| Chemical Abstract Number (CAS #) |
1024573
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| Synonyms | Heptachlor epoxide |
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2,5-Methano-2H-indeno[1,2b]oxirene,
2,3,4,5,6,7,7-heptachloro-1a,1b,5,5a,6,6a-hexahydro- (alpha, beta and gamma isomers) |
| Analytical Methods |
EPA Method 505 |
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EPA Method 508 |
EPA Method 525 |
EPA Method 608 |
EPA Method 617 |
EPA Method 625 |
EPA Method 8080A |
EPA Method 8081 |
EPA Method 8250A |
| Molecular Formula | C10H5Cl7O |
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| Use | NOT AVAIL AS COMMERCIAL PRODUCT IN USA, & IT IS NOT NORMALLY
PRESENT IN COMMERCIAL HEPTACHLOR SRP: HEPTACHLOR EPOXIDE IS
FORMED FROM HEPTACHLOR IN THE ENVIRONMENT/.
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| Melting Point | 160-161.5 DEG C
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| Molecular Weight | 389.40
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| Odor Threshold Concentration | 0.02 PPM
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| Sensitivity Data | Heptachlor is not known to be an eye irritant. Heptachlor
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| Environmental Impact | Heptachlor epoxide is not produced commercially, but rather is formed by the chemical
and biological transformation of heptachlor in the environment. In 1978, the USEPA cancelled the
registration of heptachlor and chlordane, which contains 10% heptachlor and agricultural uses of
these insecticides were phased out. After July 1, 1983 heptachlor and chlordane may only be used
for underground termite control. Heptachlor epoxide adsorbs strongly to soil and is extremely
resistant to biodegradation, persisting for many years in the upper soil layers. Some volatilization
or photolysis loss may occur. If released into water, it will adsorb strongly to suspended and
bottom sediment. Little biodegradation would be expected. Heptachlor epoxide is expected to
exist in both the vapor and particulate phases in ambient air. Vapor phase reactions with
photochemically produced hyroxyl radical may be an important fate process (an estimated half-life
of 1.5 days). Heptachlor expoxide that associated with particulate matter and aerosols should be
subject to gravitational settling and washout by rain. Due to its stability, long range dispersal
occurs, resulting in the contamination of remote areas. Some photolysis loss probably occurs but
there is no data to evaluate the rate of this process. Heptachlor epoxide is bioconcentrated
extensively. It is taken up into the food chain by plants and bioconcentrates into fish, animals and
milk. Residues in human milk primarily comes from eating meat and fish as is evident by the much
lower concn in the milk of vegetarians. However uptake in humans via inhalation of vapors in
houses treated with heptachlor and chlordane is also evident. Where monitoring at the top of the
food chain was performed such as residues in bald eagles and the ongoing Illinois Milk Survey,
levels of heptachlor epoxide have not significantly changed three years after agricultural uses of
the pesticide were being phased out. Exposure to heptachlor epoxide is primarily through the
ingestion of food containing residues of the insecticide. The food classes most likely to be
contaminated are dairy products and meat/poultry/fish.
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| Environmental Fate | TERRESTRIAL FATE: LABELED HEPTACHLOR WAS APPLIED TO SOIL.
ANALYSES INDICATED PRESENCE OF 1-HYDROXYCHLORDENE, HEPTACHLOR
EPOXIDE & A METABOLITE LESS HYDROPHILIC THAN HEPTACHLOR EPOXIDE.
TERRESTRIAL FATE: Heptachlor epoxide adsorbs strongly to soil and is extemely resistant to
biodegradation. Monitoring studies reveal that it persists for many years in soil and does not
appear to leach significantly into the lower soil layers. On the soil surface, heptachlor epoxide may
slowly photodegrade, particularly during the summer months (1% per month). Heptachlor
epoxide loss from soil in a microagricultural chamber is observed after application, but the rate of
loss decreases over the course of a few days. This loss may be due to volatilization or photolysis
of the chemical from the surface microlayer.
AQUATIC FATE: If released into water, heptachlor epoxide will adsorb strongly to suspended
and bottom sediment. Little biodegradation would be expected and photolysis probably would
only be significant in surface waters in the presence of photosensitizers. While slow volatilization
of the free molecule (half-life 60 hr from a model river) would be expected, since heptachlor
epoxide would be mainly adsorbed to particulate matter, this would not be a primary loss
mechanism. No measureable degradation occurred when 10 ppb of heptachlor epoxide was
incubated in water of the Little Miami River, a stream receiving domestic, industrial, and
agricultural wastes, for 8 wks in sealed jars under sunlight and artificial lights . Heptachlor
epoxide was very persistant in a model ecosystem, having approximately the same environmental
stability as dieldrin . Its estimated half-life in the lower Rhine River based on concentration
differences between sampling points was 35 days .
ATMOSPHERIC FATE: Based upon the vapor pressure, heptachlor epoxide is expected to
exist in both vapor and particulate phases in ambient air. In the atmosphere, vapor phases
reactions with photochemically produced hydroxyl radicals may be an important fate process. The
rate constant for the vapor-phase reaction of heptachlor epoxide with photochemically produced
hydroxyl radicals has been estimated to be 1.09X10-11 cu cm/molecule-sec at 25 deg C, which
corresponds to an atmospheric half-life of about 1.5 days at an atmospheric concentration of
5X10 5 hydroxyl radicals per cu cm . Heptachlor epoxide that is associated with particulate
matter and aerosols and should be subject to gravitational settling and washout by rain.
Contamination of lakes with heptachlor epoxide is believed to occur primarily by wet deposition.
Under the proper conditions, heptachlor epoxide bearing dust can be transported for thousands of
miles. Photolysis would be expected to occur but there are no data on the extent of heptachlor
epoxide degradation in dispersed dust and aerosols.
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| Drinking Water Impact | A 1976 REPORT INDICATES THAT HEPTACHLOR EPOXIDE HAS BEEN
FOUND IN DRINKING-WATER, GROUND-WATER & RIVER-WATER AT 7 US &
EUROPEAN LOCATIONS & IN LAKES, RIVERS, TAP-WATER FROM BIOLOGICAL
SEWAGE TREATMENT PLANT AT 28 US & EUROPEAN LOCATIONS.
DURING THE 1978 IRRIGATION SEASON, 14 GROUND WATER SAMPLES WERE
COLLECTED IN THE CENTRAL PLATEAU REGION OF NEBRASKA, AN AREA
KNOWN TO HAVE HIGH NITRATE-NITROGEN LEVELS, & ANALYZED FOR
PRESENCE OF 13 RESIDUES. LEVELS OF ORGANOCHLORINE INSECTICIDES
HEPTACHLOR & ITS DERIVATIVE, HEPTACHLOR EPOXIDE, WERE ALL BELOW THE
DETECTABLE LIMITS OF 0.005-0.010 UG/L.
HEPTACHLOR HAS RARELY BEEN FOUND IN SURFACE WATERS, & THEN ONLY
IN SMALL QUANTITIES: 5-30 PARTS PER TRILLION FOR HEPTACHLOR &/OR 5-40
PARTS PER TRILLION FOR HEPTACHLOR EPOXIDE.
Heptachlor and heptachlor epoxide have been detected in private drinking wells at
concentrations of < 0.02 ug/l.
DRINKING WATER: Heptachlor epoxide was not detected in samples of drinking water from
10 to 13 US cities collected between Oct 1975 and Mar 1982 for Infant and Toddler Total Diet
samples(1-5). Similarly, it was not found in 54 municipal and private wells sampled in agricultural
areas of California in the San Joaquin Valley and Santa Barbara and Monterey counties(7). It was,
however, reported in tap water in Ottawa, Canada at a level of <44 parts per trillion (6).
Heptachlor and heptachlor epoxide have been detected in private drinking wells at concentrations
less than 0.02 ug/L(8).
GROUNDWATER: During the 1978 irrigation season, 14 groundwater samples were collected
in the central plateau region of Nebraska, an area known to have high nitrate-nitrogen levels, and
were analyzed for the presence of 13 residues. Levels of the organochlorine insecticide,
heptachlor and its derivative, heptachlor epoxide, were all below the detectable limits of 0.005 to
0.010 ug/l . Heptachlor epoxide was detected in groundwater well in Kansas at a concentration
of 0.026 ug/L . Heptachlor epoxide was detected in groundwater underneath golf courses in
Bass River and Hyannisport, Massachusetts at concentrations ranging from 0.03 to 0.06 ug/l and
undetected levels to 0.16 ug/l with average concentrations of 0.04 and 0.07 ug/l, respectively .
Heptachlor epoxide was detected, but not quantified, in New Jersey groundwater in areas
generally devoted to agricultural land uses .
SURFACE WATER: Of the 4632 stations reporting heptachlor epoxide in ambient water in
EPA's STORET database, 36.0% contained detectable levels of the chemical with a median concn
of 0.001 ppb . In an inventory of chemical substances identified in the Great Lakes ecosystem,
heptachlor epoxide was detected in (basin, number detected/number reported): Ontario, 7/9; Erie,
11/22; St. Clair River, 2/2; Huron, 7/10; Michigan, 10/15; Superior, 4/6 . The positive results
included the lake water of all the Great Lakes in addition to rivers and creeks feeding into the
lakes . The mean concn of heptachlor epoxide in waters collected from 11 agricultural
watersheds in Ontario, in 1975-76 and 1976-77 were 1.1 and 0.5 parts per trillion, respectively
with the overall presence being 3.8 and 8.1%(7). For 1976-77, the Grand and Saugeen Rivers in
this study had mean concns in river water of 0.03 and 0.05 parts per trillion and 0.3 and 1 ppb in
suspended solids(8). 47% of samples from the lower Niagra River in 1980-81 contained
heptachlor epoxide, 0.5 ppt mean . In another study, 13.9-22.6 parts per trillion of the chemical
was found in the surface microlayer at 5 stations in the Niagra River but none was found in
subsurface water or suspended solids(6). 2-3.9 ppt was found in Lake Pontchartrain, LA, a
shallow estuary in the Mississippi delta . Despite the presence of cyclodienes in its effluent and
the continued use of heptachlor and heptachlor epoxide, heptachlor epoxide was not detected in
the water column near the ocean outfall of the Los Angeles County Sanitation District at White
Point, CA .
SURFACE WATER: Heptachlor epoxide was detected at 14 of 14 sampling stations throughout
Lake Ontario at concentrations ranging from 0.167 to 0.375 ng/L . On August 7, 1985,
heptachlor epoxide was detected at 13 of 13 sampling stations throughout Lake St. Clair at
concentrations ranging from 0.087 to 0.203 ng/L . According to the 1975 to 1980 National
Summary of the Pesticide Monitoring Network sponsored by the EPA and US Geological Survey,
heptachlor epoxide was detected at 4.5% of 177 stations across the nation with a frequency of
occurrence of 0.3% for 2,946 samples . In 1979, heptachlor epoxide was detected at 5.3% of
171 stations across the nation with a frequency of occurrence of 1.0% for 1,017 samples .
Heptachlor epoxide was listed as a contiminant of the Great Lakes including Lakes Ontario, Erie,
Huron, Michigan, Superior and St. Clair . Heptachlor epoxide was detected in Thompson's
tributary to the Niagara River at a concentration of 0.05 ng/L . In 1982, heptachlor epoxide
was detected in 3% of the surface water samples from Hamilton Harbor, Lake Ontario at
concentrations ranging from undetected levels to 1 ng/l(6). Heptachlor epoxide was detected in
waters off the coast of Argentina at concentrations ranging from undetected levels to 3.7 ng/l with
a mean of 1.9 ng/l(7).
RAIN/SNOW: According to the Canadian Network for Sampling Organic Samples in
Precipitation, 0-33%, 6% median, of samples of precipitation from the 12 sampling sites (210
samples) throughout Canada contained heptachlor epoxide . A sample from Windsor, Ontario
contained the higest levels, 46 ppt . The concn of heptachlor epoxide in rain at two sites at
opposite ends of Lake Superior ranged from ND to 1.3 ppt, which contributed to the estimate
that 17.0 kg of the chemical enters the lake from rain and snow each year . Canadian arctic
snow contained heptachlor epoxide at concentrations ranging from undetected levels of 0.41
ug/l .
EFFL: A 1976 REPORT STATES THAT HEPTACHLOR EPOXIDE HAS BEEN FOUND
IN LAND-RUNOFF EFFLUENT AT 7 US & EUROPEAN LOCATIONS & IN
EFFLUENT WATER FROM BIOLOGICAL SEWAGE TREATMENT PLANT AT 28 US &
EUROPEAN LOCATIONS.
Of the 672 stations reporting heptachlor epoxide in industrial effluents in EPA's STORET
database, 4.2% contained detectable levels of the chemical . In a comprehensive survey of
wastewater from 4000 industrial and publicly owned treatment works (POTWs) sponsored by the
Effluent Guidelines Division of the U.S. EPA, heptachlor epoxide was only identified in
discharges of publicly owned treatment works with a 1% frequency of occurrence and a median
concn of 19.3 ppb . In the National Urban Runoff Program in which samples of runoff were
collected from 19 cities (51 catchments) in the U.S., heptachlor epoxide was detected only in
Washington, DC (1% of the samples) at a level of 0.1 ppb .
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