| Chemical Abstract Number (CAS #) |
2385855
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| Synonyms | Mirex |
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1,3,4-Metheno-1H-cyclobuta[cd]pentalene,
1,1a,2,2,3,3a,4,5,5,5a,5b,6,-dodecachlorooctahydro- | Dechlorane |
| Analytical Methods |
EPA Method 617 |
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EPA Method 8081 |
| Molecular Formula | C10CL12 |
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| Use | FIRE RETARDANT FOR PLASTICS, RUBBER, PAINT, PAPER, ELECTRICAL
GOODS
INSECTICIDE USED TO CONTROL WESTERN HARVESTER ANTS, YELLOW
JACKETS, & IMPORTED FIRE ANTS (FORMER USE)
MIREX IS A STOMACH INSECTICIDE WITH LITTLE CONTACT ACTIVITY AND HAS
FOUND ITS WIDEST USE AGAINST ANTS; FOR IMPORTED FIRE ANT, BAITS
CONTAINING 0.075% ARE USED; FOR HARVESTER ANT BAIT IS 0.15%.
/Former use: Mirex is marketed under the tradename Dechlorane for use in flame-retardant
coatings for various materials.
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| Consumption Patterns | 1.88X10 7 G WERE USED AS BAIT UNDER GOVERNMENT SPONSORED
PROGRAMS TO CONTROL THE IMPORTED FIRE ANT, WHICH IS ITS MAJOR USE
(1972)
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| Apparent Color | SNOW-WHITE CRYSTALS FROM BENZENE
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| Odor | ODORLESS
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| Melting Point | 485 deg C
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| Molecular Weight | 545.59
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| Odor Threshold Concentration | Odor low 5.0667 mg/cu m; Odor high 5.0667 mg/cu m.
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| Sensitivity Data | Moderate skin irritant.
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| Environmental Impact | Mirex is a highly stable insecticide formerly used for fire ant control in the southeastern
US. Mirex was also employed as a flame-retardant. Release into the environment has occurred via
effluents from manufacturing plants and sites where mirex was utilized as a fire resistant additive
to polymers, and at points of application where it was used as a insecticide. Mirex is expected to
persist in the environment despite the 1978 ban on its use in the US. For the most part mirex is
resistant to biological and chemical degradation. Photolysis of mirex may occur. However,
sorption is likely to be a more important fate process. Persistent compounds such as kepone, and
monohydro- and dihydro- derivatives of mirex have been identified as products of extremely slow
transformation of mirex. Mirex has been shown to bioconcentrate in aquatic organisms. A Koc
value of 2.4X10 7 indicates mirex will strongly adsorb to organic materials in soils and
sediments. Therefore mirex is expected to be immobile in soil and partition from the water column
to sediments and suspended material. A Henry's Law Constant for mirex of 5.16X10-4 atm-cu
m/mole at 22 deg C suggests rapid volatilization may occur from environmental waters and moist
soils where absorption does not dominate. Based on this Henry's Law Constant, the volatilization
half-life from a model river (22 deg C; 1 meter deep flowing 1 m/sec with a wind speed of 3
m/sec) has been estimated to be 10.7 hr; however, this estimation neglects the potentially
important effect of adsorption. The volatilization half-life from an environmental pond, which
considers the effect of adsorption, can be estimated to be about 1143 years.
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| Environmental Fate | There is evidence for degradation of mirex to chlordecone (Kepone) in the environment.
AQUATIC FATE: Sediment-natural water & Daphnia magna-bluegill (Lepomis macrochirus)
models were used to study the fate of mirex in aquatic systems. Mirex was shown to move
through the food chain when daphnids were used as prey organisms.
TERRESTRIAL FATE: Mirex does not leach into the soil profile & is predicted to volatilize
only slowly. There is no evidence for any rapid transformation so it should be considered
persistent. Because it is so strongly adsorbed to the soil & stays on the surface, a major loss from
terrestrial systems would probably be erosion & particle bound into surface waters.
TERRESTRIAL FATE: Mirex did not degrade (rate constant equal to zero) at a concn of 0.5
g/100g dry weight in nine aerobic soils after six mo incubation . For the most part mirex is
resistant to biological and chemical degradation. Adsorption and volatilization are likely to be
important environmental fate processes. Persistent compounds such as kepone, and monohydro-
and dihydro- derivatives of mirex have been identified as products of extremely slow
transformation of mirex. A Koc value of 2.4X10 7 indicates mirex will strongly adsorb to soil
organic matter and therefore be immobile in most soils(2 A Henry's Law constant for mirex of
5.16X10-4 atm-cu m/mole at 22 deg C suggest that rapid volatilization of mirex from moist
soils may occur where adsorption does not dominate .
AQUATIC FATE: Mirex is expected to be extremely persistent in environmental waters. For the
most part mirex is resistant to biological and chemical degradation. Adsorption and volatilization
are likely to be more important environmental fate processes. Persistent compounds such as
kepone, and monohydro- and dihydro- derivatives of mirex have been identified as products of
extremely slow transformation of mirex. Mirex has been shown to bioconcentrate in aquatic
organisms. A Koc value of 2.4X10 7 indicates mirex will strongly absorb to organic matter
and may partition from the water column to sediments and suspended materials. A Henry's Law
constant for mirex of 5.16X10-4 atm-cu m/mole at 22 deg C suggests rapid volatilization of
mirex from natural waters . Based on this Henry's Law constant, the volatilization half-life from
a model river (22 deg C; 1 meter deep flowing 1 m/sec with a wind speed of 3 m/sec) has been
estimated to be 10.7 hr(3,SRC); however, this estimation neglects the potentially important effect
of adsorption. The volatilization half-life from a model pond, which considers the effect of
adsorption, can be estimated to be about 1100 years(4,SRC); if parameters are introduced into the
pond model to exclude adsorption effects, the volatilization half-life is reduced to 5.1 days.
ATMOSPHERIC FATE: Based upon a vapor pressure of 3.0X10-7 mm Hg at 25 deg C
mirex is expected to exist mainly in the particulate phase with a lesser proportion of mirex in the
vapor phase in the ambient atmosphere . Mirex is expected to be stable against photogenerated
hydroxyl radicals in the atmosphere.
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| Drinking Water Impact | SURFACE WATER: Mirex was detected in Niagara River water with a 12%
occurrence at concn up to 2.6 ng/l . Settling traps were used to determine the mirex concn on
particulate matter entering Lake Ontario from the Niagara River . Mirex concn ranged from 3.9
to 18 ng/g .
DRINKING WATER: Mirex was detected in 12.5% of the wells tested with an average concn
of 2 ng/l and at cocn up to 30 ng/l for rural Chesterfield County in northern SC Mirex was
detected in 72.7% of the wells tested with an average cocn of 83 ng/l and at concn up to 437 ng/l
for rural Hampton County in southern SC . Finished drinking water supplies for the city of
Niagara Falls which were drawn from the Niagara River were found to contain mirex at concn
(mo/yr) of 0.01(9/77), 0.2(8/78), 0.3(9/78), 0.9(10/78), 0.01(4/79) and 0.01(6/79) ug/l .
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