The Hidden Danger of Botulinum Toxin in Everyday Foods and How to Stay Safe

1 gram is equivalent to a lethal dose for 1 million people

The Deadly Risk of Botulinum Toxin: How Everyday Foods Can Become Lethal

This January, a woman in her 50s from Niigata City suffered from botulism poisoning after consuming a refrigerated food item that she had stored at room temperature. Her life was in grave danger.

On social media, comments surfaced questioning her decision: “Did she think it was safe just because it was cold?” and “Why would she eat that?” However, Dr. Yoshimasa Goto, director of Goryokai Clinic Shirokane-Takanawa, warns that simply following expiration dates is not enough to prevent food poisoning.

“Clostridium botulinum can lurk in common foods—vacuum-packed items, canned goods, fermented foods. Mishandling or improper storage can turn these everyday foods into lethal hazards.”

Historically, botulism outbreaks have occurred multiple times. In 1951, a mass food poisoning incident in Iwanai, Hokkaido, caused by izushi (fermented herring) resulted in 24 infections, with 4 fatalities. In 1984, an outbreak linked to karashi renkon (mustard-stuffed lotus root) in Kumamoto infected 36 people, 11 of whom died.

The true danger of C. botulinum lies in its extreme toxicity.

“The botulinum toxin produced by the bacteria is even more lethal than sarin gas. Just 1 gram is estimated to be enough to kill 1 million people. Early symptoms include fatigue, dry mouth, nausea, and stomach pain. As it progresses, double vision, drooping eyelids, slurred speech, and difficulty swallowing can occur. In the worst cases, total muscle paralysis leads to respiratory failure and death.” (Dr. Goto)

Shockingly, this deadly bacteria remains a real and present danger. Just last year, a botulism outbreak in Toyama Prefecture left four family members in critical condition. Despite a thorough investigation, health authorities were unable to determine the source of contamination.

It survives by transforming into a durable form

Identifying the source of Clostridium botulinum contamination is difficult.

“In many cases, the contaminated food has already been discarded, and even a minute amount of toxin can cause poisoning, making identification challenging. The contamination area may be extremely small, or the source could be an unexpected food item.” (Dr. Goto)

What makes C. botulinum particularly troublesome is its strong defense mechanism. When it encounters an inhospitable environment, it transforms into a highly resistant form called a spore, allowing it to withstand heat, dryness, and disinfectants. This means commonly known sterilization methods are ineffective. Dr. Goto emphasizes the danger:

“Not only is it difficult to eliminate, but without proper heating or storage, it can germinate and multiply in food, producing the deadly botulinum toxin. Homemade fermented foods, canned goods, and low-temperature-cooked foods are especially at risk, as spores can survive.”

The only way to protect yourself is through proper handling.

Refrigerate perishable foods below 10°C. Even in winter, store items labeled “keep refrigerated” in the fridge, not at room temperature. Type E C. botulinum can proliferate even below 4°C, making vacuum-packed seafood and low-salt fermented foods particularly high-risk.

Thoroughly heat food before consuming. The botulinum toxin is inactivated by heating at 100°C for at least 10 minutes. However, C. botulinum spores can survive even at 120°C for 4 minutes, meaning regular boiling is not sufficient. Proper reheating of low-temperature-cooked and vacuum-packed foods is crucial.

Never consume damaged or swollen canned goods or food with an unusual odor—these are critical warning signs. Relying on your senses and following strict safety measures are the only ways to protect yourself from this formidable threat.