 to 0.1 mg/kg, toxicity may occur if food contains as little as 4.0 mg/kg. Minimum
selenium concentrations required are usually higher in livestock than in humans. In areas with
highly seleniferous soils, excess selenium is adsorbed onto a variety of plants and grains and can
be fatal to grazing livestock. There is general agreement, however, that selenium inadequacy can
be of greater concern to health than selenium toxicity. Selenium has a comparatively short effectual

biological life in various species of organisms for which data are available. Studies with radio-
selenium-75 indicated that its biological half-life is 10 to 64 days: 10 in pheasants, 13 in guppies
and voles, 15 in ants, 27 in eels, 28 in leeches, and 64 in earthworms (Wilber 1983). Many
investigators concluded that the greatest current and direct use of selenium is in the transportation
of grains grown in seleniferous areas to selenium-deficient areas as animal and human food.
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31.3 CONCENTRATIONS IN FIELD COLLECTIONS

Selenium concentrations in nonbiological materials extend over several orders of magnitude
(Table 31.1; Lemly 1996b). In terrestrial materials, concentrations in excess of 5 mg Se/kg are
routinely recorded in meteorites, copper–nickel ores, coal and other fossil fuels, lake sediments in
the vicinity of a nickel–copper smeltery, and in sediments of flyash settling ponds. Water concen-
trations exceeding 50 µg Se/L have been documented in groundwater, especially in areas with
seleniferous soils, in sewage wastes, in irrigation drain water, and in water of flyash settling ponds.
Selenium concentrations in air samples were >0.5 µg/m

3

in the vicinity of selenium production
plants, and these were at least 500 times higher than in a control area (Table 31.1).

Table 31.1 Selenium Concentrations in Nonbiological Materials
Sample and Unit of Concentration Concentration Reference

a

TERRESTRIAL (mg/kg)

Earth’s crust 0.05 1

Soils 0.2 2
Limestones 0.08 2
Sandstones Up to 0.05 2
Shales 0.6 2
Chondrites 8.0 2
Ocean sediments 0.34–4.8 3
Coal 3.4 (0.5–10.7) 4, 5, 15
Fossil fuels 1–10 6
Petroleum 500–1650 15
Lake sediments
NY, Lake George 0.22 7
Great Lakes 0.35–0.75 8
Freshwater lakes, Canada 0.2–14.5 9

AQUATIC (µg/L)

Drinking water
Worldwide 0.12–0.44 10
Groundwater
Nebraska, U.S. <1–480 10
Argentina 48–67 10
Australia 0.008–0.33 10
France <5–75 10
Israel 0.9–27 10
Italy <0.002–1.9 10
Sewage waters
United States
Raw sewage 280 4
Primary effluent 45 4
Secondary effluent 50 4

Worldwide
Japan 480–700 2
United States 10–280 2
Former Soviet Union 1.8–2.7 2
Germany 1.5 2
River waters
Japan 0.03–0.09 11
Germany 0.015 2
Amazon River 0.021 2
United States
Ohio River <0.01 10
Mississippi River 0.14 10
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As a result of natural and anthropogenic processes, comparatively high concentrations of
selenium in nonbiological materials may offer protection or pose significant risks to fish and
wildlife. In Finland, for example, agricultural fertilizers were supplemented with 6 to 16 mg Se/kg
beginning in 1985. In Finnish lakes, selenium concentrations have increased in sediments and fish
muscle from this activity and from atmospheric fallout, but no adverse biological effects were
observed (Wang et al. 1995). In Sweden, selenium treatment raised the lake water concentrations
from 3 µg Se/L at the start to 5 µg/L. This treatment lowered mercury concentrations in mercury-
contaminated northern pike (

Esox



lucius

) and yellow perch (

Perca



flavescens

) in treated Swedish
lakes by 60 to 85% (Paulsson and Lundbergh 1991). Selenium is normally present in surface waters
at about 0.1 to 0.3 µg/L. However, at 1 to 5 µg/L, it can biomagnify in aquatic food chains and
pose a concentrated dietary source of selenium that is toxic to fish and wildlife (Lemly 1993c,
1996a).

Michigan 0.8–10 10
Nebraska <1–20 10
Colorado River 30 10
Lake waters
Sweden 0.04–0.21 11
United States 0.04–1.4 4
Great Lakes 0.001–0.036 8
Seawater
Worldwide 0.009–0.045 1, 2
Worldwide 0.09–0.45 12, 15
Worldwide 0.09–<6.0 4
Israel, Dead Sea 0.8 10
Japan 0.04–0.08 10

AIR (µg/m

3

)

Near Se industrial plant 0.7 4
Control area 0.001 4
Near Sudbury (Canada) smelter Max. 6.0 11
United States Usually <0.01 15

INTEGRATED STUDIES (µg/kg or µg/L)

California
Rainwater 0.05 10
Lake water 0.018 10
Seawater 0.058–0.08 10
Irrigation drain water
Subsurface 300–1400 13
Surface 300 13
Vicinity of nickel–copper smelter, Sudbury, Ontario
Lake waters 0.1–0.4 11
Lake sediments 2000–6000 11
Lake sediments 240 km south of Sudbury 1000–3000 11
Cu–Ni ores 20,000–80,000 11
Flyash ponds
Sediment 14,000 14
Water 350 14

a

1,

Frost and Ingvoldstad 1975;

2,

Ebens and Shacklette 1982;

3,

de Goeij et al.
1974;

4,

NAS 1976;

5,

Kuhn et al. 1980;

6,

Harr 1978;

7,

Heit et al. 1980;

8,

Adams

and Johnson 1977;

9,

Speyer 1980;

10,

Robberecht and Von Grieken 1982;

11,

Nriagu and Wong 1983;

12,

Whittle et al. 1977;

13,

Ohlendorf et al. 1986;

14,

Furr et al. 1979;

15,

USPHS 1996.

Table 31.1 (continued) Selenium Concentrations in Nonbiological Materials
Sample and Unit of Concentration Concentration Reference

a
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Selenium concentrations in representative species of freshwater, marine, and terrestrial flora
and fauna are listed in Table 31.2. Additional information on body and tissue burdens of selenium
was given by Birkner (1978), Jenkins (1980), Lo and Sandi (1980), Eisler (1981, 1985), and Wilber
(1983). It is emphasized that selenium concentrations in all organisms tended to be significantly
higher when collected from locales having certain characteristics: highly seleniferous soils or
sediments (de Goeij et al. 1974; Birkner 1978; Speyer 1980; Wilber 1983); high human population
densities (Beal 1974); heavy accumulations of selenium-laden wastes, such as effluents from
systems used to collect flyash scrubber sludge or bottom ash (Cumbie and Van Horn 1978; Sorensen
et al. 1982, 1984); and selenium-contaminated subsurface irrigation drainwater (Ohlendorf et al.
1986, 1987; Presser and Ohlendorf 1987; Schuler et al. 1990; Lemly 1993c; Hothem and Welsh
1994). Accumulation, transfer, and release of selenium by aquatic biota may affect the speciation
and toxicity of dissolved selenium in aquatic environments (Besser et al. 1994). Depletion of
dissolved selenite and increased concentrations of organoselenium compounds occur during sea-
sonal peaks in phytoplankton abundance in freshwater and marine systems. For example, green
algae (

Chlamydomonas



reinhardtii

) previously exposed to inorganic radioselenium-75 produced
increased concentrations of organoselenium species during population blooms and crashes (Besser

et al. 1994).
Among terrestrial plants, selenium accumulations in species of

Aster

,

Astragalus

, and several
other genera are sometimes spectacularly high (Table 31.2).

Astragalus

is the most widely distrib-
uted. About 24 of its more than 200 species are selenium accumulators that require selenium to
grow well. The highest reported concentration in plants was 15,000 mg Se/kg DW, in loco weed
(

Astragalus racemosus

) (Wilber 1983). Consumption of these and other selenium-accumulating
forage plants by livestock has induced illness and death from selenium poisoning. Even at much
lower concentrations, selenium may harm animals that eat considerable amounts of the forage.
Plants that accumulate selenium tend to be deeper rooted than the grasses and survive more severe
aridity, thus remaining as the principal forage for grazing in time of drought (Wilber 1983). There
is little danger to human health of selenium toxicity from consuming game that foraged in high-
selenium environments (Medeiros et al. 1993).
Selenium levels in freshwater biota are relatively low compared with those in their marine
counterparts. In freshwater organisms, about 36% of the total selenium was present as selenate,

and the rest as selenite and selenide. In marine samples, only 24% of the total selenium was present
as selenate (Cappon and Smith 1982). The implications of this difference are not now understood,
but have relevance in the ability of selenium to complex and detoxify various potentially toxic
heavy metals, such as mercury and cadmium. In a nationwide monitoring of selenium and other
contaminants in freshwater fishes, selenium ranged from 0.05 to 2.9 mg/kg FW whole fish and
averaged about 0.6 mg/kg. Stations where concentrations in fish exceeded 0.82 mg/kg (>85th
percentile) were in three areas: Atlantic coastal streams, Mississippi River system, and California
(Table 31.2) (May and McKinney 1981). Among fish from Atlantic coastal streams, those from the
Delaware River near Camden, New Jersey, had elevated whole-body concentrations (i.e., >1.0 and
<3.0 mg Se/kg FW), which were attributed to the industrialized character of the river. In the Big
Horn and Yellowstone Rivers, high selenium concentrations in fish may result from geologic sources
of the element, including coal, phosphate, and sedimentary rock. Fish from the South Platte River
near Denver, Colorado, may receive selenium from industrial effluents, or from natural and anthro-
pogenic activities associated with the removal of deposits of coal, barite, and sulfur (May and
McKinney 1981). These same trends persisted in more recent nationwide monitoring of freshwater
fishes, with selenium concentrations usually highest in whole fish from stations in Utah, Nevada,
Texas, California, Hawaii, and in arid locations of the western United States (Table 31.2; Schmitt
and Brumbaugh 1990). In California, where selenium was elevated in fish from the San Joaquin
River, it was speculated that Selocide, a selenium-containing pesticide registered for use on citrus
fruits in the 1960s, may have been a source, although contaminated irrigation drainwater was
considered a more likely possibility (Ohlendorf et al. 1986). Of seven species of fishes analyzed
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from the San Joaquin Valley, California, in 1986/1987, mosquitofish (

Gambusia



affinis

) had the
highest concentrations (11.1 mg Se/kg DW whole body); these fish were collected from canals and
sloughs in the Grasslands Water District that received large inflows of subsurface agricultural
drainage water (Saiki et al. 1991, 1992). Selenium persisted in the biota of the Grasslands drainage
regions for at least 1 year after the switch to uncontaminated drainage water (Hothem and Welsh
1994).
Selenium bioconcentrates and biomagnifies in aquatic food chains from invertebrates to birds
(Rusk 1991; Saiki et al. 1993). Maximum selenium concentrations reported in Cibola Lake in the
lower Colorado River Valley in 1989/90 were 5.0 µg/L in water, and — in mg Se/kg DW — 3.3 in
sediments, 1.2 in aquatic plants (

Myriophyllum

,

Ceratophyllum

), 4.6 in crayfish (

Procambarus
clarki

), and 9.2 in bluegills (

Lepomis



macrochirus

) (Welsh 1992). Diet is the primary source of
selenium to fish, as judged by radioselenium-75 uptake studies in Canadian oligotrophic lakes
(Harrison et al. 1990). Hatchery-reared smolts and adults of silver salmon (

Oncorhynchus



kisutch

)
had less selenium in livers than did wild fish, and this could account for the higher survival and
better health of wild fish (Felton et al. 1990).
Belews Lake in North Carolina was contaminated with selenium during the 1970s from coal-
fired power plant wastewater, causing mortality and reproductive failure in the fish population
(Lemly 1993a, 1993c). Selenium concentrations in fish tissues were as high as 125 mg Se/kg DW
and were as much as 100 times higher than those from nearby reference sites. There was a positive
relation between tissue selenium concentrations and frequency of developmental malformations for
largemouth bass and bluegill over the range 1 to 80 mg Se/kg DW tissue and 0% to 70% deformities.
In 1992, selenium residues had declined to less than 20 mg/kg DW, but were still 5 to 18 times
higher than those in reference lakes, and deformity frequency was 7 times higher (Lemly 1993a).
Alterations in zooplankton species densities and dominance — but not diversity — were observed
in Belews Lake between 1970 (uncontaminated), 1976/77 (selenium contamination), and 1984 to
1986. Observed changes are attributed to the dominance of planktivorous fishes (Marcogliese et al.
1992).
All reported selenium levels in tissues of marine invertebrates and plants were less than 2 mg
Se/kg on a fresh weight (FW) basis, or 12 mg/kg dry weight (DW). In marine algae, most of the
selenium accumulated was associated with proteins and may represent a form of storage prior to
detoxification (Boisson et al. 1995). Higher levels are routinely recorded in liver and kidney tissues

of marine and coastal vertebrates, including teleosts, birds, and mammals. Livers from adult seals
were comparatively rich in selenium (Table 31.2); however, high concentrations in liver of maternal
California sea lions were not reflected in the livers of newborn pups (Martin et al. 1976). In marine
mammals, selenium concentrations are positively correlated with increasing age (Teigen et al. 1993;
Mackey et al. 1996) and with increasing mercury residues in piscivorous mammals (Reijnders 1980;
Wren 1984; Leonzio et al. 1992; Teigen et al. 1993). The mercury:selenium ratio was close to 1.0 in
tissues of marine mammals at mercury concentrations >15 mg Hg/kg FW (Skaare et al. 1994).
Increasing mercury concentrations in tissues of marine teleosts are also positively correlated with
selenium (Ganther et al. 1972; Leonzio et al. 1982), although the evidence is conflicting (Tamura
et al. 1975; Speyer 1980; Maher 1983). Selenium varies seasonally in crustaceans (Zafiropoulos
and Grimanis 1977). In general, concentrations of selenium in various tissues are usually higher
in older than in younger organisms. Among marine vertebrates, selenium increases were especially
pronounced among the older specimens of predatory, long-lived species (Eisler 1984).
Selenium concentrations in avian tissues are modified by the age, condition, and diet of the
organism, the presence of other metals, and other variables. Fish-eating birds had the highest
selenium concentrations in livers, and herbivorous species the lowest; omnivores were intermediate
(Mora and Anderson 1995). Selenium concentrations were elevated in livers of molting birds
compared to nonmolting conspecifics (Jenny et al. 1990), elevated in feathers of older terns and
egrets when compared to younger stages (Burger et al. 1994), and elevated in tissues of marine
birds that consume invertebrate prey animals with elevated selenium burdens (Goede et al. 1993).
© 2000 by CRC Press LLC

Selenium concentrations in tissues of shorebirds were positively correlated with concentrations of
copper, zinc (Wenzel and Gabrielsen 1995), and iron (Goede and Wolterbeek 1994). Feathers have
been proposed as indicators of selenium exposure. However, variability in selenium concentrations
in whole feathers is considerable (Goede 1991) (Table 31.2). In shorebirds, for example, the highest
selenium concentrations are found in wing feathers, specifically in the outer primaries, notably
primary 8. Moreover, within the vane of a single feather, the highest selenium concentrations are
in the tip and the lowest at the basis. All of these differences need to be considered before feathers
are routinely used as indicators of selenium exposure (Goede 1991).

Subsurface agricultural drainage waters from the western San Joaquin Valley, California, had
elevated selenium concentrations, as selenate. In 1978, these drainage waters were diverted to
Kesterson Reservoir, a pond system within the Kesterson National Wildlife Refuge (KNWR), with
diversion complete by 1982. In 1983, aquatic birds at KNWR had unusual rates of death and
developmental abnormalities attributed to selenium (Presser and Ohlendorf 1987). In 1984/85,
selenium-induced recruitment failure was observed at KNWR in American avocets (

Recurvirostra
americana

) and black-necked stilts (

Himantopus



mexicanus

); unlike a nearby reference area, chicks
at KNWR of either species did not survive to fledging (Williams et al. 1989). Selenium concen-
trations in livers of diving ducks from San Francisco Bay in 1982 were similar to those of dabbling
ducks in the nearby San Joaquin Valley where reproduction was severely impaired (Ohlendorf et al.
1986b). Mean concentrations of selenium in kidneys of seven species of coastal birds collected
from the highly industrialized Corpus Christi, Texas, area usually varied between 1.7 and 5.6 mg
Se/kg FW, but were 10.2 mg/kg FW in one bird. According to White et al. (1980), selenium
concentrations of this magnitude may be sufficient to impair reproduction in shorebirds. Barn
swallows (

Hirundo

rustica

) nesting at a selenium-contaminated lake in Texas had elevated concen-
trations of selenium in eggs and tissues when compared to conspecifics at a reference site. However,
nest success of barn swallows was significantly higher at the contaminated site; development was
normal at both sites (King et al. 1994).

Table 31.2 Selenium Concentrations in Field Populations of Selected Species of Flora and Fauna (Values
shown are in mg total Se/kg [ppm] fresh weight [FW], dry weight [DW], or ash weight [AW].
Hyphenated numbers show range, and single numbers the mean; where both appear, the

range is in parentheses.)
Ecosystem, Taxonomic Group, Organism,
Tissue, Location, and Other Variables
Concentration
(ppm) Reference

a

MARINE
Algae and macrophytes

Whole 0.04–0.24 DW 1–3
Edible seaweeds, whole 0.16–0.39 DW; 0.047 FW 4

Molluscs

American oyster,

Crassostrea virginica

Redwood Creek, San Francisco, CA
Mantle 4.8 DW 5
Digestive gland 8.8 DW 5
Kidney 4.7 DW 5
Tomales Bay, CA
Mantle 2.2 DW 5
Digestive gland 6.4 DW 5
Kidney 2.5 DW 5
Transferred from Redwood Creek to Tomales Bay for 56 days
Mantle 3.5 DW 5
Digestive gland 6.5 DW 5
Kidney 3.8 DW 5
Bivalve molluscs
Shell 0.03–0.06 DW 6
Soft parts 0.1–0.9 FW; 1.3–9.9 DW 2, 6–10
© 2000 by CRC Press LLC

Muscle 1.1–2.3 DW 11
Viscera 1.6–2.5 DW 11
Edible flesh, 3 species
Total Se 0.22 (0.16–0.31) FW 12
As selenate 0.05 FW 12
As selenite and selenide 0.17 FW 12
Common mussel,

Mytilus edulis

Gills 2.0–16.0 DW 13
Viscera Up to 5.0 DW 13
Mussel,

Mytilus galloprovincialis

Gills 7.0 DW 14
Soft parts 6.0 DW 14
Mantle 5.2 DW 14
Viscera 3.2 DW 14
Muscle 1.9 DW 14
Shell <0.05 DW 14

Echinoderms

Whole, 7 species 0.8–4.4 DW 15

Crustaceans

Digestive system, 3 species 3.0–3.5 DW 11
Edible tissues sold for human consumption, 17 species 0.2–2.0 FW 4, 8, 10
Edible tissues, 2 species
Total Se 0.21 FW 12
As selenate 0.05 FW 12
As selenite and selenide 0.16 FW 12
Muscle, 5 species 2.4–4.4 DW 11
Soft tissues, 2 species 2.0–2.8 DW 11
Copepods, whole 1.8–3.4 DW 3, 16
Euphausid,

Meganyctiphanes norvegica

Viscera 11.7 DW 17
Eyes 7.8 DW 17
Muscle 1.8 DW 17
Exoskeleton 0.8 DW 17
Shrimp,

Lysmata seticaudata

Viscera 7.0 DW 14
Eyes 4.8 DW 14
Whole 2.6 DW 14
Muscle 1.9 DW 14
Exoskeleton 1.5 DW 14
Molts 0.3 DW 14

Sharks

Muscle 0.2–0.8 FW 18

Fishes

Digestive system, 4 species 1.0–2.4 DW 11
Liver
2 species 2.6–6.6 DW 19
74 species 0.6–5.0 FW 8, 10, 20
13 species 5.0–30.0 FW 8
Meals, 3 species 1.0–4.0 DW 21
Muscle

4 species 0.5–1.5 DW 11
182 species 0.1–2.0 FW 4, 8, 10, 19,
22, 23

Table 31.2 (continued) Selenium Concentrations in Field Populations of Selected Species of Flora
and Fauna (Values shown are in mg total Se/kg [ppm] fresh weight [FW], dry weight [DW],
or ash weight [AW]. Hyphenated numbers show range, and single numbers the mean; where

both appear, the range is in parentheses.)
Ecosystem, Taxonomic Group, Organism,
Tissue, Location, and Other Variables
Concentration
(ppm) Reference

a
© 2000 by CRC Press LLC

5 species, Total Se 0.4 (0.2–0.6) FW 12
As selenate 0.1 FW 12
As selenite and selenide 0.3 FW 12
Whole, 21 species 0.3–2.0 FW 8, 23, 24
Japanese tunas, 4 species
Liver 10.0–15.0 FW 25
White muscle 0.5–1.3 FW 25
Red muscle 3.5–9.1 FW 25
Snapper,

Chrysophrys auratus

; Australia; 1976; muscle Max. 0.85 FW 73

Black marlin,

Makaira indica

Muscle 0.4–4.3 FW 26
Liver 1.4–13.5 FW 26
Blue marlin,

Makaira nigricans

Kidney 23.0 FW 27
Blood 1.0 FW 27
Gill 1.0 FW 27
Muscle
Total Se 3.3 (2.5–4.1) FW 12
As selenate 0.2 (0.09–0.3) FW 12
As selenite and selenide 3.1 (2.4–3.8) FW 12
Striped bass,

Morone saxatilis

Muscle 0.3 FW 28
Liver 0.6 FW 28
Tuna, canned 1.9–2.9 FW 29
Swordfish,

Xiphias gladius

Muscle 0.3–1.3 FW 30

Birds

Kidney, 12 species 1.2–5.6 FW 31, 32
Liver; 5 species; Baja California; 1986 0.7–5.1 (0.2–7.3) FW 101
Western grebe,

Aechmophorus occidentalis

; Puget Sound,
Washington; 1986; liver
7.6–9.3 (2.2–24.0) DW 109
Great Skua,

Catharacta skua

Kidney 32.8 (13.3–89.1) DW 37
Liver 19.7 (6.7–34.6) DW 37
Oystercatcher,

Haematopus ostralegus

Kidney 12.7 (2.3–17.5) DW 37
Liver 12.8 (5.0–20.5) DW 37
Herring gull,

Larus argentatus

Kidney 14.1 (8.6–19.4) DW 37
Liver 7.9 (6.9–9.3) DW 37
Eggs; Long Island, New York; 1989–94 1.0–2.1 DW 102

Franklin’s gull,

Larus pipixcan

; Minnesota; 1994
Feathers, males vs. females 0.5 DW vs. 0.6 DW 103
Eggs 3.0 DW 103
Diet (earthworms) 4.9 DW 103
Brown pelican,

Pelecanus occidentalis

Egg 0.19–0.38 FW 36
Liver 1.0–4.2 FW 36
White-faced ibis,

Plegadis chihi

Egg 0.3–1.1 FW 33
Wedge-tailed shearwater,

Puffinus pacificus

Egg 1.1–1.3 FW 35
Black skimmer,

Rynchops niger

; breast feathers; New York 1.2–1.3 DW 104

Table 31.2 (continued) Selenium Concentrations in Field Populations of Selected Species of Flora
and Fauna (Values shown are in mg total Se/kg [ppm] fresh weight [FW], dry weight [DW],
or ash weight [AW]. Hyphenated numbers show range, and single numbers the mean; where

both appear, the range is in parentheses.)
Ecosystem, Taxonomic Group, Organism,
Tissue, Location, and Other Variables
Concentration
(ppm) Reference

a
© 2000 by CRC Press LLC

Seabirds
Liver, 11 species Means 17–107 DW 128
Most tissues, 3 species Max. 2–34 DW 128
Seabirds; northern Norway; summer, 1992–93
Kittiwake,

Rissa



tridactyla

; adults vs. fledglings
Feather 1.8 FW vs. 1.3 FW 96
Liver 16.9 DW vs. 8.9 DW 96
Common guillemot,

Uria



aalge

Feather 2.6 FW 96
Gonad 21.9 DW 96
Kidney 43.7 DW 96
Liver 17.6 DW 96
Brunnich’s guillemot,

Uria



lomvia

Feather 2.7 FW 96
Gonad 12.2 DW 96
Kidney 15.6 DW 96
Liver 17.6 DW 96
Shorebirds
New Jersey, Cape May; 3 species; feathers; 1991–92 1.3–6.2 DW 106
Pacific coast; U.S.; 1984–85; livers
Dunlin,

Calidris

alpina

12.9 (7.0–20.2) DW 105
Long-billed dowitcher,

Limnodromus



scolopaceus

11.1 (5.5–15.3) DW 105
Black-bellied plover,

Pluvialis



squatorola

9.4 (5.8–29.9) DW 105
Texas; 1984; mercury-contaminated bay vs. reference site; eggs
less shell
Forster’s tern,

Sterna

forsteri

0.71 FW vs. 0.68 FW 108
Black skimmer,

Rynchops



niger

0.8 FW vs. 0.3 FW 108
Sooty tern,

Sterna fuscata

Egg 1.1–1.4 FW 35
Common tern,

Sterna



hirundo

; feathers; Massachusetts; May–June
Adults
Age 2–3 years 1.3 DW 107
Age 9–10 years 2.1 DW 107
Age 16–21 years 2.4 DW 107

Fledglings, age 20–23 days 0.8 DW 107
Royal tern,

Sterna maxima

Egg 0.4–2.1 FW 34
Red-footed booby,

Sula sula

Egg 0.8–0.9 FW 35

Mammals

Alaska; liver
Bowhead whale,

Balaena mysticetus

0.5–1.2 FW 85
Beluga whale,

Delphinapterus



leucas

4–75 FW; usually
<20.0 FW

85
Bearded seal,

Erignathus barbatus

0.5–5.3 FW 85
Ringed seal,

Phoca



hispida

1.2–5.7 FW 85
Minke whale,

Balaenoptera rostrata

; Antarctic Ocean; 1990–91;
urine
1.5 FW 84
Pilot whale,

Globicephala macrorhynchus

Blubber 0.8–1.4 FW 38
Liver 22.8–61.6 FW 38
Kidney 3.0–10.0 FW 38

Table 31.2 (continued) Selenium Concentrations in Field Populations of Selected Species of Flora
and Fauna (Values shown are in mg total Se/kg [ppm] fresh weight [FW], dry weight [DW],
or ash weight [AW]. Hyphenated numbers show range, and single numbers the mean; where

both appear, the range is in parentheses.)
Ecosystem, Taxonomic Group, Organism,
Tissue, Location, and Other Variables
Concentration
(ppm) Reference

a
© 2000 by CRC Press LLC

Italy; 1987–89; found stranded
Striped dolphin,

Stenella coeruleoalba

Brain 9 (5–36) DW 88
Kidney 25 (50–101) DW 88
Liver 106 (2–960) DW 88
Muscle (10–55) DW 88
Bottle-nosed dolphin,

Tursiops



truncatus

Brain 4.9 (3.3–5.2) DW 88
Kidney 53 (21–186) DW 88
Liver 139 (2–2400) DW 88
Muscle Max. 48 DW 88
Saimaa ringed seal,

Phoca hispida saimensis

Muscle 0.2–2.8 FW 23
Liver 29.0–170.0 FW 23
Kidney 0.3–3.0 FW 23
Blubber 0.06–0.11 FW 23
Harbor seal,

Phoca vitulina

Juveniles
Kidney 0.6 (0.0–1.3) FW 39
Liver 2.8 (2.6–6.5) FW 39
Brain 1.1 (0.0–7.4) FW 39
Adults
Kidney 3.5 (1.9–7.3) FW 39
Liver 109.0 (Max. 409.0) FW 39
Brain 3.7 (1.5–8.2) FW 39
Norway, 1989–90
Brain, 4 species <0.01 FW 86
Grey seal,

Halichoerus grypus

Kidney Max. 4.1 FW 86
Liver Max. 21.8 FW 86
Ringed seal,

Phoca hispida

Kidney Max. 5.7 FW 86
Liver Max. 3.7 FW 86
Harp seal,

Phoca

groenlandica
Kidney Max. 7.2 FW 86
Liver Max. 3.4 FW 86
Harbor seal, Phoca vitulina
Kidney Max. 7.7 FW 86
Liver Max. 7.8 FW 86
Harbor porpoise, Phocaena phocoena; Norway; 1989–90; ages
1–5 years
Kidney 0.6–8.6 FW 87
Liver 0.7–14.2 FW 87
Seals
Liver, 4 species 6.1–170.0 FW 23, 40, 41
California sea lion, Zalophus californianus
Mothers with normal pups
Liver 260.0 DW 42
Kidney 22.0 DW 42
Normal pups
Liver 4.1 DW 42

Kidney 6.1 DW 42
Table 31.2 (continued) Selenium Concentrations in Field Populations of Selected Species of Flora
and Fauna (Values shown are in mg total Se/kg [ppm] fresh weight [FW], dry weight [DW],
or ash weight [AW]. Hyphenated numbers show range, and single numbers the mean; where
both appear, the range is in parentheses.)
Ecosystem, Taxonomic Group, Organism,
Tissue, Location, and Other Variables
Concentration
(ppm) Reference
a
© 2000 by CRC Press LLC
Mothers with premature pups
Liver 79.0 DW 42
Kidney 12.0 DW 42
Pups born prematurely
Liver 2.9 DW 42
Kidney 3.7 DW 42
FRESHWATER
Algae and higher plants
Algae, whole <2.0 DW 43
Higher plants 0.1 DW 44
Aquatic mosses 0.8 DW 44
Filamentous algae
Se-contaminated area 35.2 (12–68) DW 57
Control area <0.5 DW 57
Rooted plants
Se-contaminated area 52.1 (18–79) DW 57
Control area 0.4 DW 57
Molluscs
Mussels, 3 species, NY state

Soft parts 2.0–4.0 DW 71
Asiatic clam, Corbicula fluminea
Whole, Florida 0.7 FW 45
Arthropoda
Zooplankton 0.8–3.9 DW 46
Plankton
Se-contaminated area 85 (58–124) DW 57
Control site 2 (1.4–2.9) DW 57
Insects
Se-contaminated area 20–218 DW 57
Control site 1.1–3.0 DW 57
Mayfly, Hexagenia sp. 0.3–0.5 FW 45
Fishes
California
San Joaquin River; whole
1984–85; 5 species Max. 23.0 DW 75
1986; 5 species Max. 11.0 DW 75
1986–87; 7 species; whole
Sacramento River Max. 2.1 DW 76
San Francisco Bay Max. 3.3 DW 76
San Joaquin River Max. 11.1 DW 76
Reservoirs receiving ash pond effluent
Bluegill, Lepomis macrochirus; ovary Max. 12.0 FW 89
Largemouth bass, Micropterus salmoides; ovary Max. 7.0 FW 89
Common carp, Cyprinus carpio
Whole 1.0 (0.7–1.4) DW 47
Liver 3.6 (2.2–5.2) DW 47
Bluegill, Lepomis macrochirus
From water containing <5 µg Se/L
White muscle 0.04 FW 48

Liver 0.7 FW 48
Spleen 1.6 FW 48
Erythrocytes 0.04 FW 48
Heart 1.0 FW 48
Table 31.2 (continued) Selenium Concentrations in Field Populations of Selected Species of Flora
and Fauna (Values shown are in mg total Se/kg [ppm] fresh weight [FW], dry weight [DW],
or ash weight [AW]. Hyphenated numbers show range, and single numbers the mean; where
both appear, the range is in parentheses.)
Ecosystem, Taxonomic Group, Organism,
Tissue, Location, and Other Variables
Concentration
(ppm) Reference
a
© 2000 by CRC Press LLC
From water containing 22.6 µg Se/L
White muscle 3.1 FW 48
Liver 11.2 FW 48
Spleen 17.7 FW 48
Erythrocytes 7.2 FW 48
Heart 12.8 FW 48
Upper Mississippi River
Whole 1.2 (0.7–1.4) DW 47
California, San Joaquin Valley, 1988
Carcass
Males 2.0 (1.5–3.1) DW 80
Females 1.9 (1.2–3.0) DW 80
Gonads
Males 3.8 (3.2–4.1) DW 80
Females 3.2 (2.3–4.3) DW 80
Largemouth bass, Micropterus salmoides

From water containing <5 µg Se/L
White muscle 0.05 FW 48
Liver 0.8 FW 48
Spleen 1.8 FW 48
Erythrocytes 0.07 FW 48
Heart 1.2 FW 48
From water containing 22.6 µg Se/L
White muscle 1.7 FW 48
Liver 10.2 FW 48
Spleen 16.6 FW 48
Erythrocytes 8.0 FW 48
Heart 12.0 FW 48
Colorado River Valley; Cibola Lake, 1989–90
Liver 8.4–18.0 DW 81
Muscle 4.5–5.9 DW 81
Ovary 5.4–7.8 DW 81
Apalachicola River, Florida
Whole
Females 0.3–0.4 FW 45
Males 0.3–0.5 FW 45
Juveniles 0.3–0.5 FW 45
Eggs 0.7–1.0 FW 45
Striped bass, Morone saxatilis; California; whole; juveniles
San Joaquin River
1984 6.5 DW 74
1985 4.1 DW 74
1986 3.5 DW 74
San Joaquin Valley vs. San Francisco estuary; 1986 Max. 7.9 DW vs.
Max. 3.3 DW
74

Channel catfish, Ictalurus punctatus
Apalachicola River, Florida
Whole
Females 1.1–0.3 FW 45
Males 0.2–0.3 FW 45
Juveniles 0.4–0.6 FW 45
Eggs 0.8–2.1 FW 45
Threadfin shad, Dorosoma petenense
Whole 0.3–0.5 FW 45
Table 31.2 (continued) Selenium Concentrations in Field Populations of Selected Species of Flora
and Fauna (Values shown are in mg total Se/kg [ppm] fresh weight [FW], dry weight [DW],
or ash weight [AW]. Hyphenated numbers show range, and single numbers the mean; where
both appear, the range is in parentheses.)
Ecosystem, Taxonomic Group, Organism,
Tissue, Location, and Other Variables
Concentration
(ppm) Reference
a
© 2000 by CRC Press LLC
Green sunfish, Lepomis cyanellus
From water containing 13 µg Se/L
Liver 7.0–21.4 FW 49
Muscle 2.3–12.9 FW 49
From control site
Liver 1.3 FW 49
Muscle 1.3 FW 49
Trout, 2 species, Wyoming
From water containing 12.3–13.3 µg Se/L
Liver 50.0–70.0 FW 50
Muscle <2.0 FW 50

Skin Max. 4.8 FW 50
Mosquitofish, Gambusia affinis, whole
From Se-contaminated irrigation drainwater pond 170 (65–360) DW 57, 77
Control site 1.3 (1.2–1.4) DW 57
Coho salmon, Oncorhynchus kisutch
Muscle 0.7–1.0 DW 51
Liver 3.8 DW 51
Adults, liver
Ocean caught 8.8 DW; 1.7 FW 79
Estuary caught 8.1 DW; 1.6 FW 79
Hatchery return 7.6 DW; 1.6 FW 79
Farmed fish 4.8 DW; 1.0 FW 79
Smolts, liver
Hatchery reared 2.0 DW; 0.4 FW 79
Naturally reared 3.6 DW; 0.7 FW 79
Chinook salmon, Oncorhynchus tshawytscha
Muscle 1.6 DW 51
Razorback sucker, Xyrauchen texanus; Green River, Utah
Eggs
1988 4.9 DW 82
1991 28.0 DW 82
1992 3.7–10.2 DW 82
Milt, 1992 <1.1–6.7 DW 82
Fry, 1992 2.2 DW; 0.54 FW 82
Muscle, 1992
Females 4.4–32.0 DW 82
Males 3.6–26.0 DW 82
Maximum concentrations 11.5–54.1 DW 83
Fish
Muscle

25 species 0.0–0.5 FW 52–56
18 species 0.5–1.0 FW 53–55
3 species 1.0–2.0 FW 55, 58
3 species
Total Se 0.25 (0.15–0.34) FW 12
As selenate 0.09 FW 12
As selenate and selenide 0.16 FW 12
10 species, Western Lake Erie 0.4–1.5 FW; 1.8–8.1 DW 46
Liver
17 species 0.0–0.5 FW 59
7 species 0.5–1.0 FW 59
4 species 0.6–5.0 FW 10
Table 31.2 (continued) Selenium Concentrations in Field Populations of Selected Species of Flora
and Fauna (Values shown are in mg total Se/kg [ppm] fresh weight [FW], dry weight [DW],
or ash weight [AW]. Hyphenated numbers show range, and single numbers the mean; where
both appear, the range is in parentheses.)
Ecosystem, Taxonomic Group, Organism,
Tissue, Location, and Other Variables
Concentration
(ppm) Reference
a
© 2000 by CRC Press LLC
Whole
Nationwide, U.S.
1972 0.60 (0.57–0.64) FW 60
1973 0.46 (0.42–0.49) FW 60
1976–77 0.58 (0.53–0.62) FW 60
1978–79 0.48 FW 78
1980–81 0.46 FW 78
1984–85 0.42 FW 78

1976–84 Max. 2.3–3.6 FW 78
5 species 0.5–1.9 FW 61
4 species 0.2–0.3 DW 56
6 species 0.0–0.5 FW 62
12 species 0.5–1.0 FW 62
6 species 1.0–2.0 FW 62
6 species 2.1–6.0 FW 62
Amphibians
Southern toad, Bufo terrestris; adults; whole
From coal ash settling basins vs. reference site (sediments
4.4 mg Se/kg DW vs. 0.1 mg/kg)
17.4 DW vs. 2.1 DW 130
Transferred from reference site to settling basin for 7–12 weeks 2.1 DW vs. 3.5–5.5 DW 130
Bullfrog, Rana catesbeiana; tadpoles; South Carolina; 1997
With digestive tract
Body 9.7 DW; 1.9 FW 131
Tail 11.5 DW; 1.8 FW 131
Whole 9.3 DW; 1.9 FW 131
Without digestive tract
Body without gut 10.0 DW 131
Tail 12.6 DW 131
Whole 6.7 DW 131
Digestive tract 18.2 DW 131
Various species, liver 0.7–4.7 FW 43
Reptiles
Water snake, Natrix sp.
Whole, Florida 0.3–0.5 FW 45
Birds
Little green heron, Butorides virescens; Apalachicola River,
Florida; whole

0.1–0.5 FW 45
California
Aquatic birds; 4 species; 1985–88; Grasslands area; livers; North
Grasslands vs. South Grasslands (more Se-contaminated area)
1985 Max. 14 DW vs.
Max. 25 DW
97
1987 Max. 10 DW vs.
Max. 24 DW
97
1988 Max. 12 DW vs.
Max. 14 DW
97
Grasslands drainage area (Se-contaminated prior to 1985);
1986 vs. 1987; eggs
Mallard, Anas platyrhynchos 6 DW vs. 20 DW 98
Cinnamon teal, Anas cyanoptera 0.2 DW vs. 12 DW 98
Gadwall, Anas strepera 5.3 DW vs. 8 DW 98
Near Salton Sea; 1985; eggs
Black-crowned night heron, Nycticorax nycticorax 1.1 (0.9–1.4) FW 99
Great egret, Casmerodius albus 0.6 (0.5–0.8) FW 99
Table 31.2 (continued) Selenium Concentrations in Field Populations of Selected Species of Flora
and Fauna (Values shown are in mg total Se/kg [ppm] fresh weight [FW], dry weight [DW],
or ash weight [AW]. Hyphenated numbers show range, and single numbers the mean; where
both appear, the range is in parentheses.)
Ecosystem, Taxonomic Group, Organism,
Tissue, Location, and Other Variables
Concentration
(ppm) Reference
a

© 2000 by CRC Press LLC
San Francisco Bay, 1982
Greater scaup, Aythya marila; liver 19 (7–31) DW 100
Surf scoter, Melanitta perspicillata; liver 34 (16–59) DW 100
From Kesterson National Wildlife Refuge (KNWR), California,
nesting on Se-contaminated irrigation drainwater ponds —
1983
American coot, Fulica americana
Liver 37 (21–63) DW 57
Egg 54 (34–110) DW 57
Ducks, Anas spp.
Liver 28.6 (19–43) DW 57
Egg 9.9 (2.2–46) DW 57
Black-necked stilt, Himantopus mexicanus
Egg 32.7 (12–74) DW 57
American avocet, Recurvirostra americana
Egg 9.1 DW 57
Eared grebe, Podiceps nigricollis
Liver 130.0 DW 57
Egg 81.4 (72–110) DW 57
From Volta Wildlife Area, California, control site — 1983
American coot
Liver 5.0 (4.4–5.6) DW 57
Ducks, 2 species
Liver 4.1 (3.9–4.4) DW 57
Black-necked stilt
Liver 6.1 DW 57
KNWR vs. reference site; 1983–85
Diets >50 DW vs. <2 DW 125
Livers

Adults, 8 species 26–101 DW vs. 3–11 DW 125
Juveniles, 5 species 21–95 DW vs. 2–4 DW 125
Canada; eastern section; from freezer archives; total Se
Common loon, Gavia immer
Kidney 15 DW 129
Liver 15 DW 129
Muscle 2.8 DW 129
Common merganser, Mergus merganser
Kidney 8.5 DW 129
Liver 9.7 DW 129
Muscle 1.8 DW 129
Willet, Catoptrophorus semipalmatus; 1986; south Texas; liver 2.8–8.3 DW 110
China; feathers; 1992
Herons; chicks; 2 species 1.0–2.0 DW 111
Egrets; chicks; 3 species 1.2–2.8 DW 111
Common loon, Gavia immer
Egg 0.4 (0.3–0.7) FW 63
Red-breasted merganser, Mergus serrator
Egg 0.47–1.0 FW 72
Mallard, Anas platyrhynchos
Egg 0.28–0.81 FW 72
Flamingo, Phoenicopterus ruber; feather; France; 1988
Adults 7.1 (1.6–33.0) FW 112
Juveniles 0.8 FW; Max. 2.3 FW 112
Table 31.2 (continued) Selenium Concentrations in Field Populations of Selected Species of Flora
and Fauna (Values shown are in mg total Se/kg [ppm] fresh weight [FW], dry weight [DW],
or ash weight [AW]. Hyphenated numbers show range, and single numbers the mean; where
both appear, the range is in parentheses.)
Ecosystem, Taxonomic Group, Organism,
Tissue, Location, and Other Variables

Concentration
(ppm) Reference
a
© 2000 by CRC Press LLC
White-faced ibis, Plegadis chihi; Carson Lake, Nevada; 1985–86
Eggs 1.9–5.4 DW 113
Livers 9.6 (5–27) DW 113
Eared grebe, Podiceps nigricollis; Stewart Lake, North Dakota;
1991; eggs
4.5 (2.9–6.5) DW;
no deformities
114
TERRESTRIAL
Fungi <2.0 DW 43
Macrophytes
Western wheat grass, Agropyron smithii, South Dakota,
plant top
0.0–8.4 DW 43
Little bluestem, Andropogon scoparius, plant top 0.0–6.0 DW 43
Asparagus, Asparagus officinale, western U.S. 2.7–11.0 DW 43
Aster, whole
Aster caerulescens 560.0 DW 43
A. commutatus Max. 590.0 DW 43
A. multiflora Max. 320.0 DW 43
A. occidentalis 284.0 DW 43
Milk vetch, Astragalus argillosus
Top 385.0 DW 43
Root 27.0 DW 43
A. beathii
Top 1963.0 DW 43

Root 6.0 DW 43
A. bisulcatus
Top Max. 10,239.0 DW 43
Seed 305.1 DW 43
A. confertiflorus
Top 1372.0 DW 43
A. crotulariae
Top 2000.0 DW 43
Root 45.0 DW 43
Loco weed, Astragalus spp. Max. 46,000.0 AW;
Max. 6000.0 DW
43
Saltbush, Atriplex spp. 300.0–1734.0 DW 43
Oats, Avena sativa 2.0–15.0 DW 43
Buffalo grass, Bouteloua dactyloides 2.7 (0.0–12.0) DW 43
Indian paint brush, Castillaja spp. 0.0–1812.0 DW 43
Gumweed, Grindelia squarrosa 38 (0.0–2160) DW 43
Broomweeds
Gutierrezia spp. Max. 723.0 DW 43
Haplopappus spp. Max. 4800.0 DW 43
Tobacco, Nicotiana tabacum
Leaf 5.8 DW 43
Stem 44.2 DW 43
Rice, Oryza sativa
Grain 0.09–0.11 FW 43
Pear, Pyrus communis
Fruit 0.02 FW 43
Rye, Secale cereale 0.9–25.0 DW 43
Potato, Solanum tuberosum
Tuber 0.2–0.9 DW 43

Table 31.2 (continued) Selenium Concentrations in Field Populations of Selected Species of Flora
and Fauna (Values shown are in mg total Se/kg [ppm] fresh weight [FW], dry weight [DW],
or ash weight [AW]. Hyphenated numbers show range, and single numbers the mean; where
both appear, the range is in parentheses.)
Ecosystem, Taxonomic Group, Organism,
Tissue, Location, and Other Variables
Concentration
(ppm) Reference
a
© 2000 by CRC Press LLC
Wheat, Triticum aestivum
Grain 1.1–35.0 DW 43
Stem and leaf 17.0 DW 43
Root 36.0 DW 43
Corn, Zea mays
Grain 1.0–20.0 DW 43
Grape, Vitis sp.
Raisin <0.001 FW 43
Annelids
Earthworms, whole
From normal soil 2.2 FW 64
From selenite-enriched soil 7.5 FW 64
From soil amended with sewage sludge
Whole 15.0–22.4 DW 65
Casts 0.6–0.7 DW 65
From control field
Whole 22.1 DW 65
Casts 0.6 DW 65
Arthropods
Sow bug, Porcellio sp. 0.9 FW 43

Crane fly, larva, Tipula sp. 0.9 FW 43
“Fly larvae,” whole, from Astragalus plant with 1800 mg Se/kg 20.0 FW 43
Birds
Cattle egret, Bubulcus ibis; juveniles; 1989–91; feathers
New York 1.3 DW 115
Delaware 1.6 DW 115
Puerto Rico 1.3 DW 115
Cairo, Egypt 0.3 DW 115
Aswan, Egypt 1.0 DW 115
Barn swallow, Hirundo rustica; 1986–87; Martin Lake, Texas
(selenium-contaminated) vs. reference site
Eggs Max. 12 DW vs.
Max. 4.5 DW
116
Kidneys Max. 14 DW vs.
Max. 5.8 DW
116
Wood stork, Mycteria americana; feathers
Florida, juveniles, 1991 1.8 DW 117
Costa Rica
Adults, 1992 3.4 DW 117
Juveniles
1990 2.2 DW 117
1992 1.5 DW 117
House sparrow, Passer domesticus
Whole 0.6 DW 66
Ring-necked pheasant, Phasianus colchicus
Whole 0.6 DW 66
Common blackbird, Turdus merula
Whole 2.1 DW 66

Mammals
California; San Francisco Bay; 1989; livers
California vole, Microtus californicus 0.5–1.6 DW 90
House mouse, Mus musculus 1.5–4.8 DW 90
Deer mouse, Peromyscus maniculatus 2.3–3.5 DW 90
Table 31.2 (continued) Selenium Concentrations in Field Populations of Selected Species of Flora
and Fauna (Values shown are in mg total Se/kg [ppm] fresh weight [FW], dry weight [DW],
or ash weight [AW]. Hyphenated numbers show range, and single numbers the mean; where
both appear, the range is in parentheses.)
Ecosystem, Taxonomic Group, Organism,
Tissue, Location, and Other Variables
Concentration
(ppm) Reference
a
© 2000 by CRC Press LLC
California; Kesterson National Wildlife Refuge vs. control site;
May 1984; liver
California vole, Microtus californicus Max. 250.0 DW vs.
Max. 1.4 DW
120
House mouse, Mus musculus Max. 41.0 DW vs.
Max. 3.7 DW
120
Desert cottontail, Sylvilagus audubonii Max. 3.3 DW vs.
Max. 0.1 DW
120
South Dakota; various species; muscle 0.2–1.1 FW 95
Washington State; 1992–93; blood
Moose, Alces alces 0.015 (0.01–0.02) FW 94
Elk, Cervus elaphus 0.04–0.16 FW;

Max. 0.49 FW
94
Mule deer, Odocoileus hemionus 0.08 (0.06–0.15) FW 94
California bighorn sheep, Ovis canadensis californiana 0.09 (0.04–0.13) FW 94
Livestock >0.1 FW
(adequate selenium)
94
Wyoming; muscle; animals had access to forage grown on
medium up to 5.0 mg/L water-soluble selenium) to high (>10
mg Se/L)
American bison, Bison bison 0.5 FW; 1.7 DW 95
Cattle, Bos sp. 0.1 FW; 0.5 DW 95
Elk, Cervus elaphus 0.4 FW; 1.6 DW 95
Mule deer 0.6 FW; 2.5 DW 95
Common beaver, Castor canadensis
Liver 0.2 FW 67
Kidney 0.9 FW 67
Intestine 0.04 FW 67
Muscle 0.09 FW 67
Human, Homo sapiens
Fetus, United States
Most tissues <0.4 FW 118
Thyroid, blood <1.0 FW 118
Liver 2.8 FW 118
Adults, United States
Urine 0.002–0.113 FW 118
Milk 0.007–0.053 FW 118
Semen 0.016–0.131 FW 118
Erythrocytes 0.02–0.52 FW 118
Whole blood 0.08–0.3 FW 118

Nails 0.08–3.8 FW 118
Hair 0.6 FW 118
Pancreas, kidney 0.6–0.9 FW 118
Liver 0.6–1.7 FW 118
Diet
Fruits and vegetables Usually <0.03 FW 118
Grains and cereals 0.03–1.4 FW 118
Brazil nuts 14.7 (0.2–253.0) FW 118
Dairy products 0.01–0.1 FW 118
Meat and poultry
Muscle 0.1–0.5 FW 118
Organ meats 0.4–2.3 FW 118
Seafood 0.2–3.4 FW 118
Table 31.2 (continued) Selenium Concentrations in Field Populations of Selected Species of Flora
and Fauna (Values shown are in mg total Se/kg [ppm] fresh weight [FW], dry weight [DW],
or ash weight [AW]. Hyphenated numbers show range, and single numbers the mean; where
both appear, the range is in parentheses.)
Ecosystem, Taxonomic Group, Organism,
Tissue, Location, and Other Variables
Concentration
(ppm) Reference
a
© 2000 by CRC Press LLC
River otter, Lutra canadensis
Liver 2.1 FW 67
Kidney 1.9 FW 67
Intestine 1.1 FW 67
Muscle 0.2 FW 67
Woodchuck, Marmota monax
From flyash landfill vicinity

Adults
Liver 2.2–10.7 DW 68
Lung 1.4–4.4 DW 68
Juveniles
Liver 3.9–6.4 DW 68
Lung 2.1–2.8 DW 68
From control area
Adults
Liver 0.4 DW 68
Lung 0.4 DW 68
Juveniles
Liver 0.2–0.4 DW 68
Lung 0.2 DW 68
Field vole, Microtus agrestis
Whole 0.5 DW 66
Mule deer, Odocoileus hemionus; California; whole blood; 1981–88
Winter 0.07 FW 91
Spring 0.05 FW 91
Summer 0.09 FW 91
Fall 0.02 FW 91
Range 0.02–0.17 FW 91
Most deer <0.1 FW (Se-deficient) 92
White-tailed deer, Odocoileus virginianus
Muscle 0.16 (0.05–0.49) DW 69
Southern Florida; 1984–88
Heart 0.37 (0.01–1.0) DW 93
Kidney 3.7 (1.2–11.3) DW 93
Liver 0.7 (0.1–4.3) DW 93
Serum 0.05 (0.01–0.5) FW 93
Raccoon, Procyon lotor

Liver 1.8 FW 67
Kidney 1.9 FW 67
Muscle 0.2 FW 67
Norway rat, Rattus norvegicus
Whole 0.4 DW 66
Rock squirrel, Spermophilus variegatus
Kidney 8.9–53.0 DW;
Max. 90.0 DW
70
Mole, Talpa europaea
Whole 2.6 DW 66
INTEGRATED STUDIES
California; Kesterson NWR vs. control site; 1984–85; liver
Gopher snake, Pituophis melanoleucas 11.1 (8.2–32.0) DW vs.
2.1 (1.3–3.6) DW
121
Bullfrog, Rana catesbeiana 45.0 DW vs. 6.2 DW 121
Table 31.2 (continued) Selenium Concentrations in Field Populations of Selected Species of Flora
and Fauna (Values shown are in mg total Se/kg [ppm] fresh weight [FW], dry weight [DW],
or ash weight [AW]. Hyphenated numbers show range, and single numbers the mean; where
both appear, the range is in parentheses.)
Ecosystem, Taxonomic Group, Organism,
Tissue, Location, and Other Variables
Concentration
(ppm) Reference
a
© 2000 by CRC Press LLC
California; Kesterson NWR vs. control site; August 1983;
maximum values recorded
Water 0.3 FW vs. 0.0005 FW 124

Sediments 8.8 DW vs. not detectable
(ND)
124
Detritus 80 DW vs. 2 DW 124
Algae 330 DW vs. <2 DW 124
Rooted plants 300 DW vs. <1 DW 124
Aquatic insects 290 DW vs. <3 DW 124
Mosquitofish 290 DW vs. ND 124
California; San Joaquin River; 1987; maximum
concentrations recorded
Water 0.025 FW 122
Sediments 3 DW 122
Invertebrates 14 DW 122
Fishes 17 DW 122
Greenland; 1975–91
Bivalve molluscs; 3 species; soft parts 0.2–0.9 FW 127
Crustaceans; 6 species; whole 0.2–3.2 FW 127
Fish; 5 species
Liver 0.3–0.9 FW 127
Muscle <0.2–0.7 FW 127
Seabirds; 9 species
Kidney 3.7–17.6 FW 127
Liver 1.9–14.1 FW 127
Muscle 0.5–4.4 FW 127
Seals; 2 species
Kidney 2.6–4.2 FW 127
Liver 1.0–7.6 FW 127
Muscle 0.2–0.4 FW 127
Whales; 4 species
Kidney 1.5–6.3 FW 127

Liver 1.7–5.0 FW 127
Muscle Max. 0.2 FW 127
Skin Max. 47.9 FW 127
Polar bear, Ursus maritimus
Kidney 6.0–11.6 FW 127
Liver 3.1–9.1 FW 127
Muscle <0.2–1.3 FW 127
Norway; 1990–91; near Russian nickel smelter vs. reference site;
liver
Willow ptarmigan, Lagopus lagopus 0.9 DW vs. 0.5 DW 119
Blue hare, Lepus timidus Max. 1.8 DW vs.
Max. 0.6 DW
119
Common shrew, Sorex araneus Max. 4.6 DW vs. 4.5 DW 119
Grey-sided vole, Clethrionomus rufocanus Max. 1.8 DW vs. no data 119
Texas; shoalgrass community; Lower Laguna Madre; 1986–87
Sediments 2.8 (0.5–4.5) DW 123
Shoalgrass, Halodule wrightii; rhizomes Not detected 123
Grass shrimp, Palaemonetes sp.; whole 1.2 (0.7–1.8) DW 123
Brown shrimp, Penaeus aztecus; whole 1.8 (0.6–3.2) DW 123
Blue crab, Callinectes sapidus; whole except legs, carapace, and
abdomen
1.3 (0.4–3.9) DW 123
Pinfish, Lagodon rhomboides; whole 1.4 (0.8–2.2) DW 123
Table 31.2 (continued) Selenium Concentrations in Field Populations of Selected Species of Flora
and Fauna (Values shown are in mg total Se/kg [ppm] fresh weight [FW], dry weight [DW],
or ash weight [AW]. Hyphenated numbers show range, and single numbers the mean; where
both appear, the range is in parentheses.)
Ecosystem, Taxonomic Group, Organism,
Tissue, Location, and Other Variables

Concentration
(ppm) Reference
a
© 2000 by CRC Press LLC
31.4 DEFICIENCY AND PROTECTIVE EFFECTS
Selenium is an essential nutrient for most plants and animals. It constitutes an integral part of
the enzyme glutathione peroxidase and may have a role in other biologically active compounds,
especially Vitamin E and the enzyme formic dehydrogenase. Some animals require selenium-
containing amino acids (viz. selenocysteine, selenocystine, selenomethionine, selenocystathionine,
selenium-methylselenocysteine, and selenium-methylselenomethionine), but reportedly are incapa-
ble of producing them. Selenium also forms part of certain proteins, including cytochrome c,
hemoglobin, myoglobin, myosin, and various ribonucleoproteins (Rosenfeld and Beath 1964; Eisler
1985; USPHS 1996).
The availability of selenium to plants may be lessened by modern agricultural practices,
eventually contributing to selenium deficiency in animal consumers. For example, fertilizers con-
taining nitrogen, sulfur, and phosphorus all influence selenium uptake by plants through different
Lower Colorado River Valley; 1985–91
Sediments 1.2 (0.3–3.9) DW 126
Crayfish 3.5 (1.5–3.9) DW 126
Marsh birds, livers
Rails, 3 species 13.1–26.0 DW 126
Others, 7 species 2.6–8.5 DW 126
a
1, Chau and Riley 1970; 2, Lunde 1970; 3, Tijoe et al. 1977; 4, Noda et al. 1979; 5, Okazaki and Panietz 1981;
6, Bertine and Goldberg 1972; 7, Karbe et al. 1977; 8, Hall et al. 1978; 9, Fukai et al. 1978; 10, Luten et al.
1980; 11, Maher 1983; 12, Cappon and Smith 1982; 13, Stump et al. 1979; 14, Fowler and Benayoun 1976c;
15, Papadopoulu et al. 1976; 16, Zafiropoulos and Grimanis 1977; 17, Fowler and Benayoun 1976a; 18, Glover
1979; 19, Grimanis et al. 1978; 20, de Goeij et al. 1974; 21, Kifer and Payne 1968; 22, Bebbington et al. 1977;
23, Kari and Kauranen 1978; 24, United Nations 1979; 25, Tamura et al. 1975; 26, MacKay et al. 1975;
27, Schultz and Ito 1979; 28, Heit 1979; 29, Ganther et al. 1982; 30, Freeman et al. 1978; 31, Turner et al.

1978; 32, White et al. 1980; 33, King et al. 1980; 34, King et al. 1983; 35, Ohlendorf and Harrison 1986; 36, Blus
et al. 1977; 37, Hutton 1981; 38, Stoneburner 1978; 39, Reijnders 1980; 40, Smith and Armstrong 1978; 41, van
de Ven et al. 1979; 42, Martin et al. 1976; 43, Jenkins 1980; 44, Rossi et al. 1976; 45, Winger et al. 1984;
46, Adams and Johnson 1977; 47, Wiener et al., 1984; 48, Lemly 1982b; 49, Sorensen et al. 1984; 50, Kaiser
et al. 1979; 51, Rancitelli et al. 1968; 52, Uthe and Bligh 1971; 53, Willford 1971; 54, Tong et al. 1971; 55, Pakkala
et al. 1972; 56, Rossi et al. 1976; 57, Ohlendorf et al. 1986; 58, Schroeder et al. 1970; 59, Lucas et al. 1970;
60, May and McKinney 1981; 61, Pratt et al. 1972; 62, Walsh et al. 1977; 63, Haseltine et al. 1983; 64, Birkner
1978; 65, Helmke et al. 1979; 66, Nielsen and Gissel-Nielsen 1975; 67, Wren 1984; 68, Fleming et al. 1979;
69, Ullrey et al. 1981; 70, Sharma and Shupe 1977; 71, Heit et al. 1980; 72, Haseltine et al., 1981; 73, Chvojka
et al. 1990; 74, Saiki and Palawski 1990; 75, Saiki et al. 1992; 76, Saiki et al. 1991; 77, Saiki 1987; 78, Schmitt
and Brumbaugh 1990; 79, Felton et al. 1990; 80, Nakamoto and Hassler 1992; 81, Welsh 1992; 82, Hamilton
and Waddell 1994; 83, Waddell and May 1995; 84, Hasunuma et al. 1993; 85, Mackey et al. 1996; 86, Skaare
et al. 1994; 87, Teigen et al. 1993; 88, Leonzio et al. 1992; 89, Baumann and Gillespie 1986; 90, Clark et al.
1992; 91, Dierenfeld and Jessup 1990; 92, Oliver et al. 1990b; 93, McDowell et al. 1995; 94, Hein et al. 1994;
95, Medeiros et al. 1993; 96, Wenzel and Gabrielsen 1995; 97, Paveglio et al. 1992; 98, Hothem and Welsh
1994; 99, Ohlendorf and Marois 1990; 100, Ohlendorf et al. 1986b; 101, Mora and Anderson 1995; 102, Burger
and Gochfeld 1995; 103, Burger and Gochfeld 1996; 104, Burger and Gochfeld 1992; 105, Custer and Meyers
1990; 106, Burger et al. 1993b; 107, Burger et al. 1994; 108, King et al. 1991; 109, Henny et al. 1990;
110, Custer and Mitchell 1991; 111, Burger and Gochfeld 1993; 112, Amiard-Triquet et al. 1991; 113, Henny
and Herron 1989; 114, Olson and Welsh 1993; 115, Burger et al. 1992; 116, King et al. 1994; 117, Burger
et al. 1993a; 118, USPHS 1996; 119, Kalas et al. 1995; 120, Clark 1987; 121, Ohlendorf et al. 1988; 122, Saiki
et al. 1993; 123, Custer and Mitchell 1993; 124, Saiki and Lowe 1987; 125, Ohlendorf et al. 1990; 126, Rusk
1991; 127, Dietz et al. 1996; 128, Kim et al. 1998; 129, Scheuhammer et al. 1998; 130, Hopkins et al. 1998;
131, Burger and Snodgrass 1998.
Table 31.2 (continued) Selenium Concentrations in Field Populations of Selected Species of Flora
and Fauna (Values shown are in mg total Se/kg [ppm] fresh weight [FW], dry weight [DW],
or ash weight [AW]. Hyphenated numbers show range, and single numbers the mean; where
both appear, the range is in parentheses.)
Ecosystem, Taxonomic Group, Organism,
Tissue, Location, and Other Variables

Concentration
(ppm) Reference
a
© 2000 by CRC Press LLC
modes of action, the net effect being a reduction in selenium uptake (Frost and Ingvoldstad 1975).
The buildup of sulfur (as sulfates) in the soil — due to acid rain, fertilizers, and other sources —
interferes with selenium accumulation by crops (Frost and Ingvoldstad 1975). In addition, high
dietary levels of various heavy metals (including copper, zinc, silver, and mercury) contribute to
selenium deficiency in animals (Frost and Ingvoldstad 1975; Harr 1978), presumably as a result
of selenium binding with the metal into biologically unavailable forms (Harr 1978; Kaiser et al.
1979).
Clinical selenium deficiency in ruminants is expressed as white muscle disease, lethargy,
impaired reproduction, weight loss and reduced growth, shedding, decreased immune response,
decreased erythrocyte glutathione peroxidase, and sudden death (Knox et al. 1987; Flueck and
Flueck-Smith 1990). Selenium deficiency — as judged by blood concentrations <0.1 mg Se/L —
has been documented in California among domestic cattle, mule deer (Odocoileus hemionus),
pronghorn antelope (Antilocapra americana), elk (Cervus elaphus), and bighorn sheep (Ovis
canadensis) (Oliver et al. 1990a). More than 95% of black-tailed deer (Odocoileus hemionus
columbianus) in northern California had inadequate blood selenium levels (37 µg/kg whole blood
FW), as judged by recommended levels for cattle (>40 µg/kg) and sheep (>50 µg/kg) (Flueck 1994).
Selenium deficiency in red deer was reversed with subcutaneous injection of 50 mg Se/mL as
barium selenate at 2 mL per 50 kg body weight (Knox et al. 1987). Selenium boluses calibrated
to release 1.0 mg selenium daily, given orally to selenium-deficient adult female black-tailed deer,
effectively raised whole blood levels to 121 µg Se/kg FW. These selenium-supplemented females
produced fawns with increased survival (0.83 fawns/female) when compared to untreated does
(0.32 fawns/female) (Flueck 1994). Supplementation of selenium-deficient mule deer does with
intrarumenal selenium pellets can triple fawn survivability (Oliver et al. 1990a). Some feral animals
selectively prefer plants with comparatively elevated selenium content. The black rhinoceros
(Diceros bicornis) in Kenya, for example, prefers 10 of 103 plants ingested; preferred vegetation
contained 3.0 to 6.3 µg Se/kg FW vs. 1.8 to 2.7 µg/kg FW in nonpreferred plants (Ghebremeshel

et al. 1991).
There is a general consensus that selenium deficiency in livestock is increasing in many
countries, resulting in a need for added selenium in the food. Selenium deficiency is considered
by some researchers to constitute a greater threat to health than selenium poisoning. Studies with
animals and humans have suggested that selenium deficiency, in part, underlies susceptibility to
cancer, arthritis, hypertension, heart disease, and possibly periodontal disease and cataracts (Frost
and Ingvoldstad 1975; Shamberger 1981; Robberecht and Von Grieken 1982). These linkages have
not yet been demonstrated conclusively. For example, eye lens cataract was induced in 10-day-old
male rats by selenate, selenite, selenomethionine, and selenocystine, presumably through interfer-
ence with glutathione metabolism (Ostadalova and Babicky 1980). On the other hand, adverse
effects of selenium inadequacy have been clearly documented for a wide variety of organisms,
including bacteria, protozoans, Atlantic salmon, rainbow trout, Japanese quail, ducks, poultry, rats,
dogs, horses, domestic sheep, bighorn sheep, swine, cattle, antelopes, gazelles, deer, monkeys, and
humans (Jensen 1968; Frost and Ingvoldstad 1975; Jones and Stadtman 1975; Fishbein 1977; Harr
1978; Kaiser et al. 1979; Hilton et al. 1980; Shamberger 1981; Bovee and O’Brien 1982; Robberecht
and Von Grieken 1982; NRC 1983; Levander 1983, 1984; Knox et al. 1987; Morris et al. 1984;
Flueck and Smith-Flueck 1990; Oliver et al. 1990a; USPHS 1996). Selenium deficiency, whether
induced experimentally by use of low-selenium feeds supplemented with alpha-tocopherol or by
chronic ingestion of low-selenium diets, has caused a number of maladies:
• High embryonic mortality in cattle and sheep
• Anemia in cattle
• Poor growth and reproduction in sheep and rats
• Reduced viability of newly hatched quail
© 2000 by CRC Press LLC