Four toxic gases from food you should know - and avoid

Gas. Often dismissed as a byproduct of our digestive process, it's generally harmless, causing only awkward moments and unwelcome odors. 

Yet, amidst the benign emissions of our bodies, certain foods can emit potentially perilous gases themselves! 

These toxic gases, though rare in everyday scenarios, pose significant risks when encountered in concentrated environments, particularly in work settings where large quantities are stored with poor ventilation. For example, nitrogen dioxide from fermenting grain in silos, or hydrogen sulfide from decomposing fish in seafood cargos. 

From cyanide-laden produce to lethal byproducts of fermentation, the culinary world harbors unexpected dangers. 

Join us as we explore these hazards, shedding light on the importance of food safety and proper handling.

Bamboo flesh can release toxic gas

Let's start with a story from Thailand, where a seemingly harmless culinary staple, bamboo, turned deadly. 

A tragic incident occurred when an individual fell into a poorly ventilated 3-meter-deep well containing freshly sliced bamboo shoots.

Carried within its seemingly benign bamboo flesh is a compound called taxiphyllin, a cyanogenic glycoside. 

Slicing these shoots activates the glycosidase enzyme, triggering the production and release of hydrogen cyanide (HCN) gas. 

Cyanide affects crucial organs

Cyanide stops cells from using oxygen for energy, which can lead to cells no longer functioning. This affects crucial organs that use a lot of oxygen as their energy source, like the brain and heart, which are essential for maintaining overall body function. 

In a poorly ventilated well, a significant amount of HCN gas can claim lives within moments. It's no wonder that when seven others attempted to help, it resulted in everyone losing consciousness and ultimately leading to two fatal cardiac arrests. 

The cause was confirmed through ambient air studies and examination of the cyanide content in the bamboo shoots.

And the same goes for cassava

And it's not just bamboo. Cassava, a staple in many cuisines, also contains cyanogenic glycoside called linamarin. When processed, similar to bamboo, it can release HCN gas. 

It has occurred that workers in cassava factories, who may not even consume cassava themselves, have unknowingly inhaled cyanide gas during processing. 

This was proven by the detection of urine thiocyanate, a metabolite formed when cyanide interacts with sulfur groups inside the body.

Toxic gasses from fermentation

Another area where food becomes toxic is during some fermentation processes. 

Food fermentation is a process where microorganisms like bacteria, yeast, or fungi convert organic compounds (usually carbohydrates such as sugars and starches) into alcohol or acids, typically in an oxygen-free environment. 

Unfortunately, this process can sometimes produce toxic gases, as we will describe below.

The Rotten Egg Revelation

Ever wondered about the source of that unmistakable rotten egg smell? Look no further than hydrogen sulfide. 

The smell is primarily caused by the molecule sulfur contained in the eggs. However, other high-protein foods can also serve as sources of this smelly gas. 

Fish garbage rooms are one of the notorious sources of large amounts of hydrogen sulfide if not ventilated properly, having caused fatalities and injuries among many workers. 

As bacteria enjoy the spoiled fish in the ships, they convert the sulfur into protein-rich meat and produce this deadly gas. 

Hydrogen sulfide acts similarly to cyanide by blocking cells from using oxygen as energy. Breathing in high amounts can swiftly make you lose consciousness, earning it the nickname ‘knock-down gas’, much like cyanide.

The Silo's Silent Threat

A second example of toxic gas from fermentation is nitrogen dioxide. It is the most prevalent among a variety of gases in silos and is formed as a byproduct of bacterial fermentation on nitrate-containing molecules in corn or hay. 

Picture a farmer unloading hay from his silo, unaware that this silent, deadly gas has been accumulating at the surface of the fermented feed. 

The danger is already significant when it reaches peak concentration, typically around three days after harvesting. 

In low concentrations, the gas may not cause immediate irritation effects to the eyes and airways, leading to individuals staying at work in the silo longer than they should. 

However, prolonged exposure can result in severe lung inflammation, known as ‘silo filler's disease’, with potentially fatal consequences. 

The bleach-like odor, the sight of orange fumes leaking from silos, or birds dying around the vicinity of the silo itself serves as a grim warning of high concentrations of nitrogen dioxide, yet many fall victim to this insidious threat.

A Symphony of Gases

But wait, there's more! Fermentation processes can churn out many other gases,

from carbon dioxide to methane and beyond. 

One famous example is the wine industry where the fermentation of yeast into alcohol is a major source of CO₂.

These fermentation byproducts can displace oxygen, leading to suffocation. In separate incidents, workplace accidents related to high carbon dioxide concentrations in white wine fermentation tanks occurred in Canada and Germany. 

In Canada, tragedy struck when two workers fell victim to the noxious gas while attempting to collect samples from a 2.300-liter tank filled with fermenting grapes. 

Standing on a ladder near the tank's opening, one worker inadvertently plunged into the vat, swiftly followed by a colleague who rushed to their aid, only to find themselves trapped in the toxic environment with no means of escape.

The white wine accident

Meanwhile, in Germany, a similar scenario unfolded when an unskilled laborer ventured into a stainless-steel fermentation tank previously used for white wine production. 

Despite the tank having been emptied and sealed for five months, the worker opted to enter through the top manhole rather than employing the standard procedure of opening the bottom hatch. 

Within moments, a second worker, unaware of the danger, joined their companion within the confined space. Both were later discovered lifeless by the cellar master, submerged in the fermenting mash at the tank's base. 

These examples of tragic cases serve as a stark reminder of the need for proper food storage and ventilation.

The Ripening Gambit with Acetylene Gas

Shifting focus from the toxic gases produced by fermentation, let’s turn to another type of toxic gas: acetylene. 

Ethylene, a natural plant hormone, ripens fruits and vegetables, even in small quantities. Yet, in the vast landscape of fruit production, the demand for accelerated ripening prompts the adoption of artificial means. 

This is where acetylene comes in, a chemical cousin of ethylene, which is synthesized from calcium carbide and also expedites the ripening process. 

However, unlike its natural counterpart, acetylene comes with a distinct downside. 

Not only does it introduce an unpleasant aroma and flavor to the fruits it treats, but it also poses considerable health hazards to both consumers and handlers. 

Short-term exposure to this gas can induce a range of neurological symptoms, from headaches to dizziness and even seizures. 

While direct encounters with high concentrations of acetylene gas are rare, a poignant case highlights its potential dangers: a 5-year-old got acetylene gas intoxication from eating! 

No, she did not eat the gas. Instead, she ate unwashed fruits that were treated with calcium carbide, which produces acetylene gas inside the body.

What to do in your own kitchen

With all these examples of dangerous gases, fear not the occasional whiff of strange smells emanating from your kitchen! 

While the world of toxic food gases may seem daunting, there's no need to panic. Most dangerous scenarios require large or industrial quantities of causative foods combined with poor ventilation. However, every kitchen is unique in its storage capacity, so ensure that foods are kept in well-ventilated areas.

In work settings, be cautious of large, enclosed spaces, especially if colleagues are already affected. Even if you don't detect any odor, don't enter such areas. Instead, call for help immediately.

Armed with this knowledge, you can safely navigate potential risks while enjoying your food experiences.

Bon appétit!