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Mothballs are small balls of chemical pesticide and deodorant, sometimes used when storing clothing and other materials susceptible to damage from silverfish, mold or moth larvae (especially clothes moths like Tineola bisselliella).
Older mothballs consisted primarily of naphthalene, but due to naphthalene’s flammability, many modern mothball formulations instead use 1,4-dichlorobenzene. The latter formulation may be somewhat less flammable, although both chemicals have the same NFPA 704 rating for flammability. The latter chemical is also variously labeled as para-dichlorobenzene, p-dichlorobenzene, pDCB, or PDB, making it harder to identify unless all these names and initialisms are known to a potential purchaser. Both of these formulations have the strong, pungent, sickly-sweet odor often associated with mothballs. Both naphthalene and 1,4-dichlorobenzene undergo sublimation, meaning that they transition from a solid state directly into a gas; this gas is toxic to moths and moth larvae.[1]
Due to the health risks of 1,4-dichlorobenzene, and flammability of naphthalene, other substances like camphor are sometimes used.
Mothballs are stored in air-tight bags made of a non-reactive plastic such as polyethylene or polypropylene (other plastics may be degraded or softened). The clothing to be protected should be sealed within airtight containers; otherwise the vapors will tend to escape into the surrounding environment . Manufacturer’s instructions regularly warn against using mothballs for any purpose other than those specified by the packaging, as such uses are not only harmful and noxious, they are also frequently considered illegal.
Although occasionally used as snake repellent, mothball use as a rodent, squirrel, or bat repellent is illegal in many areas, and tends to cause more annoyance and hazard to humans than to the target pest However, mothballs continue to be advertised as squirrel repellent and are an ingredient in some commercial vermin and snake repellent products.
The US Department of Health and Human Services (DHHS) has determined that 1,4-dichlorobenzene “may reasonably be anticipated to be a carcinogen”. This has been indicated by animal studies, although a full-scale human study has not been done.The National Toxicology Program (NTP), the International Agency for Research on Cancer (IARC) and the state of California consider 1,4-dichlorobenzene a carcinogen.
Exposure to naphthalene mothballs can cause acute hemolysis (anemia) in people with glucose-6-phosphate dehydrogenase deficiency . IARC classifies naphthalene as possibly carcinogenic to humans and other animals (see also Group 2B . IARC points out that acute exposure causes cataracts in humans, rats, rabbits, and mice. Chronic exposure to naphthalene vapors is reported to also cause cataracts and retinal hemorrhage . Under California’s Proposition 65, naphthalene is listed as “known to the State to cause cancer”.
Research at the University of Colorado at Boulder revealed a probable mechanism for the carcinogenic effects of mothballs and some types of air fresheners
In addition to their cancer risks, mothballs are known to cause liver and kidney damage.
1,4-Dichlorobenzene is a neurotoxin. It has been abused as an inhalant, causing a variety of neurotoxic effects.
Mothballs containing naphthalene have been banned within the EU since 2008
As discussed in more detail at Tineola bisselliella, alternatives to mothballs to control clothes moths include dry cleaning, freezing, thorough vacuuming, and washing in hot water.Camphor is also used as a moth repellent, particularly in China.Unlike naphthalene and dichlorobenzene, camphor has medicinal applications and is not regarded as a carcinogen, though it is toxic in large doses. Red cedar wood and oil is also used as an alternative moth repellent.
Pheromone traps are also an effective diagnostic tool and can sometimes be an effective control tool to protect valuable clothing.
As a verb, “mothball” has a metaphorical usage, meaning “to stop work on an idea, plan, or job, but leaving it in such a way that work can continue in the future”.”Mothballed” is a common adjective to describe ships and aircraft stored for long periods, but not sent for scrapping.
The origins of this use of “mothballed” may have been reports that the ocean liner SS Normandie was “packed in mothballs” when in September 1939 it was ‘interned’ by the U.S. Government in New York. The papers reported a month later that “fourteen huge barrels of mothballs had been used to preserve carpets, draperies, and upholstery”.The ship was at the time expected to remain in New York for the duration of the war, but after the attack on Pearl Harbor, she was converted to a troop ship.
The U.S. Navy planned to store fighting ships in 1945, but keep them ready for rapid return to service. By 1946 these ships were referred to as being “mothballed”. The process however did not mention mothballs, but rust preventative coating, sealing compartments, removing equipment, and covering topside equipment, as well as protecting the hull. Mothballed ships were expected to be able to resume active service in just 10 days.United States Navy reserve fleets are still informally referred to as the ‘mothball fleet’.
Appearance: white solid. Flash Point: 78 deg C.
Warning! Flammable solid. Harmful if inhaled or swallowed. Causes eye, skin, and respiratory tract irritation. May be harmful if absorbed
through the skin. May cause blood abnormalities. Hygroscopic (absorbs moisture from the air).
Target Organs: Blood, respiratory system, eyes, skin.
Potential Health Effects
Eye: Naphthalene is an eye irritant. The vapor causes eye irritation at 15 ppm. Eye contact with the solid material may result in
conjunctivitis, superficial injury to the cornea, diminished visual acuity, and other effects. It may cause cataracts.
Skin: Causes mild skin irritation. May be absorbed through the skin in harmful amounts. Incidence of skin hypersensitivity is not
widespread in the general population &, based on the long history of use of naphthalene as a consumer product, this effect is mostly
confined to industrial exposure where coal tar contamination may be present.
Ingestion: Harmful if swallowed. May cause liver and kidney damage. May cause methemoglobinemia, cyanosis (bluish discoloration of
skin due to deficient oxygenation of the blood), convulsions, and death. May cause severe digestive tract irritation with abdominal pain,
nausea, vomiting and diarrhea. Ingestion of large quantities may cause severe hemolytic anemia and hemoglobinuria.
Inhalation: Harmful if inhaled. Causes respiratory tract irritation. Readily absorbed when inhaled. Material volatilizes at room temperature.
Hemolytic anemia (destruction of red blood cells) is the primary health concern for humans exposed to naphthalene for either short or
long periods of time. Other effects may include nausea, profuse perspiration, vomiting, kidney damage and liver damage. Optic neuritis
(inflammation of the optic nerve) has been observed. Cataracts have also occurred.
Chronic: Prolonged or repeated skin contact may cause dermatitis. May cause liver and kidney damage. May cause anemia and other
blood cell abnormalities. Animal studies have reported that fetal effects/abnormalities may occur when maternal toxicity is seen. Effects
may be delayed. Chronic exposure may cause lung damage. Laboratory experiments have resulted in mutagenic effects. Chronic exposure
may cause corneal injury, optical neuritis, blurred vision, and possible cataract formation. Chronic inhalation, skin absorption or ingestion
of naphthalene have caused severe hemolytic anemia.
General Information: Use proper personal protective equipment as indicated in Section 8.
Spills/Leaks: Avoid runoff into storm sewers and ditches which lead to waterways. Clean up spills immediately, observing precautions in
the Protective Equipment section. Scoop up with a nonsparking tool, then place into a suitable container for disposal. Avoid generating
dusty conditions. Remove all sources of ignition. Provide ventilation. Do not let this chemical enter the environment.
Handling: Wash thoroughly after handling. Remove contaminated clothing and wash before reuse. Minimize dust generation and
accumulation. Avoid breathing dust, vapor, mist, or gas. Avoid contact with eyes, skin, and clothing. Keep container tightly closed. Use
only with adequate ventilation.
Storage: Keep away from sources of ignition. Store in a tightly closed container. Store in a cool, dry, well-ventilated area away from
incompatible substances. Storage under a nitrogen blanket has been recommended. Store protected from moisture. Separate from
oxidizing materials.
OSHA Vacated PELs: Naphthalene: 10 ppm TWA; 50 mg/m3 TWA
Personal Protective Equipment
Eyes: Wear chemical splash goggles.
Skin: Wear appropriate protective gloves to prevent skin exposure.
Clothing: Wear appropriate protective clothing to prevent skin exposure.
Respirators: A respiratory protection program that meets OSHA’s 29 CFR 1910.134 and ANSI Z88.2 requirements or European Standard
EN 149 must be followed whenever workplace conditions warrant respirator use.
Epidemiology: Incidents in which blankets or clothing containing naphthalene caused acute hemolysis in infants, in some cases fatal,
have been described.The percutaneous absorption and systemic intoxication with naphthalene can be facilitated by oily vehicles.
Teratogenicity: Naphthalene and its metabolites have been reported to cross the human placenta in amounts sufficient to cause fetal
toxicity.Oral, rat: TDLo = 4500 mg/kg (female 6-15 day(s) after conception).Effects on Embryo or Fetus – fetotoxicity (except death,
e.g., stunted fetus) and Specific Developmental Abnormalities – other developmental abnormalities.Intraperitoneal, rat: TDLo = 5925
mg/kg (female 1-15 day(s) after conception) Specific Developmental Abnormalities – musculoskeletal system and cardiovascular
(circulatory) system.
Reproductive Effects: No information available.
Mutagenicity: Micronucleus Test: Human, Lymphocyte = 30 mg/L.; Cytogenetic Analysis: Hamster, Ovary = 30 mg/L.; Sister Chromatid
Exchange: Hamster, Ovary = 15 mg/L.
Neurotoxicity: No information available.
Ecotoxicity: Fish: Rainbow trout: LC50 = 1.60 mg/L; 96 Hr; Flow-through at 15 CFish: Fathead Minnow: LC50 = 6.14 mg/L; 96 Hr; Flow-
through at 24.5 CWater flea Daphnia: EC50 = 2.16-8.60 mg/L; 48 Hr; UnspecifiedBacteria: Phytobacterium phosphoreum: EC50 = 0.93
mg/L; 30 min; Microtox testFish: Pink salmon: LC50 = 1.24 mg/L; 96 Hr; (fry) Static bioassay at 12°C Releases into water are lost due to
volatilization, photolysis, adsorption, and biodegradation. The principal loss processes will depend on local conditions but half-lives can be
expected to range from a couple of days to a few months. When adsorbed to sediment, biodegradation occurs much more rapidly than in
the overlying water column. When spilled on land, naphthalene is adsorbed moderately to soil and undergoes biodegradation. However, in
some cases it will appear in the groundwater where biodegradation still may occur if conditions are aerobic.
Environmental: Bioconcentration occurs to a moderate extent but since depuration and metabolism readily proceed in aquatic
organisms, this is a short term problem. transport and disposal of fuel oil, coal tar, etc. In the atmosphere, naphthalene rapidly
photodegrades (half-life 3-8 hr). Naphthalene shows low biological oxygen demand and is expected to cause little O2 depletion in aquatic
systems.
Physical: Log P (oct) = 3.01 – 3.59
Other: Harmful to aquatic life in very low concentrations.
ubstances
Formula : C10H8
Molecular weight : 128,17 g/mol
CAS-No. : 91-20-3
EC-No. : 202-049-5
Index-No. : 601-052-00-2
Hazardous ingredients according to Regulation (EC) No 1272/2008
Component Classification Concentration
Naphthalene
CAS-No. 91-20-3 Flam. Sol. 2; Acute Tox. 4; <= 100 %
EC-No. 202-049-5 Carc. 2; Aquatic Acute 1;
Index-No. 601-052-00-2 Aquatic Chronic 1; H228,
H302, H351, H400, H410
M-Factor – Aquatic Acute: 10
4.2 Most important symptoms and effects, both acute and delayed
The most important known symptoms and effects are described in the labelling (see section 2.2) and/or in
section 11
4.3 Indication of any immediate medical attention and special treatment needed
No data available
SECTION 5: Firefighting measures
5.1 Extinguishing media
Suitable extinguishing media
Use water spray, alcohol-resistant foam, dry chemical or carbon dioxide.
5.2 Special hazards arising from the substance or mixture
Carbon oxides
5.3 Advice for firefighters
Wear self-contained breathing apparatus for firefighting if necessary.
5.4 Further information
Use water spray to cool unopened containers.
SECTION 6: Accidental release measures
6.1 Personal precautions, protective equipment and emergency procedures
Use personal protective equipment. Avoid dust formation. Avoid breathing vapours, mist or gas. Ensure
adequate ventilation. Remove all sources of ignition. Evacuate personnel to safe areas. Avoid breathing
dust.
For personal protection see section 8.
6.2 Environmental precautions
Prevent further leakage or spillage if safe to do so. Do not let product enter drains. Discharge into the
environment must be avoided.
6.3 Methods and materials for containment and cleaning up
Sweep up and shovel. Contain spillage, and then collect with an electrically protected vacuum cleaner or
by wet-brushing and place in container for disposal according to local regulations (see section 13). Keep
in suitable, closed containers for disposal. Contain spillage, pick up with an electrically protected vacuum
cleaner or by wet-brushing and transfer to a container for disposal according to local regulation.
Getting an accurate diagnosis can be one of the most impactful experiences that you can have.
