When most people hear the phrase “chemical reaction,” they picture bubbling beakers in a laboratory. In truth, the world around us is a nonstop chemistry lab, with reactions happening everywhere—from the invisible processes inside our bodies to the surprising transformations that occur on kitchen counters and in public spaces. Some of these off‑lab reactions are downright unsettling, and they’re happening right under our noses. These 10 disturbing chemical reactions illustrate just how pervasive and eerie chemistry can be outside the controlled environment of a lab.

Why These 10 Disturbing Chemical Reactions Matter

10 The Chlorine Smell In Pools Is Actually a Reaction Between Chlorine and Things Like Pee

Ever stroll toward a public pool and get hit by a sharp, eye‑watering aroma that seems to scream “extra‑clean”? That pungent whiff isn’t the chlorine itself—it’s a warning sign that something else is brewing in the water.

Pure chlorine is virtually odorless, but it’s a highly reactive element. When it encounters other substances, it can generate strong‑smelling by‑products. The characteristic “pool stink” is one such by‑product, born when chlorine meets various contaminants.

The culprit is a family of compounds called chloramines. They form when chlorine reacts with sweat, body oils, cosmetics, and, most infamously, urine. That’s why many facilities ask swimmers to shower before diving in—to strip away the very compounds that create chloramines.

Ironically, that acrid scent doesn’t indicate a more sanitized pool. In fact, chloramines are far less effective disinfectants than free chlorine, meaning the water’s cleaning power has actually diminished. The stronger the smell, the weaker the pool’s actual sanitation.

9 A High School Student Lost Her Fingers to a Chemical Reaction in Art Class

Art class often feels like the carefree corner of school where creativity reigns and safety rules are a distant memory. Yet even the most benign‑looking project can turn hazardous in an instant.

In 2007, a 16‑year‑old student attempted to sculpt a replica of her own hands. She was instructed to create a clay mold and then fill it with plaster, but she misheard the teacher and plunged her hands straight into plaster of Paris instead. Unaware of the chemistry at play, she didn’t realize the plaster would behave like cement when water was added.

Plaster of Paris undergoes an exothermic reaction—a heat‑releasing process similar to what occurs when cement sets. The powdered gypsum, once heated to drive out moisture, recombines with water, releasing energy as it hardens.

As the mixture cured around her hands, the water molecules reacted with the plaster, spiking the temperature to around 60 °C (about 140 °F). The heat built up while the plaster solidified, essentially baking her fingers in a scorching, rigid shell.

By the time teachers managed to pry her free, the burns were severe enough that she lost all but two of her fingers, a tragic reminder that even school projects can involve dangerous chemistry.

8 Adipocere Is The Result of a Chemical Reaction Turning Body Fat Into a Waxy Substance In A Coffin

When we think about burial, the image that usually comes to mind is a skeleton slowly emerging from the earth. The decomposition process, however, has many fascinating stages that most of us never consider.

Under the right conditions—moisture paired with limited oxygen—a corpse can produce a wax‑like material known as adipocere, or “grave wax.” This substance forms when the body’s fat tissues break down in a specific chemical environment.The transformation occurs through the hydrolysis of triglycerides, splitting them into glycerin and free fatty acids, a reaction strikingly similar to the soap‑making process. The resulting waxy layer initially feels slick but eventually crumbles, yet it can preserve the body for years, offering a macabre glimpse into post‑mortem chemistry.

7 Pistachios Will Spontaneously Combust In the Right Circumstances

Americans devour roughly 0.7 pounds of pistachios each year, making these green gems one of the nation’s most beloved snacks. Their popularity, however, masks a hidden hazard that can turn a simple storage room into a potential fire trap.

Pistachios absorb oxygen after harvest while simultaneously releasing carbon dioxide. In a confined space, a bulk collection of nuts can create an environment where the nuts themselves become a source of oxygen, setting the stage for oxidation.

Because pistachios contain very little water and a high concentration of fat, they are prone to spontaneous combustion. As the nuts oxidize, the breakdown of fats into fatty acids releases heat. If the temperature climbs high enough, the fat acts as fuel and the nuts can burst into flames—a phenomenon sometimes dubbed a “pistachio bomb,” especially concerning when massive shipments are stored together.

6 Pit Stains Are Caused By a Reaction To Your Deodorant

The global deodorant market is worth nearly $70 billion, reflecting our collective desire to stay fresh and avoid unsightly sweat marks. Yet, for many wearers of white shirts, a dreaded yellow armpit stain can appear, and surprisingly, it isn’t your sweat that’s to blame.

The culprit lies in the aluminum compounds found in many antiperspirants. When aluminum reacts with the proteins in sweat, it forms a yellowing agent that embeds itself in fabric, creating the infamous “pit stain.” This reaction doesn’t affect everyone, but for those who experience it, the result is an embarrassing discoloration.

If you’re plagued by these stains, switching to an aluminum‑free antiperspirant can often prevent the reaction, keeping your shirts bright and your confidence intact.

5 A Chemical Reaction Between Tin Foil and Lasagna Causes “Lasagna Cell”

Lasagna is arguably the most beloved pasta dish among Millennials, and for good reason—it’s hearty, comforting, and endlessly customizable. Yet, a little‑known chemical quirk can turn your leftovers into a tiny battery if you’re not careful.

Storing lasagna in a metal container or covering it with aluminum foil sets the stage for a phenomenon known as the “lasagna cell.” The salty tomato sauce acts as an electrolyte, and when it contacts aluminum, a galvanic corrosion process begins.

In this tiny electrochemical cell, the aluminum foil becomes the anode, while the metal dish (if it’s a different metal) serves as the cathode. Within a few hours, you may notice tiny holes in the foil and specks of corroded metal on the surface of your lasagna—clear evidence of the reaction at work.

4 The Smell of Pennies Is Actually Your Own Odor After Reacting to Pennies

Ever pick up a penny and notice an odd, slightly metallic odor that seems to cling to your fingertips? The coin itself isn’t the source of that smell; it’s a reaction taking place on your skin.

Copper in the penny interacts with the natural oils on your hands, producing volatile compounds that your nose interprets as a metallic scent. The same sort of reaction occurs with other metals like brass and iron, each generating its own distinctive odor profile.

Because individuals have different skin chemistry, the exact smell can vary from person to person. What you perceive as a “metallic” odor is actually a subtle form of body odor generated by the metal‑oil reaction.

3 A Chemical Reaction Causes Beer, Weed, and Skunks to Smell Similar

When a bottle of beer goes “skunky,” the unpleasant aroma often reminds us of the notorious scent of a skunk’s spray. This isn’t a coincidence; the same chemical pathway is at work in all three cases.

Beer contains iso‑alpha acids from hops that provide bitterness. When exposed to light, these acids break down, reacting with sulfur‑containing compounds in the brew. The resulting molecule is 3‑methyl‑2‑butene‑1‑thiol, commonly called prenyl‑thiol.

This thiol is also a major component of skunk spray and is found in especially pungent cannabis. Its presence explains why “skunky” beer, skunk odor, and certain weed strains share a remarkably similar smell.

2 Humans Cause Their Own Indoor Air Pollution

When we discuss air pollution, we usually picture smoggy city skylines and industrial smokestacks. Yet, the air inside our homes can become a hidden source of pollutants, thanks largely to our own bodies.

Human skin secretes an oily substance called squalene. When this oil meets ambient ozone, it undergoes a chemical transformation that creates an “oxidation field” around each person, producing new volatile compounds.

These reactions generate hydroxyl radicals—highly reactive species that, in the open atmosphere, help break down pollutants. Inside a sealed room, however, they can react with everyday household chemicals, forming potentially harmful by‑products.

Outdoors, sunlight and wind disperse these radicals, keeping them beneficial. Indoors, the lack of ventilation means the radicals linger, increasing the chance of toxic compound formation.

The issue isn’t new, but the COVID‑19 pandemic sparked renewed interest in indoor air quality, prompting scientists to investigate how our own chemistry contributes to the air we breathe at home.

1 Babies Produce a Chemical That Makes Women Aggressive But Does the Opposite to Men

Imagine a scent so subtle it can tweak human behavior. While the idea of pheromones influencing us feels like science‑fiction, research shows that a compound emitted by newborns can indeed shift aggression levels.

The molecule, hexadecanal, is released from a baby’s head. Studies reveal that exposure to this chemical reduces aggression in men but heightens it in women, suggesting a gender‑specific response to the same odor.

Evolutionary biologists speculate this reaction serves a protective purpose: heightened aggression in mothers may make them more vigilant protectors, while calmer fathers pose less of a threat to the infant. Similar scent‑driven behaviors appear across many animal species.

Scientists are at it again. This time, they’re creating new viruses and bacteria in their laboratories. In this roundup of the 10 deadly viruses and bacteria engineered in labs, we explore how researchers tinker with pathogens, the controversies that follow, and why these creations matter for global health.

10 Deadly Viruses Overview

10 Horsepox

Scientists at the University of Alberta have created horsepox, a lethal virus closely related to the equally deadly smallpox. Unlike smallpox, horsepox does not affect humans and is only fatal to horses. The scientists created the virus during a six‑month study sponsored by pharmaceutical company Tonix. The researchers purchased DNA pieces via mail order and arranged them to form the virus. The entire project was not expensive. The DNA pieces used to create the virus cost just $100,000.

The study caused a dilemma at the time it was revealed. Other scientists were concerned that governments or even terrorists could use the knowledge to create smallpox virus for biological weapons. A smallpox epidemic could become deadly for us today. We no longer get vaccinated for it because we eradicated the disease in 1980.

The researchers clarified that they created the virus because they wanted to develop improved smallpox vaccines. Tonix later revealed that it had produced a smallpox vaccine with the horsepox virus. Other scientists say that the researchers could have extracted horsepox from wild horse populations instead of creating it from scratch. Tonix said they would have done just that if they had known they had natural access to the virus. However, lead researcher David Evans said they recreated the virus because Tonix would have been unable to commercialize the horsepox virus taken from the wild.

9 Black Death

Between 1347 and 1351, millions of Europeans were afflicted with a mysterious disease that killed over 50 million people. Today, we know this disease is the Black Death, which is caused by the Yersinia pestis bacteria. Although the Black Death is still around, it is not as potent as it used to be.

A few years ago, researchers from several schools, including the University of Tubingen in Germany and McMaster University in Canada, recreated the deadly bacteria from DNA samples extracted from the teeth of a victim who died during the plague. They got only 30 milligrams of the bacteria from the teeth, but that was enough to recreate it.

As a result, researchers confirmed the original bacteria’s relationship to the Black Death around today. Some scientists had claimed that the bacteria were of different strains, but they are now confirmed to be the same. The one we have around today only became less deadly after it mutated.

8 Polio

Like their counterparts at the University of Alberta, scientists at the State University of New York have created a deadly artificial virus by buying DNA pieces via mail order. This time, it is polio, and it is as potent as the natural one. Mice exposed to the artificial polio got sick just as they would have if exposed to natural polio.

The laboratory‑created polio was controversial among scientists. The researchers who produced it had taken its code from databases available to almost anybody. Other researchers fear that people with ulterior motives could develop their own artificial polio, which is much easier to make than other dangerous viruses like smallpox.

Smallpox’s genetic code is 185,000 letters long while polio’s is just 7,741 letters long. Although we are already at the brink of eradicating polio, scientists fear that we will still need to be vaccinated against the disease because it could be recreated.

7 Mousepox

A few years ago, researchers at the Australian National University and the Commonwealth Scientific and Industrial Research Organization (CSIRO) produced a deadly mutated strain of mousepox by mistake. Mousepox is another lethal virus that belongs to the same family as horsepox and smallpox.

The researchers were trying to develop birth control for mice at the time that they mistakenly created the virus. They inserted a gene that promoted the creation of interleukin 4 (IL‑4) into mousepox, which they injected into some mice. The mice were vaccinated and were not supposed to be harmed by the mousepox.

Instead of making the mice infertile as researchers had expected, the weakened virus turned lethal and destroyed the immune systems of the mice, killing them in nine days. The new mousepox was so dangerous that it was resistant to vaccination. Half of the other vaccinated mice exposed to the mutated mousepox also died.

The researchers were so scared by their invention that they did not want to publish their findings. They even met with the Australian military to confirm if it was safe to publish. Scientists fear that human smallpox could also mutate and become deadlier if injected with IL‑4. However, they are unsure because no one has tried it yet. We know it’s only a matter of time before some scientist does.

6 SARS 2.0

Severe acute respiratory syndrome (SARS) is a lethal virus. More than 700 people were killed during a SARS epidemic that infected 8,000 people in 29 countries between 2002 and 2003. Now, scientists have made it deadlier.

The new mutant SARS virus was created by a group of researchers led by Dr. Ralph Baric of the University of North Carolina. They call it SARS 2.0. The researchers developed the virus by adding some protein to the naturally occurring SARS. SARS 2.0 is immune to vaccines and treatments used to cure the naturally occurring SARS virus.

The team said that the research was necessary because the natural SARS virus could mutate and become immune to our vaccines. By creating a deadlier and mutated virus, we could develop stronger vaccines that will save us from a more lethal SARS epidemic. That is, if the natural SARS ever mutates.

However, other scientists are concerned because the SARS 2.0 that is supposed to save us from a deadly SARS epidemic could start that epidemic if it ever escapes from the lab.

5 MERS‑Rabies Virus Hybrid

Scientists have created a MERS‑rabies hybrid virus. The idea is to use the virus to develop a vaccine that will protect us from both viruses. Rabies is a deadly disease that can be transmitted to humans through the bites of infected dogs that usually have the virus in their saliva.

Middle East Respiratory Syndrome (MERS) is a new virus that appeared in Saudi Arabia a few years ago. It is closely related to SARS and is spread from bats to camels and, finally, to humans. MERS infected 1,800 people at the time of its first epidemic and killed over 630. Its fatality rate is around 35 percent.

As we mentioned in the previous entry, SARS infected over 8,000 people during a 2003 epidemic but killed just over 700. Although SARS caused more deaths in absolute terms, it has a lower fatality rate than MERS. Only about 10 percent of SARS victims died. And for now, we do not have any vaccine for MERS.

To create the MERS‑rabies hybrid, researchers took some proteins from the MERS virus and added it to rabies. They used the new virus to develop a new vaccine that made mice resistant to rabies and MERS. They believe that the vaccine can also be used for humans and camels at risk of getting MERS.

4 Phi‑X174

Phi‑X174 is another artificial virus we have produced in laboratories. It was created by researchers at the Institute of Biological Energy Alternatives in Rockville, Maryland. The researchers modeled the artificial virus after the natural phiX virus. PhiX is a bacteriophage, a category of viruses that infect and kill bacteria. However, it has no effect on humans.

The researchers created the artificial virus in 14 days, yet it resembles the natural virus so much that it is impossible to tell them apart. The researchers hope that the new virus is the first step in developing mutant and artificial bacteria that can be used for the benefit of man.

3 Unnamed Virus

Researchers from University College London and the National Physical Laboratory have created an unnamed virus that kills bacteria and behaves like a real virus. Like phi‑X174, it is a bacteriophage but deadlier.

The unnamed virus attacks any bacteria around it. Within seconds, it breaks into smaller parts that attach and create holes on the bodies of the bacteria. The holes quickly become larger, forcing the bacteria to leak their contents. The bacteria die soon after.

Despite its scary potency, the unnamed virus is not dangerous to humans and did not attack human cells during tests. However, it could enter human cells just like natural viruses. Researchers hope the results will be used for treat and study bacterial diseases in humans. The virus could also be used to alter the human gene.

2 Bird Flu

Some Dutch scientists have created a mutant and deadlier version of the already‑lethal bird flu. Natural bird flu is not easily transmitted among humans. However, the researchers altered it so that it could be. To test their new virus, the researchers exposed some ferrets to it. Ferrets were chosen because they had similar bird flu symptoms to humans.

Ten generations later, the already‑changed virus mutated again and became airborne. Natural bird flu is not an airborne disease. The study was controversial in the science community. It became even more so when the Dutch researchers attempted to publish the process to create the deadly virus.

Although scientists fear that terrorists could use the study to produce a deadly biological weapon that could kill half the people in the world, the researchers involved say that the study was necessary to allow us prepare for a mutated bird flu epidemic.

1 H1N1 Virus

In 1918, the world witnessed the arrival of a deadly flu epidemic. This was the H1N1 virus. By the time it was over, up to 100 million people were dead. The flu caused blood to seep into the lungs of victims. They released blood from their noses and mouths before drowning in the blood inside their lungs.

The flu returned in 2009. But it was less lethal even though it was mutated and deadlier than it should have been. Scientist Yoshihiro Kawaoka took samples of the mutated strain that caused the 2009 epidemic and used it to create a deadlier strain that was resistant to vaccines. This strain was similar to the one that caused the 1918 epidemic.

Kawaoka was not planning to produce a more lethal version of the flu at the time. He only wanted to create the original version of the flu so that he could study how it mutated and was able to bypass our immunity. The deadly virus is stored in a lab and could become fatal if ever released.