Technical Factsheet on Heptachlor and Heptachlor Epoxide

Technical Factsheet on: HEPTACHLOR AND
HEPTACHLOR EPOXIDE
List of Contaminants
As part of the Drinking Water and Health pages, this fact sheet is part of a larger publication:
National Primary Drinking Water Regulations
Drinking Water Standards (in mg/L)
MCLG MCL HALflday)
Heptachlor: zero 0.0004 0.01
- epoxide zero 0.0002 0.01
Health Effects Summary
Acute: EPA has found heptachlor to potentially cause liver and central nervous system damage from
short-term exposures at levels above the MCL.
Short-term exposures in drinking water which are considered "safe" for a 10-kg (22 lb.) child consuming 1
liter of water per day: a one- to ten-day exposure to 0.01 mg/L.
Chronic: Heptachlor and its epoxide have the potential to cause extensive liver damage from long-term
exposure at levels above the MCL.
Cancer: There is some evidence that both heptachlor and heptachlor epoxide have the potential to cause
cancer from a lifetime exposure at levels above the MCL.
Usage Patterns
Production of heptachlor in 1982 was nearly 100,000 lbs, all of which was used as a non-agricultural
insecticide. Most uses of the product were cancelled in 1978. The only permitted commercial use of
heptachlor products is for fire ant control in buried, pad-mounted electric power transformers, and in
underground cable television and telephone cable boxes.
Release Patterns
Heptachlor may be released directly to the soil in connection with its use in termite and fire ant control.
However, heptachlor has been found in treated wastewater from some types of industrial facilities. Based
on monitoring data, mean loadings in various wastestreams are: coal mining - 0.0081, foundries - 0.030
and nonferrous metals manufacturing - 0.0008.
Heptachlor epoxide is not produced commercially, but rather is formed by the chemical and biological
transformation of heptachlor in the environment.
Environmental Fate
Release of heptachlor to soil surfaces will result in volatilization from the surface, especially in moist soils,
but volatilization of heptachlor incorporated into soil will be slower. Hydrolysis in moist soils is expected to
be significant. In soil, heptachlor will degrade to 1-hydroxychlordene, heptachlor epoxide and an
unidentified metabolite less hydrophilic than heptachlor epoxide. Biodegradation may also be significant.
Heptachlor is expected to adsorb strongly to soil and, therefore, to resist leaching to groundwater.

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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.
Release of heptachlor to water will result in hydrolysis to 1-hydroxychlordene (half-life of about 1 day) and
volatilization. Adsorption to sediments may occur. Biodegradation of heptachlor may occur, but is
expected to be slow compared to hydrolysis. Direct and photosensitized photolysis may occur but are not
expected to occur at a rate comparable to that of hydrolysis. Heptachlor epoxide will adsorb strongly to
suspended and bottom sediment when released to water. Little biodegradation is expected.
In air, vapor phase heptachlor will react with photochemically generated hydroxyl radicals with an
estimated half-life of 36 min. Direct photolysis may also occur. Heptachlor epoxide is expected to exist in
both the vapor and particulate phases in ambient air. Vapor phase reactions with photochemically
produced hydroxyl radical may be an important fate process (an estimated half-life of 1.5 days).
Heptachlor epoxide 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.
Bioconcentration of heptachlor may be significant: bioconcentration factors average around 12,000 in
various fish species. Bioconcentration may be limited, however, by the rapidity of heptachlor hydrolysis in
water and the adsorption of heptachlor to sediments. Heptachlor epoxide is bioconcentrated extensively.
It is taken up into the food chain by plants and bioconcentrates into fish, animals and milk.
Chemical/ Physical Properties
CAS Number: Heptachlor- 76-44-8; Heptachlor epoxide- 1024-57-3
Color/ Form/Odor: White to light tan waxy solid with a camphor-like odor. Available as emulsifiable
concentrates and oil solutions. The epoxide is formed from heptachlor in the environment.
M.P.: 95-96 C B.P.: 145 C
Octanol/Water Partition (Kow): Log Kow = 3.9 to 5.4 (est.)
Density/Spec. Grav.: 1.57 at 9 C
Solubility: 0.03 mg/L of water at 25 C; insoluble in water
Vapor Pressure: 3x10-4 mm Hg at 25 C
Soil sorption coefficient: Log Koc estimated at 4.48; low to very low mobility in soil
Odor/Taste Thresholds: N/A
Bioconcentration Factor: 5000 to 15,000 in fish; potential to bioconcentrate in aquatic organisms.
Henry's Law Coefficient: 2.62x10-3 atm-cu m/mole;
Trade Names/Synonyms: 3-Chlorochlordene; Aahepta; Agroceres, Hepta, Heptachlordane, Heptagran,
Heptamul, Heptox, Gold Crest H-60, Rhodiachlor, Velsicol 104, Basaklor, Soleptax, Termide

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Other Regulatory Information
Monitoring For Ground/Surface Water Sources:
Initial Frequency- 4 quarterly samples every 3 years
Repeat Frequency- If no detections during initial round:
2 quarterly per year if serving >3300 persons;
1 sample per 3 years for smaller systems
Triggers - Return to Initial Freq. if:
Heptachlor detected at > 0.0004 mg/L, or
epoxide detected at > 0.0002 mg/L
Analysis:
Reference Source Method Numbers
EPA 600/4-88-039 505; 508; 508.1; 525.2
Treatment- Best Available Technologies:
Granular Activated Charcoal
For Additional Information:
EPA can provide further regulatory and other general information:
EPA Safe Drinking Water Hotline - 800/426-4791
Other sources of toxicological and environmental fate data include:
Toxic Substance Control Act Information Line - 202/554-1404
Toxics Release Inventory, National Library of Medicine - 301/496-6531
Agency for Toxic Substances and Disease Registry - 404/639-6000
National Pesticide Hotline - 800/858-7378

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