Moth balls are small, solid pesticide spheres designed to protect stored clothing and fabrics from insect damage. They function as a chemical fumigant, slowly releasing a gas that deters or kills pests in an enclosed space. Understanding their composition and function is important because these products contain powerful volatile chemicals.
The Primary Chemical Components
Modern moth balls typically contain one of two main active ingredients: Naphthalene or 1,4-Dichlorobenzene (Paradichlorobenzene or PDB). Both are white, crystalline organic solids classified as pesticides. Naphthalene is the older formulation, traditionally derived from coal tar, and is recognized for its strong, pungent odor. Due to concerns about Naphthalene’s flammability and higher toxicity profile, many current moth ball products rely on 1,4-Dichlorobenzene instead. PDB is also used in other household products, such as certain toilet and trash can deodorizer blocks. While both chemicals serve the same function in pest control, they are distinct compounds. The specific active ingredient must be listed on the product label, as the health risks and regulatory status of the two compounds are not identical.
How Moth Balls Work to Repel Pests
Moth balls work through sublimation, the physical process where a substance transitions directly from a solid state into a gas without first becoming a liquid. The chemical slowly vaporizes over time, releasing a concentrated toxic gas into the surrounding air. This vapor is the active agent in the pest control process.
The chemical fumes build up to a lethal concentration within a sealed or airtight storage container. These vapors are toxic to the larval stage of fabric-eating insects, such as clothes moths and carpet beetles. The toxic gas either kills the larvae or acts as a potent repellent.
For the moth balls to be effective, the vapors must be trapped. If used in an open closet or room, the fumes dissipate too quickly to kill pests, and this misuse increases the potential for human and pet exposure.
Health and Environmental Safety Concerns
Moth balls are classified as pesticides, meaning they are inherently designed to be toxic, which raises health and safety concerns for humans and pets. Exposure can occur through inhaling the fumes, direct skin contact, or accidental ingestion, with the latter posing the most severe risk. Children and pets are particularly vulnerable to accidental ingestion because the small, white spheres can be mistaken for candy or toys.
Inhalation of the vapors can lead to acute symptoms like headaches, dizziness, nausea, and irritation of the eyes and respiratory tract. Exposure to Naphthalene specifically has been linked to a condition called hemolytic anemia, which involves the rapid destruction of red blood cells. This is a particular risk for infants and individuals with a genetic condition called glucose-6-phosphate dehydrogenase (G6PD) deficiency.
Both Naphthalene and 1,4-Dichlorobenzene are considered by various international and national organizations to be possible human carcinogens. Chronic exposure to these chemicals has also been associated with potential liver and kidney damage. The lingering odor on clothing stored with moth balls is a sign of residual chemical that can continue to off-gas, leading to ongoing low-level exposure.
Improper disposal of moth balls poses environmental risks, as the chemicals do not simply disappear. When moth balls are placed in soil or water, the active ingredients can contaminate the environment. The chemicals can leach into the soil, potentially harming plants and wildlife, or contaminate water supplies.
Safer Storage and Alternative Methods
When using moth balls, strictly follow the instructions on the product label, which generally requires placing them inside an airtight container with the items being stored. Using them in any way not specified on the label, such as scattering them outdoors to deter animals, is ineffective, often illegal, and increases health risks. Any clothing stored with moth balls should be thoroughly aired out and washed before use to eliminate residual chemical vapors.
Many people choose to avoid chemical moth balls entirely and opt for safer, non-toxic alternatives for fabric protection. Natural materials like cedar blocks and shavings contain oils that act as a repellent for moths, though they do not kill the pests. For continued effectiveness, cedar items may need to be refreshed periodically by lightly sanding the surface.
Other natural options include sachets filled with dried herbs such as lavender, rosemary, cloves, or mint, which also deter insects with their strong scents. A primary preventative measure is ensuring all garments are cleaned before storage, as moths are attracted to human smells and food stains on textiles. Storing items in clean, sealed plastic bins or vacuum-sealed bags provides a physical barrier against pests without the use of chemical fumigants.