How to Correct
Chlordane Home Contamination

Application to
Outside Wood Surfaces

Chlordane was frequently applied to the outside wood surfaces of many homes built before 1988. This would have been done because of an actual termite problem or as a preventive safeguard from a worried homeowner. Under first consideration, the application to the outside of the home would not appear as a problem, however, as described in research on the chlordane web site, conducted by Dr. Kaye Kilburn of the the University of California, even outdoor applications of the chemical can find their way indoors to contaminate the interior to a level that can cause a variety of health problems from increased infections to increases in many neurological disorders including - anger, migraine headaches and depression.

Correction Procedure


The least expensive way to correct contamination of the exterior wood surfaces of a home is to seal the wood with a hard, enamel based paint. The most efficient method for correcting this problem is to identify which side of the home the problem exists and to then replace the contaminated wood pieces. If the home is constructed of 4x8 sheets of plywood siding, these sheets can be easily replaced for a materials cost of about $25.00 per sheet. Check with the pest control company who applied the chlordane and ask if their records show where chlordane was applied.

Infiltration up through the Foundation of the Home

This is the same route that radon has been found to contaminate homes throughout the U.S. When a home was built before 1988, standard procedure was to literally saturate 100 gallons of chlordane into the soil per 1000 square feet of home area just before the concrete foundation was poured. Therefore, a 2000 square foot home would have 200 gallons of chlordane saturated into the soil. After several years of "settling," cracks form in the foundation and basement walls or around plumbing pipes which has been found to allow for entry of the chemical into the home.

Correction Procedure


Success has been shown with underground infiltration problems by simply identifying where the cracks in the foundation are located and sealing these with an acrylic caulking or similar compound. It is also recommended to caulk around all plumbing pipe entry points through the foundation. As chlordane was often concentrated in the outer one or two foot perimeter just underneath the foundation, there needs to be a good caulking seal at the point where the wall meets the floor

Attic Contamination

As the attic of a home is comprised of wooden 2x4 support beams, these were often sprayed with chlordane by a pesticide company to ward off future termite problems. Unfortunately, when the applicator is spraying the beams, the chemical can easily drip onto the ceiling drywall sheets that were nailed to the 2x4's. Drywall is made of rock powders that act like a sponge, quickly absorbing the chemical and then outgas the chlordane into the living area below. Contamination would then occur to the area below which could be either the kitchen, living room or bedroom.

Correction Procedure

Ceiling drywall that has soaked up chlordane due to an attic application of chlordane can be widespread. Ceiling drywall can be purchased inexpensively in 3/8 inch thicknesses for around $5.00 for a 4x8 foot sheet. It is recommended that these be placed over existing ceiling drywall or to completely remove the existing drywall and to then apply new drywall.

Accidental Spills

The research has documented spills of chlordane containers occurring during testing research and has certainly happened to an unknown percentage of homes built before 1988. The spills could range from a few ounces to one gallon or 55 gallon containers. If one room registers a much higher chlordane level than another room - the possibility of a chlordane spill should be considered.

Correction Procedure

If a significant amount of chlordane has been spilled onto any inside flooring the two correction procedures in order of effectiveness include - painting the floor with an enamel based paint or laying ceramic or hard vinyl tile over the contaminated area.

Normal Application Residue

Although chlordane was routinely used outside the home up through March of 1988, it was often used for the indoor control of roaches and ants up until 1981. Chlordane was easily purchased by homeowners from department stores before this date as an effective roach and ant pesticide. Indoor areas routinely treated with chlordane include underneath the kitchen sink, behind the refrigerator, behind the dishwasher and along baseboards throughout the bedrooms. Sometimes the chemical odor of chlordane underneath a kitchen sink is "overwhelming" due to this area receiving repeated chlordane applications. Chlordane contamination still occurs today as many "garden/tool sheds" still have bottles of outdated chlordane on the shelves.

Correction Procedure

If contamination under the kitchen sink is suspected, perform a chlordane air test underneath the sink. High levels found here can be "sealed in" using new plywood or if air chlordane contamination is exceptionally high, the homeowner may be better off replacing the old counter top with a new one. Baseboards along the floor can be sealed with an enamel paint or can be replaced at a cost of 30 cents to $1.00 per foot.