EPA 910-R-96-019
Toxiclty and Exposure Concerns
to Arsenic in Seafood'
An Arsenic Literatim Review for Risk Assessments
Prepared by: Christine M. Chew
ICF Kaiser - Region X ESAT
Seattle, WA 98101
Revised: March 1996
ICF KAISER
Submitted in fulfillment of Region X ESAT Work Unit Document 4038 under
Technical Instruction Document 10-9601-815 as requested by Patricia drone,
Task Monitor and (JSEPA Risk Evaluation Unit Chief.
-------
Toxscsty and Exposure Concerns
to Arsenic in Seafood:
An Arsenic Literature Review for Risk Assessments
Prepared by: Christine M. Chew
ICF Kaiser - Region X ESAT
Seattle, WA 98101
Revised: March 1996
Submitted in fulfillment of Region X ESA T Work Unit Document 4038 under
Technical Instruction Document 10-9601-815 as requested by Patricia drone,
Task Monitor and USEPA Risk Evaluation Unit Chief.
-------
TABLE OF CONTENTS
INTRODUCTION 1
Objectives 1
PROPERTIES AND ENVIRONMENTAL SOURCES 1
Species of Arsenic ,,,.,, 1
Physical and Chemical Properties 2
Environmental Sources , , , 2
Biological Sources , 4
CONSIDERATIONS FOR 4
Points of Exposure 4
Contributions from Environmental Media 4
Seafood Exposure Contributions 5
Species Present 6
Pacific Northwest Speciated Data 13
Measurement and Speciation Methods 14
Exposure Assessment 18
Sources Assessed 18
Consumption of Seafood 19
Potential Tools 25
CONSIDERATIONS FOR TOXICITY ASSESSMENTS 26
Metabolism 26
Inorganic Arsenic and Methylated Metabolites 26
Organic Arsenic Species found in Seafood 28
Toxicity 30
Inorganic Arsenic and Methylated Metabolites 31
Organic Arsenic and Seafood Arsenic Species 37
RISK ASSESSMENT IMPLICATIONS 40
Regulatory Criteria 40
National United States Standards , 40
Other Standards 42
Applications 43
Friberg (1988) Study 43
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Puget Sound Seafood Risk Assessment 44
Kensington Mine Risk Assessment 45
Lower Columbia River Bi-state Program 46
CONCLUSIONS 48
REFERENCES 50
in
-------
INTRODUCTION
Arsenic is a naturaJly occurring element found in all environmental matrices (soil, air and water)
as well as in living matter. It is found in comparatively high levels in fish and other edible seafood.
Consequently, its influence on human health is of interest in health risk assessments pertaining to
individuals or populations exposed to edible marine or freshwater organisms. Arsenic in the environment
can be found in elemental form as well as many other species, both inorganic and organic. In seafood,
the organic forms tend to dominate, but inorganic forms are also present.
Objectives
The objectives of this report are: 1) to determine a range of conservative concentrations of
inorganic arsenic in seafood (including fish, invertebrates and algae) for use in Region 10 human health
exposure assessments and related activities; 2) to identify speciation methods which may be used by the
EPA Region 10 laboratory to study inorganic and total arsenic content in northwest fish, shellfish and
edible marine plants which currently do not have documented data available; and, 3) to present facts and
implications of the toxic potential of arsenic in seafood to human populations ingesting this seafood and
discuss related exposure assessment approaches. How significant is dietary intake of inorganic arsenic
from seafood? What is currently known about the long-term effects of organic arsenic from seafood
consumption? These questions in particular, and others related to the stated objectives, will be discussed
in this report. This report has been prepared for use by US EPA Region 10; consequently, references
to "the northwest" apply to the region's four states; Alaska, Idaho, Oregon and Washington.
PROPERTIES AND ENVIRONMENTAL SOURCES
Speties of Arsenic
Arsenic has two primary valence states: trivalent (As*3) and pentavalent (As*5). Arsenic in each
of these valence states forms both inorganic and organic compounds. The different species of arsenic
vary in reactivity, solubility, toxicity and other properties. Of greatest interest in human health risk
assessments are those species taken up by people, and the biotransformed products that result. Inorganic
arsenic may be taken up in trivalent or pentavalent form; associated species found in urinary excretions
are the two inorganic arsenic forms and the monomethylated arsenic (MMA) and dimethylated arsenic
(DMA) species. Arsenic species specifically associated with seafood include a limited amount of
inorganic arsenic, arsenobetaine (a.k.a. carboyxmethyl(tri-methyl) arsonium bromide), arsenocholine
(a.k.a. 2-hydroxyethyl(trimethyl)arsonium bromide) and arsenosugars (mostly found in seaweeds). Fipre
1 depicts the structure of some arsenosugars. Table 1 lists some of the more common arsenic compounds
and their structures.
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EPA 91Q-R-96-Oly
Toxlcity and Exposure Concerns
to Arsenic In Seafood:
An Arsenic Literature Review for Risk Assessments
Prepared by: Christine M. Chew
ICF Kaiser - Region X ESAT
Seattle, WA 98101
Revised: March 1996
ICF KAISER
Submitted in fulfillment of Region X ESA T Work Unit Document 4038 under
Technical Instruction Document 10-9601-815 as requested by Patricia drone,
Task Monitor and USEPA Risk Evaluation Unit Chief.
-------
-------
TABLE OF CONTENTS
INTRODUCTION 1
Objectives 1
PROPERTIES AND ENVIRONMENTAL SOURCES I
Species of Arsenic 1
Physical and Chemical Properties 2
Environmental Sources 2
Biological Sources 4
CONSIDERATIONS FOR EXPOSURE ASSESSMENTS 4
Points of Exposure 4
Contributions from Environmental Media , 4
Seafood Exposure Contributions 5
Species Present 6
Pacific Northwest Speciated Data 13
Measurement and Speciation Methods 14
Exposure Assessment 18
Sources Assessed 18
Consumption of Seafood 19
Potential Tools 25
CONSIDERATIONS FOR TOXICITY ASSESSMENTS 26
Metabolism 26
Inorganic Arsenic and Methylated Metabolites 26
Organic Arsenic Species found in Seafood 28
Toxieity 30
Inorganic Arsenic and Methylated Metabolites 31
Organic Arsenic and Seafood Arsenic Species 37
RISK ASSESSMENT IMPLICATIONS , 40
Regulatory Criteria 40
National United States Standards 40
Other Standards 42
Applications 43
Friberg (1988) Study 43
-------
-------
Puget Sound Seafood Risk Assessment 44
Kensington Mine Risk Assessment 45
Lower Columbia River Bi-state Program 46
CONCLUSIONS 48
REFERENCES 50
in
-------
-------
INTRODUCTION
Arsenic is a naturally occurring element found in all environmental matrices (soil, air and water)
as well as in living matter. It is found in comparatively high levels in fish and other edible seafood.
Consequently, its influence on human health is of interest in health risk assessments pertaining to
individuals or populations exposed to edible marine or freshwater organisms. Arsenic in the environment
can be found in elemental form as well as many other species, both inorganic and organic. In seafood,
the organic forms tend to dominate, but inorganic forms are also present,
Objectives
The objectives of this report are: 1) to determine a range of conservative concentrations of
inorganic arsenic in seafood (including fish, invertebrates and algae) for use in Region 10 human health
exposure assessments and related activities; 2) to identify speciation methods which may be used by the
EPA Region 10 laboratory to study inorganic and total arsenic content in northwest fish, shellfish and
edible marine plants which currently do not have documented data available; and, 3) to present facts and
implications of the toxic potential of arsenic in seafood to human populations ingesting this seafood and
discuss related exposure assessment approaches. How significant is dietary intake of inorganic arsenic
from seafood? What is currently known about the long-term effects of organic arsenic from seafood
consumption? These questions in particular, and others related to the stated objectives, will be discussed
in this report. This report has been prepared for use by US EPA Region 10; consequently, references
to "the northwest" apply to the region's four states: Alaska, Idaho, Oregon and Washington.
PROPERTIES AND ENVIRONMENTAL SOURCES
Species of Arsenie
Arsenic has two primary vaJence states: trivalent (As*3) and pentavalent (As*5). Arsenic in each
of these valence states forms both inorganic and organic compounds. The different species of arsenic
vary in reactivity, solubility, toxicity and other properties. Of greatest interest in human health risk
assessments are those species taken up by people, and the biotransformed products that result. Inorganic
arsenic may be taken up in trivalent or pentavalent form; associated species found in urinary excretions
are the two inorganic arsenic forms and the monomethylated arsenic (MMA) and dimethylated arsenic
(DMA) species. Arsenic species specifically associated with seafood include a limited amount of
inorganic arsenic, arsenobetaine (a.k.a. carboyxmethyl(tri-methyl) arsonium bromide), arsenocholine
(a.k.a. 2-hydroxyethyl(trimethyI)arsonium bromide) and arsenosugars (mostly found in seaweeds). Figure
1 depicts the structure of some arsenosugars. Table 1 lists some of the more common arsenic compounds
and their structures.
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S'
i t
2CHCI
s\—(a1
OH OH
81
A-X !
A-XI
A-XII
A-XIII
A-XIV
A-XV
R2
-OH
R3
-OH
3.
-OPOCH,CH SOH »CH,OH
1 ' '
-so
Physical and Chemical Properties
Arsenic is a metalloid in group
V(A) of the Periodic Table. Arsenic
exists as a metalloid in the zero
oxidative state; it also exists in two
other oxidative states, trivalent (+3 or -
3) and pentavalent (+5) (Hindmarsh
and McCurdy 1984). In both the
trivalent and pentavalent states, arsenic
is able to form stable compounds.
Being in the same group as
phosphorous, arsenic competes, in
biological environments, for
phosphorous binding sites. Two arsenic
analogues to the phosphorous species
phosphatidyl choline and acetylcholine have been identified (Hedlund et a!. 1982, Christkopoulos et al.
S988b), Arsenic binds covalently with many nonmetals to form a variety of organic and inorganic
compounds (Hindmarsh and McCurdy 1984).
-OH
-so3
-SO,
SOURCE: Shibataero/. 1993
Figure 1 Arsenosugars
The reactivity and toxicity of these compounds varies with the nature of the compounds. Of
primary importance is the valence state of the arsenic (Edmonds and Francesconi 1993). Trivalent arsenic
is more reactive and has demonstrated a higher toxicity than pentavalent arsenic. Yet, when ingested by
people, pentavalent arsenic is converted by the body to trivalent arsenic, which undergoes subsequent
detoxification.
Arsenic (III) solubility is low in water but high in acid or alkaline solutions. In water, arsenic
is usually found as arsenate or arsenite (JonnaJagadda and Rao 1993). Pentavalent arsenic is more
prevalent in well oxygenated surface waters; however, in the reducing coastal zones and in estuaries with
high biological activity, levels of trivalent arsenic and sometimes, methylated species, meet or exceed
those of arsenic (V) (Mafaer and Butler, 1988),
Environmental Sources
Arsenic is released from earth's crust into the environment via volcanic activity and weathering
of arsenic-containing sulfides (Phillips, 1990). It is ubiquitous in the environment and naturally cycles
through it, traveling from soils into the air and plants through ocean and lake sediments and into
groundwater. A more in-depth discussion of this cycle can be found in the Hindmarsh and McCurdy
review (1984).
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Tabft 1 Some Common Arsenic Compounds
Name Formula
Arsenate HjAsOA HAs042", As043"
Arsenite HjAs031", HAs032", As033'
Monomethylarsonic acid CH3AsO|OH)2
Oimethyiarsrnic acid
Arsenobetains
Arsenocholine
Arsenous Acid
Arsenic Acid
Arsenic Pentoxide
Arsenic Trioxide
Trimethylarsine oxide
Tetramethyiarsonium
ion
Dimethylarsinylethanol
(CH3)2AsO(OH|
(CH3)3Ast-CH2COOH
(CH3)3As*CH2CH2OH
H3As03
H,As04
(CH3)3AsO
Arsenic is also released into the
environment from human activities.
Primary anthropogenic sources include
mining/smelting activities, generation of
coal power, pesticide
manufacture/application, and wood
preservative treatment (Leonard and
Lauwerys 1980). In 1983 Woolson
estimated tliat anthropogenic arsenic
sources accounted for more than three
times the natural releases of arsenic into
the environment (Hindmarsh and
McCurdy 1984), Three mechanisms
influence the fate of arsenic in
environmental matrices: (1) methylation
and volatilization, (2) adsorption and
precipitation, and (3) oxidation and
reduction (Hindmarsh and McCurdy
1984).
SOURCES; Hindmarsh and McCurdy (1984),
Shibata et al. (1992S
Tablt 2 Background Concentration Ranges of Arsenic in
Environmental Media
Media
Concentration Source
sO.Ol
0.1-40 trig/Kg
Arsenic
concentrations in
environmental media vary
depending on surrounding
anthropogenic contributors.
Table 2 lists total arsenic
concentrations considered
"background* levels.
Arsenic is the tenth most
abundant element in the sea
(JonnaJagadda and Rao 1993)
and the twentieth most
abundant element in the
earth's crust, with a mean concentration of 2 ppm (Leonard and Lauwerys 1980). Associated with this,
elevated arsenic concentrations have been found in hot springs in Central America (Lacayo et al. 1992).
Air
Soils
Freshwater
Saltwater
2-5 fjg/L
23x1 0-f M
Hindmarsh 4 McCurdy 1984
Hindmanh 4 MeCurdy 1984
Mahtr & Byttar 1933
Hirtdrrwrsh 4 WeCurtly 1984
Leonaitf «nd Lauweryi 1980
JonralBgadds & Rao 1993
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Biological Sources
Arsenic from environmental media is also circulated through the biosphere through piant uptake
and the food chain. As with environmental media, biological organisms host a broad range of arsenic
compounds. Species of arsenic in aquatic environments are reflective of the food chain's influence as
they include not only inorganic pentavalent and trivalent arsenic, but also their biological metabolites;
monomethylarsonate (MMA) and dimethylarsinite (DMA) (Maher and Butler, 1988).
Levels of arsenic in terrestrial animals are usually less than 1 ppm-dry weight. Within the animal
kingdom, fish contain highest total arsenic levels. Studies of Quebec wildlife and marine organisms are
consistent with this generalization (Langlois and Langis 1995). Concentration ranges include: 2.5-4.9
mg/kg in bottom feeding fish (e.g., cod, halibut, flounder); 1.2-10.9 mg/kg in crustaceans (including
clams, scallops, lobster and shrimp); and 0.2-0.8 mg/kg in non-bottom-feeding fish (including pickerel,
pike, smelt, whitefish, saJmon, bluefsn tuna and herring) (Hindmarsh and McCurdy 1984). In general,
total arsenic concentrations range from 0.1 ppm (in herring) to about 140 ppm (in sole) (Hall et at. 1978).
Arsenic in aquatic organisms occurs as both lipid-soluble and water-soluble species (Lunde 1977).
Marine organisms have the ability to convert inorganic arsenic to organic arsenic species (Lunde
1977). Arsenobetaine is the major form of arsenic found in fish and shellfish; it is suspected to be the
metabolic endpoint for arsenic in marine environments (Cuilen and Reimer, 1989). Arsenosugars are the
primary arsenic species found in algal organisms (Edmonds and Francesconi 1993). Organic arsenic
compounds isolated from marine organisms include: arsenobetaine, methylated arsenic acids,
arsenosugars, arsenocholine and unidentified lipid soluble compounds (Irgolic ei al. 1977, Lunde 1977
Shinagawa et al. 1983).
CONSIDERATIONS FOR EXPOSURE ASSESSMENTS
Points of Exposure
Arsenic, in its various forms, is present in soil, air, water and biological tissue. Significant
human exposure pathways are ingestion and inhalation. Inhalation is primarily concerned with respiratory
intake of arsenic from air (as opposed to dermal contact with arsenic in air), Ingestion occurs from three
sources: incidental ingestion of soil, ingestion of drinking water, and ingestion of foods containing
arsenic. Human exposure involves both inorganic and organic arsenic compounds; bioavailability is
dependent upon the nature of the specific compound. For example, arsenic (III) and arsenic (V) are
absorbed efficiently across the gastrointestinal tract, but to a lesser extent than arsenobetaine.
Contributions from Environmental Media
Concentrations of arsenic have generally been measured as total arsenic and represent a range of
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organic and inorganic arsenic contaminants. As it has become increasingly apparent that the particular
species of arsenic in an exposure defines its toxic potential and course of action, reported concentrations
are beginning to be detailed by species.
According to the World Health Organization, normal daily intake of inorganic arsenic is generally
less than 50 jig (Vahter et al, 1983). Total intake ranges from 0,5-4.2 rag/day, and is
on diet. Two of the most significant contributors to arsenic ingesdon are drinking water and seafood.
Soil arsenic content is of greater concern in residential scenarios involving incidental ingestion of
contaminated soil by children. Inhalation exposure to arsenic usually contributes less than 1 jig/day to
arsenic intake, but may be of greater concern in an occupation setting (Leonard and Lauwerys 1980).
...__. As noted in table 2,
Table 3 Percentage of Inorganic Arsenic Compared to
Total Arsenic in Selected Foods a11 environmental
_ contain some background
Psrcentagt °
Food inorganic Arsenic concentrations of
~"*" ' — — — — ' j _-___—__— , — , which may contribute to
Milk and dairy products 75 ,
exposure. However, the
Meat- beef and pork 75 concentrations presented
Poultry 65 indicate total arsenic content
Fish-- saltwater 0 and do not differentiate
different arsenic
-freshwater 10
compounds. Due to the
Cereals 65 ,
extensive information
e available, a general consensus
Vegetables 0.5 exists that inorganic arsenic is
Potatoes 10 harmful to people.
Frujts 10 Therefore, inorganic arsenic
content is of particular
interest Table 3 displays
of
that inorganic arsenic
for various of foods. Values for fish inorganic arsenic content are not widely
accepted; a discussion is below.
Seafood Exposure Contributions
Arsenic, because it is ubiquitous in the environment, has been identified in various forms in most
freshwater and saltwater fish, shellfish and seaweed. Winger et al, (1990), in a study of 102 fish and
fiddler crabs from the lower Savannah River, measured total arsenic concentrations in these organisms.
-------
They found that arsenic does not biomagnify and it does not accumulate in fish to the same extent as it
does in lower trophic organisms. They also found that arsenic concentrations in planktivorous fishes were
elevated over predators and omnivores. Suedel et al. (1994) reiterate Penrose's conclusions that little
evidence exists for food-chain biomagnification of arsenic in marine ecosystems; however, arsenic may
biomagnify in tertiary consumers who do not have the same abilities to convert it to less harmful organic
arsenic species.
In other studies, Zook et al, (1976) found that total arsenic concentrations in different seafood
species varied more than other metal contents and were comparatively elevated above other metals in
some species. Consistent with these findings, the Group of Experts on Scientific Aspects of Marine
Pollution (GESAMP) data indicate that the dwelling area of seafood will influence its arsenic content
(Friberg 1988). In experiments with flounder and cod from Norway, Staveland (1993) found that total
arsenic concentrations in fish are essentially independent of age, sex and, for the most part, season.
Species Present
Species of arsenic present in seafood vary among organisms. Both inorganic and organic arsenic
compounds exist in seafood. In fmfish and shellfish, the principal arsenic species identified has been
arsenobetaine; findings of lesser amounts of arsenocholine have also been reported (Edmonds and
Francesconi 1993, Vahter 1994). Inorganic arsenic has been found in fish and shellfish at concentrations
ranging from 0-9.5 percent of total arsenic (see tables 4 & 5). Trace amounts of other species have also
been identified. Arsenic species reported in seaweed are primarily arsenosugars (see figure 1) and
inorganic arsenic, at concentrations ranging from 0-60 percent of total arsenic (see table 6),
Fish/Species
Table 4 Speciated Arsenic Concentrations in Finfish
Location Total Inorganic Percent
of Arsenic Arsenic Inorganic
Sample frrtg/kgS* (mg/kgl* Arsenic
Source
Anchovy
Barracuda
Chrysophrys
major
Conger
Eel
Flounder
Garfish
Japan
Japan
Japan
Japan
Japan
Japan
Australia
2.33
0.88
1.21
2.88
0.15
7.2
1.3
0
0
0
0.12
0
0
0.01
0
0
0
4.2
0
0
0.8
Kaise et al, 1 988
Kaise et al. 1988
Kaise &t al. 1 988
Mohri et al. 1 990
Mohri et aL 1 990
Shinagawa et al.
Mahsr and Butier
1983
1988
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Fish/Species
Goby
Haddock
Hairtail
Halibut .
Herring
Mackerel
N&odiirsma
ransonneti
Op/ggnathus
fasciatus
Panpris tipoma
trillineatum
Pneumatopttorus
japonicus
Prionurus
micmlspido tii3
Salmon
Sardine
Saury
Shark
Siganus
Skate
Sole
Table 4 Speciated Arsenic Concentrations in Finfish
Location Total Inorganic Percent
of Arsenic Arsenic inorganic
Sample (mg/kgl* (mg/kg)' Arsenic Sourc®
Australia
Japan
U.K.
Japan
Japan
Australia
Japan
U.K.
Japan
Japan
Japan
Japan
Japan
Japan
Japan
Japan
Japan
Japan
Japan
Japan
Japan
Japan
Japan
Japan
0.5
0.74
2.6
1.4
1.91
1.1
1.3
1.1
5.1
1.36
0.32
0.72
9.38
0.62
1.1
0.1
0.7
3.5
4.51
1.1
2.1
0.47
64.05
2.3
0
0
0.02
0.05
0
0.01
0
0.04
0.01
0
0
0
0
0
0
0
0.01
0.06
0
0.04
0.2
0
0
0
0
0
0.8
3.6
0
0.9
0
3.6
0.2
0
0
0
0
0
0
0
1.4
1.7
0
3.6
9.5
0
0
0
Maher and Butler 1 988
Kaise ef al. 1 988
Brooke and Evans 1981
Mohri ef al. 1 990
Kaise ef al. 1988
Maher and Butler 1988
Kaise ef al. 1 988
Brooke and Evans 1 981
Shinagawa ef al. 1 983
Kaise ef al. 1 988
Kaise ef al, 1 988
Kaise ef al. 1 988
Kaise ef al. 1 988
Kaise ef al. 1 988
Shinagawa ef al. 1 983
Kaise ef al. 1 988
Mohri ef al. 1 990
Shinagawa ef al. 1 983
Kaise ef al. 1 988
Shinagawa ef at. 1 983
Yasui 1978
Kaise ef al. 1 988
Mohri ef al. 1 990
Kaise et al. 1988
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Tabls 4 Speciated Arsenic Concentrations
Fish/Species
Stephanolepids
cirrhifsr
Stingfish
Stingray
Whiting
Yellowtail
Location
of
Sample
Japan
Japan
Japan
Australia
Japan
Total
Arsenic
(mi/kg)'
4,35
2,9
17,08
2.2
1
Inorganic
Arsenic
(mg/kgl*
0
0
0
0.01
0.03
" Maasursmsnts ar» primarily of muscle tissue (not whole body}
although this is not always plainly noted in the source materials
Percent
Inorganic
Arsenic
0
0
0
0.5
3.0
and assumed to
in Finfish
Source
Kaise et al. 1 988
Mohri et al, 1 990
Mohri ef al. 1 990
Maher and Butler 1
Shinagawa ef al. 1
t>» givan in rng/kg W«t Weight,
988
983
Fish/Species
Abaione
Barnes dilatsts
Clam
Cockle
Crab
Lobster
Table 5
Location
of
Sample
Japan
Japan
Japan
Japan
Japan
Japan
Japan
Japan
Japan
Japan
Japan
Japan
Japan
Japan
Speciated
Total
Arsenic
Cmg/kgJ*
2.6
0.2
3,5
6.8
1.72
6.82
2,8
1.91
1.95
3.17
4.6
4.2
29.6
12.4
Arsenic Concentrations
inorganic
Arsenic
(mg/kgl*
0.01
0.19
0.01
0.03
0.05
0
0.07
0
0.05
0.07
0.08
0.06
0.28
0.09
Percent
Inorganic
Arsenic
0.38
95
0.29
0.44
2.91
0
2.5
0
2.56
2,21
1.74
1.43
0.95
0.73
in Shellfish
Source
Shiorni 1984
Mohri 1990
Shinagawa 1983
Shiomi 1984
Mohri 1 990
Kaise er si. 1 988
Shiorni 1984
Kaise ef si. 1 988
Ranjak 1 984
Flanjak 1 984
Maher and Butler 1
Maher and Sutler 1
Ranjak 1 984
Maher and Butler 1
988
988
988
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Table S
Location
of
Fish/Species Sampl®
Mollusc
Mussel
Oyster
Prawn
Scallop
Hon@Kong
Japan
Japan
Japan
Japan
Japan
Japan
Japan
Japan
Japan
Japan
Japan
Japan
Japan
Japan
Japan
Japan
Japan
Japan
Japan
Australia
Japan
Japan
Japan
Japan
Australia
Australia
Australia
Australia
Japan
U.K.
Japan
Japan
Japan
Speeiated Arsenic Concentrations in Shellfish
Total Inorganic Percent
Arsenic Arsenic Inorganic
Imglkgl* Img/kg}* Arsenic Source
19.4
3
5,1
8.9
33.9
16.8
44,2
36,9
52.2
67,9 ,.
1,02
1.31
1,08
1.64
3.53
17.28
126.92
38.73
123.79
61.61
3
2,4
4.36
4.2
9.S5
6,6
3.17
4.2
8.3
3.6
14
7.2
1.1
1.93
0.3
0
0.07
0.1
0.34
0.02
0.18
0.3
0.57
0.27
0
0
0
0
0
0
0
0
0
0
0,04
0.01
0
0.08
0
0.08
0.07
0.04
0
0,02
0,04
0.04
0.01
0
1,55
0
1.37
1.12
1
0.12
0.41
0.81
1.09
0.4
0
0
0
0
0
0
0
0
0
0
1.33
0.42
0
1.43
0
1.21
2.21
0,95
0
0.56
0,29
0.56
0.91
0
Phillips & Depledge 86
Shlnagawa 1983
Shiomi 1984
Shiomi 1984
Shiomi 1984
Shiomi 1984
Shiomi 1984
Shiomi 1384
Shiomi 1984
Shiomi 1984
Kaise et al. 1 988
et al. 1 988
Kaise et al. 1 988
et a/. 1 988
Kaise et at, 1 988
Kaise et al. 1 988
et at. 1 988
et at, 1 988
Kaise et al. 1 988
Kaise et al. 1 988
Maher and Butler 1988
Shiomi 1984
Kaise et al. 1 988
Shiomi 1984
et al. 1988
Flanjak 1 982
Flanjak 1983
1984
Shinagawa 1 983
Mahur and Butter 1 988
Brook® and Evans 1981
Maher and Butler 1 988
Shiomi 1984
Kaise ef al. 1 988
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Table 5 Speciated
Location Total
Fish/Species
Shrimp
'Measurements are
materials.
Of
Samp!®
Japan
Japan
assumed to be
Arsenic
{mg/kg!*
1.9
1.17
Arsenic Concentrations
inorganic Percent
Arsenic
(mg/kg)*
0.03
0
given in mg/kg Wet Weight,
inorganic
Arsenic
1.58
0
although this is
in Shellfish
Source
Maher and Butler 1 988
Mohri 1 990
not always plainly noted in the source
Seaweed/
Species
Brown,
unspecified
Cystoprion
manitoformus
Estnia bicyrlis
Elkonia radiate
Hinkie fusiforme
Laminariu
jttponica
Nmnaeystus
decipiens
Red, unspecified
Table 6
Location
of
Sample
Japan
Australia
Japarv
Australia
Japan
Japan
Japan
Japan
Japan
Japan
Japan
Japan
Japan
Japan
Japan
Japan
Speciated
Total
Arsenic
{mg/kg!*
19.6
11,4
8,9
9
6,1
1.2
41.31
9.3
8.2
6.1
31.21
49.76
2.5
0.14
21
16.5
Arsenic Concentrations
Inorganic
Arsenic
(mg/kg)'
1.9
0.31
0,2
0,36
0.6
0,48
1.47
5
2.3
3,7
0.23
0
0.08
0.08
0.7
4.7
Psreent
Inorganic
Arsenic
9.69
2,72
3,39
4
9.84
40
3.56
53.76
28.05
60.66
0.74
0
3,2
57,14
3.33
2S.4S
in Seaweed
Source
Le et al, 1 994b
Maher and Butler 1988
Yasui 1978
Maher and Butler 1 988
Yasui 1978
Mohri et at. 1 990
Kaise era/. 1988
Yasui 1978
Yasui 1978
Shtnagawa et al. 1 983
Mohri et al. 1 990
Kaise et al. 1 988
Shinagawa et al. 1 983
Mohri era/. 1990
L« et al. 1 994b
Mohri ef al. 1 990
10
-------
TabS® 8 Speciated Arsenic Concentrations in Seaweed
Seaweed/
Species
Sargassum
bractaolosam
Undaria
pinnatifida
Maesuremartts
materials.
Location
of
Sample
Australia
Japan
Japan
Japan
are assumed to b#
Total
Arsenic
Img/kg}"
7.9
1.78
1.6
0.8
given in ing/kg
Inorganic
Arsenic
-------
findings, revealed inorganic arsenic percentages of approximately one percent for organisms with Sow
arsenic concentrations to approximately half a percent for organisms with total arsenic levels approaching
20 mg/kg, A second linear regression including the Lunde data yielded similar results, none of which
concur with the GESAMP analysis (Edmonds and Francesconi 1993).
Currently, specific data for species in question will provide the best quantification of inorganic
arsenic present. In general, data in table 4 show inorganic arsenic concentrations in fish to range from
zero to one percent of total arsenic concentrations, which is in keeping with Edmond's and Francesconi's
analyses. However, the exceptions of 3.6% inorganic arsenic in saury (Shinagawa et al. 1983, herring
(Brooke and Evans 1981) and hairtail (Mohri et al. 1990), 4.2% in conger (Mohri el al. 1990) and 9.5%
in shark (Yasui et al. 1978) indicate that Friberg's interpretation of 2-10% inorganic arsenic is not
entirely incorrect. Shellfish, because of their bottom-dwelling location and their filter-feeding revealed
slightly higher percentages of inorganic arsenic. Data in table 5 range from 0-2.91%, without any
apparent outliers.
Further investigation into inorganic arsenic content in shellfish has been conducted by Kalman
(1987) who examined human urine following shellfish ingestion. For three weeks, the entire protein
portion of the diet of human volunteers was replaced with either crab, shrimp, oysters, mussels, clams
or squid. While the laboratory conducting this investigation is located in Seattle, Washington, the source
of this seafood in unspecified; furthermore, how and when urine samples were taken is unspecified. Total
and inorganic urinary arsenic concentrations were analyzed; data were presented from subjects consuming
oysters, mussels, crab and clams.
Kalman (1987) calculated percentages inorganic arsenic in the urine, finding a range from 4%
(clam consumption) to 77% (mussel consumption). In the control (no seafood replacement in diet),
inorganic arsenic accounted for over 75%, however, the total urinary arsenic concentration for the control
was over an order of magnitude lower than the experimental subjects. Kalman's inorganic arsenic
measurements represent a total of Arsenic (III), arsenic (V), MMA and DMA (those species detected
from hydride generation preparations). Since a significant amount of organic seafood arsenic is not
expected to be converted to inorganic arsenic via human metabolic pathways (see later discussion on
metabolism), these data seem to point at highly elevated levels of inorganic arsenic in seafood.
As it has been found that most ingested organic seafood arsenic (primarily arsenobetaine) is
excreted in human urine unchanged (see later discussion on metabolism), Kalman's data seem to imply
that a significant portion of the arsenic ingested was inorganic. However, seafood arsenic content is not
reported for comparison. Whether or not seafood came from a contaminated source may also have
influenced type and level of seafood arsenic content. Furthermore, other portions of the subjects' diets
may have influenced the amount and type of ingested arsenic. Kalman's data confirm a need for further
studies to determine how reflective human urinary excretion data are of seafood arsenic content. These
data are presented in table 7, along with speciated data from Kaise « al, (1988) for comparison purposes.
12
-------
inorganic
Species
(Source
Medium)*
Oyster-
oyster tissue
human urine
Mussel
mussel tissui
human urine
Crab
human urine
Clam
clam tissue**
human urine
Table 7
Arsenic
% A$lMS<
(As** &
As**}
0
—
0
—
..
0
3
«
Comparison of
Percentage of
Total Arsenic
in Shellfish and Human Post-Shellfish-lngestion
i
% MWA
0
--
0
--
-
0
0
"
% DMA
5
--
10
„
--
24
17
-•
% Hydrid®
Generating
As I As,W8,
DMA.MMA!
5
57
10
77
4
24
20
48
Urine
%Tri-
methylated
organic As
species
95
43
90
23
96
76
80
52
-Indicates no measurement was made.
'Human urine data from Kalman (1987); seafood tissue data from Kaise et al, (19881.
"Second set of seafood tissue data for clam from Mohri et a/. (199Q),
Pacific Northwest Specwted Data
Data on speciation of arsenic in Pacific Northwest seafood has been collected in conjunction with
regionaJ risk assessment reports. Table 8 lists inorganic arsenic content in six free-swimming fish of the
Lower Columbia River, Percentages ranged from ,45 to 8,5%, making it difficult to generalize among
species (Tetra Tech 1995), Data representing organic arsenic content of seafood connected with the
ASARCO Tacoraa Smelter Site (Parametrix 1993, Parametrix 1995) is presented in Table 9, Since these
data were collected for risk assessment purposes in areas subject to possible contamination, it may be
inappropriate to look at these concentrations in light of determining "background" and/or "safe*
concentrations of inorganic arsenic in fish; however, data are particularly valuable in advancing an
overall understanding of seafood arsenic content within region 10. The context in which these data were
collected is further discussed in a subsequent section of this report.
13
-------
Measurement and Speciation
Methods
Background
Information from
Laboratories
Fish tissue can be
analyzed for arsenic content
either via concentration of
tissue sample to a dried
powder or digestion of tissue
sample. Analysis of dried
powder using x-ray
fluorescence is a multi-
element technique not often
Table
Fish
Species
coho
Chinook
sturgeon
sucker
carp
steelhead
SOURCE:
8 Percentages Asinof9 in Lower Columbia River Fish
Mean AsltW5
Concentration
(00/fl)
0.003
0.013
0.039
0.014
0.001
0.007
Tetra Tech 1 995
Mean As,ot
Concentration
U*S/fl!
0.373
0.960
0.577
0.148
0.221
0.711
Percent Aslrax,
.80
1.4
6,9
8.5
.45
.94
Table
Seafood
Species
striped
seapgreh
(EmbiotocB
lateraiis)
rock sole
mussels
(Mytilus
sp.)
sea
lettuce
9 Arsenic
As+3
Cone.
o.oiu.
O.Q02U-
0.077
0.02-0.05
0.01U-0.04
Concentrations
As+s
Cone,
0.01U
0.002U-
0.082
0.15-0.31
0.19-1.78
in Seafood
MMA
Cone.
0.02U
0.002U-
0.002
0.01 U-
0.02U
0.02U-
0.04U
at ASARCO
DMA
Cone.
(0S/S)'
0.02U
2.2-6.6
0.01 U-
0.02U
0.02U-
0.04U
Tacoma Smalter Site
"Si^g "Swt
Cone. % Cone.
I0g/gl" Aslno,8" 108/81*
0.01 1.9
0,6-8.6
0,17-0.3$ 9.4
0.2-1. 82
'SOURCE: Weston (1996}
"SOURCE: TsujH1993!
employed for measurement of trace contaminants due to its 1-2 ppm detection limit, but it may sometimes
be appropriate for arsenic measurements (personal communication with Dr. Eric Crecelius, Battelle
Northwest Laboratories, 03/01/96). Most frequently, however, arsenic speciation in fish tissue is begun
with a digestion. How aggressive the digestion is will effect the extent to which arsenic compounds will
S4
-------
be available for detection. Total arsenic measurements mandate a more aggressive digestion than
inorganic arsenic only measurements. Conditions related to the arsenic-containing medium can effect the
digestion efficiency. For example, in order to measure total arsenic in some slags, a particularly
aggressive digestion was employed in order to insure release of the arsenic from a silica rind (personal
communication with Dr. J. Lowry, NEIC lab, 02/27/96).
Standards can help to assess the recovery efficiency of a particular digestion system. However,
standards represent optimal analytical bias (personal communication with J.Lowry, 02/27/96) and for
many species standards are not available. Dr. Lowry suggested that total arsenic standards are available
in an albacore tuna medium and a new arsenobetaine standard in a shellfish medium may also be available
(personal communication, 02/27/96). Dr. Lowry also discussed some of the limits of hydride generation,
noting that-the arsenic-organic bond is not necessarily broken, and for detection purposes, it'must be
cleaved. Furthermore, he noted that a microwave system is not necessarily an optimaJ approach to total
arsenic detection because the pressure build-up of a closed system becomes the rate-limiting step;
however, the newer, focused microwave system allows for settings which do not volatilize the arsenic,
thereby enabling operation of an open system (personal communication with J.Lowry, 02/27/96).
Samples
Most experiments addressing detection methods have measured arsenic from laboratory distilled
water and other liquid samples, including seawater, freshwater, urine and blood. Detection of arsenic
from fish tissue has relied upon digestion techniques, For hydride generation techniques, which do not
speciate among various organic arsenic compounds, digestion techniques involving virtually
indistinguishable breakdown of organic compounds are sufficient. However, for more specific
chromatographic techniques, more sophisticated extraction procedures must be used. As discussed below,
investigations into more sensitive detection procedures is ongoing; such extraction methods will depend
on the needs of specific detection techniques. The importance of developing such techniques is discussed
briefly by Vela et al. (1993), who suggest that supercritical fluid extraction (SFE) may show promise.
Seafood may also be dried into a powdered form which can be analyzed for total arsenic using x-ray
fluorescence; however, this is a multi-element technique not often applied to environmental samples due
to its high detection limit, on the order of 1-2 ppm (conversation with E.Crecelius 03/01/96).
Defection and Spedation
Historically, arsenic measurement in biota and environmental media have reflected total arsenic
content. Arsenic from inorganic species has been grouped with arsenic from organic species; arsenic in
water soluble structures has been grouped with arsenic in iipophilic structures. Differences in the
physiological effects of various arsenic compounds were just beginning to be articulated by Coulson and
in the earlier half of the twentieth century (Lunde 1977). It was not until the nineteen eighties and
15
-------
nineties that reasonable laboratory speciation techniques allowed for such detailed measurements; current
methods, however, are still in need of refinement,
The most efficient approach to arsenic speciation/detection should be one in which a single
procedure allows for speciation and identification of each individual arsenic species, both organic and
inorganic. In keeping with toxicity and regulatory exposure data, detection ability would be in the range
of parts per billion (ppb). Furthermore, such a method could be employed with environmental samples,
animal tissue samples, and blood and urine samples. Recent developments by Le et al. (1994b), Ataliah
and Kaiman (1991) and Momplaisir et al. (1994) have advanced this line of thinking. The following
paragraphs discuss the development of their procedures as well as current limitations.
One of the most common approaches to measuring inorganic arsenic and its human metabolites
is the hydride generation (HG) preparation and subsequent detection, usually by atomic absorption
spectrophotornetry (AAS). Hydride generating methods, while able to detect arsenic in the parts per
billion range, are limited. Two drawbacks have been discussed: (1) HG can cause an underestimation
of arsenic present because of DMA's slower reaction rate. (2) HG has a tendency to produce non-linear
standard curves, leading to overestimated results at low concentrations when linear regression analysis
is used to estimate the calibration equation (Murer et al, 1992b).
Le et al. (1993) found that addition of cysteine to the reaction will stabilize the DMA alleviating
the need to significantly lower pH, which would create non-optimal conditions for the other species.
Murer and colleagues (1992b) suggested that the use of standard additions and flow injection analysis
(FIA)-AAS appears capable of monitoring long-term, low-dose exposures. This method has two primary
limitations: a 20% reduced recovery of arsenate, and inability to address organic arsenic species found
in seafood. Murer et al. (1992b) further recommended use of Larsen's recently optimized Zeeman-AAS
methods. While detection limits for these techniques are reasonable, they do not speciate and measure
organic arsenic species commonly found in seafood (KaJman 1988, Hanna et al. 1993).
In order to account for these trimethylated arsenic species (i.e., arsenobetaine and arsenocholine)
a strong acid digestion, or other manipulation, is required prior to hydride generation and subsequent
detection (Le et al. 1993, Le a al. 1994b, Buchet et al. 1994, Mohri et al, 1990, Kaise et al, 1988).
A common digestion is conducted using nitric, sulfurie and perchloric acids (Fanner and Johnson 1990).
In 1992, Navarro et al. introduced a microwave dissolution in a closed teflon bomb; this technique
accelerated digestion. More recently, Le et al. (1993) attempted a microwave oven digestion aided by
potassium persulfate and sodium hydroxide; this method convened organoarsemeals to arsenate, but
recovery was poor. Experiments in microwave digestion continue (Sheppard et al, 1994)
Following digestion of the trimethylated arsenic species, HG preparation may be used and
concentration may be measured utilizing AAS or atomic emission spectrometry (AES) techniques.
Concentration of seafood organic arsenic is then calculated as the difference in arsenic concentrations
16
-------
detected in samples with and without the strong acid digestion step. This method does not allow for
speciation of the trirnethylated compounds.
A chromatographic system can be employed to separate out arsenic species, Nixon and Moyer
(1992) found that silica-based cation-exchange cartridges allowed for a faster fractionation over HPLC
columns. A chromatographic system utilizing inductively coupled plasma (ICP) and AES can detect all
arsenic species without a need for chemical alteration (e.g., hydride generation). However, the sensitivity'
of such a method is approximately 35 times less than that of the HG-AAS system (Murer et al. 1992a).
Replacing the AES with mass spectrometry (MS) improves sensitivity significantly (Larsen et al. 1993a);
however, this technique has not been widely tested and MS equipment costs may be prohibitive.
While chromatography can assist in separation of arsenic compounds, its application is not
entirely straightforward. Arsenic (III), arsenic (V), MMA and DMA can be separated with an anion
exchange column; but arsenobetaine and arsenocholine require a cation exchange column. Le et al,
(1994b) implemented such a two-column system using one column to separate inorganic species, their
metabolites and arsenosugars, and the second column to separate arsenobetaine and arsenocholine. Murer
et al. (1992a) found that running the two exchange columns in series produced arsenic (V) and
arsenobetaine as co-eiutants, Le et al. (1994a) avoided this problem by using a polymer-based anion
exchange column. Improvement to HPLC-ICP-MS techniques has been achieved with the elimination
of chloride interference (Story et al. 1992). Desemay et al. (1994) were able to employ HPLC-ICP-MS
techniques with detection limits of arsenic species ranging from ten to thirty picograms.
An alternative system has been developed dependent upon HPLC separation of arsenic species
followed by conversion of all arsenic species to arsenate using an on-line photo-oxidation system;
subsequent detection is conducted with AAS (Atallah and Kalman 1991). Atallah and Kalman's method
has only been shown to work with aqueous solutions and may be impeded by ammonium ion and urea
interference with photo-oxidation. Capillary zone electrophoresis (CZE) also shows promise for
separation of species (Vela et al, 1993), but it has yet only been used to separate arsenic III, arsenic V,
MMA and DMA (Li and Li 1995, Lin et al. 1995).
Applications of gas chromatography (GC) are discussed by Kalman (1987) and Kaise et al.
(1988). Kalman (1987) incorporated a GC separation into the HG-AAS approach, but it was only
applicable to inorganic arsenic plus its metabolites. Kaise et al. (1988) used GC-MS for detection of
arsenic compounds following alkaline digestion and subsequent sodium borohydride reduction. Their
system demonstrated successful separation and detection. One limitation was that arsenocholine was not
converted to trimethylarsine (TMA) as other trimethylated arsenic species were. Also, this method
would not be able to detect separate trimethylated arsenic species as they should all have been digested
and reduced to a single compound, TMA. Another potential drawback to this detection method is that
arsenosugars are converted to DMA, and therefore could not be distinguished (Le et al. 1994b, Mohri
1990).
17
-------
Momplaisir el a/., (1994) have tried yet another approach to arsenic speciation: on-line hydride
generation. Using a specially designed silica T-tube, the authors were able to interface HPLC with AAS
detection. Species were first separated on a cyanopropyl chromatographic column prior to on-line
therrnochemical hydride generation, which enabled conversion of all arsenic species, including
trimethylated compounds, to their respective hydrides. Both inorganic arsenic species, and their
monomethyl and dimethyl metabolites, in addition to arsenobetaine, arsenocholine,
phosphorylarsenochoiine and tetramethylarsonium ions, were completely separated from each other.
Further investigation and possible refinements to this method must be executed; however, it appears
promising.
Current Detecnon/Speciation in the Northwest
Arsenic speciation data for both the Lower Columbia River study (Tetra Tech 1995) and the
ASARCO Tacoma Smelter Sediment Site (Parametrix 1993, Parametrix 1995) were determined at Battelle
Pacific Northwest Laboratories (conversation with Battelle PI, E.Crecelius 03/01/96). The method that
Battelle is employing is a difference method, determining inorganic arsenic content separately from total
arsenic content; organic arsenic is calculated from the difference in totals. Total arsenic measurements
are performed using a nitric acid digestion followed by ICP-MS analysis. Inorganic arsenic detection
requires a milder digestion, and has been accomplished using hot dilute acid (e.g. 2M HC1 solution) or
base leach (e.g. 2M NaOH solution). This digestion is followed by the hydride generation-AAS detection
approach which speciates among trivalent and pentavalent inorganic arsenic as well as MMA and DMA
(Battelle 1986).
The relative advantages and disadvantages of these methods have been discussed above.
Depending on the outcome of studies into toxicity of organic arsenic found in seafood and determination
of northwest seafood arsenic species (particularly regarding arsenocholine), a method able to speciate
trimethylated organic arsenic compounds may not be necessary. Furthermore, Battelle's method does
allow for separate speciation of DMA, the carcinogenic potential of which is currently under
investigation. Hence, this method may be sufficient for regional needs.
Exposure Assessment
Sources Assessed
Table 10 outlines the exposure concerns generally assessed in arsenic exposure assessments. As
indicated by McKone and Daniels (1991), drinking water ingestion and food ingestion are the primary
exposure pathways of concern. Drinking water contributions to arsenic intake have been of concern in
locations with elevated arsenic concentrations in the drinking water supplies; this arsenic tends to be
mostly inorganic. A review of selected studies was conducted by Brown and Chen (1994). A survey
18
-------
of dietary arsenic
contributions of *"ma™ms**^
Tabit 10 Human Arsenic Exposure Points Commonly Assessed*
various food
groupings was Air Gfound' Surface Soi! Food
water Water Chain
COndUCted in SiX =a=ss=s=ai i^~Jaii~-J^r^-Jiaaa—r; an-=, 'is.,, • -= SI-TIT. - • aassag- .....———-
Canadian cities. Of inhalation 0,P :»
dietary intake, fish ingestion --- P — P" p
contributes the Derma! Contact
greatest percentage -=-=-^--=-.-^==*=- ===:=:== —^s==^ =, .=:t= . _
.. ,, . 0 indicates specific to occupational exposures; P indicates general
of arsenic with the papulatim exposures.
meat and poultry "Soil ingest/on is most commonly associat&d with childho&d exposure in
grouping a distant ^rMOfn^semarto^^^^^^^^^^^^^^^^^^^^^^
second; mean
concentration of
total arsenic was
1662 ng/g (an average of 64%) for fish and 24.3 ng/g for mean and poultry (Dabeka et a/. 1993).
Marine fish contained more total arsenic than freshwater fish and shellfish arsenic content fell between
the two.
Consistent results are reported by the USEPA (1988) and Leonard and Lauwerys (1980). USEPA
determined, from FDA studies, that average dietary intake of inorganic arsenic is approximately 50 jig,
approximately 80% of which is accounted for by the meat, fish and poultry component of the diet.
Leonard and Lauwerys report that average daily oral intake of total arsenic ranges from 0,5-4.2 mg/day,
depending on diet. They also note that inhalation exposure to arsenic has been measured at under 1
fig/day for nonoccupational exposures. Hence, ingested contributions for the general population are of
greater concern. Bennett (1981) completed his own study to determine representative dietary total arsenic
intake from terrestrial foods was about 40 pg/day and from seafood was about 80 ^g/day. Bennet tallied
one year of human ingested arsenic to amount to a total of 15 mg from terrestrial foods, 33 mg from
aquatic foods and 0.5 mg from drinking water, or 48.5 mg-As/year. This translates to an average of 133
|ig-As/day.
Consumption of Seafood
Default Ingestion Rates
The US EPA draft Exposure Factors Handbook (1995) breaks down fish consumption rates into
four categories: general population, recreational marine anglers, recreational freshwater anglers and
Native American freshwater anglers. The EPA lists several intake rates for each category, rather than
calculating a combined mean rate because of differences among individual surveys. Table 11 outlines
19
-------
Table 11 United States Fish Intake Rates
Average*
fi/day)
95*
Percent!!®
!g/day»
general population
- per capita
general population
- consumers only
recreational marine
anglers
recreational freshwater
anglers
Native American
freshwater anglers
11-17"
117-124
37-50*"
7-24
63-305
42
284
146-339
107""
15-94
170-913 *
the intake rates presented in the Draft
Exposure Factors Handbook. It is
noted that recreationai marine anglers
consume more fish than recreational
freshwater anglers.
The EPA recommends that
whenever possible, consumption rates
for the population(s) involved in a
given risk assessment be specifically
investigated because data will vary
with location, climate, season and
ethnicity of the angler/consumer
population^). If such a study is not
possible, data from EPA should not
be averaged; data from a study with
similar characteristics to the
population and location of concern
should be chosen from those in the
recommendations section of the
Exposure Factors Handbook (EPA
1995), The EPA also recognizes that ««»™"^^
consumption of fish internal organs
may increase exposure to certain
contaminants. Two attributes of fish concentration data should be carefully noted: (1) Is concentration
given in units of contaminant per gram of fish bodyweight or in units of contaminant per gram of fish
fat content? (2) Is the concentration given in wet weight or dry weight terms? It is important that
consistent units be applied for comparison purposes. A Canadian study reports that for both freshwater
and marine species, cooked fish contains a higher concentration of arsenic per gram of fish bodyweight,
However, this increase in concentration agreed closely with the resultant decrease in weight from the
cooking process (Dabeka et d. S993),
Northwest Seafood and Other Fish
Seafood and fish consumption in the northwestern United States includes a diverse set of
organisms. Both marine and freshwater systems provide food to surrounding populations; some diets
include fish from both sources, some from only one. There are numerous subpopulations in the
northwest, each of which consumes a distinct set of these organisms. Subpopulations are divided by
ethnicity, profession, and location. Unfortunately, specific, detailed studies regarding types of seafood
consumed have not been carried out for these northwest populations. Table 12 lists marine and
Average presented is tn arithmetic mean,
"These valuta nfltet consumption of fish from »H sources
including stars-boughs, canned, seff-csught, etc.
'"Ths study with t msmn of SO yielded a median of 21,
""The 107 is t 9Q* percent/I*.
* These percent/las were listed as "upper percsnti/as * and were
not funhw specifi&ti.
SOURCE: USEPA 1995
20
-------
freshwater organisms that comprise part of the diet of at least one northwest subpopulation. Local studies
have been conducted, around the lower Columbia River and in Puget Sound, to determine fish
consumption rates. Results of these studies are presented in Table 13.
Tabl® 12 Seafood Consumed
Fish/Species
FINFiSH
Albacore tuna
Atlantic cod iGadus morhua]
Bass, striped
Bluefin tuna
Buffalo fish
Cabezon
Carp
Catfish, channel
Chinook salmon
Coho salmon
Eel
Eel, conger
Eulachon jcandlefish)
Filefish (Stephanotepic cirrhifisr]
Flounder
Greenling
Grtenling-- ling cod
Hairtail Ibsitfishl
Halibut
Herring
Japanese striped knifejaw (Oplegnathus
fascfaws)
Largtscale sucker
Pacific cod (Gadus macrocepitalus)
Pacific flounder (Platichthys stellars]
Pacific hake fwhiting)
in the Northwest
Aqueous
Environment
marine
marine
freshwater
marine
freshwater
marine
freshwater
marine
freshwater
freshwater
freshwater
marine
marine
marine
marine
marine
marin®
marine
marine
marine
marina
freshwater
marin®
marine
marine
Source"
local
imported
imported
imported
imported
local
local
local0
local
focal
imported
imported
local
imported
imported,
local
local
local
imported
local
local
imported
local
local
local
loca!
21
-------
Table 12 Seafood Consumed
Fish/Species
Pacific mackerel IScontier japonicus)
Pacific smelt
Pile Perch (Rhacocheifus vacca)
Pmumatophortts jsponicus
Pomfret
Rabbit fish (Sfganus fuscescens)
Rainbow trout (onchorhynchus mykiss)
Rock fish
Sablefish fblack cod)
Salmon
Saury
Shark
Sinx Peron (Embiotocidae]
Skate
Skipjack tuna
Smelt
Sole
Squawfish (PtychocheiSus}
Steelhead trout
Stingray
Suckers (Catastomus)
Tai/Sgabream IChrysophrys major)
Ulapia
White sturgeon
Yellowfin tuna
in the Northwest
Aqueous
Environment
marine
marine
marine
marine
marine
marine
freshwater
marine
marine
marine
marine
marine
marine
marine
marine
marine
marine
freshwater
freshwater
marine
freshwater
marine
freshwater
freshwater
marine
Soures*
local
local
local
local
imported
imported
local0
local
local
local0
locai
local,
imported
local
local,
imported
imported
local
local,
imported
local
local
imported
local
imported
localc
local
imported
SHELLFISH/OTHER
Abalone
Clam/cockie
marina
marine
imported0,
local
local,
imported
22
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Table 12 Seafood Consumed
Fish/Species
Conch
Crab, blue
Crab, Pacific dungeness
Crab, Alaskan king
Crab, red rock
Crab, tanner
Crayfish
Freshwater prawn {Macrobrachium)
Goose barnacles
Herring roe
Lobster
Mantis shrimp (PseudosQuillal
Moon snail
Mussel
Octopus
Oyster
Saltwater prawn
Scallop
S®a cucumber
Sea urchin
Sea urchin roe
Shrimp
Squid
in the Northwest
Aqueous
Environment
marine
marine
marine
marine
marine
marine
marine,
freshwater
freshwater
marine
marine
marine
marine
marine
marine
marine
marine
marine
marine
marine
marine
marine
marine
marine
Source*
imported
imported
local
local
local
imported
local
imported
local
local
imported
imported
local
local,
imported
local,
imported
local,
imported0
local,
imported
local,
imported0
local,
imported
local
local
local,
imported
local,
imported
23
-------
Fish/Species
Table 12 Seafood Consumed in the Northwest
Aqueous
Environment
Source"
'Local includes sny organisms harvested for human consumption from
Alaska, Idaho, Oregon or Washington. Imported implies from another
state or nation,
e'Indicates a cultured species
SOURCE: Consultation with Dr, C.Michael Watson, USEPA Region 10
Toxicologist. November 1995.
Table 13 Northwest Fish Consumption Rates
Study Group
Shore and boat
Arithmetic
Mean
Ig/dsy)
39
50th
Percentile
(g/day)
10
iOth
Percent!!®
Ig/dayJ
78
Source
Pierce st »/. 1981
anglers - some
shellfish, no salmon
Shore anglers - no 55
shellfish
Boat Anglers 15
Squaxin population 54
Squaxin - shellfish 13
only
Lower Columbia 63.2
River population
25
5
33
5
38.9
157 Tens Tech 1988
45 TatraTeoh 1988
161 Toy et a/. 1995 draft
41 Toy si st. 1395 draft
97.2 CRITFC 1994
Seaweed Consumption
Seaweed consumption in the northwest is not weS! defined. Little to no local seaweed is available
at the locaJ markets in the Seattle area (personal visits); hence, most local seaweed of concern is gathered
independently and non-cornmerciaJSy. Currently, an investigation into the eating habits of Asian-Pacific
Islander populations in the northwest is underway (personal communication from Dr. R.Lorenzana,
USEPA Region 10 Toxicologist, 11/95). Results from this study may help to identify northwest seaweed
species of concern. Common forms of marine algae ingested by Japanese populations include Japanese
nori, wakame, konbu and hijiki; scientific classification of these species, respectively, are; Porphyru
spp., Undaria pinnatifida, Laminaria spp. (mostly Laminariajaponica) and Hizitia-Jusiforme (Edmonds
24
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and Francesconi 1993). As indicated above, seaweed consumption is of concern because of the significant
percentage of Inorganic arsenic which it contains (see table 6), However, this percentage varies greatly
with species, and therefore, arsenic content of particular northwest species of concern should be assessed.
In Washington state, for example, while absolutely no commercial seaweed harvesting is
permitted, recreational harvesting to a maximum of ten pounds wet weight per day is allowed.
Prevention of commercial harvesting is strongly enforced by the state, but enforcement of recreational
limits is somewhat loose. Hence, small scale resaJe ventures may occasionally occur (conversation with
T, Mumford, WDNR, 03/04/96). Tom Mumford of Washington state's Department of Natural Resources
(conversation 03/04/96) provided some information about seaweed species gathered in Washington. Four
species commonly gathered and ingested are Sargassam muplcum, Alaria marginata, Laminaria
groenlandica and nereo cyspis (also called bulk kelp, a floating variety with a long hollow stalk ending
in a bulb with blades- blades are ingested portion). The first of these species, the Sargassam, is closely
related to the Japanese Hizilda, which is known for high arsenic concentrations. Korean populations in
Washington are known to gather the Sargassam and pickle it into a spicy, kimchi-like dish, hence further
knowledge of its speciated arsenic content is of great interest (conversation with T. Mumford, WDNR,
03/04/96).
Potential Tools
The Exposure Commitment Method was developed by the Monitoring and Assessment Research
Centre (MARC) to (1) allow for comparisons between exposure pathway contributors, and (2) to estimate
equilibrium concentrations which will be established based on continued release of a contaminant. Bennet
(1981) illustrates the application of this method to arsenic. The following exposure analysis, based on
a unit exposure of 1 mg/year, is described: ingestion of one mg-terrestriaJ foods/year contributes 0.28
jig-total-arsenic/kg-BW to a person; and ingestion of one mg-seafood/year contributes to a concentration
of 0.14 /ig-organic arsenic/year. This exposure commitment method is designed as "a time-independent
approach to pollutant assessment" and measures both intensity and duration of a contaminant's
environmental presence.
Bennett used the model to discover the following. He found that representative dietary total
arsenic intake was about 40 |*g/day from terrestrial foods and about 80 |ig/day from seafood. Greater
than 80% of dissolved Inorganic arsenic is absorbed across the gastrointestinal tract and organic arsenic
is "readily" absorbed. Organic forms of arsenic are found to be retained in the body only about half as
long as inorganic forms. In his analysis, Bennett assumes that aquatic intake sources provide organic
arsenic only, and that a 90% absorption of this arsenic across the gastrointestinal tract is expected.
Inorganic arsenic was determined to have an 8-day residence time and organic arsenic to have a 4-day
residence time. This exposure commitment method is not readily found in subsequent arsenic literature,
however, it may be a useful tool for risk assessments.
25
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Pathway Exposure Factors (PEFs) were introduced by McKone and Daniels (1991) to describe
the relationship between environmental concentrations of contaminants and human exposures to those
contaminants, A PEF is given in as a lifetime-equivalent chronic daiiy intake in units of mg/kg-day;
these values are both medium-specific and exposure route-specific (e.g., one PEF may be for ingestion
of soil and another for dermal uptake from water). Arsenic is used as an example. The authors assume
that arsenic's movement in the environment is governed by its solubility and its attachment to mobile
particles. Major pathways for arsenic exposure are ingestion associated with soil-based pathways and
ingestion connected with water-based pathways (i.e., ingestion of fruits, vegetables, grains, drinking
water and fish). No distinct values are provided, but again, this may be a useful tool for arsenic risk
assessments.
CONSIDERATIONS FOR TOXICITY ASSESSMENTS
The toxicity of arsenic is highly dependent upon its species and its valence state (Leonard and
Lauwerys 1980, Vahter 1994, Edmonds and Francesconi 1993) In general, inorganic arsenic has greater
toxicity than organic arsenic; trivalent arsenic is more toxic than pentavalent arsenic. However, there
are certainly exceptions to this generalization, as well as potential areas for research which could further
refute it. Arsenic species associated with seafood are fairly representative of the variety, though not the
distribution, present in the overall environment. Finfish and shellfish primarily contain trimethylated
arsenic species (i.e., arsenobetaine and arsenocholine), while seaweed tends to concentrate organosugars
(Vahter 1994). Inorganic arsenic is also present is some seafood, but at significantly lower levels than
organic arsenic species (Edmonds and Francesconi 1993). Seaweed can be an exception to this as some
forms contain up to 60% of total arsenic as inorganic arsenic (Shinagawa et al. 1983). How each arsenic
compound is treated by the body is dependent on many factors. For example, absorption of either
inorganic or organic arsenic species from the gastrointestinal tract is partially dependent on the water
solubility of the given compound (Hindmarsh and McCurdy 1984).
Metabolism
Inorganic Arsenic and Methylated Metab<tes
Inorganic arsenic is absorbed across the gastrointestinal tract, although not as efficiently as many
water soluble organic arsenic species. Inorganic arsenic is excreted by humans in feces in small, well-
defined amounts (Tarn et al, 1982). Fecal excretion of ingested soluble forms of arsenic have been
measured at levels as low as 3.5% for trivalent and 6% for pentavalent arsenicals; however, insoluble
arsenicals have low absorption (Hindmarsh and McCurdy 1984). Recovery rates of arsenic from human
urine range from 48% to 86% (Johnson and Farmer 1991, Buchet et al. 1994, Crecelius 1977).
Johnson and Farmer (199 i) studied one volunteer consuming single doses of 66 ^g-arsenate/day
for ten consecutive days and two volunteers each consuming a single dose of 220 p.% arsenate. For the
tea day study, only 48.2% arsenic was recovered in urine after eighteen days; for the single dose study,
26
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66.4% arsenic was recovered from urine within seven days. Interpretation of data should consider that
different measurement techniques were used to determine the amount of arsenic ingested and amount
excreted. However, this study does raise the question of the validity of single dose studies for estimating
percentage of dose retained in the body.
Once absorbed into the bloodstream, arsenate (As(V)) cars be reduced to arsenite (Asflll)), which
tends to exist in protonated form at physiological pH (Vahter 1994). Arsenic (III) is methylated to
monomethy! arsenic (MMA) and dimethyl arsenic (DMA) (Thomas 1994). Buchet and Lauwerys (1994)
found that it takes several hours following ingestion of inorganic arsenic for the methylated derivatives
to be the primary arsenicals excreted in the urine. It has been suggested that at a given exposure dose
the methylation capacity may become saturated (Thomas 1994, Smith et al. 1992); Buchet and colleagues,
in 1981, proposed the saturation point to be at 500 pg/day (Carlson-Lynch et al. 1994). (Methylation
saturation is an ongoing debate and is discussed in more detail below.)
Methylation has been considered the detoxification pathway for inorganic arsenic; however, this
is currently under debate (see discussion on DMA toxicity below). Both methylated and unmethylated
arsenic forms are excreted in the urine. For example, Hindmarsh and McCurdy (1984) report an
experiment with humans who had ingested wine rich in arsenite: 50% of the arsenic was excreted as
dimethylarsinic acid, 14% was methylarsonic acid and 8% was excreted as inorganic arsenate and
arsenite. The mono- and di-methylated forms are excreted more efficiently than the unmetabolized
inorganic arsenic (Vahter 1994). It has also been proposed that inorganic arsenic detoxification may
occur via protein binding (Snow, 1992), but extensive discussion of this possibility is not available.
In their review, Hindmarsh and McCurdy (1984) discuss the body's retention of inorganic arsenic
species. Inorganic arsenic, particularly from trivalent exposures, is retained by the body with increasing
percentages as dose increases. This may be due to decreasing methylation efficiency. At lower doses,
inorganic arsenic retained by the human body is deposited in hair, skin and nails. Studies in mice show
that arsenic retained by the body subsequent to inorganic arsenic exposure is retained in the skin,
epithelium of the upper gastrointestinal tract, epididymis and the stomach wall. Trivalent and pentavalent
forms show similar distribution patterns; in general, pentavalent arsenic experiences shorter retention
times than trivalent arsenic.
Dimethylarsenic
In general, DMA is very stable to chemical degradation and is not decomposed by hydrochloric
or nitric acids, even with heating; however, microbial demethyiation has been demonstrated. DMA
administered to mice, rabbits, and humans has been recovered in urine. In rats, significant demethyiation
of administered DMA has not been observed (Vahter et al. 1984). Vahter and colleagues (1984)
performed a study on the metabolism of DMA, as administered orally to mice and rats. Eighty percent
of the oral dose of DMA was absorbed from the gastrointestinal tract. After three days, mice had
27
-------
eliminated over 99%-of the dose, and rats, about 50%. The rats tended to accumulate the DMA in red
blood cells. For mice, highest initial concentrations were in the kidneys, lungs, intestinal raucosa,
stomach and testes. The organs, in mice, with the longest DMA retention times were lungs, thyroid,
intestinal walls and lens. A previous study with cows showed DMA accumulation in liver, spleen and
pancreas. In the Vahter study, no demethylation of the DMA was observed, although some DMA in
tissues was in a complexed form.
As an Essential Element
Various animal studies have suggested that arsenic may be an essential element to the human diet
(Neilsen 1990). Walkiw and Douglas (1975), Hindmarsh and McCurdy (1984) and Shibata ei al. (1992)
have reviewed many such studies to conclude that insufficient evidence exists to confirm this hypothesis.
In an experiment with rats, a group without supplemental arsenic in its feed was shown not to grow to
the extent that a group with supplemental arsenic did. However, Hindmarsh and McCurdy caution that
simply because an agent has a positive effect on growth does not make it essential; the mechanism of
arsenic action as a growth promoter is not yet adequately understood to make such a determination.
Furthermore, in order to be an essential element, the agent must play a unique role, and none has yet
been demonstrated for arsenic (Hindmarsh and McCurdy 1984). EPA's risk assessment forum
acknowledges that information to establish this is weak though incomplete incomplete and recommends
that the likelihood be "weighed qualitatively along with risk assessment information for carcinogenic
effects" (USEPA 1988).
Organic Arsenic Species found in Seafood
Organic arsenic found in fish and shellfish has been shown to be efficiently absorbed from the
gastrointestinal tract and to be rapidly excreted in unchanged form (Lunde 1977, Tarn et al. 1982). Yet,
it was not until 1977 that Edmonds el al, isolated and identified the predominant seafood organic arsenic
compound, arsenobetaine, from rock lobster (Vahter et al, 1983). Coulson's early experiments with rats
in the 1930s demonstrated that a greater percentage of inorganic seafood arsenic (18%) than organic
seafood arsenic (0.7%) was retained over time, three months in this case (Lunde 1977).
More recent experiments have confirmed the low retention time of organic arsenic in seafood.
Freeman et al, (1979) conducted a study on six male volunteers who, in a single day, consumed two
meals containing a total of 5 pg of "seafood arsenic". After eight to nine days, little arsenic was still
being cleared from the urine of five subjects; and a mean of 77% of the total "seafood arsenic" ingested
had been cleared. In 1982, Tarn et al. calculated similar results: 15 men consumed a single meal offish
containing 10.1 mg of "seafood arsenic" and, after eight days, had renally excreted 76% of the total.
Generally, urinary excretion of seafood arsenic ranges from 60-70% in humans (Tarn et al. 1982, Vahter
1994), with some exceptions; Jongen et al. (1985) cite several reports of at least 80% of arsenic ingested
via human fish consumption being eliminated in urine within a few days.
28
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More extensive studies on the distribution, retention and biotransformation of arsenobetatne and
arsenochoiine have been conducted by Vahter, Marafante and their colleagues (Valuer et al. 1983,
Marafante et a/, 1984) and by Christkopoulos et al. (1988a). Research from both groups supports the
theory that, in marine environments, arsenochoiine is a precursor of arsenobetaine. The Vahter and
Marafante studies were performed by exposing mice, rats and rabbits to radio-labeled "As arsenobetaine
or arsenochoiine, while the Christkopouios study was performed with rat liver hepatocytes. Marafante
et al, (1984) explore two proposals regarding the metabolic fate of arsenochoiine: (i) Arsenochoiine is
incorporated into the phospholipids as choline is, (2) Arsenochoiine is oxidized to arsenobetaine,
Rodent exposures to arsenobetaine (Vahter et al. 1983). BAs arsenobetaine was administered
both orally and intravenously to mice, rats and rabbits. As with humans, the primary route of excretion
was urine. A very smaJl percentage of the dose was excreted in the feces of intravenously exposed
rodents; and only a smaJl amount was found in the feces of orally exposed mice. Nearly all arsenobetaine
was excreted by rats and mice within three days, while 74% had been excreted by rabbits. The latter is
comparable to human excretion of seafood arsenic (Freeman et at. 1979, Tam et al. 1982). In all cases,
greater than 99% of the radio-labeled urinary arsenic was in the form of arsenobetaine; no radio-labeled
inorganic or methylated arsenic acids were found in urine. Clearance of arsenobetaine from most tissues
in mice appeared to be described by first order kinetics. Due to the low retention times, reasons for
retention, such as a specific binding, could not be established. Tissues with comparably lengthy retention
times included testes, epididymis, seminal ducts and seminal vesicles for ait three rodents, and also
muscle in the rabbits. These are obviously different retention locations than those for inorganic arsenic.
The rabbits demonstrated a significantly longer tissue retention time than the mice.
Rodent exposures to arsenochoiine (Marafante et al. 1984). ^As arsenochoiine was administered
both orally and intravenously to mice, rats and rabbits. Nearly all of the arsenocholine administered
orally was absorbed across the gastrointestinal tract. As with arsenobetaine, the primary route of
excretion was urine; in all three species, 70-80% of the total dose was excreted in urine within three
days. Unlike with arsenobetaine, the unmetabolized form of arsenochoiine was only present in urine in
significant amounts on the first day and accounted for only about ten percent of the total dose. Retention
times for arsenochoiine, as observed over four weeks of study, regardless of the exposure route, were
significantly higher than for arsenobetaine. Rabbit tissue levels averaged five times, and rat tissue three
times, that of mice. After three days, concentration of radio-labeled arsenic in the brain, though low
compared to other tissues, was three to four times that in the blood. Extractions from mice showed over
90% of water-soluble arsenic to be in the form of arsenobetaine. The tissue distribution of arsenochoiine
was similar to that of arsenobetaine. The elimination of arsenochoiine appeared dependent on the rate
of oxidation of arsenochoiine to arsenobetaine in tissues; elimination from most tissues appeared to follow
first order kinetics. Arsenic distribution throughout the body following uptake of arsenochoiine is likely
reflective of the distributions of both arsenobetaine and phosphatidy! arsenochoiine (synthesized via
choline kinase and incorporation into phospholipids).
29
-------
Biotransformation of arsenocholine (Christkopoulos et al. 1988a). Rat liver hepatocytes were
incubated separately with arsenobetaine and arsenocholine. In the incubation of arsenocholine, the
biotransformation to arsenobetaine occurred via the formation of arsenobetaine aldehyde; and the volatile
compound liberated during arsenocholine oxidation was found to be trimethylarsine (TMA).
Trimethylarsine oxide (TMAO) was formed in a side reaction, presumably from arsenobetaine aldehyde,
during the oxidation process. Despite formation of TMA and TMAO, most arsenochoiine was
metabolized to arsenobetaine; however, experiments with arsenobetaine have not revealed formation of
TMA or TMAO. In humans, arsenobetaine is excreted in the urine; however, trimethylarsine oxide may
be reduced in vivo to trimethylarsine, one of the more toxic forms of arsenic.
In Seaweed
Inorganic arsenic found in marine algae is primarily in the form of arsenosugars comprised of
a pentavalent arsenic atom bonded to two methyl groups, an oxygen atom and a carbon atom of a ribose
sugar (Edmonds and Francesconi 1993). Such dimethylarsenosugars are suspected to undergo degradation
to DMA, but this is still uncertain (Vahter, 1994). However, there is a great deal of interindividual
variation regarding the metabolism of arsenosugars, and this metabolism itself is not well understood.
Le et al, (1994b) conducted a single-exposure study of one arsenosugar administered to human
volunteers who had not ingested any seafood during the three days prior to the experiment. The
arsenosugar was administered during a meal in a serving of nori made from a red algae containing the
arsenosugar. While urinary excretion of total arsenic was elevated in seven of the nine volunteers, peak
urinary excretion rates ranged from ten to sixty hours, and two volunteers exhibited no elevation in
urinary total arsenic levels. To confound the matter, four of the volunteers were from the same family,
sharing similar diets and activity levels, yet their results varied; one family member did not even register
a change in urinary arsenic output.
Algae have been shown to synthesize lip id- and water-soluble organic arsenic species from
inorganic arsenic in a growth medium (Lunde 1977). Marine algae also contain a significant percentage
of inorganic arsenic. In HiziMafusiforme, a Japanese seafood, approximately half of the total arsenic is
inorganic arsenic; other edible forms of seaweed contain lower amounts of inorganic arsenic (Edmonds
and Francesconi 1993). (Discussion of inorganic arsenic metabolic fate and toxicity is presented
elsewhere throughout the toxicity assessment section of this document.) Unfortunately, little information
is available regarding arsenic and marine algae.
Toxiciiy
Hindmarsh and McCurdy (1984) present a general ordering of the toxicity of various arsenicals:
arsines > arsenites (inorganic trivalent compounds) > arsenoxides (organic trivalent compounds) >
arsenates (inorganic pentavalent compounds) > arsonium compounds > metallic arsenic. This ordering
30
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is in support of the argument put forth by Edmonds and Francesconi (1993): The valence of arsenic in
a given compound has a greater bearing on that compound's toxicity than whether it is organic or
inorganic.
Clearly, the trivalent arsenic species, including organic compounds, are of greater toxicity than
the pentavalent species. Also apparent in this ranking is the fact that trimethylated arsonium compounds
found in seafood (arsenobetaine and arsenocholine) are less toxic than inorganic trivalent arsenic
compounds. Thomas (1994) adds the extent of methylation to the list of general toxicity-gauging criteria.
Inorganic Arsenic and Methylated Metabolites
Employment of arsenic as a poison predates chemistry textbooks; and the first case linking arsenic
exposure with cancer occurred in the 1880's (Jongen et al. 1985), Hence, it has been wel! established
that inorganic arsenic, under various conditions, is toxic to people. Several epidemiological studies
linking arsenic with a range of toxic effects have been conducted on populations with high arsenic content
in their drinking water supplies. Arsenic is associated with a variety of both acute and chronic effects.
Some evidence suggests that diet may play a role in arsenic toxicity and metabolism. Nutritional factors
such as intake of nutrients involved in methylation may effect arsenic toxicity (Carlson-Lynch et al.
1994).
The trivalent form of inorganic arsenic is commonly associated with arsenic's toxic effects.
Known suifhydryl reagents, trivaJent arsenicals inhibit several thiol-dependent enzyme systems in many
different tissues. In their review, Leonard and Lauwerys (1980) discuss some of the specific actions of
trivalent arsenic. At low (on the order of micromolar) concentrations, it inhibits decarboxylation of an
acid essential to the Krebs cycle. It can block metabolism at levels not high enough to impact cell
division. At higher concentrations it can cause mitotic arrest; it effects DNA synthesis and repair. Since
pentavalent arsenic has a lower affinity for hydroxy and thiol groups, it inhibits fewer enzyme systems.
Consequently, it has a lower toxicity than trivalent arsenic, but it is not non-toxic. Pentavalent arsenic
inhibits ATP synthesis via uncoupling of oxidative phosphorylation to replace the phosphoryl group
(Leonard and Lauwerys 1980). The following paragraphs discuss the toxic effects induced by various
inorganic arsenic compounds.
Acme Effects
In a review, Philipp (1985) summarizes the acute effects of arsenic poisoning in three progressive
stages: (!) nausea, vomiting, diarrhea, inflammation and ulceration of mucous membranes, and kidney
damage; (2) bloody diarrhea, abdominal pains, thirst, dizziness, dehydration, muscle cramps, cyanosis,
delirium and convulsions; (3) marked weakness, shock, muscle paralysis, liver and kidney damage and
death due to circulatory failure.
31
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Chronic Effects: General
Arsenic is also responsible for a great number of chronic effects in exposed persons. In his
review, Philipp (1985) lists the following chronic effects due to long-term, low-dose exposure to
inorganic arsenic: loss of appetite/weight, diarrhea alternating with constipation, gastrointestinal
disturbance, cirrhosis of the liver, peripheral neuritis, conjunctivitis, hyperkeratosis and melanosis of the
skin. Gherardi el al. (1990) concur with the link to peripheral neuropathy and also note that arsenic
appears to cross the blood-brain barrier with ease.
Hartmann and Speit (1994) found that sodium arsenate induces DNA damage in white blood cells.
This damage was detected as DNA migration in the single cell gel (SCO) assay. The authors further
explain that while arsenic has induced DNA strand breaks, sister chromatid exchanges and chromosomal
aberrations, it has not induced detectable gene mutations at specific gene loci. These results suggest that
arsenic toxicity is manifested as interference with the replication and/or repair-dependent processes. Such
effects may be mediated through a reaction with sulfhydryl groups of tissue proteins and enzymes
(Jonnalagadda and Rao 1993).
Chronic Effects: Cancer
Cancer is another chronic manifestation of arsenic exposure. There are two primary exposure
sources linked with arsenic-induced cancers: ingestion of contaminated waters and exposure in an
occupational setting (e.g., pesticide manufacture/application and smelting activities). Inorganic arsenic
exposure has been shown to increase human risk of lung cancer (via inhalation of trivalent arsenic) and
skin cancers (via ingestion of inorganic arsenic in drinking water) (Fowler et al. 1993).
In a 1994 review, Brown and Chen summarize the epidemiological studies of regions in Chile,
Argentina, Mexico, and Taiwan to conclude that the occurrence of dermatological lesions symptomatic
of arsenic exposure occurred at arsenic concentrations in drinking water of at least 0.3 to 0.4 ppm.
Further, no physical manifestations of arsenic toxicity have been reported at drinking water concentrations
of less than 0.2 ppm.
Evidence in support of the increased Sung cancer risk include a recent study of gold miners.
Kabir and Bilgi (1993) identified a statistically significant increase in risk for primary cancer of the
trachea, bronchus or lung for gold miners with a minimum of five years of "dusty gold mining
experience". Additionally, a fifteen year latency period was found.
Arsenic is thought to be a co-carcinogen or promoter, as opposed to an initiator (Fowler 1993,
Hindmarsh and McCurdy, 1984). The mechanisms of arsenic in careinogenesis are discussed in detail
by both Stohrer (1991) and Snow (1992), Stohrer considers that arsenic has caused chromosome breaks
in the absence of point mutations and that it has induced gene amplification. Inorganic arsenic has also
32
-------
been shown to induce genes in heat shock/stress response; and it has activated herpes simplex and herpes
zoster viruses. Hence, Stohrer reiterates McDonnell et al.'s 1989 speculation that arsenic may cause
cancer in humans via activation of an oncogenic virus such as the human papiiloma virus. Stohrer
supports the potential for this argument, noting that both arsenic and human papiiloma virus are
associated with rare precancerous skin lesions known as Bowen's disease as well as with cancer of the
epithelial tissues.
In her review, Snow (1992) summarizes that arsenic exhibits comutagenic, cocytogenic and gene
amplification/expression alteration effects. Inorganic arsenic increases expression of the multi-drug
resistance gene. Snow attributes arsenic carcinogenesis to two actions: (1) inhibition of essential proteins
leading to alterations in cellular metabolism, and (2) gene amplification which may cause the expression
of several known cancer-related genes. Arsenic itself is not mutagenic, but it does produce chromosomal
damage in mammalian cells resulting in an increase in mutagenic response to other agents. Inorganic
arsenic has also been found to inhibit enzymes required for oxidative phosphorylation (Snow 1992). It
has been demonstrated both in vitro and in vivo that trivalent arsenic exposure is responsible for the
induction of stress proteins, including herne oxygenase (referenced by Fowler et al. 1993). Of further
note is the fact that arsenic is used as a growth promotor/inducer for chickens and swine (Vahter 1994).
The ability of arsenic to induce the mechanistic activities discussed above is partially dependent
on the length of time it is retained in a given location within the body. Further considering that
detoxification of arsenate involves oxidation to arsenite followed by two methylation steps, exposure
duration of internal tissues to various arsenic species is dependent not only on rate of clearance of a given
species from that tissue, but also on the rate of oxidation/reduction effecting the existence of that species
(Thomas 1994). The availability of a methyl donor is also critical to arsenic methyiation; and subsequent
effects on availability of methy! groups for other reactions has not been extensively explored. Via such
action pathways, arsenic may alter gene expression, leading to pronounced toxic or carcinogenic effects.
Also, saturation at the step of conversion of monornethyl arsenic to dimethyl arsenic is supported with
evidence, but not proven (Thomas 1994). (A more in depth discussion of the debate over methylation
saturation is provided later in this report.)
Animal Studies
The toxicity of various arsenic compounds has also been tested on different animal species.
Shukla and Pandey (1985) review investigations of the effects of heavy metals on freshwater fish: (1)
Arsenic is precipitated in the mucous film formed on the body of the fish- thus death is caused by
suffocation. (2) Arsenic in fish gills is at concentrations seven to eight times the concentration in the
whole fish. (3) Breathing distress in fish is caused by clogging of the gills with precipitated mucous and
from heavy metal ions which lead to anoxia and collapse of blood vessels. Buhl and Hamilton (1990)
conducted two studies, in clear waters, of placer mining contaminants, including arsenic. They found
that arsenic was less toxic to salmonids than copper, zinc ajid lead; juveniles were more sensitive than
33
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aievins or swim-up fry. Buhl and Hamilton (1991) also found arsenic to be comparatively (to other
common placer mining contaminants) moderate in toxicity to arctic grayling, eoho salmon and rainbow
trout.
Cockell et al, (1991) investigated the toxicity of dietary disodium arsenate to juvenile rainbow
trout. The most prevalent indicator of chronic toxicity was inflammation of the sub-epithelial tissues of
the gallbladder wall. Other indicators included: decreased growth rate, mild to moderate anemia, and
active feed refusal (for higher exposure levels). In comparing the results of this study to those from a
similar study, conducted by Oladimeji el al., with sodium arsenite, Cockell el al. suggest that pentavalent
arsenate may be as toxic as trivalent arsenite in dietary exposure to juvenile rainbow trout.
The effects of sodium arsenate on ducklings have been studied by Hoffman et al. (1992). Diets
of 200 ppm sodium arsenate given to day-old mallard ducklings caused some reduction in growth. Other
ducklings were fed diets with selenium and selenium & arsenic together. Arsenic was found to at least
partially alleviate some of the toxic effects of selenium, supporting the idea that arsenic has antagonistic
effects on the toxicity of selenium.
Weis et al. (1992) investigated the effects of arsenic contained in the wood preservative
chromated-copper-arsenic (CCA), which is often used in the construction of pilings and bulkheads in
estuarine environments. A sea urchin fertilization test was conducted; and wood treated with CCA was
found to reduce fertilization by 90% and to completely inhibit the development of fertilized larvae.
However, a smaller piece of wood (0.4 cm2) did not significantly effect fertilization or development.
Snails exposed to CCA treated wood experienced 100% mortality within one week; and in that same time
period, exposed algae underwent chlorosis.
The toxicity and excretion of inorganic arsenrc were studied in C57 BL/6J mice fed 0.5 mg-
sodium arsenite/kg-BW (Morel et al. 1995). Urinary excretion was measured and interindividual
differences were found with inorganic arsenic and MMA, but not with DMA. Urea, SAM and creatine
excretions were also measured. The authors claim that their results imply that interindividual variability
in total arsenic metabolite excretion is reflective of the GSH-dependent redox state. Further, these
experiments support the theory that the intracellular GSH-dependent redox state may be involved in the
first, but not second methylation step. Reduction from pentavalent arsenic to trivalent arsenic may be
enzymatically catalyzed; and, two different enzyme systems may be involved in the methylation of
inorganic arsenic in mammals. Hence, the authors propose that the second methylation is not regulated
by the GSH-mediated pathway, so individual differences in.GSH do not effect the production of DMA,
once the MMA is produced. [These conclusions may be considered in light of the methylation pathway
saturation debate.]
34
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Dimethylarsenic
Animal data has also been used to suggest an alternative hypothesis for inorganic arsenic toxicity:
that inorganic arsenic itself is not the toxin. Methylation may actually create a more toxic compound,
rather than "a detoxified one. While this theory lacks compelling supporting evidence, brief discussion
is provide by Thomas (1994), In his review, he identifies three toxic effects attributed to dimethyl
arsenic: induction of teratologic effects in rats, acute Sung injury in mice and single-strand DNA breaks •
(perhaps via peroxyl radical formation).
Recent findings suggest that dimethylarsinic acid (DMA), the most common mammalian
metabolite of ingested inorganic arsenic, may be carcinogenic, or at least a promoter of carcinogenesis.
Due to its more rapid elimination and lower tissue retention, DMA has been thought to be a detoxified
product of inorganic arsenic. However, in oral ingestion experiments with rats, it has demonstrated
carcinogenic promotional activity in the bladder, kidneys, liver and thyroid gland (Yamamoto et al,
1995). As early as 1984, Johansen et al. suggested that DMA may be a promoter, although seemingly
a weaker one than As (III).
Johansen et al., in unpublished results, found DMA to be as toxic as As(ffl) and As(V) in toxicity
tests, and went on to investigate DMA's carcinogenic potential (Johansen et al. 1984). Utilizing a two-
stage liver model with rats, they induced carcinogenesis through administration of the initiator,
diethylnitrosamine(DENA)and subsequently administered DMA to a subgroup of the DEN A-treated rats.
From the 11 DEN A-treated rats, two tumors were identified; three tumors were found in the seven
DENA/DMA exposed rats. The difference in the number of tumors formed was not statistically
significant and the authors recommended testing with lower initial DENA doses, so that non-promoted
tumor production might be low enough to observe a significant difference. They did observe an increase
in the number of liver lesions in the DENA/DMA exposed animals, furthering the suspicion that DMA
may be a promoter.
Following the work of Johansen et al., several studies linking DMA with various types of cellular
damage were published (Endo el al. 1992, Dong et al. 1993, Yamanaka et al. 1991, Murai et al, 1993).
In previous studies, Yamanaka et al. (1991) had shown that DMA administered orally to mice induces
lung-specific strand scissions in mouse DNA. In 1991, through study of cellular response to DMA-
induced oxidative damage in the lung, they were able to attribute pulmonary DNA damage to radicals
formed as a result of the metabolism of DMA (Yamanaka et al. 1991).
In 1992 Endo and colleagues investigated the genotoxicity of nine different organic and inorganic
arsenic compounds. DMA alone was found to induce tetraploids and mitotic arrest. Many structurally
unrelated compounds, which all induce mitotic arrest, are also known to cause aneuploid and cell
transformation. Since DMA was found to produce mitotic arrest, the authors suggest that it may also
cause cell transformation. Furthermore, Endo et al. postulate that DMA-inhibition of lymphocyte ceil
35
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division is likely a direct action. They also proposed that DMA may be the ultimate arsenic carcinogen,
particularly when considering effects from inorganic arsenic exposure; and they suggest that tetraploid
induction coyfd be one of the stages responsible for DMA's carcinogenieity,
Murai and others (1993) investigated the effects of oral administration of DMA to 4-week-old
rats. DMA exerted dose dependent effects on weight and mortality. General signs of toxicity included
kidney lesions, papillary necrosis, hyperplasia of the covering epithelium of renal papillae, and proximal
tubular necrosis. Also considering that the kidney is a major route of elimination of inorganic arsenic
and its methylated metabolites, Murai et al. suspected the major cause of death to be renal failure. Rat
death from DMA exposure was accompanied by marked weight loss and piloerection, with symptoms
showing up as early as eight weeks in females and twenty weeks in males.
3QWks
J
I :DEN
• :DMA
f :MNU f :OMH
® : Siscrrtica
' BBN
!:DHPN
Drawing upon these and
other results suggesting that DMA
possesses both clastogenic and
genotoxic properties, Yamamoto
et d. (1995) investigated DMA's
carcinogenic potential in male rats.
Five groups of twenty rats were
treated, over four weeks, with a
DMBDD multi-organ
cardnogenesis bioassay (see figure
2) and given no further treatment
for two weeks. Two groups of
twelve were untreated for these six
weeks. At week six, four of the
first groups were administered
DMA at various concentrations (5,
100, 200, 400 ppm) in their'
drinking water; the second two groups, at week six, were also administered different concentrations (100
& 400 ppm) of DMA in their drinking water, DMA was found to significantly enhance tumor induction
in urinary bladder, kidneys, liver and thyroid gland, in the DMBDD-initiated rats. Bladder cancers were
markedly enhanced at all concentrations of DMA. Kidney and thyroid cancers were moderately enhanced
in a dose-dependent fashion. Liver carcinogenesis was strongly enhanced in groups administered DMA
at concentrations exceeding 200 ppm. Lung and skin carcinogenesis did not appear to be enhanced.
Yamamoto and colleagues (1995) point out that DMA has clearly demonstrated promoting ability,
yet it is still unclear whether or not it has any initiating activity. In the kidneys of rats treated with DMA
only at a concentration of 100 ppm, biochemical data indicated significant eel! proliferation, but the
mechanism for this was not readily apparent. In the past, Cohen and Ellwien suggested that increased
Experimental protocol of muiUotgEB cardnogesesis biowwy (DMBDD mod-
el). Aniraiij were sequentially treated wild DEN (anw. 100 mg/kg body weight, i.p^
single dose), MNU (f, 20 mg/kg body weight i.p.. 4 limes, on d»y» 5. 8, 11, »nd 14),
DMH (V, 40 rug/kg body weight. s.e.. 4 times, on dsyi 18, 22, 26. and 30), BBN (•.
UWr in the drinking water, during weeks 1 ind 2), and DHPN (HI 0.1% in the drinking
« aicr. dunng weeks 3 and 4), After a 2-week interval, groups 2-5 were given 50. 100.
ZW. or 400 ppm DMA. respectively, in the drinking water (0), Al! survivors were killed
3t »eek 30 (»).
SOURCE: Yamamoto et al, 1995
Figure 2 Multiorgan Carcinogenesis Bioassay Protocol
36
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cell proliferation may account for carcinogenicity of nongenotoxic compounds. Hence, it is possible that
in longer-term, lower dose exposures, DMA may be carcinogenic, that is, it may demonstrate both
initiating and promoting activities,
Microbiological Experiments
De Vincente et al, (1990) investigated the effects of heavy metals on resistance to antibiotics.
Marine environments with little fecal pollution were found to harbor the highest frequencies of resistance
to arsenic; these same environments also had the highest incidence of multi-resistant strains. Rani and
Mahadevan (1993) found the Pseudomonas strain MR1 to have resistance to arsenic, possibly because
of its energy-dependent arsenate efflux system. Of six heavy metals tested, the organism was most
resistant to arsenic.
Organic Arsenic and Seafood Arsenic Species
Organic arsenic species, particularly arsenobetaine, found in fmfish and shellfish have, since the
earlier half of this century, been generally accepted as being nontoxic (Jongen et al. 1985).
Arsenobetaine, while it is efficiently absorbed across the gastrointestinal tract, is excreted rapidly and
unchanged (Brown et al. 1990, Vahter, 1994). Consequently, little motivation has existed to investigate
the toxic potential of humaji exposure to inorganic seafood arsenic; long-term seafood exposure studies
are not readily identifiable.
At the onset of their group's investigations into the distribution, retention and biotransformation
of arsenobetaine (Vahter et al. 1983) and arsenocholine (Marafante et al. 1984), Vahter et al. (S983)
caution that "Although it seems clear that the arsenic compounds in seafood have less acute toxicity than
inorganic arsenic or methylated arsenicacids...the metabolism and possible effects following long-term
exposure in mammals are largely unknown."
Arsenobetaine
The rodent studies of arsenobetaine yielded little evidence indicative of toxicity. In three days,
over 70% of arsenic dose was excreted unchanged in the urine as arsenobetaine (Vahter et al. 1983).
Toxicity studies conducted with mouse embryocytes (Sabbioni et al, 199!) and rat hepatocytes
(Christkopoulos et al, 1988a) also did not display any toxic effects of arsenobetaine.
Jongen et al. (1985) investigated the toxic properties of arsenobetaine in vitro. Specifically, the
promoting and initiating capabilities of arsenobetaine were studied; and synergistic/agonistic effects were
investigated. At 1 mg-arsenobetaine/plate, no mutagenic effects were found in a bacterial assay with S.
typhimurium, in the sister chromatid exchange (SCE) assay, or in the assay of forward mutation on the
HGPRT gene. Differences in cytotoxicity with above assays were surprising; however, differences in
37
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exposure may be the cause. In the HGPRT forward mutation assay, cells were exposed to the test
compound during pre-incubation, and arsenobetaine appeared to demonstrate a higher sensitivity to this
pre-incubation than other test compounds.. Initiating and promoting potential were found to be negligible
in the systems tested. No synergistic and/or antagonistic effects were observed in various test systems.
Jongen et al, (1985) also note that other experiments have confirmed the low acute toxicity of
arsenobetaine and arsenochoiine in rats and chicks.
In 1988 experiments were conducted on rat embryos to investigate the embryotoxicity of both
arsenobetaine and arsenochoiine (Irvin and Irgolic 1988), Arsenobetaine, in and out of presence of rat
liver homogenate (S-9), demonstrated no embryotoxicity or embryolethality. Results implied that from
several micrograms to several hundred micrograms of arsenic per gram no subacute or acute prenatal
toxic effects are pronounced. Neither arsenobetaine nor arsenochoiine was found to impair embryonic
growth in the absence of S-9. No toxic effects with arsenochoiine or arsenobetaine occurred with
approximately 20 ng (S.Sfig-As/cm3 for arsenobetaine bromide and 6.1 ^g-As/cm3 for arsenochoiine
bromide). Irvin and Irgolic (1988) recommend that determination of whether or not microsomal
homogenates from tissue of pregnant rats metabolize arsenobetaine and arsenochoiine should be made.
Arsenochoiine
Arsenochoiine studies gave more cause for suspicion, but elucidated no overt signs of toxicity.
ArsenochoSine was retained longer than arsenobetaine in rodent body tissues; it was metabolically
transformed to arsenobetaine and it was potentially incorporated into phospholipids in the cells. For these
reasons, Marafante et al. suggest that despite arsenocholine's small contribution to total seafood arsenic,
it may be of greater toxic concern than arsenobetaine (Marafante ei al, 1984).
Work by Christkopoulos el al, (19€8a) further supports Marafante et al. 's conclusions. Although
rat hepatocytes incubated with arsenochoiine yielded no indications of cytotoxicity, or loss of cell
viability, arsenochoiine metabolism did produce some side-products. As noted under metabolism
(above), Christkopoulos et al. (1988a) found that during its metabolic transformation to arsenobetaine,
arsenochoiine may form trimethylarsine oxide, which may in turn be reduced in vivo to trimethylarsine,
one of the more toxic forms of arsenic. Christkopoulos et al. (1988a) then suggest that understanding
the fate of arsenochoiine ingested by man via seafood consumption may be important to understanding
the potential toxicity of seafood arsenic to humans.
Francesconi et al, (1989) have also explored the biotransformation of arsenochoiine .to
arsenobetaine. They fed three groups offish raw cubes of beef dosed with arsenobetaine, beef dosed with
arsenochoiine and undosed beef, respectively. Fish dosed with either arsenobetaine or arsenochoiine
retained muscle concentrations of arsenic forty times those in the control group. 37% of arsenic from
ingested arsenobetaine was retained; while 39% from the arsenochoiine was retained. Arsenic species
were extracted from fish in the arsenochoiine group; and less than 0.2% of the arsenic present was found
38
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in the form of arsenocholine. The major arsenic fraction of from the extraction was determined to be
arsenobetaine.
In Seaweed
Two medical studies offer evidence of arsenic poisonings from ingestion of kelp-based health
supplements (Walkiw and Douglas 1975), One patient admitted to the hospital (for an unconnected
reason) was found to have elevated urinary arsenic levels, which were eventually attributed to kelp-basal
health' supplements. These supplements were found to have a total arsenic content of 27,8 ng/g; one
caplet contained 20 jig. Twenty-six days subsequent to the patient's discontinuation of the kelp-based
supplements, urinary arsenic levels no were no longer elevated. A second patient showing signs of
peripheral neuropathy was found to have elevated urinary arsenic concentrations, also attributed to kelp-
based health supplements. Thirty days following discontinuation of supplements, the patient's urinary
arsenic levels were one of the concentrations, and after ninety days, urinary arsenic levels
had to "normal" (Walkiw and Douglas 1975). Considering the lengthy
times, particularly in the case, and noting the occurrence of peripheral neuropathy, it
likely that a significant percentage of the from the kelp was inorganic.
Measurements made were limited to total arsenic, and speciation is not discussed.
Other Organic Arsenicals
Philipp (1985) reports that trtmethylarsine, a highly volatile and poisonous form of arsenic, has
been found to be produced via methylation of inorganic or organic arsenic by fungi. Inhalation of this
compound has ended in death.
Leonard and Lauwerys (1980) affirm that although organic arsenicals are found to be stored in
the human placenta, they have not been found to cross the plaeental wall in humans, cat or rabbit.
Cfaong et al, (1989) conducted a study to identify binding sites of organic arsenicals in the
erythrocyte. Organic containing a single lipophiiic or ary! group, such as lewsite or
(PDA), are known to and the skin,
the they are primarily by erythrocytes and are readily
to other tissues. For PDA, glutathione (GSH) was identified as the principal' binding site in erythrocytes.
Jonnalagadda and Rao (1993) determined that organic are first metabolized to a trivalent
before toxic and that toxicity can be by dithiols.
39
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RISK ASSESSMENT IMPLICATIONS
Regulatory Criteria
National United States Standards
Numerical Criteria
The US EPA's Integrated Risk Information System (IRIS) (USEPA 1995) presents exposure
limiting factors under the heading of "inorganic arsenic" considering both arsenic's hazardous properties
and its carcinogenic properties. For hazardous effects, a critical oral dose of 0,0008 mg/kg-day (derived
from Tseng's NOAEL of 0.009 mg-As/L-water), with an uncertainty factor of 3 is listed with a reference
dose of 3E-4 mg/kg-day. These data are presented with "medium confidence". The inhalation reference
dose has been removed from the database. Arsenic is listed as a group A human carcinogen with an oral
slope factor of 1.5/(mg/kg-day) and a unit risk of 5E-5/(/tg/L), Its inhalation slope factor is 4E-
3/(jtig/rn3). One in a mil! ion risk levels of 2E-2 jig/L under oral and 2E-4 ^g/m3 under inhalation are
listed in IRIS (USEPA 1995). A maximum contaminant level (MCL) for drinking water is listed as 0.05
mg/L. Most of these values are being criticized by various parties; criticisms are discussed below. No
regulatory limits are presented for seafood content.
Criticisms
Perhaps the most.widely criticized of the United States regulatory criteria is the drinking water
MCL. The MCL is accused of by some as being too restrictive and by others as not being adequately
restrictive. This value of 50 ^ig/L was set by the US Federal Water Quality Administration around 1942,
prior to the existence of the USEPA (Stohrer 1991). This level is currently under court mandate to be
re-evaluated by the USEPA. Stohrer (1991) noted that the US MCL is half that recommended by the
Royal Commission on Arsenic, and, is four times less than what the Royal Commission views as the
threshold for arsenic toxicity. Based on Taiwanese epidemiological data, Stohrer placed the threshold
from 100-150 ng/L; a single threshold dose for all toxic effects of arsenic is consistent with the theory
of arsenic being an indirect, gene-inducing carcinogen.
Conversely, the MCL Is farther criticized by Smith el al. (1992) who presented results of brief
calculations which claimed that if arsenic in drinking water were at a concentration of 50 Mg/L, and
individuals consumed one liter of contaminated water per day, based on linear extrapolation of
epidemiological data from Taiwan populations, the individual cancer risk may be as high as 13 in 1000.
They further claimed that at the MCL drinking water could contribute up to 100 jig-arsenic per day;
USEPA currently claims that drinking water contributes approximately 5 |*g-arsenie/day. Such drinking
water supplies could cause arsenic to account for approximately 90% of daily arsenic intake (or 80% for
consumption of only one liter of contaminated water). Smith et al. asserted that risk of developing lung
and liver cancers based on arsenic exposure at the MCL would increase.
40
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Other scientists have been critical of EPA's unit risk for airborne arsenic. Viren and Silvers
(1994) evaluated three cohort studies to conclude that the present unit risk may overestimate effects of
airborne arsenic by nearly three times. The studies evaluated occupational arsenic exposures for smelter
workers. Results from a northwest study based in Tacoma, Washington were evaluated, along with new
Swedish data and a previous Montana study. Unit risk was established based on methods analogous to
those used by EPA to derive the previous value of 4,29xKJ3, Viren and Silvers advised that the
relationship between urinary arsenic and airborne arsenic should be clarified in order to better assess the
relationship of this arsenic and various cancers,
Carlson-Lynch et al. (1994) questioned the USEPA's arsenic oral cancer slope factor which was
established in 1988, Their primary reservation about the slope factor was the assumption of a linear
dose-response relationship with data from the Taiwan epidemiological study relating skin cancer to arsenic
ingestion. Such an assumption does not allow for the possibility of a threshold or sublinear dose-response
relationship for low doses of arsenic, Carlson-Lynch et al, further questioned USEPA's use of the
Taiwan epidemiologicai study out of context. They pointed out that dietary habits, including nutritional
deficiencies (such as reduced protein and methionine intake) that may compromise methylation capacity,
were not taken into account. Carlson-Lynch et al, also claimed that the volume of drinking water
consumed is not wel! supported; and toxic and carcinogenic potential of other pollutants in the drinking
water, such as fluorescent humic acids which are associated with bladder cancers, was not adequately
addressed.
An ongoing debate discusses the likelihood of saturation of the arsenic methylation pathway in
humans and its effect on exposure assessment data. Current USEPA cancer potency factors do not
assume that a threshold exists in arsenic response for cancer. Several researchers in the scientific
community exploring this problem have concurred that such a threshold appears to exist and that a
probable explanation for this threshold is a saturation of the metabolic methylation step (Carlson-Lynch
et al. 1994, Buchet et al. 1994, Vahter 1994, Beck et al. 1995, Thomas 1994). However, there also
exists a faction which challenges the methylation saturation theory (Hopenhayn-Rich et al. 1993, Smith
et al. 1992, Mushak and Crocetti 1995). Based on the analysis of several arsenic ingestion/excretion
studies, Hopenhayn-Rich et al, (1993) revealed that regardless of dose, the proportion of unmetabolized
inorganic arsenic to the sum of unmetabolized inorganic arsenic plus mono- and di-mettiylated arsenic
remains relatively constant across the groups.
While this conclusion itself does not disprove the methylation saturation theory, it does challenge
supporters of the theory to better characterize its mechanisms. (Other explanations may exist for the
constant ratio, such as alternate routes of excretion for unmethylated arsenic.) In response to this
challenge, Carlson-Lynch et al. (1994) raised several points. First, they noted that the average arsenic
exposures in studies used by Hopenhayn-Rich (1993) were below the suggested saturation levels; Buchet
et al, previously suggested complete saturation at doses exceeding 500 Mg^day, and the beginnings of
saturation from 200-250 Mg/day. Carlson-Lynch and colleagues further contended that use of grab
41
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samples (as in studies utilized by Hopenhayn-Rich et al. 1993) could not accurately represent renal
elimination of the arsenic dose as urinary excretion demonstrated considerable inter individual variation;
a 24 or 48 hour total was recommended. Beck et al, (1995) submitted the approach of comparing the
ratio of monomethyl arsenic to dimethyl arsenic; they note three studies which considered this ratio and
found it to increase with increasing dose, Del Razo et al. (1994) have used this ratio to imply that
metnylation saturation is likely to occur at the second step rather than the first.
The methylation debate is ongoing (Beck et al. 1995, Smith er d. 1995, Mushak and Crocetti
1995, Thomas 1994), and its implications bear heavily on arsenic risk assessment. Furthermore, as more
information becomes available on the carcinogenic potential of DMA, it will impact this debate. Should
DMA itself be found to be carcinogenic, the methylation pathway will no longer be considered a
detoxification pathway,
Tabli 14 National Regulatory Criteria for Seafood Arsenic Content
Country Maximum Permissibl« Source
Arsenic Content
Australia
Hong Kong
1 mg-AsjIW8/kg-fish
6 mg-Aslot()|/ks-fish
Edmonds & Francesconi 1993
Edmonds & Francosconi 1993
Malaysia
New Zealand
Norway
10 mg-As,Ma(/kg-shellfish
1 //g-As^/g-fish-WW
2 mg-As
4.0 mg-Ast<,!8,/kg-edible-fish-
WW
Mat 1994
Edmonds 81 Franoesconi 1933
Sakulic era/. 1993
Other Standards
Some
countries do
provide regulatory
limits for seafood
arsenic content.
Among these
countries are
Australia, Hong
Kong, Malaysia,
New Zealand, and ______
Norway. The
maximum
permissible limits
established by these countries, as depicted in table 14, are provided in different units. Some countries,
like Australia and New Zealand, focus strictly on inorganic arsenic content, while others present limits
in terms of total arsenic. Most countries specify limits as per kg of organism, but Norway specifies its
limit in terms of edible fish tissue. Such a restriction may be difficult to establish in the northwest, as
various subpopulations consume different parts of the total organism. Also of note is that Hong Kong's
limits are given separately for fish and shellfish.
Other agencies have set non-seafood-specific limits. For example, die Royal Commission on
Arsenic has set a maximum daily intake factor for total arsenic of 450 ng/d%y (or 225 j*g/L) based on
consumption of two liters of water per day. Additionally, many states within the USA have set their own
drinking water standards. These standards range from 7.2 jig/L in Virginia to 190 j*g/L in New York
(Stohrer 1991).
42
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Applications
Currently, seafood-arsenic risk assessments focus on inorganic arsenic content. For the most
part, the organic fraction has been labeled "non-toxic" and consequently disregarded. The following
paragraphs illustrate various approaches to risk assessments of human arsenic exposure from seafood
ingestion.
Fnberg (1988) Study
Friberg (1988) evaluated the human health effects, particularly the carcinogenic potential of a
number of metals, including arsenic. He acknowledged that seafood-mediated arsenic exposure may be
substantial,-but conceded that most seafood arsenic is comprised, of arsenobetaine, a relatively atoxic
compound. However, Friberg further contended that extreme seafood consumption could result in
significant exposures to inorganic arsenic, and he quantified this exposure to be up to several hundred
micrograms of arsenic per day. Such an exposure may be connected with a lifetime increased chance of
developing skin cancer.
Data used by Friberg (1988) were taken from the GESAMP study discussed earlier in this report.
Exposure to inorganic arsenic from seafood ingestion is dependent on fish content as well as eating habits.
Friberg calculated ingestion rates of arsenic depending on concentrations in fish. He assumed that
seafood contains two to ten percent inorganic arsenic as percentage of total arsenic. This assumption was
taken from a World Health Organization 1981 report, Environmental Health Criteria 18 (Arsenic). (A
challenge to the 2-10% assumption and a discussion of it is presented earlier in this report.) Four seafood
consumption rates corresponding to approximately one meaJ per week, three meals per week, one meal
per day, and an "extreme consumer" were examined in comparison to two different fish inorganic arsenic
concentrations: ten percent of 1.0 pglg in "most commercially important fish species" and five percent
of 10 p,g/g in bottom feeding fish species. The investigation yielded consumption rates of inorganic
arsenic from fish from 2-500 Mg/day; specific results are shown in table 15. Friberg assumed that
bioavailability of inorganic arsenic from fish was equivalent to that of drinking water.
Friberg (198S) compared the risk from arsenic exposure via seafood consumption to cancer
responses presented in the WHO document, which estimated a five percent increase in arsenic-induced
skin cancer from 10 g-As/lifetime, or a daily intake of 0.4 mg inorganic arsenic over a lifetime, or a
daily intake of one milligram inorganic arsenic over 25 years. Hence, except for the extreme consumer,
Friberg concludes that fish consumption alone should not pose a significant increase in cancer risk; but
it may impact significantly upon total arsenic ingestion, and consequently contribute to raised cancer risk.
Even considering the possibility that Friberg's values were overestimated, there exists a strong possibility
that for extreme consumers, seafood arsenic exposure may contribute to an incremental increase in cancer
risk.
43
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Table 15 Friberg's Daily Inorganic Arsenic Intake from Seafood for Four Consumer Levels
As, Consumption Rates (jig/day?
Mean
Seafood Aswt-
Concentration
U/Q/Q)
most commercially 1
important fish
bottom-feeding 1 0
fish/crustaceans
Percentage Seafood Consumption Rates (g/day)
Aslnor8 in
Fish 20 60 150 1000
10 2 6 15 100
5 10 30 75 500
SOURCE: Fribsrg 1988
Puget Sound Seafood Risk Assessment (Tetra Tech 1988)
Tabli 16 Puget Sound Saafoad Consumption Rates
Organism
fish
shellfish
kelp
nori
SOURCE: Tetra
Average
Consumption
{g/day}
12.3
1,1
0.006
4.1
Tech 1 988
High-end
Consumption
!g/day!
95.1
21,5
0.023
16.2
In 1988 a human health risk
assessment was conducted in consideration
of chemical contamination found in Puget
Sound seafood (Tetra Tech 1988). The
assessment focused soleiy on contributions
to risk from ingestion of seafood.
Consumption rates, displayed in table 16,
were derived from various local data.
Consumption rates for fish were derived
from studies on Puget Sound recreational
anglers' catch and consumption practices,
Median shellfish rate was taken from a
regional study conducted by Nash in 1971; high' exposure to shellfish was based on an estimate of one
meal of 151 grams per week. Algal consumption rates were based on marketing information from a local
marieulture facility that specialized in nori. Median consumption values were based on United States
habits and high end values were based on Japanese consumptions.
Arsenic was evaluated in terms of carcinogenic risk. The assessment considered exposures over
a 70 year lifetime using a cancer potency factor of 1.5, the interim recommendation of the USEPA Risk
Assessment Forum. Total arsenic concentrations were measured, and the assumption was made that one
44
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Table 17 Cancer
Organism
fish
shellfish
kelp
nori
SOURCE: Tetra
Risk from ingestion
Total Arsenic
Concentration
(pg/kg-WW)
3441
3252
2559
2279
Tech 1988
of As from Puget
Average
Exposure
Cancer Bisk
9E-6
8E-7
1E-8
3E-9
Sound Seafood
High Exposure
Cancer Risk
8E-5
2E-5
1E-5
3E-6
percent of total arsenic
was in the inorganic
form. No citation was
made regarding the one
percent assumption,
Risk results are
presented in table 17, •
High end exposures
indicated carcinogenic
risks exceeded the
standard one in a
million risk. Risks for
seaweed exposure may
be underestimated due
to the assumption of one percent inorganic .arsenic. The differences in inorganic arsenic content among
fish, shellfish and macroalgae is not extensively discussed.
Kensington Mine Risk Assessment (PTI, 1995)
Potential human health risks associated with arsenic releases from the mining outfall were
evaluated by the mine's owners in conjunction with the permitting process for a gold mining project at
Kensington Mine in Alaska. Since the intended outfall location was located in seawater, the only human
arsenic exposure pathway of concern was that of seafood ingestion. Best case assumptions regarding the
pre-discharge treatment of outfall predicted arsenic concentrations in the outfall would be lower than
receiving seawater background concentrations (average of 1.45 /ig/L); however, worst case assumptions
were analyzed, allowing for an arsenic discharge concentration of up to 3
Standard adult residential exposure parameters were used as appropriate, leaving the fish
consumption and fractional intake parameters to be site-specific selections. The amount of arsenic that
the discharge would contribute to seafood was calculated based on an estimated bioconcentration factor
(BCF) of 640 for salmon and halibut, and 1,550 for crab. BCF values were found to vary significantly
with species and laboratory /field conditions. Those chosen were in conservative ranges. Based on the
Edmonds and Francesconi (1993) evaluation of GESAMP data, and the Health Risk Assessment of
Chemical Contamination in Puget Sound Seafood (PSEP 1988), a fraction of one percent of total arsenic
was used to estimate inorganic arsenic levels in all three species considered.
Seafood consumption rates were based on surveys, conducted by the Alaska Department of Fish
and Game Division of Consumption, of two local communities which utilized part of the proposed outfall
area as fishing locations. Total catch was tallied for each group and the total usable pounds of fish or
crab harvested for home use by the population of the applicable community was divided by the population
45
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of that community. This average
consumption value was then doubled. _ ., ,„-,.„ . n . „
Table 18 Seafood Consumption Rates for Kensington Mine
Table 18 depicts derived consumption Communities
rates. The fraction of this seafood Community Fish lngestion Crab |ngestjon
which would be contaminated by the (kg/day} Skg/dayS
mining outfall based on the fraction ===:'-~—-" - - - -1-
Haines 0.158 0.0047
of the fishing area impacted by the
outfall. The mixing zone was Hoonah °'446 0-0085
determined to be no more than 0.002 SOURCE: PTI, 1995
percent of the fishing waters for both
the fish and the crabs.
In choosing toxicity data for comparison with exposure data, the assessment presents a brief
review of studies supporting the threshold theory. Following consultation with relevant scientists, the
cancer slope factor was recalculated using the exposure assumptions used by the EPA to determine the
RfD. This reduced the slope factor from 1.75 (mg/kg-day)"1 to 1.13 (mg/kg-day)'1. The EPA's current
oral RfD of 0.0004 mg/kg-day was used; however a recalculated RfD of 8x10"" mg/kg-day was also
applied to illustrate the impact of re-evaluating the Taiwanese epidemiological data to account for arsenic
contributions made by yams and rice. (An alternate slope factor accounting for such a re-evaluation was
calculated to be 0.77 (mg/kg-day)"1). Both carcinogenic risks and non-carcinogenic risks were evaluated
using the factors indicated above. Risk contributions from arsenic outfaS! ranged from hazard indices of
0.099-0.23 and incremental cancer risks of 2xlO"n-8xlO'10.
Lower Columbia River Bi-state Program (Tetra Tech 1995 draft)
As part of the Lower Columbia River Bi-state Program, a report was prepared regarding the
human health risks associated with ingestion of fish from the river. Of the many associated chemicals
of concern, arsenic was among those whose contributions to health risks were evaluated. Contaminant
concentrations were measured in three resident species (largescale sucker, carp and white sturgeon) and
three non-resident species (steelhead, chinook and coho). Risks from arsenic exposure were evaluated
for three populations: the general public, recreational anglers and subsistence anglers.
Arsenic concentrations were speciated into total and inorganic concentrations. Total arsenic was
measured using ICP-MS techniques and inorganic arsenic (plus methylated metabolites) was measured
via HG-AAS. Samples for arsenic speciation were digested with sodium hydroxide, which would not
decompose the organic arsenic species, to allow for detection of inorganic arsenic. Arsenic was detected
in all six target species. Table 8 presents percentages of inorganic arsenic in each species. These
percentages are elevated above Edmonds and Francesconi (1993) estimates.
46
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Because arsenic is a carcinogen, chemical specific chronic daily intakes were calculated over both
a 30-year and a 70-year exposure duration. Consumption rates used were 6.5 g/day for the general
population, 54 g/day for the recreational anglers and 59 g/day for the subsistence angiers. The first two
rates are based on EPA data and the third is based on a study conducted by the Columbia River Inter-
Tribal Fish Commission in 1994, Standard assessment parameters were applied for most values,
however, an arithmetic average, rather than some sort of maximum value, was used for the exposure
point concentration (in the edible fish tissue). Risk evaluations were made using EPA's oral RfD of 3E~4
and oral slope factor of 1.75. Risk estimates are presented in table 19. It should be noted that several
exceed a one in a million cancer risk. For an upcoming draft of this report, risks were evaluated for
ingestion rales ranging from nearly zero to 300 g/day; risks were found to increase proportionally
(personal communication with Dana Davoii, USEPA, 03/25/96).
Population Typ® of
fFish Risk
Table 19 Risk Contribution from Arsenic in Lower Columbia River Fish
Arsanlc Contributions to Risk fby species)
Consumption
Rat® (fl/dayj)
General Public
(6.5)
Recreational
Anglers (54)
Subsistence
Anglers (591
General Public
(6.5)
Recreational
Anglers (54)
Subsistence
Anglers (59)
General Public
(8.5)
Recreational
Anglers (54)
Subsistence
Anglers (53)
(Exposure
DurattonJ
cancer
(30 year)
cancer
(30 year)
cancer
(30 year}
cancer
(70 year)
cancer
(70 year)
cancer
(70 year)
hazard
(30 year)
hazard
(30 year)
hazard
(30 year!
Carp
6.68E-08
5.55E-07
6.06E-07
1.83E-07
1 .3BE-OS
1 .4S1-06
3.10E-04
2.57E-03
2.81 E-O3
Chinook
8.57E-07
7.12E-06
7.78E-08
2.03E-08
1 .73E-05
1 .89E-G5
3.97E-03
3.30E-02
3. 61 £-02
Coho
1.78E-07
1 .481-06
1.626-06
4.33E-07
3.SOE-06
3.S3E-06
8.25E-04
6.86E-03
7.49E-03
Sucker
8.35E-07
6.93E-06
7.58E-06
2.03E-08
1.69E-05
1 .84i-05
3.87E-03
3.21E-02
3.51 E-Q2
Stasihaad
4.34E-07
3.61E-06
3.941-06
1.06E-06
8.78E-OS
3.59E-Oi
2.01 E-03
1.67E-02
1 .83E-02
Sturgeon
2.61 E-OS
2.17E-05
2.37E-OS
6.35E-06
5.28E-05
5.76E-05
1.21E-02
1.01E-01
1.10E-01
Note: Risk values in bold exceed the one in a million cancer risk of the hazard index of 1.
SOURCE: Tetra Tech 1995
47
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CONCLUSIONS -
Unquestionably, the science behind arsenic risk assessment has advanced considerably over the
past fifteen years. The primary species present in seafood was identified as arsenobetaine. Speciation
techniques now allow not only for quantification of organic arsenic species, but also for speciation of
them. The database quantifying inorganic arsenic contributions to total seafood arsenic concentrations
has grown. Mechanisms of human arsenic detoxification have been better characterized, Toxicity of
seafood organic arsenic species has been further elucidated. Yet, despite these advances, there is still
much to be accomplished and understood.
A single value for seafood inorganic arsenic content cannot adequately represent the variety of
inorganic arsenic concentrations present in the various seafood consumed. Freshwater and saltwater
organisms vary in content; bottom-dwelling fish and fish residing higher in the water column vary in
arsenic content; free-swimming fish, shellfish and macroalgae also vary in arsenic content. Furthermore,
broad agreement for a given type of organism has not been established; because of inherent variations
as well as the ongoing debate surrounding inorganic arsenic content, it is difficult to determine which
percentage is most appropriate. Not only would such a choice be controversial, it would require
establishment of other dietary habits of northwesterners as well as approximation of drinking water
arsenic content, both of which influence arsenic intake. Both vary greatly depending on the location and
ethnicity of the population(s) in question. Such values must be measured on a site-specific basis.
Options exist among speciation methods for making such measurements. Since current leanings
are towards inorganic arsenic being the only species of concern in finfish and shellfish, methods which
will separate individual organic arsenic species may be unnecessary. Such an assumption allows for
employment of methods involving destructive digestion of organic species to allow for hydride generation
and subsequent detection. However, should arsenocholine be identified in northwest fish and shellfish,
methods which can speciate among organic arsenic species will be of greater concern. For such
measurements, the ICP-MS detection methods when used with ionic separations, currently is the most
well-developed option. Other methods discussed above, such as HPLC-AAS with on-line hydride
generation also show promise, but further improvements to these methods are needed.
More confident determinations must be made regarding the potential content of arsenocholine in
northwest seafood, and particularly in shellfish. Once it has been established whether or not
arsenocholine is present, the need for its inclusion in northwest arsenic risk assessments can be assessed
and appropriate speciation and measurement techniques can be identified. The percentage of inorganic
arsenic in northwest seafood must also be better characterized. While a conservative percentage often
can be used to make worst case evaluations, such evaluations may inflate actual risks by a full order of
magnitude. Data from the Columbia River study indicate that even at lower percentages, inorganic arsenic
from seafood can pose and/or contributed a health threat. Therefore, measurements should be collected.
A separate project to more specifically identify species of concern and to measure arsenic in these species
48
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could be conducted. However, It may be more appropriate to measure arsenic species of particular
concern in conjunction with those concerns, and to maintain a growing database of species and
concentrations.
Resolution should be reached as to whether or not DMA is carcinogenic. If DMA is determined
to be carcinogenic, methylation can no longer considered to be a detoxification pathway in humans.
Furthermore, evidence leading to the methyiation saturation theory should be re-evaluated to assess other
possible conclusions. Most importantly, should DMA be determined to be carcinogenic, speciated
measurements among inorganic arsenic, MMA and DMA content should be made when measuring
seafood arsenic concentrations for risk assessments.
* ACKNOWLEDGEMENT Credit must be extended to Michael Garry for completing the groundwork
for this report. Before ESAT began the project, Mr. Garry had gathered the first set of references,
identified most of the available speciated seafood arsenic concentrations and assembled an initial report,
As instructed by the WUD, ESAT employed this information as a base to assist in completion of its report.
49
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REFERENCES
Ahmed, Farid E., Dale Hattis, Richard E. Wolke and David Steirunan. 1993. Risk Assessment and
Management of Chemical Contaminants in Fishery Products Consumed in the USA. Journal
of Applied Toxicology 13(6): 395-410.
Atallah, RJ. and D.A. Kalman. 1991. On-line Photo-oxidation for the Determination of
Organoarsenic Compounds by Atomic-Absorption Spectrometry with Continuous Arsine
Generation, Talama 38(2): 167-173,
Battelie, Pacific Northwest Laboratories. 1986. Speciation of Selenium and Arsenic in Natural
Waters and Sediments, Volume 2: Arsenic Speciation, Final Report. Sequim, WA:
Prepared for Electric Power Research Institute: EA-4641, Vol.25 Research Project 2020-2.
Beck, B.D., P.D. Boardman, G.C. Hook, R.A. Rudel, T.M. Slayton and H. Carlson-Lynch. 1995.
Response to Smith et al. Environmental Health Perspectives 103(1): 15-17.
Bennett, B.G. 1981. Exposure of Man to Environmental Arsenic - An Exposure Commitment
Assessment. The Science of the Total Environment 20: 99-107.
Brooke, P.J. and W.H, Evans, 1981. Determination of Total Inorganic Arsenic in Fish, Shellfish
and Fish Products. Analyst 106: 514-520.
Brown, Kenneth G, and Chien-Jen Chen. 1994. Observed Dose-Response for Internal Cancers and
Arsenic in Drinking Water in the Blackfoot Disease Endemic Region of Taiwan. In Arsenic:
Exposure and Health, W.R. Chappell, C.O. Abernathy and C.R. Cothern, Eds. Northworth:
Science and Technology Letters, pp. 153-170.
Brown, R.M., D. Newton, CJ. Pickford and J.C. Sherlock. 1990. Human Metabolism of
Arsenobetaine Ingested with Fish. Hum Exp Toxicol 9: 41-6.
Buchet, J.P., J. Pauwels, R, Lauwerys. 1994. Assessment of Exposure to Inorganic Arsenic
following Ingestion of Marine Organisms by Volunteers. Environ Res 66(1): 44-51.
Buchet, J.P. and R. Lauwerys. 1994. Inorganic Arsenic Metabolism in Humans. In Arsenic:
Exposure and Health. W.R. Chappell, C.O, Abernathy and C.R. Cothern, Eds. Northworth:
Science and Technology Letters, pp. 181-190.
Buhl, Kevin J. and Steven J. Hamilton. 1991. Relative Sensitivity of Early Life Stages of Arctic
Grayling, Coho Salmon, and Rainbow Trout to Nine Inorganics. Ecoioxicology and
Environmental Safety 22: 184-197.
Buhl, Kevin J. and Steven J. Hamilton. 1990. Comparative Toxicity of Inorganic Contaminants
Released by Placer Mining to Early Life Stages of Salmonids. Ecotoxicology and
Environmental Safety 20: 325-342.
Carlson-Lynch, Heather, Barbara D. Beck and Pamela D. Boardman. 1994. Arsenic Risk
Assessment. Environmental Health Perspectives 102(4): 354-356.
50
-------
Chong, Steven, Kilian Dill and Evelyn McGown. 1989, The Interaction of Phenyidichloroarsine
with Erythrocytes. Journal of Biochemical Toxicology 4(1): 39-45.
Christkopoulos, Alexandras, Harold Norin, Margareta Sandstrom, Hjordis Thor, Peter Moldeus and
Ragnar Ryhage. 1988a. Cellular Metabolism of Arsenocholine, Journal of Applied
Toxicology 8(2): 119-127,
Christkopoulos, A., B. Hamasur, H, Norin and I. Nordgren. 1988b, Quantitative Determination of
Arsenocholine and Actylarsenocholine in Aquatic Organisms Using Pyrolysis and GC/MS.
Biomed Environ Mass Spec IS: 67-74.
Cockell, K.A., J,W. Hilton and W.J. Bettger. 1991. Chronic Toxicity of Dietary Disodium
Arsenate Hepatahydrate to Juvenile Rainbow Trout (Oncorhynchus mykiss). Archives of
Environmental Contamination and Toxicology 2li 518-527,
Columbia River Inter-Tribal Fish Commission (CRJTFC), 1994. A Fish Consumption Survey of the
Umatilta, Nez Perce, Yakarna and Warm Springs tribes of the Columbia River Basin.
Technical Report 94-3. Portland, OR: CRITFC.
Crecelius, E.A. 1977. Changes in the Chemical Speciation of Arsenic Following Ingestion by Man.
Env Health Persp 19: 147-150.
Cullen, W.R. and K.J. Reimer. 1989. Arsenic Speciation in the Environment. Chem Rev 89: 713-
764,
De Vicente, A., M. Aviles, J.C. Codina, J.J. Borrego and P. Romero. 1990. Resistance to
Antibiotics and Heavy Metais of Pseudomonas aeruginosa Isolated from Natural Waters,
Journal of Applied Bacteriology 68: 625-632.
Dabeka, Robert W,, Arthur D. McKenzie, Gladys M.A, Lacroix, ChantaJ Cleroux, Susan Bowe,
Russell A. Graham, Henry B.S. Conacher and Pam Verdier. 1993. Survey of Arsenic in
Total Diet Food composites and Estimation of the Dietary Intake of Arsenic by Canadian
Adults and Children, Journal of AOAC Intemationan6(l): 14-25.
Del Razo L, Luz Maria, 1994. Urinary Excretion of Arsenic Species in a Human Population
Chronically Exposed to Arsenic via Drinking Water: A Pilot Study. In Arsenic: Exposure
and Health. W.R. Chappell, C.O. Aberaathy and C.R. Cothern, Eds. Northworth: Science
and Technology Letters, pp. 91-100.
Demesmay, C., M. OSSe and M. Porthault. 1994. Arsenic Speciation by Coupling High-performance
Liquid Chromatography with Inductively Coupled Plasma Mass Spectrometry. Fresnius'
Journal of Analytical Chemistry 348: 205-210.
Dong, Jin-Tang and Xian-Mao Luo. 1993. Arsenic-induced DNA-Strand Breaks associated with
DNA-Protein Crosslinks in Human Fetal Lung Fibroblasts. Mutation Research 302: 97-102.
Edmonds, John S. and Kevin A. Francesconi. 1993. Arsenic in Seafood: Human Health Aspects
and Regulations. Marine Pollution Bulletin 26(12): 665-674,
51
-------
Edmonds, J.S., Y. Shibata, K.A. Francesconi, J. Yoshinaga and M. Morita. 1992. Arsenic Lipids
in the Digestive Gland of the Western Rock Lobster Panulirus cygnus: An Investigation by
HPLC ICP-MS. The Science of the Total Environment 122; 321-335.
Endo, Ginji, Koichi Kuroda, Akiyoshi Okamoto and Shun'ichi Horiguchi. 1992. Dimethylarsenic
Acid Induces Tetraploids in Chinese Hamster Cells. Bulletin of Environmental Contamination
and Toxicology 48: 131-137.
Farmer, J.G. and L.R. Johnson. 1990. Assessment of Occupational Exposure to Inorganic Arsenic
Based on Urinary Concentrations and Speciation of Arsenic. British Journal of Industrial
Medicine 47: 342-348.
Flanjak, Johann. 1982. Inorganic and Organic Arsenic in Some Commercial East Australian
Crustacea. Journal of the Science of Food Agriculture 33: 579-583.
Fowler, Bruce A., Hiroshi Yamauchi, E.A. Conner and M. Akkerman. 1993. Cancer Risks for
Humans from Exposure to the Semiconductor Metals. Scand J Work Environ Health
19(suppl.l): 101-103.
Francesconi, Kevin A., John S. Edmonds and Robert V. Stick. 1989. Accumulation of Arsenic in
Yelloweye Mullet (Aldrichetta forsteri) following Oral Administration of Organoarsenic
Compounds and Arsenate. The Science of the Total Environment 19: 59-67.
Freeman, H.C., J.F. Uthe, R.B. Fleming, P.H. Odense, R.G. Ackman, G. Landry and C. Musial.
1979. Clearance of Arsenic Ingested by Man from Arsenic Contaminated Fish. Bulletin of
Environmental Contamination and Toxicology 22; 224-229,
Friberg, Lars. 1988. The GESAMP Evaluation of Potentially Harmful Substances in Fish and Other
Seafood with Special Reference to Carcinogenic Substances, Aquatic Toxicology 11: 379-
393.
Gherardi, Remain K., Patrick Chariot, Muriel Vanderstigel, Denis Malapert, Josette Verroust, Alain
Astier, Christian Brun-Buisson and Annette Schaeffer. 1990. Organic Arsenic-induced
Guillain-Barre-like Syndrome due to Melarsoprol: A Clinical, Eleetrophysiological and
Pathological Study. Muscle & Nerve, pp. 637-645.
Hall, R.A., E.G. Zook, G.M. Meabura, 1978. National Marine Fisheries Service Survey of Trace
Elements in the Fishery Resource. NOAA Technical Report NMFA SSRF-721.
Hanna, C.P., J.F. Tyson and S. Mclntosh. 1993. Determination of Inorganic Arsenic and Its
Organic Metabolites in Urine by Flow-Injection Hydride Generation Atomic Absorption
Speetrometry. Clln Chem 39(8): 1662-1667.
Hartmann, Andreas and Gunter Speit, 1994, Comparative Investigations of the Genotoxic Effects of
Metals in the Single Cell Gel (SCG) Assay and the Sister Chromatid Exchange (SCE) Test.
Environmental and Molecular Mutagenesis 23: 299-305.
Hedlund, B., H. Norin, A. Christkopoulos, et al. 1982. Acetyiarsenocholine: A Cholinergic
Agonist. / Neurochem 39(3): 871-873.
52
-------
Hindmarsh, J.Thomas and Ross F, McCurdy, 1984. CiinicaJ and Environmental Aspects of Arsenic
Toxicity. CRC Critical Reviews in Clinical Laboratory Sciences 23(4); 315-347.
Hoffman, David J., Caroline J. Sanderson, Leonard J, LeCaptain, Eugene Cromartie and Grey W.
Pendleton. 1992. Interactive Effects of Arsenate, Selenium , and Dietary Protein on
Survival, Growth, and Physiology in Mallard Ducklings. Arch, Environ. Contam. Toxicol
22: 55-62.
Hopenhayn-Rich, C., A.M. Smith and H.M, Goeden, 1993. Human Studies do not Support the
Methylation Threshold Hypothesis for the Toxicity of Inorganic Arsenic. Env Res 60' 161-
177.
Hughes, James P., Lincoln Polissar and Gerald van Belle, 1988. Evaluation and Synthesis of Health
Effects Studies of Communities Surrounding Arsenic Producing Industries. International
Journal of Epidemiology 17(2): 407-413.
Irvin, T.Rick and Kurt J. Irgolic. !988. Arsenobetaine and Arsenocholine: Two Marine Arsenic
Compounds without Embryotoxicity, Applied Grganometallic Chemistry 2: 509-514.
Johansen, M.G., J.P. McGowan, S.H. Tu and D.Y. Shirachl 1984. Tumorigenic Effect of
DimethySarsinic Acid in the Rat. Proceedings of the Western Pharmacological Society 27;
289-291.
Johnson, L.R. and J,G. Farmer. 1991. Use of Human Metabolic Studies and Urinary Arsenic
Speciation in Assessing Arsenic Exposure. Bull Environ Contam Toxicol 46: 53-61.
Jongen, W.M.F., J.M. CardinaaJs and P.M.J, Bos. 1985. Genotoxicity Testing of Arsenobetaine,
the Predominant form of Arsenic in Marine Fishery Products. Food and Chemical Toxicology
23(7): 669-673.
Jonnalagadda, S.B., P.V.V. Prsada Rao. 1993. Mini Review: Toxicity, Bioavailability and Metal
Speciation. Camp, Biochem. Physiol. 106C(3): 585-595.
Kabir, Habib and Chandra Bilgi. 1993. Ontario Gold Miners with Lung Cancer. JOM 35(12):
1203-1207.
Kaise, T., K. Hanaoka, S. Tagawa, et al. 1988. Distribution of Inorganic Arsenic and Methylated
Arsenic in Marine Organisms. App Qrganomet Chem 2: 539-546,
Kalman, David A., James Hughes, Gerald van Belle, Thomas Burbacher, Doug Bolgiano, Kimberly
Coble, N.Karle Mottet and Lincoln Polissar. 1990, The Effect of Variable Environmental
Arsenic Contamination on Urinary Concentrations of Arsenic Species. Environmental Health
Perspectives 89; 145-151.
KaJman, D.A. 1988. Quantitation of Arsenic Species in Urine for Exposure Assessment Studies. J
Res Nat Bureau Standards 93: 315-318.
Kalman, D.A. 1987. Dietary Contributions to Arsenic Species in Urine. In: Trace Elements in
Human Health and Disease. Edited by: P. Granjean. Environmental Health 20, WHO,
Copenhagen.
53
-------
Lacayo, Martha L., Adela Cruz, Sandra Calero, Julio Lacayo and Inge Fomsgaard, 1992. Total
Arsenic in Water, Fish and Sediments from Lake XoSotian, Manasgua, Nicaragua, Bull,
Environ, Comam. ToxicoL 49; 463-470.
Langlois, Claude and Rene Langis. 1995. Presence of Airborne Contaminants in the Wildlife of
Northern Quebec. The Science of the Total Environment 160/161: 391-402.
Larsen, Erik H., Gunnar Pritzl and Steen Honore Hansen. !993a. Arsenic Speciation in Seafood
Samples with Emphasis on Minor Constituents: An Investigation Using High-performance
Liquid Chromatography With Detection by Inductively Coupled Plasma Mass Spectrometry.
Journal of Analytical Atomic Spectrometry 8: 1075-1084.
Larsen, Erik H,, Gunnar Pritzl and Steen Honore Hansen. 1993b. Speciation of Eight Arsenic
Compounds in Human Urine by High-performance Liquid Chromatography with Inductively
coupled Plasma Mass Spectrometric Detection Using Antimonate for Internal
Chromatographic Standardization. Journal of Analytical Atomic Spectrometry 8: 557-563.
Le, Xiao-Chun, William R. Cullen and Kenneth I. Reimer. 1994a, Speciation of Arsenic
Compounds by HPLC with Hydride Generation Atomic Absorption Spectrometry and
Inductively Coupled Plasma Mass Spectrometry Detection. Talanta 41(4): 495-502.
Le, X-C, W.R. Cullen and K.J. Reimer. 1994b. Human Urinary Arsenic Excretion after One-time
Ingestion of Seaweed, Crab and Shrimp. Clin Chem 40(4): 617-624.
Le, Sean X.C., William R.Cullen and Kenneth J. Reimer. 1994c. Speciation of Arsenic Compounds
in Some Marine Organisms. Environ. Sci. Technol. 28: 1598-1604,
Le, Xiao-Chen, William R. Cullen and Kenneth J. Reimer. 1993. Determination of Urinary Arsenic
and Impact of Dietary Arsenic Intake. Talanta 40(2): 185-193.
Leonard, A. and R.R. Lauwerys. 1980. Carcinogenicity, Teratogenicity and Mutagenicity of
Arsenic. Mutation Research 75: 49-62.
Li, Ke and Sam F.Y. Li. 1995. Speciation of Selenium and Arsenic Compounds in Natural Waters
by Capillary Zone Electrophoresis after On-column Preconcentration with Field-amplified
Injection. Analyst 120: 361-366.
Lin, Li, Jiansheng Wang and Joseph Caruso. 1995. Arsenic Speciation Using Capillary Zone
Electrophoresis with Indirect Ultraviolet Detection, Journal of Chromatographic Science 33;
177-432.
Lunde, G. 1977. Occurrence and Transformation of Arsenic in the Marine Environment.
Environmental Health Perspectives 19: 47-52.
Lunde, Gulbrand. 1973, Separation and Analysis of Organic-bound and Inorganic Arsenic in Marine
Organisms. Journal of the Science of Food Agriculture 24: 1021 -1027,
Lunde, Gulbrand. 1969. Water Soluble Arseno-organlc Compounds in Marine Fishes. Nature 224.
54
-------
Maher, W, and E, Butler. 1988. Arsenic in the Marine Environment. App. Organometal, Chem. 2;
191-214.
Maher, W.A. 1985. The Presence of Arsenobetaine in Marine Animals. Comp. Biochem, Physiol.
80C(I): 199-201.
Marafante, Erminio, Marie Vahter and Lennart Dencker. 1984. Metabolism of Arsenocholine in
Mice, Rats and Rabbits. The Science of the Total Environment 34: 223-240.
Mat, L 1994. Arsenic and Trace Metals in Commercially Important Bivalves, Anadara granosa and
Paphia undulata. Bull Environ, Contain. Toxicol. 52: 833-839.
McKone, Thomas E. and Jeffrey I. Daniels. 1991. Estimating Human Exposure through Multiple
Pathways from Air, Water and Soil. Regulatory Toxicology and Pharmacology 13: 36-61.
Mohri, T., A. Hisanaga, N. Ishinishi. 1990. Arsenic Intake and Excretion by Japanese Adults: A
7-Day Duplicate Diet Study. Fd Chem Toxic 28(7): 521-529.
Momplaisir, G-M. T. Lei and W.D. Marshall. 1994. Performance of a Novel Silica T-tube
Interface for the AAS Detection of Arsenic and Selenium Compounds in HPLC Column
Eluate. Anal Chem 66: 3533-3539.
Morel, G., J.L. Cluet, P. Teloahy, H.M. Yang, N. Thieffry and J. de Ceaurriz. 1995.
Interindividual Variability in the Urinary Excretion of Inorganic Arsenic Metabolites by C57
BL/6J Mice: Possible Involvement of a Thiol/Disulfide Exchange Mechanism. Toxicology
Letters 78: 111-117,
Murai, Takashi, Hiroyuki Iwata, Tatsuyuki Otoshi, Ginji Endo, Shun'ichi Horiguchi and Shoji
Fukushima. 1993. Renal Lesions Induced in F244/DuCrj Rats by 4-weeks Oral
Administration of Dimethylarsinic Acid. Toxicology Letters 66: 53-61.
Murer, A.J.L, A. Abildtrup, O.M. Poulson and J.M. Christensen. I992a. Effect of Seafood
Consumption on the Urinary Level of Total Hydride-Generating Arsenic Compounds.
Instability of Arsenobetaine and Arsenocholine. Analyst 117: 677-680.
Murer, Arm J.L., Anne Abildtrup, Otto M. PouSsen and Jytte Molin Christensen. 1992b. Estimation
of the Method Evaluation Function for the Determination of Hydride-Generating Arsenic
Compounds in Urine by Flow-Injection Atomic-Absorption Spectrometry. Talanta 39(5):
469-474.
Mushak, Paul and Annemarie F. Crocetti. 1995. Risk and Revisionism in Arsenic Cancer Risk
Assessment. Environmental Health Perspectives 103(7-8): 684-689.
•Navarro, M., H, Lopez, M.C. Lopez and M. Sanchez. 1992. Determination of Arsenic in Fish by
Hydride Generation Atomic Absorption Spectrometry. Journal of Analytical Toxicology 16:
169-171.
Nielsen, Forrest H. 1990. New Essential Trace Elements for the Life Sciences. In: Biological
Trace Element Research. Edited by: G.N. Schrauzer. Publisher: The Humana Press, Inc.
55
-------
I
Nielson, Kirk K,, Arthur W. Mahoney and Vern C. Rogers. 1991, Occurrence of Arsenic in \
Seafood from Fast Foods Analyzed by X-Ray Fluorescence, Journal of Food Composition
and Analysis 4: 285-292. I
Nixon, David E. and Thomas P. Moyer. 1992. Arsenic Analysis II: Rapid Separation and
Quantification of Inorganic Arsenic Plus Metabolites and Arsenobetaine from Urine. Clin.
Chem. 38(12): 2479-2483.
I
Parametrix, Inc. 1995. Phase 1 Data Report and Phase 2 Sampling and Analysis Approach:
Expanded Remedial Investigation and Feasibility Study ASARCO Sediments Superfund Site, 1
Final. Kirkland, WA. September 1995.
Parametrix, Inc. 1993. Site-Specific Residue Levels in Edible Seafood at the ASARCO Tacoma 1
Smelter Site, Draft Data Report.
PTI Environmental Services. 1995. Risk Estimates for Consumption of Seafood Collected Near the I
Proposed Kensington Mine Outfall. *
Philipp, Robin. 1985. Arsenic Exposure: Health Effects and the Risk of Cancer. Reviews on I
Environmental HealthV(1); 27-57. I
Phillips, D.J.H. 1990, Arsenic in Aquatic Organisms: A Review, Emphasizing Chemical |
Speciation. Aquatic Tox. 16: 151-186. I
Phillips, D.J.H. and M.H. Depledge. 1986. Distribution of Inorganic and Total Arsenic in Tissues |
of the Marine Gastropod Hemifusus ternatanus. Mar Ecol Prog Ser 34: 261-266. \
Pierce, R.S., D.T. Noviello, S.H. Rogers. 1981. Commencement Bay Seafood Consumption .
Report. Preliminary Report. Tacoma, WA: Tacoma-Pierce County Health Department. I
Rani, D.B. Rajini and A. Mahadevan. 1993. Patterns of Heavy Metal Resistance in Marine _
Pseudomonas MR1. Indian Journal of Experimental Biology 31: 682-686. I
Sabbioni, E., M. Fiscbach, G. Pozzi, et al. 1991. Cellular Retention, Toxicity and Carcinogenic
Potential of Seafood Arsenic. I. Lack of Cytotoxicity and Transforming Activity of
Arsenobetaine in the BALB/3T3 Cell Line, Carcinogenesis 12(7): 1287-1291. I
Sekulic, Bogdan, Jasenka Sapunar and Davorin Bazulic. 1991, Arsenic in Norway Lobster
(Nephrophs norvegicus L.) from Kvarneric Bay—Northeastern Adriatic. Bull, Environ §
Contam. Toxicol. 51: 460-463. *
Sheppard, Brenda S. Douglas T. Heitkemper and Cynthia M, Gastoo. 1994. Microwave Digestion I
for the Determination of Arsenic, Cadmium and Lead in Seafood Products by Inductively I
Coupled Plasma Atomic Emission and Mass Spectrometry, Analyst 119: 1683-1686.
Sheppard, Brenda S,, Joseph A. Caruso, Douglas T. Heitkemper and Karen A. Wolnik. 1992. I
Arsenic Speciation by Ion Chromatography with Inductively Coupled Plasma Mass
Spectrometric Detection. Analyst 117: 971-975. g
Shibata, Yasuyuki, Masatoshi Morita and Keiichiro Fuwa. 1992. Selenium and Arsenic in Biology:
Their Chemical Forms and Biological Functions, Adv. Biophys, 28: 31-80. •
56
-------
Shinagawa, A,, K. Shiorai, H. Yamanaka and T. Kikuchi. 1983. Selective Determination of
Inorganic Arsenic (III), (V), and Organic Arsenic in Marine Organisms, Bull J Soc Sci Fish
49(1): 75-78,
Shlomi, K., A. Shinagawa, T. Igarasht, et al. 1984. Contents and Chemical Forms of Arsenic in
Shellfishes in Connection with their Feeding Habits. Bull J Soc Set Fish 50(2): 293-297.
Shukla, N.P. and G.N. Pandey, 1985, Effect of Heavy Metals on Fish - A Review. Reviews on
Environmental Health V(l): 87-99.
Smith, Allan H,, Mary Lou Biggs, Claudia Hopenhayn-Rich and David KaJman. 1995. Arsenic Risk
Assessment. Environmental Health Perspectives 103(1): 15-17.
Smith, Allan H., Claudia Hopenhayn-Rich, Michael N. Bates, Helen M. Goeden, Irva Hertz-
Picciotto, Heather M. Duggan, Rose Wood, Michael J. Kosnett and Martyn T. Smith. 1992.
Cancer Risks from Arsenic in Drinking Water. Environmental Health Perspectives 97: 259-
267.
Snow, Elizabeth T. 1992. Metal Carcinogenesis: Mechanistic Implications. Pharac, Ther. S3: 31-
65.
Stary, J., K. Kratzer, J. .Prasilova and T. Vrbska. 1982. The Cummulation of Chromium and
Arsenic Species in Fish (Poecilia reticulata). International Journal of Environmental
Analytical Chemistry 12: 253-257.
Staveland, G., II Marthinsen, G. Norheim and D. Julshamn. 1993. Levels of Environmental
Pollutants in Flounder (Plaiichthys fleus L.) and Cod (Gadus morhua L.) Caught in the
Waterway of Glomrna, Norway. II. Mercury and Arsenic. Arch. Environ, Comam, ToxicoL
24: 187-193.
Stohrer, Gerhard. 1991. Arsenic: Opportunity for Risk Assessment. Archives of Toxicology 65:
525-531.
Story, W.Charles, Joseph A. Caruso, Douglas T, Heitkemper and Larry Perkins. 1992. Elimination
of the Chloride Interference on the Determination of Arsenic Using Hydride Generation
Inductively Coupled Plasma Mass Spectrometry, Journal of Chromatographic Science 30:
427-432,
Suedel, B.C., J.A. Boraczek, R.K. Peddicord, P.A. Clifford and T.M. Dillon. 1994. Trophic
Transfer and Bioraagnification Potential of Contaminants in Aquatic Ecosystems. Reviews of
Environmental Contamination and Toxicology 136: 21-89.
Tarn, G.K.H., S.M. Charbonneau, F. Bryce and E. Sandi. 1982. Excretion of a Single Dose of
Fish-Arsenic in Man. Bulletin of Environmental Contamination and Toxicology 28: 669-673.
Tamaki, S. and W.T. Frankenberger Jr. 1992.. Environmental Biochemistry of Arsenic. Reviews of
Environmental Contamination and Toxicology 124: 79-110.
57
-------
Tetra Tech. 1995, Draft Report; Assessing Human Health Risks from Chemically Contaminated
Fish in the Lower Columbia River: Risk Screening. Lower Columbia River Bi-state
Program. TC 9968.05.
Tetra Tech 1988. Health Risk Assessment of Chemical Contamination in Puget Sound Seafood.
Puget Sound Estuary Program.
Thomas, David J. 1994. Arsenic Toxicity in Humans: Research Problems and Prospects.
Environmental Geochemistry and Health 16(3/4): 107-111.
Toy, K.A., G.D. Gawne-Mittelstaedt, N.L. Polissar and S. Liao. 1995. A Fish Consumption
Survey of the Tulalip and Squaxin Island Tribes of the Puget Sound Region, DRAFT.
Tulalip Tribes, Natural Resources Department, 7615 Totem Beach Road, Marysville, WA
98271.
Tseng, W.P., H.M. Chu, S.W. How, et al. 1968. J Nad Cancer Insi 40: 453-463.
Tsuji, Joyce S, at Kle'mfelder, Inc. 1993. Memorandum dated Aupst 30, 3993, to Mr. Michael R.
Thorp at Heller, Ehrman, White and McAuliffe.
United States Environmental Protection Agency (USEPA), 1995. Online Integrated Risk Information
System.
United States Environmental Protection Agency (USEPA). 1989. Exposure Factors Handbook.
Internal Review Draft. National Center for Environmental Assessment. Washington D.C.
NCEA-W-005.
United States Environmental Protection Agency (USEPA). 1988. Special Report on Ingested
Inorganic Arsenic: Skin Cancer; Nutritional Essentiality. Risk Assessment Forum:
Washington, D.C. EPA/625/3-87/013.
United States Environmental Protection Agency (USEPA). 1984. Health Assessment Document for
Inorganic Arsenic. Research Triangle Park, NC.
Vahter, Marie. 1994. Review: Species Differences in the Metabolism of Arsenic Compounds.
Applied Organometallic Chemistry 8: 175-182.
Vahter, Marie, Erminio Marafante and Lennart Dencker. 19S4, Tissue Distribution and Retention of
74As-Dimethylarsinic Acid in Mice and Rats. Archives of Environmental Contamination and
Toxicology 13: 259-264.
Vahter, Marie, Erminio Marafante and Lennart Dencker. 1983. Metabolism of Arsenobetaine in
Mice, Rats and Rabbits. The Science of the Total Environment 30: 197-211.
Vela, Nohora P., Lisa K. Olsen and Joseph A. Caruso. 1993, Elemental Speciation with Plasma
Mass Spectrometry. Analytical Chemistry 65(13): 585A-597A.
Viren, John R. and Abraham Silvers. 1994. Unit Risk Estimates for Airborne Arsenic Exposure:
An Updated View Based on Recent Data from Two Copper Smelter Cohorts. Regulatory
Toxicology and Pharmacology 20: 125-138.
58
-------
WaJkiw, 0, and D.E. Douglas, 1975, Health Food Supplements Prepared from Ke!p»A Source of
Elevated Urinary Arsenic. Clinical Toxicology 8(3): 325-331.
Weis, Peddrick, Judith S, Weis, Arthur Greenberg and Thomas J, Nosker, 1992. Toxicity of
Construction Materials in the Marine Environment: A Comparison of Chromated-Copper-
Arsenate-Treated Wood and Recycled Plastic. Archives of Environmental Contamination and
Toxicology 22: 99-106.
Weston. 1996. ASARCO Sediments Site Human Health Risk Evaluation: Proposed Approach for
Evaluating Seafood Ingestion. Seattle, WA. January 24, 1996.
Winger, Parley V,, Donald P. Schultz and W.Waynon Johnson. 1990. Environmental Contaminant
Concentrations in Biota from the Lower Savannah River, Georgia and South Carolina. Arch,
Environ. Contam, ToxicoL 19: 101-117.
Yamamoto, Shinji, Yoshitsup Konishi, Tsutomu Matsuda, Takashi Murai, Masa-Aki Shibata, Isao
Matsui-Yuasa, Shuzo Otani, Koichi Kuroda, Ginji Endo and Shoji Fukushima. 1995. Cancer
Induction by an Organic Arsenic Compound, Dimethylarsinie Acid (Cacodylic Acid), in
F344/DuCrj Rats after Pretreatment with Five Carcinogens. Cancer Research 55: 1271-
1276.
Yamanaka, Kenzo, Akira Hasegawa, Ryoji Sawamura and Shoji Okada. 1991. Cellular Response to
Oxidative Damage in Lung Induced by the Administration of Dimethylarsinie Acid, a Major
Metabolite of Inorganic Arsenic, in Mice. Toxicology and Applied Pharmacology 108: 205-
213.
Yasui, A., C. Tsutsumi and S. Toda. 1978. Selective Determination of Inorganic Arsenic (III), (V)
and Organic Arsenic in Biological Materials by Solvent Extraction-Atomic Absorption
Spectrophotometry, Agric Biol Chem 42; 2139-2145.
Zook, Elizabeth G., John J. Powell, Betty M. Hackley, John A. Emerson, James R. Brooker and
George M. Knobl, Jr. 1976. National Marine Fisheries Service Preliminary Survey of
Selected Seafood for Mercury, Lead, Cadmium, Chromium and Arsenic Content. Journal of
Agricultural Food Chemistry 24(1): 47-53.
59
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