Above: Image © serazetdinov, iStockphoto.com

Do you suffer from chemophobia?

Dihydrogen monoxide can kill you if you breathe it in. Also, drinking too much of it can make you sick and extended exposure can cause skin damage. Sounds like a scary chemical you should avoid, right? Actually, dihydrogen monoxide is another name for water! And you couldn’t live without water.

Many people suffer from chemophobia which is the (irrational) fear of chemicals. They will try to avoid anything that contains chemicals and look for products labeled as “chemical-free.” But what does that mean? Can anything really be chemical free? No! Everything is made up of chemicals. In 2008, the Royal Society of Chemistry even offered a million pounds (about two million Canadian dollars) to anyone who could produce a chemical-free material. As of 2015, no one has claimed the prize.

Did you know? Your skin is a protective barrier that keeps you safe from many harmful chemicals. It prevents them from entering your body and potentially making you sick.

What is a chemical?

A chemical can be a solid, liquid, or gas. A chemical is any substance that is made up of a constant composition of small particles called atoms. Atoms are the tiny particles that make up chemical elements.  When two or more atoms join together with a chemical bond they are called a molecule.

Atoms—and, by extension, chemicals—are found in everything. For example, the water molecules you drink are made up of two hydrogen atoms and one oxygen atom. Also, the carbon dioxide in the air you breathe out is made up of one carbon atom and two oxygen atoms.

Should you fear the strawberry?

The food you eat is full of chemicals. For example, strawberries naturally contain hundreds of different chemicals. Some of them have scary names like hexenal and indole-3-acetic acid. However, these compounds are what give the fruit its flavour, colour, and aroma. The important thing to remember is that these chemicals are found in the strawberry in very, very small amounts. If you did consume large amounts of indole-3-acetic acid it would kill you, but in small amounts it is harmless.

However, it’s not only the amount of a chemical that determines whether it’s toxic. Sometimes it depends on how the chemical enters your body. Chemicals can be inhaled through the nose, be ingested by eating or drinking them, or absorbed by coming into contact with our skin.

For example, if water comes into contact with your skin or if you drink it, it will not harm you. But if you inhale large amounts of water, you may drown. This is true with many other chemicals. They may cause you no harm if you touch them or smell them, but they can hurt you if you ingest them.

Did you know? Cyanide is naturally found in fruits like peaches, apples and apricots.

Measuring toxicity

“Solely the dose determines that a thing is not a poison.” A famous Swiss doctor named Paracelsus wrote that about 500 years ago. It is the key idea behind toxicity: determining whether or not a chemical will harm a living thing. Some chemicals are very toxic and should be avoided even in very small amounts. Other chemicals will have little or no effect on you unless you consume a very large amount (or ingest them in a particular way).

Consider sodium fluoride. This chemical is often added to drinking water in very small amounts to keep your teeth healthy. However, in large quantities, it can make you very sick or even kill you. On the other hand, acrylonitrile, a chemical used to make plastics, is very toxic and can be fatal if inhaled, even in very small amounts.

Did you know? Tetrodotoxin (C11H17N3O8) is the chemical that makes improperly-prepared pufferfish a potentially deadly meal. A dose of just a couple of milligrams can kill an adult.

Scientists measure the toxicity of a chemical in terms of lethal concentration (LC) or lethal dose (LD). When a chemical is in the air or water, LC50 is the concentration that kills 50% of test animals exposed to it. Likewise, when a chemical is ingested or injected, LD50 is the dose of that kills 50% of test animals. A small value for LC50 or LD50 means that a chemical is very toxic, since even a very small amount can cause serious harm.

LD50 is often expressed in terms of milligrams per kilogram (mg/kg). That way, it refers to how many milligrams of a chemical are toxic to a kilogram of body weight. That’s an important thing to know, since humans are a lot heavier than small test animals like rats and mice.

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A funny joke: Why can’t you trust atoms? Because they make up everything! And it’s true: atoms - chemical elements - make up everything in your world. They sometimes combine to make the water you drink and need to live. But if you drink too much or breath it in, even water can kill you! Remember, it’s the dose that makes the poison.

Learn more!

News article and infographics about chemophobia:

What Are You Afraid of? (2014)
Katharine Sanderson, Chemistry World

Natural vs. Man-Made Chemicals – Dispelling Misconceptions (2014)
Compound Interest

Magazine article, blog entry and scientific journal article about the chemistry of strawberries:

What’s in your strawberries (2012)
Simon Cotton, Education in Chemistry

How to make a strawberry (2010)
The Tribal Scientist

Strawberry Flavour: Analysis and Biosynthesis (1997)
I. Zabetakis & M. A. Holden, Journal of the Science of Food and Agriculture 74

Kelly Resmer

Kelly is a chemistry undergraduate laboratory instructor in Halifax.  She loves working with students in the lab, watching chemistry happen! She has a PhD in chemistry and is very interested in studying and learning about bacteria, the good and the bad ones! 

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