Indoor Use of Pesticides and Safety

An exterminator performing pest control
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Safety is one of the first, and most important, things to consider when deciding to apply pesticide chemicals to treat or prevent a pest infestation, especially if you are planning to apply the chemical indoors. 

The​ pesticides that homeowners typically use fall into two broad categories: insecticides (which kill insects) and rodenticides (which kills rodents/mammals). The accidental poisoning dangers of the two are quite different.

  • Most rodenticide poisoning occurs when dogs, cats, or children eat a solid bait formulation, thinking that it is food.
  • Most insecticide poisoning occurs when the applicator or other non-pest absorbs the product through his or her skin or breathes in airborne particles of the insecticide that is being sprayed, dusted, fogged or fumigated.

What is Pesticide Safety?

To start off, let's define safety. Safety is the combination of the toxicity of a certain compound and the amount of exposure a non-target organism has to it.

For both rodenticides and insecticides, the chemists who combine the active and inert ingredients in the pesticides strive to create products with the lowest levels of mammalian toxicity, carcinogenic (cancer-causing) likelihood, and mutagenic (congenital disabilities) profile possible.

But, no matter how safe a modern insecticide may be, there are countless products which were used for years nonchalantly that are now believed to be linked to cancer and other diseases. Chlordane, once commonly used for termite control, and DDT, once a very popular pesticide, are two examples. The manufacturers may have been completely honest with the public about the "safety" of their current products at the time of their use, only to find later that there were unknown or unexpected negative results from exposure.

Controlling Pesticide Exposure

So, your role in safety is to control exposure. Exposure can occur through inhalation, skin or eye contact, or ingestion. The level of toxicity of a particular product wouldn't matter if you or others weren't exposed to it: don't allow the pesticide to enter your body through your skin, lungs, eyes, or mouth.

Dermal (skin) exposure is the most common form, so it is important to cover your skin always wear gloves when using any pesticide. When applying pesticide, whether wet (spray), dust (powder), or fumigation (fog), your safety is enhanced by wearing things like:

  • Long sleeves and pants.
  • Shoes and socks (not flip-flops).
  • Chemical-resistant gloves.

Depending on the product and the form it takes, you may also be told to wear a dust mask or a respirator.

Read and Follow All Pesticide Label Directions

Always read every bit of the label on the product you are using, not just the mixing instructions. This will likely tell you not to have people (other than the applicator) or pets in the area being treated. The important words on labels give you a fair indication of how toxic a product is:

  • "Caution" is mildest.
  • "Warning" is more hazardous.
  • "Danger" is for products with the most harmful possible effects.

To minimize exposure, choose a gel or solid over a fog or spray. And for sprays, non-aerosol products use fewer chemicals and are easier to control; they produce fewer airborne particles.

However, there are no "safe" pesticides. Some are safer than others—boric acid is one example. You can choose pesticides that are organic or labeled "non-toxic," but often they must be reapplied and they take longer to work. Pyrethrin, derived from flowers of the mum family, is very effective in pest control and is available commercially.

Some of the more toxic indoor insecticides are organophosphates. If you are concerned about toxicity, avoid products containing the following ingredients: phosmet, naled, tetrachlorvinphos, diazinon, malathion, chlorpyrifos, and dichlorvos.

Before beginning, also assess the area you are about to treat. Are there plants that might be exposed or harmed by the treatment? Are there any pets present that could be exposed? Fish and other aquatic creatures are especially susceptible to insecticide toxicity. Reptiles and birds are also usually at higher risk than mammals to insecticide poisoning.

One Final Note on Pesticide Toxicity

Consider all of the prescription medication we take. Most of them can kill you if you take enough of them, yet we swallow pills on a daily basis without much of a thought about it. It's all about dosage. Hopefully, you won't be chemically treating your house every day. Nor will you intentionally allow pesticide to get into your eyes or mouth or come in contact with your skin.

It's also nice to note that we are much, much larger than most of the insects we are trying to eradicate. In some cases, in addition to the massive dosage discrepancy, the insects also possess more chemical receptor sites for the particular active ingredient than mammals do.

But with all pesticides, apply your materials to locations that are most likely to be contacted by your target pests, and least likely to be contacted by your family and pets. Always thoroughly read and follow all label directions.