Food toxins you should worry about, according to toxicologists

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Food toxins you should worry about, according to toxicologists

There’s a lot of talk online about toxins.

A lot!

Much of it is conflicting. Some of it is BS.

Let’s be real – toxins exist in our food and can be very dangerous. For example, eating even small amounts of tetrodotoxin (from puffer fish) or shiga toxin (from E. coli) are bad for everyone. Not to mention some severe allergies!

But, not all toxins are this dangerous (hazardous). What about other naturally-occurring toxins or synthetic toxicants in foods? How do we define “toxin?” WTF even is a “toxicant?”

I went back to school last week to attend this year’s Toxicology symposium at the University of Guelph. The topic was toxicology and food safety – and there are lots of toxins in our foods that we should be concerned about!

Let me share some info about food toxins we should worry about, according to toxicologists.

NOTE: I shared some key points from the day on Twitter.

First of all, what is a toxin?


What is a toxin?

Toxins are everywhere – including in your food.

Define “toxin”

According to Merriam-Webster dictionary, a toxin is:

a poisonous substance that is a specific product of the metabolic activities of a living organism and is usually very unstable, notably toxic when introduced into the tissues, and typically capable of inducing antibody formation

Yep! Toxins are harmful substances produced by living things (e.g. bacteria).

Define “toxicant”

A toxicant is:

a toxic agent; especially : one for insect control that kills rather than repels

That makes synthetic pesticides and heavy metals like cadmium (that are not produced by living things) “toxicants,” not toxins!

Define “toxic”

What makes toxins and toxicants toxic?

containing or being poisonous material especially when capable of causing serious injury or death

Essentially, they’re bad for your health – a substance that can cause serious injury or death is toxic. Another way of saying injury to health is an “adverse event.”

And the food toxins that are particularly concerning are food safety issues (more on that below).


How risky are these toxins?

What kind of “serious injuries” are we talking about?

The tetrodotoxin and shigatoxin examples above are potent toxins that everyone reacts to in small amounts. There are others that certain people react to in small amounts (hello food allergies and anaphylaxis).

If a little bit of a toxin/toxicant goes a long way to adverse events, these are very hazardous.

Define “hazard”

Hazard is defined as:

a source of danger

In the case of :

  • Tetrodotoxin from puffer fish, it slowly paralyzes all muscles, and eventually paralyzes the diaphragm so the person stops breathing and can die.
  • Shigatoxin from E. coli, it causes massive diarrhea and vomiting that can cause severe dehydration, and can cause serious kidney injury and death.
  • Anaphylactic allergens cause severe allergic reactions (in some people) that causes the airway to swell, and inability to breathe (and without an immediate dose of epinephrine/adrenaline), can also cause death.

FUN FACT: I am anaphylactically allergic to Brazil nuts – they’re a life threatening toxin to me! I always carry an EpiPen, but I’m lucky that those nuts aren’t very common.

These are extreme examples where a tiny dose makes the poison.

These are examples of hazard.


Hazard is just one-half of the equation to determine how much risk there is.

The other half is exposure. How much of the toxin do we need to be exposed to before our bodies react?

Hazard is just one-half of the equation to determine how much risk there is to health. The other half is exposure. #hazard #risk #exposure #toxins Share on X

Define “exposure”

Exposure is:

the condition of being subject to some effect or influence

The three examples above, tetrodotoxin, shigatoxin, and anaphylactic antigen, are ones where the risk is high because even a tiny exposure can result in serious injury or death.

A high hazard, with a small exposure can mean a high risk.

But, what about toxins with a smaller hazard? Or a smaller exposure?

To be honest – we eat toxins all the time.

Like, All. The. Time!

I’m talking about tiny amounts of toxins. Some are naturally-occurring in foods (toxins) and others are synthetic.

And if the hazard is small, our bodies can usually handle a larger exposure. As the hazard goes down, the risk of adverse effects goes down too.

Which leads us to the real thing we should look out for, which is risk.

Define “risk”

Risk is:

possibility of loss or injury

Being concerned about a high hazard and low exposure may be necessary (as in the case of anaphylaxis). Alternately, a low hazard and high exposure isn’t that bad either.

What we actually should be concerned about is:

  • How toxic is it (what’s the hazard)? AND
  • How much are we exposed to?

Not just how toxic is it!


When it comes to toxins, we should be concerned about: 1) how toxic is it (what's the hazard)? AS WELL AS 2) How much are we exposed to? Toxicity is just half of the equation! #toxins #risk #hazard #exposure Share on X

Scientists look at each of these separately.

Estimating Hazard

Toxicologists evaluate the hazard – and not just on the short-term health of someone who would eat the toxin/toxicant. Often, studies are also conducted on the long-term effects, effects on reproduction, and even effects on future generations.

Estimating Exposure

Scientists also look at the exposure – How much would someone be reasonably exposed to through food, water, etc?

One of the main ways this is estimated is through the NHANES study (National Health and Nutrition Examination Survey). This study is ongoing, and updates are published every other year. It’s essentially a survey of thousands of people asking them how much of different foods they eat, and how often.

Estimating Risk

When we have a good idea of both how toxic something is, and how much of it a person would be exposed to, that’s when we can figure out what the real risks of the toxins are.

And when we have a good idea of the risk, we add in some safety factors. Sometimes a factor of 100 is added on to account for unknowns and variables like people at greater risk (e.g. children, elderly, people with illnesses, etc.).

And in some cases, there is zero tolerance! For example, certain food allergens MUST be properly labelled, or they will be recalled – there is no room for life-threatening anaphylactic reactions!

When we have a good idea of both how toxic something is (hazard), and how much of it a person would be exposed to (exposure), that's when we can figure out what the real risks of the toxins are. #toxins Share on X



Our bodies are freaking amazing at detoxifying and eliminating most of these toxins and toxicants! I spent years at the University of Guelph studying the different modes of toxicity and detoxification.

There are lots of things that can affect how well our bodies detoxify these. One is having a nutrient-dense diet that provides enough of all of the essential nutrients! Our livers, kidneys, etc. can’t do their awesome detox jobs if they’re not given the tools to do them, right? They need vitamins and minerals to help the detox enzymes function, and enough protein and amino acids to make those detox enzymes in the first place.

Our bodies are freaking amazing at detoxifying and eliminating most toxins! Of course, our livers, kidneys, etc. can't do their awesome detox jobs if they're not given the essential nutrients to do them, right? #detox #toxins #science Share on X

FUN FACT: This is where my grad studies came in. I worked with Dr. Jim Kirkland, a vitamin B3 expert whose research looked at how levels of vitamin B affects chemotherapy.

If you are sick of hearing “but we get all the nutrients we need from our diet” rhetoric, like I am have a look at a post I wrote showing study after study that we do have nutrient deficiencies (and insufficiencies)!


Toxins in food – History

Sometimes we reminisce about the food our ancestors ate. Before the advent of modern agriculturel there were small organic farms everywhere. Extended families lived together. There was more of a community feeling (and cleaner air and oceans) than in today’s society.

Of course, there is always more to the story… Here’s one of those “mores” that has to do with food toxins – and it’s super-interesting.

In the 1870’s in Canada, can you guess what percent of the food supply was adulterated with inferior or foreign substances?

Yes, intentionally adulterated!

I’m talking regular food that was for sale in the little shops way back then.

Any guesses?

If you guessed “more than now,” you’re right.

The answer:

Fifty percent!

Yup! Believe it or not, half of the food for sale in Canada about 150 years ago had weird shit in it.

Most of this adulteration was done as a cost-savings measure for the producer.

People used to:

  • Add sand into sugar.
  • Dilute milk with water and sometimes even add chalk as well.
  • Add Plaster of Paris, ashes, or even sand to bread.
  • Include ground twigs or gravel in black pepper.
  • Add leaves or even floor sweepings into tea.

Unbelievable (and gross), eh?

Believe it or not, half of the food for sale in Canada in 1870 had weird shit in it! It was intentionally adulterated by adding sand, diluting with water, or even adding floor sweepings! #foodsafety #adulteration #foodhistory Share on X

Because of issues like these, the first version of Canada’s Food & Drugs Act was created. This act, and the laws that fall under it explicitly prohibit adulteration or misleading labelling. Now there is enforcement, recall processes, consequences for doing these… and a higher level of food safety.


Toxins in food – Now

Let’s be honest, though – stuff like this still happens!

NOTE: If you read the article linked above, you’ll see that increasing inspections results in more compliance (i.e. safer food).

There are food recalls happening almost daily for one reason or another (not necessarily for adulterating). That’s where advisories, alerts and recalls are required.

Foods today can be unsafe for a number of reasons:

  • Intentional adulteration (locally, or from imported foods);
  • Poor processing/handling practices;
  • Accidents; or
  • Inaccurate labelling.

Not to mention that outbreaks are tracked, lab test results are much faster and more accurate, and there is a specific process for recalling products that are risks to public health.

A recall is when the food, usually a specific lot number, must be removed from the market due to it being unsafe. It doesn’t mean that it’s never allowed to be sold again – that would be a removal or withdrawal from the market. A recall just takes back a certain amount of product that’s on the market.

If you have any safety concerns with something you ate or drank, you should see a doctor, and you can also report safety concerns here.


Random Fact I Learned at the Toxicology Symposium

I will end of this post with a totally random fact: Camelina oil has no history of safe use in humans! It’s considered a “novel food” and had to pass strict regulatory hurdles to prove its safety before it was allowed on the market a few years ago.



Food toxins are real, and cause food safety and health concerns! Some cause quick-acting or serious consequences for many people (or few people in the case of anaphylaxis), or no consequences at all, even with long-term exposure. And anywhere in-between.

They can result from intentional adulteration, poor processing/handling, accidents, or inaccurate labelling. These food safety issues are the toxins that we should be concerned about in our food.

When scientists evaluate the risk, they look at both the hazard (how bad the adverse events can be), and the exposure (how much is needed to create the adverse event).  They calculate the risk, and then huge safety factors are added to ensure that the levels will be safe to consume, even for vulnerable people. In some circumstances, those levels are zero – for example for a risk of life threatening anaphylaxis.

Food safety has come a long way in the past 150 years!


Signing off and toasting: To being concerned about real food toxins (and toxicants), and nourishing our bodies to ensure they detox as they’re designed to!


Over to you

Have you experienced a toxic food safety issue? Do you have first-hand knowledge of any? Any questions about toxicology? I’d love to know (in the comments below)!



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I’m Leesa Klich, MSc., R.H.N.
Health writer – Blogging expert – Research nerd.

I help health and wellness professionals build their authority with scientific health content. They want to stand out in the crowded, often unqualified, market of entrepreneurs. I help them establish trust with their audiences, add credibility to their services, and save them a ton of time so they don’t have to do the research or writing themselves. To work with me, click here.


  1. Loved this article – I have been wondering what a toxicant is!

    Those crazy ingredients from the 1870s are still alive and well in American fast food – McDonald’s hamburger buns contain calcium sulfate – AKA Plaster of Paris! Yuck!

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