United States
Environmental Protection
Agency
Office of Water
4601
EPA811-F-95-002n-T
October 1995
National Primary Drinking
Water Regulations
Thallium
CHEMICAL/ PHYSICAL PROPERTIES
CAS NUMBER: 7440-28-0 (metal)
COLOR/ FORM/ODOR: Thallium is a metallic element that exists in
nature only in as salts and other combined forms. '
SOIL SORPTION COEFFICIENT: N/A; strongly adsorbed to some clays
at alkaline pH. ' '
BIOCONCENTRATION FACTOR: Log BCFs = 5 to 5.2 in fish, inverte-
brates; expected to bioconcentrate
SOLUBILITIES:
acetate
carbonate-
chloride-
nitrate-
oxide-
sulfate-
very soluble
4% (w/w) cold water
2.9g/Lat15.5degC
39.1 g/L to 95.5 g/L at 20 deg C
insoluble
48.7 g/L at 20 deg C
COMMON ORES: Thallium is a trace metal associated with potas-
sium in copper, gold, zinc, and cadmium ores.
DRINKING WATER STANDARDS
MCLG: O.OQ05mg/l
MCL: 0.002 mg/l
HAL(child): 1-to 10-day: 0.007 mg/L
Longer-term: 0.007 mg/L
HEALTH EFFECTS SUMMARY
Acute: EPA has found thallium to potentially cause the
following health effects from acute exposures at levels
above the MCL: gastrointestinal. irritation; peripheral
neuropathy.
Short-term exposures considered "safe" for a 10-kg
(22 Ib.) child consuming one liter of water per day: upto a
7-year exposure to 0.007 mg/L.
Chronic: Thallium has the potential to cause the
following health effects from long-term exposures at
levels above the MCL: changes in blood chemistry;
damage to liver, kidney, intestinal and testicular tissues;
hair loss. '
Cancer: There is no evidence that thallium has the
potential to cause cancer from lifetime exposures in
drinking water.
USAGE PATTERNS
There is no domestic production of thallium. Approxi-
mately 4,500 Ibs. of thallium and its .compounds were
imported in 1987. In 1984, US industry consumed thal-
lium compounds as follows: electronics industry, 60-
70%; the remainderwas used in Pharmaceuticals, alloys
and glass manufacture.
Thallium compounds are used in infrared spectrom-
eters, in crystals, in other optical systems, and for color-
ing glass; in semiconductor research; with mercury for
switches and closures which operate at subzero tem-
peratures; in photoelectric cells, lamps, and, in electron-
ics, in scintillation counters; as catalyst in organic synthe-
sis; as a rat poison, as an ant bait, and as a reagent in
analytical chemistry. It was also formerly used as a
depilating agent by dermatologists and as a cosmetic
depilatory cream.
RELEASE PATTERNS
In nature, thallium is present as a trace compound in
many minerals, mainly associated with potassium and
rubidium.
Man-made sources of thallium pollution are gaseous
emission of cement factories, coal burning power plants,
Toxic RELEASE INVENTORY -
RELEASES TO WATER AND LAND:
1987 TO 1993
TOTALS (in pounds)
Top Five States
TX
OH
MN
CO
IN
Water
2,606
6
1.500
1,100
0
0
Major Industries*
Primary copper smelting 1,856
Petroleum refining 750
Primary nonferrous metals 0
Blast furnaces, steelworks 0
Land
2.770
2,020
0
0
500
250
765
1,255
500
250
October 1995
Technical Version
Printed on Recycled Paper
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and metal sewers. The leaching of thallium from ore
processing operations is the major source of elevated
thallium concentrations in water. Thai; < is a trace metal
associated with copper, gold, zinc, and cadmium.
.Water concentrations of 1 to 88 parts per billion have
been reported in rivers draining metal mining areas.
From 1987 to 1993, according to the Toxics Release
Inventory thallium releases to land and water totalled
over 5,000 Ibs., of which about half was to water. These
releases were primarily from copper smelting and petro-
leum refining industries. The largest releases occurred in
Texas and Ohio.
ENVIRONMENTAL FATE
i.
In a study of thallium movement in a simple aquatic
ecosystem, concentrations of thallium decrease slowly in
the water and increase tenfold in the vegetation and fish.
Definite transport of thallium occurred among water, fish,
and vegetation, but no transport was seen between the
sand other ecosystem components.
It was found that increasing pH decreased thallium-
inorganic interactions. Increases in pH, however, pro-
duced extensive thallium-humic acid interaction. It ap-
pears that thallium-organic interactions may be important
in most natural water systems.
In reducing environments, thallous species may pre-
cipitate as a sulfide; otherwise, it will remain in solution.
Thallium sulfate has been used as a rodenticide in
Japan, where it was sprayed over forest areas, but was
not found to persist in water for more than a month. Since
thallium is soluble in most aquatic systems, it is readily
available to aquatic organisms and is quickly bioaccumu-
lated. Goldfish have a higher rate of uptake for thallium
than for the five most common alkali metals. Some algae
are able to concentrate thallium by a factor of 127 to 220
within one hour; in comparison, the concentration factors
of 2.7 hours exposure were 114for lead, 30 for cadmium,
80 for zinc, and 313 for copper.
Bioconcentration factors: in freshwater fish,-factor of
100,000; in marine invertebrates, factor of 150,000; in
marine fish, factor of 100,000; in freshwater and marine
plants, factor of 100,000; in clams (Mya arenia), factor of
17.6-18.6; in mussel (Mytilus edulis), factor of 10.9-12.4;
and in Atlantic salmon, factor of 27-1430.
OTHER REGULATORY INFORMATION
MONITORING:
- FOR GROUND WATER SOURCES:
INITIAL FREQUENCY- 1 sample once every 3 years
REPEAT FREQUENCY- If no detections tor 3 rounds, once every 9 years
- FOR SURFACE WATER SOURCES:
INITIAL FREQUENCY- 1 sample annually
REPEAT FREQUENCY- If no detections for 3 rounds, once every 9 years
- TRIGGERS - If detect at > 0.002 mg/L, sample quarterly.
ANALYSIS:
REFERENCE SOURCE METHOD NUMBERS
EPA 600/4-79-020 279.2
NTIS PB 91-231498 200.8; 200.9
Standard Methods 3113:31138
TREATMENT
BEST AVAILABLE TECHNOLOGIES •. •
Activated alumina; Ion Exchange
FOR ADDITIONAL INFORMATION:
4 EPA can provide further regulatory and other general information:
• EPA Safe Drinking Water Hotline - 800/426-4791
f Other sources of lexicological and environmental fate data include:
• toxic Substance Control Act Information Line - 202/554-1404
• Toxics Release Inventory, National Library of Medicine - 301/496-6531
• Agency for Toxic Substances and Disease Registry - 404/639-6000
October 1995
Technical Version
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