Chlordane is an organochlorine compound with the formula C₁₀H₆Cl₈, used as a pesticide in the United States from 1948 to 1988. It was sold under trade names like Octachlor® and Velsicol 1068®.
Chlordane is a thick liquid that can range in colour from colourless to amber, depending on purity. It may have no smell or a mild, irritating odour.
Chlordane is not a single substance but a mixture of related chemicals — about 10 main ones — including
trans-chlordane
cis-chlordane
beta-chlordene
heptachlor
trans-nonachlor
Chlordane does not dissolve in water, so it must be mixed with emulsifiers (soap-like substances) to create a milky spray mixture for use.
What is Chlordane used for?
Chlordane was used as a broad-spectrum pesticide from 1948 to 1988.
From 1983 to 1988, its only approved use in the U.S. was for termite control — applied underground around home foundations.
Before 1978, it was also used on:
Crops
Lawns
Gardens
As a fumigant
In 1978, the EPA cancelled food crop uses and began phasing out above-ground applications over 5 years.
Since 1988, all U.S. uses have been cancelled, though it may still be manufactured and exported to other countries.
Chlordane could be used to control fire ants, but no products are currently registered for this use.
Chlordane was used as pesticide in the United States from 1948 to 1988.
In the Environment
Chlordane enters the environment through past use on crops, soil, and homes.
In soil:
Strongly binds to topsoil, unlikely to reach groundwater
May remain for over 20 years, especially in heavy or clay soils
Evaporates from surface — faster in light, sandy soils, slower in heavier soils
In water:
Some binds to sediments, some evaporates
Unclear if it breaks down significantly in water or sediments
In the atmosphere:
Breaks down by reacting with light and chemicals
Can travel long distances before settling in water or soil
In living organisms:
Chlordane or its byproducts accumulate in fat of fish, birds, mammals, and even humans
Still detected in food, air, water, and soil today
Sources and Routes of Exposure
Sources of Exposure
Before 1988, exposure occurred in workplaces — manufacturing, applying, or handling chlordane (e.g., farmers, pest control, lawn care).
Indoor air studies reported chlordane levels ranging from <1 to 610,000 ng/m³.
Today, the highest exposure occurs in homes treated for termites — indoor air may remain contaminated for years.
Digging soil around treated homes can also expose people — soil levels ranged from 22 to 2,540 ppm in tested areas.
Food grown on land treated decades ago may still contain chlordane residues.
Listed as a pollutant of concern under the EPA’s Great Waters Programme due to
Persistence
Bioaccumulation
Toxicity
Routes of Exposure
Main ways people can be exposed to chlordane:
Inhalation
Skin absorption
Ingestion
Skin or eye contact
Health Effects
Acute Effects
Exposure to high levels of chlordane can cause neurological symptoms in both humans and animals, such as
Headache
Dizziness
Irritability
Convulsions
Chlordane can also affect the blood.
Animal studies have shown that chlordane has high acute toxicity in short-term tests (e.g., in rats).
Chronic Effects
Long-term (chronic) exposure to chlordane, especially through inhalation, mainly affects the nervous system in humans.
Animal studies have reported effects on:
Liver
Kidneys
Blood
Thyroid
Respiratory system
Nervous system
Reference Values:
Reference Concentration (RfC): 0.0007 mg/m³ (based on liver effects in rats)
Reference Dose (RfD): 0.0005 mg/kg/day (based on liver necrosis in mice)
Reproductive & Developmental Effects
A study of women living in homes repeatedly treated with chlordane showed increased ovarian and uterine disease, but it’s unclear if chlordane alone caused these effects.
In animals:
One study showed biochemical and behavioural changes similar to male sex steroids.
Another reported altered reproductive behaviour in male rats exposed to chlordane.
Cancer Risk
An occupational study found increased odds of non-Hodgkin’s lymphoma among men who used chlordane as an insecticide.
Other studies found no link to leukaemia or multiple myeloma.
Animal studies have shown liver cancer in mice and male rats after ingesting chlordane.
The EPA classifies chlordane as a Group B2 carcinogen — a probable human carcinogen.
Safety
First Aid Measures
Inhalation:
Chlordane is not likely hazardous by inhalation, but if exposed:
Move person to fresh air
Keep them warm and at rest
Skin Contact:
Hazardous by skin contact
Remove contaminated clothing and shoes immediately
Wash skin with mild soap or detergent for at least 15 minutes
If burns occur, cover with sterile, dry dressing
Seek immediate medical attention
Eye Contact:
Rinse eyes with plenty of water for at least 15 minutes
Lift eyelids occasionally to remove any residue
Call a physician
Ingestion:
Chlordane is toxic if swallowed
Do not induce vomiting or use gastric lavage
The person should drink a large amount of water or milk (100-fold dilution)
Call a physician immediately
Exposure Control & Personal Protection
Engineering Controls
Use natural ventilation
Ensure access to a safety shower and eyewash station
Personal Protective Equipment (PPE)
Respiratory Protection: Not required
Gloves: Highly recommended
Eye Protection: Safety glasses with side shields
Clothing: Lab coat or long-sleeved garment
Regulation
United States
EPA: The Environmental Protection Agency guidelines for drinking water suggest that no more than 60 ppb chlordane should be present in drinking water that children consume for no longer than 10 days. Drinking water should contain no more than 0.5 ppb for children or 2 ppb for adults if they drink the water for longer periods. All use of chlordane were cancelled on food crops, effective March 1978. Until 1988, EPA permitted chlordane use for termite control or dipping the roots or tops of nonfood plants. On April 14, 1988, however, EPA stopped all sales and commercial use of chlordane. Federal regulations limit the amount of chlordane that factories can release into wastewater. The EPA requires industry to report releases or spills of 1 pound or more. A temporary guideline of the National Research Council indicated that 0.005 mg/m³ should be the maximum amount allowed in the air of military housing.
FDA: The Food and Drug Administration has established that the levels of chlordane and its breakdown products in most fruits and vegetables should not be greater than 300 ppb and in animal fat and fish should not be greater than 100 ppb.
OSHA: The Occupational Safety and Health Administration regulates chlordane levels in the workplace. The maximum allowable level in workplace air is 0.5 mg/m³ for a person who is exposed for 8 hours per workday and 40 hours per workweek.
NIOSH: The National Institute for Occupational Health and Safety also recommends an exposure limit of 5 mg/m³ for a person exposed to chlordane in the workplace for 8 hours per workday and 40 hours per workweek.
Australia
Safe Work Australia: Safe Work Australia has established a Time Weighted Average (TWA) concentration for chlordane of 0.5 mg/m³ for a 40-hour workweek.
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