| Chemical Abstract Number (CAS #) |
77474
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| Synonyms | Hexachlorocyclopentadiene |
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1,3-Cyclopentadiene, 1,2,3,4,5,5-hexachloro- | HCP | Perchlorocyclopentadiene |
| Analytical Methods |
EPA Method 505 |
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EPA Method 525 |
EPA Method 612 |
EPA Method 625 |
EPA Method 8081 |
EPA Method 8120A |
EPA Method 8250A |
| Molecular Formula | C5Cl6 |
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| Use | Intermediate for many insecticides, polyester resins, and flame retardants.
Intermediate for resins, dyes, pharmaceuticals.
/Used to make shock proof plastics, acids, esters, ketones, and fluorocarbons.
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| Consumption Patterns | ESSENTIALLY 100% AS A CHEMICAL INTERMEDIATE
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| Apparent Color | YELLOW GREEN LIQUID; Dense, oily liquid
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| Odor | Pungent odor
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| Boiling Point | 239 DEG C AT 753 MM HG
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| Melting Point | -9 DEG C
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| Molecular Weight | 272.77
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| Density | 1.7019 AT 25 DEG C/4 DEG C
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| Odor Threshold Concentration | 0.15 ppm or 1.7 mg/cu m
Odor low: 1.5 mg/cu m; Odor high: 3.3 mg/cu m
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| Sensitivity Data | Inhalation of mist is highly irritating to mucous membranes, causing lacrimation, sneezing
& salivation. Contact with eye causes severe irritation. Liquid is extremely irritating to skin
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| Environmental Impact | Potential sources of release of hexachlorocyclopentadiene are emissions and effluent
discharges from: those facilities which manufacture or use this compound as an intermediate;
application and disposal of contaminated pesticides; and emissions from the combustion of certain
chlorinated wastes. Hexachlorocyclopentadiene is not a persistent environmental contaminant. If
released to soil, hexachlorocyclopentadiene is predicted to be relatively immobile.
Hexachlorocyclopentadiene has the potential to photolyze on soil surfaces. Volatilization from
soil surfaces is expected to be dependent upon organic carbon content. In moist soil, this
compound would be subject to chemical hydrolysis (half-life hours to weeks) and biodegradation.
If released to water, this compound will degrade primarily by photolysis and chemical hydrolysis.
During daylight hours, in clear shallow water, the photolytic half-life is expected to be on the
order of 2-8.5 minutes. 2,3,4,4,5-Pentachloro-2-cyclopentenone, hexachloro-2-cyclopentenone,
and hexachloro-3-cyclopentenone have been identified as primary photodegradation products. In
unlit or deep, turbid water, chemical hydrolysis is expected to be an important fate process.
Hydrolytic half-lives range from several hours to 2-3 weeks in waters with temperature in the
range of 20-30 deg C. Hexachlorocyclopentadiene has the potential to adsorb extensively to
suspended solids and sediments; nevertheless, adsorption does not significantly affect the rate of
hydrolysis. Volatilization from water is expected to be a significant removal mechanism, although
in highly turbid waters adsorption to suspended solids and sediments could substantially limit
losses volatilization. The volatilization half-lives from a model river and a model pond with or
without adsorption have been estimated to be 5 hours, 37 days and hours, respectively.
Biodegradation is expected to be of minor importance. Hexachlorocyclopentadiene could
potentially bioaccumulate in some aquatic organisms depending upon the species. If released to
the atmosphere, this compound is expected to exist almost entirely in the vapor phase. In the
atmosphere, direct photolysis is expected to be the dominant removal mechanism. Reaction with
photochemically generated hydroxyl radicals, reaction with ozone molecules, washout, and dry
deposition are not expected to be environmentally significant fate processes. Certain segments of
the population may be exposed through ingestion of contaminated drinking water or contaminated
fish. People living in the vicinity of hazardous waste disposal sites containing this compound may
be exposed through inhalation of contaminated air. Workers involved in the manufacture or
handling of this compound or treatment of wastes containing this compound could potentially be
exposed by inhalation or dermal exposure.
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| Environmental Fate | AQUATIC FATE: Hexachlorocyclopentadiene underwent chemical alterations in water
forming both lipophilic and hydrophilic products. The water soluble substances included at least
11 unidentified breakdown products.
TERRESTRIAL FATE: If released to soil, hexachlorocyclopentadiene should be immobilized by
strong adsorption to organic matter. Potential exists for significant losses via photolysis on soil
surfaces. Below the soil surface, photolysis would not be a significant fate process due to light
attenuation. Volatilization from soil surfaces is expected to be of minor importance. In moist soil,
this compound would be subject to chemical hydrolysis (half-life hours to weeks) and
biodegradation under aerobic and anaerobic conditions. Radiolabelled
hexachlorocyclopentadiene at an initial concn of 1 mg/kg was added to soil contained in a glass
flask covered with perforated aluminum foil and kept on a laboratory shelf which was exposed to
sunlight. After 7 days incubation, recovery of nonpolar compounds (hexachlorocyclopentadiene
and nonpolar metabolites) was 6.1% in unaltered, nonsterile soil (approx 72% was polar and
nonextractable), approx 6% in nonsterile soil at pH 4, approx 9% in nonsterile soil at pH 8,
36.1% in autoclaved soil (33.5% was polar and nonextractable), approx 15% in sodium azide
treated soil, and approx 3% in flooded soil. These data indicate that loss of
hexachlorocyclopentadiene from soil is the result of abiotic and biotic degradation as well as
partitioning within the media .
AQUATIC FATE: If released to water, hexachlorocyclopentadiene will degrade primarily by
photolysis and chemical hydrolysis. During daylight hours, hexachlorocyclopentadiene found in
clear, shallow water is expected to photodegrade with a half-life on the order of 2-8.5
minutes(1,2). 2,3,4,4,5-Pentachloro-2-cyclopentenone, hexachloro-2-cyclopentenone, and
hexachloro-3-cyclopentenone have been identified as primary photodegradation products of
hexachlorocyclopentadiene. In unlit or deep, turbid water, chemical hydrolysis is expected to be
an important fate process. Hydrolytic half-lives ranging from several hours to 2-3 weeks are
predicted for waters with temperatures in the range of 20-30 deg C(1,3-5).
Hexachlorocyclopentadiene has the potential to adsorb extensively to suspended solids and
sediments; nevertheless, adsorption does not significantly affect the rate of hydrolysis .
Volatilization from water is expected to be a significant removal mechanism, although in highly
turbid waters adsorption to suspended solids and sediments could substantially limit losses via
volatilization. The volatilization half-lives from a model river and a model pond with and without
adsorption have been estimated to be 5 hours, 37 days and 58 hours, respectively(6,7,SRC). It
appears as though hexachlorocyclopentadiene may also be susceptible to biodegradation. Potential
exists for bioaccumulation in some aquatic organisms depending upon the organism and the
species.
ATMOSPHERIC FATE: Organic compounds having a vapor pressure of greater than 1X10-4
mm Hg at ambient temperature are expected to exist almost entirely in the vapor phase in the
atmosphere . Hexachlorocyclopentadiene has a vapor pressure of 0.063 mm Hg at 25 deg C ;
therefore, it is expected to exist predominantly in the vapor phase in the atmosphere. If
released to the atmosphere, direct photolysis is expected to be the dominant removal mechanism.
Reaction of hexachlorocyclopentadiene with photochemically generated hydroxyl radicals or
ozone molecules is predicted to be too slow to be environmentally significant. The relatively low
water solubility of hexachlorocyclopentadiene, suggests that there is little potential for washout in
precipitation.
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| Drinking Water Impact | SURFACE WATER: U.S EPA STORET Data Base - 85 samples, 0.1% pos., median
concn <10 ug/L . 1978-79, Ohio River at Wheeling, WV, Huntington, WV, Louisville, KY,
Evansville, IN and 10 other locations, 106 samples, 5.7% pos., detection limit 0.04 ug/L, max
concn 0.1 ug/L . Qualitatively identified in water samples from Lake Ontario, but not found in
water samples from Lake Erie and Lake Michigan . Detected in Rhine River water samples
collected during January 1978 .
DRINKING WATER: Identified in drinking water obtained from Athens, GA during Nov. and
Dec. 1976, 4 samples, 100% pos., avg concn 37.5 ng/L . Tentatively identified in drinking
water obtained from the Torresdale Water Treatment Plant in Philadelphia, PA during Oct.
1976 . Qualitatively identified in drinking water obtained from an undisclosed location in the
United Kingdom during Nov. 1978 .
GROUNDWATER: Identified in leachate from the Occidental Chem Co. S-Area landfill in
Niagara Falls, NY which is located adjacent to the Niagara Falls drinking water treatment
plant .
EFFL: USEPA STORET Data Base - 1,228 samples, 0.9% pos., median concn <10 ug/L .
Qualitatively identified in stack emissions from an hazardous waste incinerator test burn . Air
samples collected during May and June 1978 at the Memphis (TN) North Treatment Plant
contained hexachlorocyclopentadiene . Hexachlorocyclopentadiene was identified in samples of
wastewater effluent from a chemical plant in Michigan which was manufacturing this
compound .
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