Have you ever smelled moth balls? While that is the first part of a good joke ("yes", "Well, how'd you get their little feet apart?") it is also a subject of concern today, as we learn that many of the compounds around the home that we used to think we harmless, turn out not to be.
Question: I have heard that there is a substance in mothballs that causes cancer. Is it safe to use mothballs in my home to keep away moths and other pests?
Answer: There are two compounds which are commonly used as moth control agents/animal repellents in mothballs: 1,4-dichlorobenzene and naphthalene. Of these two, 1,4-dichlorobenzene (para-DCB) is considered by some to be a carcinogen. Para-DCB is also as a space deodorant in products such as room deodorizers, urinal and toilet bowl blocks, and diaper pail deodorants. It is a colorless solid at room temperature, but it is volatile and slowly transforms into a vapor. As a vapor, it acts a deodorant and insecticide.
Thus, most of the exposure to this chemical in household applications comes from breathing it into the lungs. However, some also may enter the body through the skin while handling the products containing para-DCB or through ingestion if a product is accidently swallowed, especially by young children.
There is no evidence that brief low level or moderate-level exposures to household products containing para-DCB will cause human health effects. At levels many times higher than the usual household exposures, the onset of headaches, dizziness, and significant eye irritation can occur. Chronic exposures to very high levels, usually associated with certain occupational exposures, can result in liver and kidney damage. The U.S. Department of Health and Human Services has concluded that para-DCB may be reasonably anticipated to be a carcinogen. The state of California has gone further and declared this compound to be a human carcinogen. There is no direct evidence from human studies to indicate that this compound is a human carcinogen. However, these determinations were made based on the results of animals showing that the log-term exposure resulted in cancer in treated laboratory animals. Also, other animal studies indicate the possibility of birth defects at very high level exposures. These animal studies point to the potential for such toxic effects in humans but in no way provide definite proof of their occurrence, especially at low, intermittent exposure levels.
If the idea of even a very small potential health risk concerns a person, there are alternatives to 1,4 dichlorobenzene available for household applications. mothballs containing naphthalene can be safely used for moth/pest control. Cedar blocks can also be utilized to repel insects and moths. Many aromatic and nontoxic air-freshening products which may be substituted for para-DCB are available in the marketplace.