Although our sense of smell may not be as highly developed as that of a dog, humans
can smell a wide range of scents.
A study in the journal Science found that humans can discriminate at least 1 trillion
odors.
However, scientists are still trying to understand how humans can distinguish between a “good”
smell and a “bad” smell.
One theory is that humans make this distinction based on “chemical cues,” while another
theory proposed by researcher Val Curtis is that “our disgust toward certain sights
and smells” is an “adaptation . . . that evolved to keep us from coming into contact
with infection and disease.”
With this in mind, let us explore what literally makes life stink in this episode of The Infographics
Show, “Top 10 Worst Smells
in the World.”
10.
Skunk Spray Most of us have heard the stories about how
bad skunk spray smells, and some of us have had the unfortunate experience of smelling
it firsthand.
On Quora, one person who was sprayed by a skunk at close range described the smell as
“nauseating, noxious, putrid.”
He added, “While your brain is trying to process this sudden whiff of Hell that has
engulfed your olfactory system, your eyes will start pouring out tears, you may vomit,
and you will become dizzy and disoriented.”
What makes skunk spray smell so overwhelmingly bad?
According to the Iowa Department of Natural Resources, the “primary stinky compounds
are thiols and thioacetates, both rich in sulfur—the same element that makes rotten
eggs gag-inducing.”
Sulfur atoms in these compounds form very stable bonds with other atoms, which is why
skunk odor is so hard to get rid of.
An interesting side note reported by one source is that thiols “happen to be highly flammable”
too.
9.
Lesser Anteater Spray The lesser anteater is also known as the collared
anteater and the southern tamandua.
It is native to the forests of South America.
Like the skunk, the lesser anteater emits its stinky spray from its anal glands when
it feels threatened.
While the smell of skunk spray is bad, the smell of lesser anteater spray is even worse.
Some animal websites say it is about 4-7 times stronger than skunk spray, while others say
it is 5-7 times stronger.
Despite its highly stinky spray, a few people dare to keep lesser anteaters as exotic pets.
8.
Titan Arum (Amorphophallus titanum) This large flowering plant is native to Sumatra
and western Java.
A Live Science article states that titan arum “plants typically can grow to a massive
8 feet (2.4 m) tall and the leaves can be as big as 13 feet (4 m) wide.”
It can take up to 7 years or longer for a titan arum plant to bloom, yet the bloom lasts
for only 24 to 36 hours.
While the titan arum bloom may look like a huge flower, it is actually what is called
an inflorescence, which Live Science describes as “a stalk with many flowers.”
There is a good reason why the titan arum is also called a “corpse flower.”
While it blooms, it gives off a stench similar to rotting flesh in order to attract carnivorous
insects that will pollinate the flower.
According to Live Science, the “smell and the dark burgundy color of the corpse flower
are meant to imitate a dead animal to attract these insects.”
A chemistry website called Compound Interest states that several chemical compounds are
responsible for the titan arum’s deathlike odor.
These include dimethyl trisulfide, dimethyl disulfide, isovaleric acid, methylthiol acetate,
and trimethylamine.
Together these chemical compounds create a dreadful combination of unpleasant scents
– dead animal, garlic, sweaty feet, cheese, and dead fish – that has earned the titan
arum or corpse flower a spot on our list.
7.
Rotten Food Most of us have had the unpleasant experience
of discovering old food that looks and smells like a lab experiment.
We are often in such a hurry to throw out the rotting food that we don’t think what
could cause its horrible odor.
According to one science website, the scent of rotting food “is most often due to the
growth of spoilage microbes such as bacteria, yeasts and mold.”
The smell could be the result of chemicals produced by the decomposition process, or
they are “produced directly by the microbes themselves.”
Different spoilage microbes can produce different odors.
For example, molds can “give off musty, earthy aromas” as they break down food,
while “some yeasts produce sulfur compounds that resemble human flatulence.”
Some of the worst smelling foods in the world are the product of intentional instead of
accidental spoilage.
For instance, Icelandic hákarl, which one source describes as “rotten Greenland shark
meat,” has an “overwhelming scent of ammonia.”
The shark meat has to be allowed to rot or “ferment” because fermentation lowers
the toxin levels in the meat to a level safe enough for human consumption.
And then there is surströmming, which is Baltic sea herring that “is fermented in
barrels for six months.”
The scent of this rotten fish is so bad that the “official Swedish government actually
recommends that the tins of surströmming only be opened outdoors because of the massively-rancid
stench.”
6.
Garbage The smell of garbage is often composed of
many disagreeable odors caused by the decay of disagreeable substances.
Just think about all of the things people throw out in the trash.
Besides spoiled food, they toss out gross stuff like used cat litter, dead rodents caught
in mouse and rat traps, and paper towels and rags used to clean up vomit, urine, and feces.
Northern Colorado Disposal estimates that 18 billion used diapers are thrown away each
year as well.
Most garbage ends up in landfills where they produce various foul-smelling gases.
According to the New York State Department of Health, “odors in landfill gas are caused
primarily by hydrogen sulfide and ammonia, which are produced during breakdown of waste
material.”
It notes that “hydrogen sulfide has the foul smell of rotten eggs, while ammonia has
a strong pungent odor.”
These gases are not only smelly, but they can create negative health effects as well.
Exposure to high levels of hydrogen sulfide and ammonia in the air “can cause coughing,
irritation of the eyes, nose, and throat, headache, nausea, and breathing difficulties.”
5.
Human Feces Knowing the physical components of human feces
can help you understand why it smells so bad.
While a “typical bowel movement” is about 75% water according to the GI Society, the
“other 25% is a mixture of things” that include “dead and living bacteria,” “food
waste,” “undigested parts of foods,” and “substances contributed by the intestines
and liver, such as mucus and bile.”
Besides waste products that your body can’t break down, human feces can also contain smelly
chemical compounds.
It depends on what you eat.
For instance, the GI Society notes that “meat produces more smell than vegetables and intestinal
bacteria produce several sulphur-containing compounds” that produce smelly hydrogen
sulfide.
Other objectionable odors come from fatty acids and skatole, “a product resulting
from the naturally-occurring process of amino acids being broken down in the intestine.”
4.
Sewage It is no surprise that raw sewage smells awful.
If you thought your poop smelled bad, imagine how bad the poop of thousands or even millions
of people smells when it ends up in the sewer.
Besides all that poop, raw sewage contains things like urine, vomit, soap, cleaning products,
used toilet paper, and wastewater from sinks and showers.
As bacteria break down some of the organic components in raw sewage, they create sewer
gas, which the City of Marion Water Pollution Control Department describes as “a mixture
of inorganic gases” that can include “hydrogen sulfide, ammonia, carbon dioxide, methane,
nitrogen, and hydrogen.”
The department considers hydrogen sulfide as the “odor culprit” that makes sewer
gas smell bad.
3.
Gangrene Gangrene smells bad because it involves what
the Mayo Clinic describes as the “death of body tissue.”
Some forms of gangrene involve bacterial infection, which create wretched odors and toxins as
the bacteria feed upon your tissue.
The bacteria will eventually kill the tissue if they are not stopped.
An article about bad operating room smells notes that “gas gangrene, in which bacteria
infects and kills tissue with particular vigor, reeks.”
A medical student described the smell produced by Fournier’s gangrene, a type of gangrene
that affects the genital area, as “the worst smell ever, like poop and sewage sludge and
rot and dead stuff all rolled into one.”
2.
Dead Human Body If a small part of someone’s body reeks
because it is being killed off by gangrene, it is reasonable to think the smell of an
entire dead body is many times worse.
Even if you don’t see a dead human body, you may be able to smell one if it has been
decomposing long enough.
Think of those accidental discoveries of dead bodies because neighbors noticed an awful
stench coming from someone’s house or from the trunk of an abandoned car.
One online magazine interviewed twenty people who have smelled a dead body.
From their descriptions, you can tell the smell is quite revolting.
One person described the smell as “rotten eggs, feces, and a used toilet left out for
a month x 1000,” while another person noted a “very sharp, foul smell similar to horrible
cheese mixed with the same smell you get from a full trash can in the sun.”
What makes us stink so bad after we die?
Microbes breaking down our bodies are to blame.
For instance, a Guardian article reports that gut bacteria multiplies after we die because
there is no functioning immune system to keep them in check, and this bacteria literally
eats us from the inside out.
They “feed on the body tissues, fermenting the sugars in them to produce gaseous by-products
such as methane, hydrogen sulphide and ammonia, which accumulate within the body, inflating
(or ‘bloating’) the abdomen and sometimes other body parts, too.”
During the decomposition process, several foul-smelling chemical compounds are also
produced to create what one source calls the “stench of death.”
One of them is cadaverine, which is “responsible for the foul smell of rotting flesh and is
also found in urine and semen.”
A second chemical is putrescine, which “smells fairly similar to cadaverine” and contributes
to bad breath odor.
Finally, there are skatole and indole, which are “major components of feces.”
But that’s not all.
According to a Daily Mail article, “researchers have found a 'cocktail' of five chemical compounds
given off by decomposing bodies that are unique to human flesh when compared to other animals.”
These compounds are called esters, which the researchers described as “degradation products
of muscles, fat tissue and carbohydrates.”
The five esters have fruity smells.
For instance, propyl hexanoate is a “chemical used to recreate the smell of pineapples and
blackberries,” while 3-methylbutyl pentanoate has “a ripe apple odour.”
However, these results are based on “small tissue samples rather than whole bodies,”
and it is possible that “decomposition in the outside environment may also influence
the smell.”
1.
Other Dead Animals Many other animals go through a process of
decomposition similar to humans after they die.
The science journal Nature notes the presence of “chemical byproducts such as ammonia,
cadaverine, hydrogen sulfide, and putrescine” as their bodies decay.
Some animals that smelled bad in life smell even worse than humans in death.
For example, if you thought skunk spray was bad, try getting a whiff of fresh skunk roadkill
on a hot June day.
You get a double whammy of smelly thiols from the skunk spray and the odor of a rotting
carcass baking in the sun.
Other dead animals create an overwhelming stench that can be worse than that of a dead
human simply because of their large size.
Dead beached whales are a good example.
They are literally what one article calls “tens of thousands of pounds of foul smelling,
decomposing flesh.”
According to forensic toxicologist Wolfgang Weinmann, dead whales also bloat like other
animals most likely because of putrefaction and fermentation, and there have been some
instances where whales will spontaneously explode because of a heavy build-up of gases
that form during the decomposition process.
One well-known whale explosion occurred in 2004 in Tainan, Taiwan.
BBC reported that “passers-by and cars were soaked in blood and body parts were sprayed
over a road after the bursting of the whale.”
One resident remarked, "What a stinking mess.
This blood and other stuff that blew out on the road is disgusting, and the smell is really
awful."
Is there another bad smell that you think should be added to this list?
Let us know in the comments!
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