An 18-year-old girl who was hospitalized with scaly skin on her hands, elbows and legs, unsteadiness and mental sluggishness shows the risks of sniffing mothballs, French doctors say.

Doctors were initially puzzled by her condition. The woman's twin sister showed similar but less severe skin lesions and an unsteady gait, but there was no family history of such problems and brain scans were normal.

After several days, cleaning staff at the Hospital of Timone in Marseille "accidentally discovered a bag of mothballs" in the first woman's room.

"It turned out that both sisters had been encouraged by classmates to use mothballs as a recreational drug," Dr. Lionel Feuillet and his colleagues said in a letter appearing in Thursday's issue of the New England Journal of Medicine.

The sickest twin said she had been "bagging" or inhaling mothball fumes for 10 minutes per day for the previous four to six months.

She also chewed half a mothball per day for two months, and continued the habit while in hospital without realizing it was the cause of her symptoms.

Mothballs contain paradichlorobenzene, or PDB, a chemical that can cause liver and kidney failure and severe anemia.

Abuse likely underestimated

"PDB is derived from aromatic hydrocarbons, which form one of the families of volatile substances that are
commonly abused," the doctors said.

They urged doctors to be aware of the symptoms, noting the medical literature includes three other cases of people getting high from mothballs.

PBD is easy to abuse since it is found in mothballs and other household products such as air fresheners, toilet bowl and diaper pail deodorizers and insect repellents, the letter writers noted.

"Moreover, since young people usually deny practicing self-intoxication, the incidence of this type of recreational activity is probably underestimated."

The sicker twin improved after she was mothball-free for two months, and her full recovery took six months.

Her sister, who sniffed mothballs for a few weeks, recovered completely in three months.