Mothball or naphthalene odor removal & mothball chemical & gas hazards:
The US EPA estimates that about 7.5 million pounds of naphthalene are marketed in the U.S. each year as a pesticide, of which the major use is in moth repellant products. (US EPA 2008).
Here we describe the detection of and risks of exposure to mothball chemicals & odors when moth repellent products are applied indoors in buildings.
In this article series, we describe how to get rid of mothball odors in buildings, building furnishings, clothing, or vehicles.
In this article series, we also provide research explaining the health hazards from exposure to mothball odors (and gases) as well as the child hazard of eating mothballs or moth repellent products. We discuss methods to reduce mothball chemical & gas exposure.
We cite authoritative sources of information about safe and proper use of moth repellents and about mothball and moth repellent chemistry, child hazards, indoor air quality and health concerns, and proper application and use of these products.
Page top photo, courtesy of Wikipedia commons, shows a cluster mothballs, or a solid form of naphthalene.
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Mothballs, like those shown at the top of this page, are fumigants containing naphthalene or paradichlorobenzene and act as a pest repellent and possibly act also as a pesticide used to protect clothing and other soft goods from attack by clothes moths (Tineola bisselliella or the casemaking clothes moth Tinea pellionela)
If you are looking for information on how to get rid of mothball odors, go directly to
GET RID of MOTHBALL ODORS - separate article
Mothballs, moth flakes, crystals, and bars are insecticides that are formulated as solids. As such, mothballs are registered as pesticides because they contain high concentrations of one of two active ingredients—naphthalene or paradichlorobenzene (sometimes referred to as 1,4-dichlorobenzene).
Through sublimation, they exude gas, acting as a fumigant. - (Fishel 2017)
[Click to enlarge any image]
Naphthalene has been used as insecticide world wide since about 1880 (Pyenson 1936), but its health effects, also discussed here, were studied a bit later, beginning around 1900 (Nash 1903).
"Clothes moths" Tinea & Tineola sp. (Family: Tineidae), like that shown in this illustration from "Clothes Moths & Carpet Beetles" (USDA 1953), are small 1/2-inch beige or buff colored moths.
Clothes moths are yellowish-tan to buff-colored with a wingspread of about 1/2 inch. The larvae are white with brown to black heads, and are also about 1/2 inch long. (Kass 1981).
Clothes moths attack animal fibers such as wool, felt, and silk, but they may also attack feathers, furs, and even leather. Those materials contain a fibrous protein (keratin) that provides food for clothes moth larvae.
Naphthalene or paradichlorobenzene fumigants are said by manufacturers of mothballs or moth-flakes to kill or at least deter moths and caterpillars.
Really? Some sources, such as the U.S. California state department of Pesticide Regulation, say that mothballs, in fact, do not repel rats, mice, nor moles.
In addition, some people try using these products to repel other animals or pests even though that use is not recommended and may not be permitted.
However, the use of naphthalene as an animal pest repellant was included in the US EPA's description of that material in its 2008 Registration Eligibility document cited below. (US EPA 2008)
Also see REPELLENTS for ANIMAL PESTS
Below, we provide links to reference documents on how to use mothballs safely. Here, excerpting from those sources we list some basic steps in using mothballs.
Photo: a common clothes moth Tineola bisselliella - photo source & these moths are cited & described below.
Photo: common clothes moth, adult form. (Leillinger, cited below) [Click to enlarge any image]
In the U.S., the EPA permits use of moth balls to repel moths and caterpillars only. Because moth balls are toxic to humans and pets, mothballs are not permitted for use in buildings to repel animal pests like squirrels or bats.
Watch out:Some people have also tried using moth repellent products like mothballs to keep rodents and other pests out of certain building areas or out of stored vehicles.
Placing an open box of mothballs under the hood of my MG Midget while it was stored kept squirrels and mice from nesting in the engine compartment, and leaving a box of mothballs inside the car was an attempt to keep the same pests out of the vehicle interior, too.
Watch out: we do not recommend placing mothballs, moth cakes, or moth repellent flakes inside building rooms, crawl spaces, attics, wall or ceiling cavities, trash cans, nor inside vehicles, both because the fumes and chemicals can be hazardous to humans and because the odor can later be difficult to get rid of. We explain this problem in detail below.
Watch out: because mothballs are a registered pesticide and because of the toxicity of their chemicals, it is illegal to use mothballs or moth crystals, cakes, etc. as a repellent for animal pests (birds, cats, deer, dogs, moles, pigeons, mice, skunks, raccoons,snakes, squirrels, etc.) [19]
The clothes moth image shown just below is from Stone & Stock, PNW who provide an excellent guide to moth control. [19]
As stated at PESTICIDE EXPOSURE HAZARDS
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.
Every registered pesticide has a “signal” word on the label, ranking the level of toxicity to humans, as follows:
Mothballs contain one of the chemicals, paradichlorobenzene or naphthalene. Paradichlorobenzene is classified as a possible human carcinogen by the EPA, and its vapors can irritate skin, eyes, and the respiratory tract.
Large doses can damage the liver. Mothballs are not intended to be placed in open spaces such as rooms, closets, or vehicles. Rather they should be used in an airtight space such as a clothes storage bag. [7]
The moths shown here are not clothes moths. The insects shown are attacking our fig plant but not our clothing. - Ed.
Mothballs are fumigants that will dissolve or sublime at lower temperatures; mothballs thus work by a process of sublimation - the solid ball of chemicals converts directly to a gas that enters the air nearby. [2][7]
But believe it or not, mothballs or moth crystals may also be a child hazard if eaten - as has happened. [3][6][7]
Symptoms of exposure to naphthalene include headache, nausea, dizziness, and difficulty breathing. Paradichlorobenzene is also a potential hazard, although typically less so compared to naphthalene...
Eating just one mothball containing naphthalene can damage a young child’s red blood cells.... [7]
Exposure to naphthalene promotes hemolytic anemia, associated with fatigue in mild cases and acute kidney failure in severe cases. Poisonings of infants have been reported after dressing the children in clothing stored in naphthalene mothballs.
Below: an edited (excerpted) page from a 1963 Boys Life magazine describing a do-it-yourself home science project using moth balls, water, baking soda, and vinegar.
Watch out: we do not recommend repeating this experiment unless under supervision of your science teacher or another suitable expert.
Mothballs are a particular hazard to children, especially small children who may mistake a mothball for something edible.
FYI for our Australian readers, there have been recent news reports inquiring if mothballs are harmful to babies - we're researching that question.
Certainly eating or sucking on mothballs, and probably exposure to high levels of mothball offgassing can be harmful to babies, and mothball odors can trigger problems for people with allergies and asthma (including this site editor). (Sudakin 2011).
Dawson, back in 1958, documented this concern: it's certainly not "new" news.
Watch out: at TERMITES & NAPHTHALENE HAZARDS we point out that there can also be naturally occurring sources of naphthalene in buildings. These, too, might be at a sufficient concentration to pose a health hazard.
Watch out: See details about mothball or naphthalene odor hazards
at NAPHTHALENE POISONING SYMPTOMS
Shown here: older "moth-proofing", moth blocking, and moth repellent products from Fuller Products and Avon Products.
On 2017-07-27 by Laurie Davis - What is the life expectancy of a moth ball in a hot area?
What is the life expectancy of a moth ball in a hot area? How long does it continue to release the harmful fumes?
On 2017-07-27 by (mod) - Life Expectancy of Mothballs Used in Buildings - Mothball Sublimation Rate
Laurie,
If you will permit me to wave my arms about mothball sublimation rates as a preface to giving an opinion about how long a mothball will "last" in use, then my estimates of mothball life will, perhaps, make more sense.
Tennakone (1978) looked at the sublimation rate for mothballs - but I've not yet gotten a copy of the full article to support the following opinion with science.
Mothballs exposed to the open air will be seen to shrink in size, eventually disappearing, following a process called sublimation: the solid (mothball) converts to a gas without ever entering an intermediate liquid state.
The rate of sublimation of mothballs is determined principally by the amount of air available to or circulating around the mothball.
That's because the sublimation rate of mothballs depends on the relative naphthalene gas or para-dichlorobenzene vapor pressure difference between the thin layer of air at the surface of the mothball and the surrounding air.
When mothballs are kept in a small sealed container or relatively-airtight bag (as they are in a sealed box of mothballs in the store), the gas vapors are trapped around the mothballs, slowing their rate of sublimation to almost nothing.
But when the same mothballs are spread about in more open air, the vapor pressure differences of the mothball gases permit them to continue to off-gas into the surrounding area.
Mothballs that are actually in the spherical form, about 1/2" in diameter when new, will last from a month to several years or longer depending on the type of mothball and how they are placed.
Furthermore, the life of mothballs depends on the product chemistry: naphthalene mothballs take much longer to dissipate than mothballs comprised of para-dichlorobenzene.
Photo: A moth photographed by the author on the Osa Peninsula, Costa Rica, in 2018. This is NOT a clothes moth.
For example, based on simple experiments and observations of mothballs I've placed in buildings, closets, bureaus, or kept in closed packages, I estimate that:
In a hot area like an attic, where convection currents may be moving more air about, those mothball life expectancies will be less due to the effects of both temperature and air movement or air velocity on the sublimation rate of the mothballs of either formula. Moisture might also be a factor in the the rate of mothball sublimation.
"In air, the half-life of naphthalene and paradichlorobenzene is less than one day and about 31 days, respectively." (Fishel 2014) [1] atReferences or Citations .
But that half-life expression is misleading. It would only be accurate if we could obtain a measured volume of these two gases ALONE, that is, without a source that continues to emit them, and if we could then obtain more specific information about the concentration of those gases in the space and the rate of fresh air ventilation of the space as well as quite a few other factors.
Watch out: however, the fumes from these gases may permeate and remain in clothing or building materials after the actual mothballs or moth crystals have dissipated.
Above are two different moth ball products sold by Enoz®. Enoz® Paradichlorobenzene moth balls and Enoz® "old fashioned" or naphthalene mothballs.
These two mothball substances are chemically different, having different properties.
Naphthalene mothballs produce an off-gassing (through sublimation) that creates an environment that repels moths as well as some other creatures. Naphthalene mothballs, and the odor they produce, remains in the environment of use longer than Paradichlorobenzene mothballs.
That is, it will take longer for the Naphthalene odor to dissipate even when the mothball source has disappeared consumed or been removed.
Paradichlorobenzene mothballs produce less noticeable odor (to humans) and its gas will dissipate in free air more quickly than the offgassing product of Naphthalene mothballs.
According to Enoz®, "Para" mothballs for clothing are approved by the Environmental Protection Agency and sport EPA registration number: 1475-39
If all other parameters are the same (air movement, temperature, etc), Paradichlorobenzene mothballs produce a higher concentration of gas in the treatment area than Naphthalene mothballs, possibly increasing the effectiveness of Paradichlorobenzene for the death or at least the discouragement of moths.
Above photos of adult clothes moths cited in the article just below: The adult forms of: left - the common clothes moth (Tineola bisselliella photo by Olaf Leillinger, CC BY-SA 2.5, via Wikimedia Commons); and below, the case-bearing clothes moth or casemaking clothes moth (Tinea pellionela) (photo by Malcolm Storey, CC BY-NC-SA 4.0, via BioImages)
Moved to GET RID of MOTHBALL ODORS
This discussion has moved
to MOTHBALL ODOR IMPACT on REAL ESTATE SALES
These mothball or naphthalene poisoning symptoms are now found
at NAPHTHALENE POISONING SYMPTOMS - separate article
These details have moved to
RESEARCH on NAPHTHALENE HEALTH HAZARDS - separate article
This topic is now found
at NAPHTHALENE / PARABENTIOL OFF-GAS TESTING
This topic has moved to its own page at
TERMITES & NAPHTHALENE HAZARDS - separate article
...
Below you will find questions and answers previously posted on this page at its page bottom reader comment box.
On 2020-07-03 - by (mod) - Is sunlight enough to neutralize naphthalene?
Carla
"Neutralize" suggests a chemical reaction of which I cannot offer an opinion in this case. You can read some details in the article above - note the use of the term sublime or sublimation.
Any household cleaner or upholstery cleaner will remove some but often not all of the mothball odor, as can professional cleaning.
I'm not sure I've convinced you to review the material in this article and its companions. My best suggestions are in the articles above. Please take a look and let me know what you think.
Often fresh air and sunlight will speed off-gassing of mothball odors.
On 2020-07-03 by Carla De Vries - neutralize naphthalene?
Is sunlight enough to neutralize naphthalene?
my daughter is concerned with toxicity due to dermal transmission (her children touching the upholstery and getting pesticide poisoning), not odor.
What product, if any, cleans away naphthalene?
On 2020-06-29 - by (mod) - ok to store oriental rugs rolled up with mothballs ?
Scott
An "overdose" of mothball odors can be very difficult to remove from porous materials including oriental rugs stored in the intense conditions you are considering.
I'd defer to advice from a rug expert, such as those at George Washington University GWU - where experts warn:
Most moth and carpet beetle infestations appear in stored rugs. The source of the infestation may have occurred earlier when the piece was being used, but in the quiet, dark surroundings of storage the infestation may quickly grow. - retrieved 2020/06/29 original source: George Washington University Museum, museum.gwu.edu/storing-oriental-carpets
Left alone I'd probably have the rugs professionally cleaned now, then when absolutely dry, rolled in clear polyethylene or polypropylene and stored in a cool, dry place; the wrapping can be mothproof without dosing the rugs themselves. If there were space you might store rugs flat, separated by acid-free paper.
Illustrated here: U-Haul (and others) sell plastic bags intended for rug storage.
Watch out: don't store oriental rugs for a long time folded - the creases can damage the fibres and can also be hard to remove later.
Watch out: while experts agree on plastic as a storage wrapper - it has the advantage of being moth resistant - take care that your particular roll of polyethylene does not have its own horrible smell. Varying significantly by source as well as, I opine, production run, some poly off-gasses a terrible and hard-to-remove smell that can be sickening. Sniff first, use second.
On 2020-06-29 by Scott
Thanks for your wonderfully-informative site. I just discovered a moth infestation in a back room with about 10 oriental rugs rolled-up for storage [lots of wool and silk threads]. The rugs were valuable at one time, but that market shrank about 15 years ago -- There are probably 10x as many sellers as buyers ...
Nobody wants to even look at them with moth infestation, so I'm tempted to load them in heavy plastic bags with mothballs for a few months. The question then becomes: is it realistic to hope that the rugs can eventually be cleaned in a way that eliminates the mothball odor ?
Thanks for any guidance you can offer on this !
On 2019-08-28 - by (mod) - is mothball odor harmful?
Bonnie
The possible health effects of exposure to mothballs or mothball odor (naphthalene) are discussed on this page - a good place to look is at
On 2019-08-28 by Bonnie Hughes
The smell of moth balls is exceptionally strong in the hallway of my apartment complex...is it harmful
On 2019-02-18 - by (mod) - minimum mothball odor exposure to cause health problems
Unfortunately there's not a simple right answer to it the way you phrase it.
That's because with any environmental hazard the time duration of exposure is only part of the equation when assessing the hazard level or risk. It's the concentration level that is critical as well. In the article above we state
the sublimation rate of mothballs depends on the relative naphthalene gas or para-dichlorobenzene vapor pressure difference between the thin layer of air at the surface of the mothball and the surrounding air.
And that's just one of several scientific details. Indoor air movement, temperature, and humidity level would also be factors. So no one based on an e-text can tell you how long a generic exposure to mothball odors would have to occur for anyone to suffer any ill effect.
Nevertheless in this is subjective opinion I can state that I certainly haven't seen research claiming that a brief exposure has produced lasting health effects.
I'll do some further research to see if we can put some additional numbers on this interesting question.
On 2019-02-18 by Sarah -
What is the minimum time of exposure to a very very strong smell of moth balls to potientially cause health problems to young children or an unborn baby. I know there is a certain type of anemia it can cause.
And again, smell was overwhelming, not sure how many moth balls or where in the house, but obviously a lot to cause such a strong odor through the whole house in such a strong form
...
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