Are Mothballs Toxic?

By Dr. Killigan
Are Mothballs Toxic?

I slowly lifted up the heavy lid. It creaked in relief. Tattered books, a thin scarlet-red wool blanket and a picture frame—the glass damaged, cracked—lay stacked, one on top of the other. Like neatly pressed crisp garments, the items were carefully placed in a tidy rising tower. As I strained to truly see the dull black-and-white photo of my mentor’s parents, I lost focus. The smell of the mothballs—powerful, overwhelmingly, intrusive—blurred my vision. I began to cough.

In the late 1800s, mothballs were made exclusively from naphthalene. Inhalation of naphthalene caused skin and eye irritation; gastrointestinal symptoms, such as nausea, vomiting, abdominal cramps, and diarrhea; neurologic symptoms, such as confusion, excitement, and convulsions; renal problems, such as acute renal shutdown; and hematologic features, such as icterus and severe anemia.

Mothballs are no longer made from naphthalene, due to its high levels of flammability and toxicity. However, its replacement—paradichlorobenzene-rich mothballs—are just as toxic, just as dangerous, and perhaps just as flammable.

What Are Mothballs?

Closeup of mothball

Mothballs are small, milky-white harmless-looking clouds of fluff that are readily available for purchase at your local discount store. The labeled use is to kill clothes moths, their larvae, and their eggs, which occurs through the strong fumes that the mothballs release. They are to be used in indoor storage areas such as closets, attics, and basements.

How Do Mothballs Work?

Mothballs work by releasing toxic chemicals. These chemicals slowly change to gasses and become fumes within their enclosed environment, thus killing the moths (and creating that very pungent mothball smell).

When using mothballs, very clear instructions on the packaging explain that they are to be placed inside tightly closed containers along with the clothing or materials; tightly closed so that their chemical components will not be further released. (These instructions also inform you that using mothballs as a snake or rodent deterrent is illegal.)

These chemicals easily burn and fully evaporate within four to six weeks, though they can last even longer if the container is tightly sealed. The smell on your garments, though, will last much longer.

Are Mothballs Safe?

Though the smell of mothballs may remind you of your grandmother’s attic or that heirloom cedar chest in your great aunt’s spare bedroom, mothballs, especially if they’re the "old fashioned" kind, are not safe. They are all dangerous and can have multiple negative effects. I’m going to discuss seven of those dangers. 

  1. Mothballs are poisonous. They are considered carcinogenic. When you inhale the scent of a mothball, you are inhaling the insecticide. When you wear an article of clothing that was stored with mothballs, the toxicity of the mothballs is absorbed through the skin.
  2. Mothballs are pesticides. They are commonly 100% made up of naphthalene or paradichlorobenzene, both of which are hazardous to humans.
  3. Naphthalene, an aromatic hydrocarbon found in coal tar or petroleum, has been a mothball-banned ingredient in the European Union since 2008, but is still commonly found (in mothballs) in homes here in the United States. Though toxic, it is used today in the manufacture of plastics, resins, fuels, and dyes, specifically PVC, insecticides (insect killing chemicals), dyes, toilet deodorant blocks, and phthalic anhydride. Because it is produced when things burn, it is found in cigarette smoke, car exhaust, and smoke from forest fires.
  4. Paradichlorobenzene, also called PDB or 1,4-dichlorobenzene, is a toxic chlorinated aromatic hydrocarbon that is used as a fumigant insecticide and repellent. Today, it is commonly used as the only ingredient in mothballs, and also found in deodorant blocks made for trash cans and toilets.
  5. Mothballs release heavier-than-air vapors. These fumes, because of their vapor density, don’t readily dissipate into the atmosphere. Rather, they accumulate along floors or aggregate at the bottom of enclosures, thus posing a higher danger to small children and pets.
  6. Mothballs damage the environment. Mothballs contribute to air pollution because the chemicals that make them up, which are solid at room temperature, slowly change to gasses when they are made into round balls, flakes, or cakes. These gasses become toxic fumes in the air. They can also contaminate soil and water, as both naphthalene and PDB mothballs leach chemicals into the soil and potentially the groundwater, as rains wash some of the chemicals into storm sewers, wells, and waterways.
  7. Mothballs harm your pets. As little as one mothball could poison a dog. The toxic dose depends on the size of your pet, the size of mothball, the type of mothball, and whether the mothball was ingested, or if the pet was only exposed to the fumes. Though cats are more sensitive to their toxic effects, dogs are more likely to ingest mothballs due to their curious nature.
  8. Mothballs can be mistaken for candy. Whether it was a genius marketing strategy or completely accidental, mothballs often look like tasty treats. In fact, there was once a candy deemed ‘the mothball candy’ that was popular in the 19th century and the early 20th century. It is also known as the cream filbert.
  9. Mothballs can cause liver and kidney damage. Mothballs can make you very sick. This occurs because the poison from the chemicals (either naphthalene or paradichlorobenzene) destroys or changes your red blood cells so that they cannot carry oxygen.

Final Word on Mothballs

As the wind billowed through the open windows, the toxic fumes were lifted up and away. My eyes cleared. The cough subsided. I felt numb, numb with the knowledge of the dangerous effects of mothballs; My thoughts couldn't run from them. I yearned for these thoughts to, like the wind, billow and pass. They wouldn’t. Ignorance can be bliss. Ignorance can also be cruel. I wasn’t with my mentor when he had passed, but I began to wonder about the levels of toxicity in his body that accumulated over the years—if that had somehow contributed to loosing him too soon.

Don’t use mothballs in your home. Keep Clothing Moth Traps in your closets and drawers and master your mind with how-to-get-rid-of-clothing-moths understanding. Before storing, dry clean, freeze, or wash your clothing-moth-attractive clothes in hot water to ensure that any moths, larvae, or eggs are killed. (I recommend storing these garments in non-reactive plastic or, even better, durable, breathable, plastic-free bags such as those made from PEVA vinyl or non-woven fabrics). Vacuum your home frequently. Know the facts when it comes to pest control. Together, let’s do all that we can to keep your home toxic-free.


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1 comment
  • I had no idea that mothballs were so toxic. I started reading this and texted my mother to make sure that she didn’t have any in her home. She used to cough a lot and couldn’t figure out the source. Now I’m wondering if it was the mothballs!

    Marie on

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