In the past, most mothballs contained camphor, which is “quite toxic,” said Dr. Michele Burns, an emergency room physician at Children’s Hospital and medical director of the regional poison control center for Massachusetts and Rhode Island.. Camphor-based mothballs are not sold anymore in the US, she said, but many people still have supplies bought years ago.

At high doses — either eating or simply inhaling fumes close up — camphor can cause nausea, vomiting and seizures.

With the more-common naphthalene-based mothballs, the real risk is for people with a genetic problem called glucose-6-phosphate dehydrogenase deficiency, which is more common in people of African-American or Asian descent, said Dr. Stephen Traub, co-director of the division of toxicology at Beth Israel Deaconess Medical Center. These people can develop a serious kind of anemia from eating naphthalene mothballs.

The safest mothballs are those containing paradichlorobenzene, which is “pretty benign,” said Dr. Edward Boyer, a toxicologist at Children’s. The fumes from these mothballs can irritate eyes or airways if exposure is high. But generally, there is very little toxicity linked to this kind of mothball.

Bottom line? While occupational exposure, like working in a mothball factory, may pose a risk, the fumes from a box of open mothballs in the bedroom closet won’t hurt you. Eating mothballs, however, does pose more risk, so keep mothballs away from children and pets. If you’re still worried about the fumes just put the clothes you want to protect in sealed plastic containers with the mothballs.