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 |
HAL(1day) |
| 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.
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
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
List of Contaminants
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