| Chemical Abstract Number (CAS #) |
319846
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| Synonyms | alpha-BHC |
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Cyclohexane, 1,2,3,4,5,6-hexachloro-, (1-alpha, 2-alpha,3-beta, 4-alpha, 5-beta,
6-beta)- | HCH-alpha |
| Analytical Methods |
EPA Method 508 |
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EPA Method 608 |
EPA Method 617 |
EPA Method 625 |
EPA Method 8080A |
EPA Method 8081 |
EPA Method 8250A |
| Molecular Formula | C6H6Cl6 |
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| Use | COMPONENT OF BENZENE HEXACHLORIDE, BHC-FORMER INSECTICIDE
/SRP, Former Use/: HCH is often used with DDT Hexachlorocyclohexane
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| Apparent Color | MONOCLINIC PRISMS FROM ALCOHOL OR ACETIC ACID
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| Boiling Point | 288 DEG C
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| Melting Point | 159-160 DEG C
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| Molecular Weight | 290.85
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| Density | 1.87 AT 20 DEG C
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| Odor Threshold Concentration | Detection in water for alpha-lindane of unspecified purity at 0.088 ppm
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| Sensitivity Data | Symptoms of HCH poisoning are often delayed up to 3 hr. They include , respiratory
difficulty. Other symptoms of HCH contact are skin irritation, skin sensitization, scabis and
pediculosis. Hexachlorocyclohexane
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| Environmental Impact | Small amounts of alpha-hexachlorocyclohexane (alpha-HCH) may result from the
isomerization of lindane (gamma-HCH) upon exposure to sunlight. Release of alpha-HCH to the
environment probabaly occurs mainly from the use of technical hexachlorocyclohexane as a
pesticide. When released to water, alpha-HCH is not expected to volatilize or hydrolyze
extensively. Release of alpha-HCH to the soil will most likely result in slow leaching to
groundwater. Slow volatilization may also occur. Alpha-HCH entering the atmosphere, by
analogy to lindane, may be subject to rain-out and dry deposition. The estimated half-life for the
reaction of alpha-HCH with hydroxyl radicals in the atmosphere is 1.63 days. Biodegradation may
occur slowly in aerobic surroundings and is expected to occur rapidly and extensively under
anaerobic conditions. Alpha-HCH has been reported to photodegrade in water in spite of the lack
of a photoreactive center, but photolysis is not considered to be a major process in its
environmental fate. Alpha-HCH will bioconcentrate slightly in fish and other aquatic organisms.
Monitoring data indicate that alpha-HCH is a contaminant in air, water, sediment, soil, fish and
other aquatic organisms, foods, and humans. Human exposure results primarily from food.
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| Environmental Fate | TERRESTRIAL FATE: After two weeks in unsterilized, submerged Casiguran sandy
loam, the concentration of alpha-hexachlorocyclohexane (alpha-HCH) declined from about 16
ppm to <1 ppm compared to a decline from about 18 ppm to 15 ppm in a sterilized
preparation . Fifteen years following the application of technical hexachlorocyclohexane to a
sandy loam soil in Nova Scotia, Canada, 4% of the applied alpha-HCH remained in the soil . Of
this amount, about 92% was found between 0-20 cm, indicating minimal leaching . The soil was
under cultivation yearly throughout the fifteen years, increasing the likelihood that volatilization
may have occurred . Incubation of aerobic and anaerobic soil suspensions of alpha-HCH for
three weeks resulted in disappearence of 11.0% and 26.2% of the added compound,
respectively . This result was said to indicate that anaerobic degradation is more extensive than
aerobic biodegradation .
AQUATIC FATE: No data on the rate of hydrolysis of alpha-hexachlorocyclohexane
(alpha-HCH) is available. Hydrolysis half-lives of 92-771 hr have been reported for lindane in
natural waters , however, and based on the relatively greater stability of alpha-HCH compared
to lindane imparted by its smaller number of axial chlorines, it may hydrolyze more slowly than
lindane.
ATMOSPHERIC FATE: The half-life of the reaction of alpha-hexachlorocyclohexane
(alpha-HCH) with hydroxyl radicals in the atmosphere was estimated to be 1.63 days . Dry
deposition and rainfall have been found to remove atmospheric lindane at 3.3 and 2.5% per week,
respectively . Alpha-HCH should also be subject to these processes.
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| Drinking Water Impact | DRINKING WATER: Alpha-hexachlorocyclohexane (alpha-HCH) levels in municipal
drinking water samples collected in January 1980 from 12 locations in Canada ranged from
2.7-20.3 ppt in winter and from 0.45-9.7 ppt in summer(7). Tap water from Ottawa, Ontario
Canada contained 17 ppb alpha-HCH(8). GROUNDWATER: Samples from New Jersey taken
during 1977-1979 ranged from ND-0.1 ppb, 15.7% of the samples were positive(9). Five
subsurface water samples collected along the Niagara River from Lake Erie to Lake Ontario
contained from small range < 0.005-0.007 ppb alpha-HCH(11). SURFACE WATER: Samples
from New Jersey taken during 1977-1979 ranged from ND-0.8 ppb, 39% of the samples were
positive(9). Samples from Washington, DC and Denver, CO were 20% positive and alpha-HCH
concentrations ranged from 0.0027-0.1 ppb(10). 75 raw water samples collected at Niagara on
the lake in 1980-1981 were 100% positive for alpha-HCH with mean and median concentrations
of 10.5 and 9.7 ppt, respectively(12). RAIN/SNOW: Great Lakes ecosystem precipitation
samples - 1-35 ppt, 15 ppt avg ; Enewetak Atoll rain samples - 3110 ng/cu m . Lake Superior
(Isle Royale) - May-Oct 1983 rain samples, 19-65 ppt avg . Lake Superior (Caribou Island) -
April-May 1983, 3.9-46 ppt mean . Canada (12 sites) - rain and frozen samples, April 1977 -
Dec 1980, 75-100% pos, ND (< 0.001 ppb)-0.1300 ppb, 0.03 ppb avg . Great Lakes (Canadian
side) - 49 rain samples, 59% pos, 11.7 ppt avg, 41 ppt max, 17 snow samples, 0.9 ppt avg .
Portland, OR - southwest, rain samples, March - April 1982, 5.9 ppt avg, southeast, rain samples,
Oct-Dec 1982, 47 ppt avg(6).
EFFL: Alpha-hexachlorocyclohexane (alpha-HCH) residues in treated wastewater effluents from
a variety of industries were as follows: coal mining- 47 samples, 6.4% positive, 0.10-2.2 ppb, 1.5
ppb avg; founderies-13 samples, 100% positive, 5-6 ppb, 5.1 ppb avg . In organic chemicals
manufacturing/plastics, 3 of an unspecified number of samples contained a mean alpha-HCH
concentration of 10 ppb .
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