| Chemical Abstract Number (CAS #) |
58082
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| Synonyms | Caffeine |
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3,7-Dihydro-1,3,7-trimethyl-1H-purine-2,6-dione |
| Analytical Method |
EPA Method 553 |
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| Molecular Formula | C8H10N4O2 |
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| Use | Medication
FOOD ADDITIVE; IN BEVERAGES
MEDICATION (VET)
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| Apparent Color | White, prismatic crystals ; Prism-like crystals
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| Odor | ODORLESS
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| Boiling Point | 178 DEG C (SUBLIMES)
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| Melting Point | 238 DEG C (ANHYD)
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| Molecular Weight | 194.19
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| Density | 1.23 @ 18 DEG C/4 DEG C
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| Environmental Impact | Caffeine is both a naturally occurring and a commercially produced organic compound
which is used in soft drinks, medicines and other consumer products. It may be released to the
environment as a fugitive emission during its production or use and in wastewater effluent, landfill
leachate, or incinerator fly ash. If released to soil, caffeine will display very high mobility. It will
not volatilize from either moist or dry soil to the atmosphere. Limited data indicate that caffeine
has the potential to biodegrade in soil. If release to water, caffeine will not volatilize from water
to the atmosphere. It will not bioconcentrate in fish nor will it adsorb to sediment. Limited data
indicate that caffeine has the potential to biodegrade in water. If released to the atmosphere,
caffeine may undergo a gas-phase reaction with photochemically produced hydroxyl radicals at an
estimated half-life of 2.5 hrs; however, caffeine will exist predominately adsorbed to particulates
in the atmosphere, which may attenuate the rate of this process. Occupational exposure to
caffeine may occur by inhalation of dust or dermal contact during its production, formulation or
use. The general population will be exposed to caffeine by the ingestion of foods, medicines or
consumer products in which it is contained.
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| Environmental Fate | TERRESTRIAL FATE: If released to soil, estimated soil adsorption coefficients ranging
from 18 to 22(1-3,SRC) indicate that caffeine will display very high mobility . An estimated
Henry's Law constant of 1.9X10-19 atm-cu m/mole at 25 deg C(4,SRC) indicates that it will not
volatilize from moist soil to the atmosphere. An estimated vapor pressure of <1X10-8 mm
Hg at 25 deg C(2-4,SRC) indicates that it will also not volatilize from dry soil to the
atmosphere. Limited data indicate that caffeine has the potential to biodegrade in soil(6,7).
AQUATIC FATE: If released to water, an estimated Henry's Law constant of 1.9X10-19 atm-cu
m/mole at 25 deg C(1,SRC) indicates that caffeine will not volatilize from water to the
atmosphere. Estimated bioconcentration factors ranging from 0.52 to 2.25(2-4,SRC) indicate that
caffeine will not bioconcentrate in fish and aquatic organisms. Estimated soil adsorption
coefficients ranging from 18-22(2-4,SRC) indicate that it will not adsorb to sediment and
suspended organic matter. Limited data indicate that caffeine will biodegrade in water under
aerobic conditions(5-7). The pKa of caffeine, 14(7), and its pKb, 14.2(8), indicates that it is both
a weak acid and a weak base; however, it may exist as a dissociated (zwitterionic) species under
aqueous conditions.
ATMOSPHERIC FATE: If released to the atmosphere, an estimated rate constant for the
gas-phase reaction of caffeine with photochemically produced hydroxyl radicals of 1.52X10-10 cu
cm/molec-sec translates to an atmospheric half-life of 2.5 hrs . The estimated vapor pressure
of caffeine, <1X10-8 mm Hg at 25 deg C(2-4,SRC) indicates that it will exist predominately
absorbed to particulates in the atmosphere , which may attenuate the rate of hydroxyl radical
oxidation.
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| Drinking Water Impact | SURFACE WATER: Caffeine was detected in 8 of 204 water samples obtained from
waterway sites collected throughout the United States, 1975-6, at concns ranging from 1 ppb to 6
ppb . It was detected in 4 of 13 samples taken from the Lake Michigan basin at concns ranging
from 1-4 ug/L . Caffeine was also detected in trace quantities in samples from the River Lee,
UK , date not provided, and the Delaware River, 1976 . It was detected, but not quantified,
in water samples from the lower Fox River, WI, 1976-77 . The concn of caffeine in the Rhine
River, the Netherlands, was 0.1 ug/L, 1979(6). Caffeine was qualitatively detected in river water
samples taken in the Kitakyushu area, Japan, date not given(7).
DRINKING WATER: Caffeine was qualitatively detected in Philadelphia's drinking water supply,
1975-7 . It was qualitatively detected in treated drinking water supplies in the U.K. .
EFFL: Caffeine was qualitatively detected in 1 of 10 secondary effluents taken at Illinois
wastewater treatment plants, 1980 . Caffeine was detected in 6 of 6 effluent samples obtained
from 3 different publicly owned treatment works in NJ, date not provided, at concns ranging from
3-20 ppb . It has been detected in 7 of 46 US industrial effluent samples . Caffeine has also
been detected in Los Angeles County wastewater treatment plant effluent samples, 1980-81, at 40
ug/L . It was detected in the effluent from a municipal wastewater treatment plant in
Vancouver, BC, Canada, at concn ranging from 16-292 ug/L . Caffeine was qualitatively
identified in the leachate of a Barcelona, Spain, sanitary landfill(6). It was qualitatively detected in
the fly ash samples collected from a municipal incinerator in Toronto, Canada(7).
Found in primary domestic sewage plant effluent at 0.010-0.046 mg/l
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