Pesticide abandoned indoors (C) Daniel FriedmanPesticide Exposure in buildings

  • PESTICIDE EXPOSURE HAZARDS - CONTENTS: Health effects of exposure to pesticides in buildings. Exposure to common pesticides used indoors including Dursban and Lorsban, and Chlordane in older homes. How to reduce indoor exposure to pesticides
  • POST a QUESTION or READ FAQs about pesticide exposure in buildings: detection, testing, hazard reduction
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Indoor pesticide exposure:

Here we describe the detection of and risks of exposure to pesticides applied indoors in buildings. We discuss methods to reduce indoor pesticide exposure as a step in improving health and indoor air quality in homes. Our page top photo shows an abandoned pesticide bottle found during a home inspection.

When we find old pesticide containers indoors we caution home buyers that a previous owner may have been applying chemicals without proper expertise. Read the label and use pesticides as directed.

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Pesticide Indoor Exposure Hazards & Health Effects

Bug on the garage door (C) Daniel Friedman

This article includes excerpts or adaptations from Best Practices Guide to Residential Construction, by Steven Bliss, courtesy of Wiley & Sons.

Watch out: OPINION: don't panic about insects or bugs that you may see on or around your home.

A single bug like the one shown at left (clambering around on our garage door) does not merit a declaration of chemical warfare. Most insects seen on or around homes are harmless and should not be attacked.

The health risks to humans from overdoing chemical sprays and treatments applied in a panic can be significant.

Worse, misapplication of pesticides inside the home can lead to serious indoor health hazards for the building's human or pet occupants.

On the other hand, as our photo at left (termite mud tubes) illustrates, even with care to avoid or fix building leaks (a key attractant to classes of termites, carpenter ants, and other wood destroying insects), is not always enough.

Sometimes it may be necessary to consult with a professional pest inspector or pesticide applicator. See INSECT INFESTATION / DAMAGE for details about preventing or correcting problems from wood destroying insects.

Termite activity on a foundation(C) Daniel FriedmanAs stated in Best Practices Guide to Residential Construction:

Pesticides are a special class of organic chemicals designed to kill living organisms. In addition to the compounds used in the home and garden, the class of chemicals regulated as pesticides also include kitchen and bath disinfectants, flea and tick products, and swimming pool chemicals.

In most cases, both the active ingredient targeted to one or more pests and the “inert” carriers are organic chemicals that are toxic to humans.

Studies indicate that up to 80% of most people’s exposure to pesticides occurs indoors and that measurable levels of up to a dozen pesticides have been found in the air inside homes.

Because of its widespread use for over 30 years, more than 80 percent of Americans already have traces of Dursban in their bodies, according to the Centers for Disease Control.

Another study found Dursban in the carpet dust of 67 percent of homes surveyed.

Also, remember that a pesticide found “safe” to use today may be determined to be unsafe tomorrow.

Chlordane, the most widely use termiticide for decades, was banned in 1988 because of its toxicity to humans and its persistence in the environment.

Chlordane was largely replaced by Dursban (chlorpyrifos), an organophosphate.

Dursban became the most widely used pesticide in the United States until it was phased out starting in 2000, along with the popular pesticide diazinon, because of the risks they posed to humans, especially to the growth and nervous system development of children.

How safe is Dursban (chlorpyrifos)?

Chlorpyrifos, described by some writers as a "nerve gas pesticide"[1] at REFERENCES. What's that about? What makes chlorpyrifos very effective against insect pests is that it attacks the central nervous system. I [DF] certainly observed what looked like a neurological effect when spraying older chlorpyrifos-containing versions of RAID™ on insects. They would top quickly and writhe madly in place.

Chlorpyrifos has been shown to cause brain damage in humans and other animals, reducing I.Q.s, causing tremors in children, and being linked to both lung cancer and Parkinson's disease in adults.

Chlorpyrifos is already ubiquitous in the environment. In 2012 a study testing for chlorpyrifos in umbilical cord blood found chlorpyrifos in 87% of newborn babies in the U.S. The following information is from the U.S. EPA.

To address health and environmental risks from chlorpyrifos exposure, the following restrictions have been placed on pesticide products containing chlorpyrifos:

In 2017 the Trump administration rejected the U.S. EPA's proposed ban on the use of chlorpyrifos for agricultural an doutdoor use. [Dow Chemical who produces chlorpyrifos donated $1 Million to the Trump inauguration. Dow stands by the safety of chlorpyrifos. [1] ] This is the case even though the US EPA found up to 140 times the safe level of chlorpyrifos in fruits and vegetables sold in the U.S.

Health Effects of Exposure to Pesticides

Signs of risk of termite attack (C) Daniel Friedman

Our photo shows drill marks we found in the rim joist of an older home in the Hudson Valley of New York.

As we explain in detail at INSECT INFESTATION / DAMAGE, these drill marks were evidence of an amateur attempt at pesticide application: the location, irregularity, angle, and other details of these drill marks made us nervous.

We tested a sliver of this wood and found that it was still contaminated with Chlordane - misapplied on the building interior.

There are nearly 900 pesticides registered for use in the United States. Nearly all are at least moderately toxic to humans and pets and many are highly toxic.

Symptoms of overexposure to pesticides include irritation to the eyes, nose, and throat, headaches, blurred vision, nausea, loss of coordination, muscular weakness, and damage to the central nervous system, liver, and kidneys.

Every registered pesticide has a “signal” word on the label, ranking the level of toxicity to humans, as follows:

Some of the more problematic pesticides used in and around households include:

How to Reduce Indoor Exposure to Pesticides

When possible, the best approach is to find non chemical approaches to pests. When chemicals must be used, choose the least toxic option, and use it outdoors, if possible, and away from areas used by pets and children who will track it back into the house.

-- Adapted with permission from Best Practices Guide to Residential Construction.

If you Smell Pesticides or Other Chemicals Watch Out for Fatal Hazards

As we mention also at ODORS GASES SMELLS, DIAGNOSIS & CURE, pesticide odors can be more than annoying.

Odors from pesticides or other chemicals applied in or around a building may be harmful, even fatal to building occupants.

As with just about any chemical or substance, the hazard level depends on the dose and exposure, but as we discuss at ENDOCRINE DISRUPTERS at BUILDINGS even extremely low concentrations, as little as a single molecule of some substances can have very serious health effects depending on exposure conditions and who is being exposed.

Watch out: Be sure that the person selecting and applying pesticdes in or around your building is a properly trained, experienced, and licensed pest control operator.

In the 1980's we intercepted a newly-hired pest control operator who, standing under a literal rain of chlordane, was spraying both a wood-sided home in Poughkeepsie, NY (for carpenter ant control) and was about to soak the ground around the property's water supply well. We asked the operator if he was worried about being soaked with Chlordaine.

"Nah," he replied, "I've been doing this for three months now and I feel just fine."

While pesticide exposure studies may be performed on rats rather than human subjects, rats are little mammals; they're not pet rocks. It would be ridiculous to claim that a chemical that kills rats can be safely assumed to be harmless to humans, particularly to pre-natal and infants.(Barnett 1985).

Improper application of pesticides inside or even outside and around buildings and in building crawl spaces, attics or other areas can be far worse than ineffective against pests: it can be fatal for building occupants. In January 2017 four children died from breathing lethal gases that were generated when Weevil-Cide was sprayed under a home, then later tried to address a pesticide odor in the home by spraying water into the same area.

The result, reported by various sources including CNN and AcrossAmerica Patch ( was the production of a toxic gas that killed children in the home and left others very ill.

Reader Question: How can we get rid of an annoying mothball odor in our Condo?

We moved into a condo, which is a concrete block structure 3 months ago. Shortly after the move we began to smell moth balls. After following the smell we were able to find out that the unit above us displaced several moth balls throughout there unit, tightly sealed the unit up without air conditioning on(we live in Florida) and left for the summer.

As the smell increased in our unit we begged parties involved to rid the unit of the moth balls and air it out.

Finally this was done, however even though the smell appears to be gone sometimes, other times we can still smell a bad odor, sometimes now the odor is less mothball smell and just simply a bad odor.  We have tried everything and are desperate to solve the problem. Is it possible to get rid of this toxic odor?  Any help would be greatly appreciated. - B.P. 9/22/2012

Reply: How to get rid of mothball odors in buildings, contents, clothing, furnishings

Moth (C) Daniel Friedman

Indeed the odor from moth repellent products (paradichlorobenzene or naphthalene) penetrates many materials including even drywall and furnishings.

It can take quite a while for the smell to diminish.

at MOTHBALL ODORS we have included your question again in the FAQs section where we also have provided a detailed list of suggestions for getting rid of mothball odors, starting with ventilating the source area but adding other steps as well.

Please take a look at that article and let us know if questions remain.

The photo at left, though a white moth-like insect, is not a clothing-attacking moth, as you'll read at our mothball odor article.

More about odor sources, hazards, & solutions is at ODORS GASES SMELLS, DIAGNOSIS & CURE.

Reader Question: my neighbour is spraying pesticide on my air conditioner

(Mar 29, 2013) Deborah So. CA said:
I am concerned that my psychopath neighbor is spraying a pesticide on my air conditioning unit. How can I test for this? Is there a city or county inspector I should seek out?


I suggest:

Contacting an environmental testing lab to confirm that you can use a sterile wipe (sterile cotton or swab) to wipe a representative surface for the lab to test. Discuss the common pesticides available in spray form and assure that the test will cover those chemicals. Typically you purchase one or several sterile swabs in sealed containers, use the swab, and return it to the test lab.

You might also set up a webcam to record activity.

You have the option of hiring a professional environmental test consultant but frankly, the cost - benefit sounds doubtful to me.

Research & Resources on Pesticide Hazards In & Around Buildings


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