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How Onion Peels Landed One Farmer in the Hospital
Credit: Marcin Wos/Shutterstock

Workers may like to complain that their job is making them sick, but for one man in Japan, that turned out to be the case: The 62-year-old, who worked as an onion farmer, developed a rare allergic reaction from repeated exposure to moldy onion peels, according to a new report of the man's case.

The mold growing on the onion peels turned out to be Aspergillus niger, a common type of mold that can grow on fruits and vegetables. For some people, inhaling spores from this mold can cause inflammation in the lungs, according to the report, which was published online in December in the journal Respiratory Medicine Case Reports.

In the man's case, he had been working as an onion farmer for several years when he developed shortness of breath, fatigue and a dry cough. After about two weeks of these symptoms, he was admitted to the hospital. [27 Oddest Medical Cases]

Doctors diagnosed the farmer with "hypersensitivity pneumonitis," also known as "extrinsic allergic alveolitis." The condition occurs in some people after they inhale certain substances found in the environment — such as molds, bacteria, proteins or chemicals — which triggers an immune response and causes the tiny air sacs known as alveoli in the lungs to become inflamed, according to the National Heart, Lung and Blood Institute (NHLBI).

Normally, these tiny air sacs stretch and relax with each breath. But when the tissue lining these sacs becomes inflamed, they become less flexible and may even develop scar tissue over time, making breathing difficult, according to the Mayo Clinic

Regular exposure to substances such as bird droppings, feathers, dust, mold and animal furs may trigger a strong immune response, the NHLBI says. But not every person who repeatedly inhales particles from these substances develops this reaction to them

The man had also been a smoker for 35 years, but had stopped smoking when he was 56, said report co-author Dr. Akira Yamasaki, a respiratory medicine specialist at Tottori University Faculty of Medicine in Yonago, Japan, who treated the man. It's not clear whether his smoking history affected his hypersensitivity pneumonitis, Yamasaki added.

When the man was admitted to the hospital, lab tests and a CT scan of his chest revealed high levels of inflammation in the lungs. But the man's symptoms and test results gradually improved during his hospital stay — without any treatment. [9 Weirdest Allergies]

However, blood tests revealed that the man had been exposed to Aspergillus

The patient told doctors he first developed his symptoms after completing one of his chores at work: cleaning up onion peels using an air compressor, according to the case report.

Usually, the man said he wore a thick mask while he worked. But he told the doctors that he had not been wearing the mask when his shortness of breath and cough first started, Yamasaki told Live Science.

It appears that the Aspergillus got into the man's lungs because the air compressor spread the black mold on the onion peels into the air, Yamasaki said. Without the protective mask, he repeatedly inhaled the mold, Yamasaki added.

Doctors suspected that the man's symptoms eased while he was in the hospital because he was no longer exposed to the mold. So, to confirm that Aspergillus was indeed the trigger, the man was asked to complete a three-day provocation test when he returned home.

On the first day, the man stayed home and had no symptoms. On the second day, he went to work and cleaned up the onion peels with the air compressor. On the third day, he returned to the hospital complaining of a cough and a low-grade fever that showed up 3 hours after cleaning the onion peels. [8 Strange Signs You're Having an Allergic Reaction]

Doctors repeated the three-day provocation test. They used the same steps except on the second day, the man went to work but did not clean onion peels. This time, he experienced no symptoms.

From these tests and along with sampling the mold found in his workplace and home, doctors concluded that the man's lung problems were caused by the species Aspergillus niger, which is a rare cause of hypersensitivity pneumonitis, according to the case report.

The farmer did not need to quit his job. He was advised to wear a thick filtered mask while working and was not prescribed any medication, according to the case report.

When doctors last saw the man, he was doing well and had no lung problems, Yamasaki said.

Originally published on Live Science.