The short answer is: yes!! While you may or may not be setting chemical limits any time soon, the limits others set affect you and the people around you.  


It is in everyone’s best interest to understand how these limits are set, participate in the public consultation process for chemicals that are of concern to you and to help this process evolve so that it can become as accurate and as transparent as it can be. 



The word “chemical” has gotten a bad reputation. The word conjures up images of Walter White wearing a chemistry suit and standing over a vat of coloured, thick fuming liquid. In popular usage, it is often misrepresented to mean something scary, man-made or to be avoided at all costs. But chemicals aren’t inherently “bad” or “good”. Chemicals are just chemicals. All matter is made of chemicals. We are all made of chemicals. The food we eat, the things we touch and the air we breathe are all made of chemicals.


Even though chemicals are just chemicals, there are lots of ways to slice and dice them into categories. You can categorize them based on what they look like, what they do, or even the role they play in our lives. When categorized by the roles they play in our lives, chemicals can be essential for human life or they can be useful but not essential or they can be contaminants. There are many essential chemicals such as the water we drink and oxygen in the air we breathe. Chemicals that are not essential for human life but useful include things such as caffeine in coffee or petrolatum in moisturizer. Other chemicals such as mercury in fish, or lead in the water supply are neither essential nor useful for human life. These substances are considered contaminants.


the poison is in the dose



what is human health risk assessment?



is human health risk assessment relevant to me?



Human health risk assessments are done by any group tasked with protecting human health from chemicals. These include governments and government agencies, non-profits, academics and industry. Government and government agencies set air, water and soil quality limits. Other types of limits they set include worker protection limits, and limits for chemicals in foods and dietary supplements. Industry sets limits to ensure the quality and safety of their products and their workers. 

The individuals who conduct risk assessments are often toxicologists or people with advanced degrees in the health sciences. In most cases, a risk assessment is not done by a single person. Experts in many other fields are often brought in to work on risk assessments. These fields include biostatistics, bioinformatics, chemistry, pharmacokinetics, pathology, risk communication and exposure science. Thus, like many aspects of human endeavor, human health risk assessment is a team effort.

Human health risk assessment is the process that is used to set limits for chemicals. This process involves understanding all the different types of effects a chemical can produce, the doses or exposures required to produce those effects and then estimating a “safe” dose or exposure level. Details on the process can be found here .

who does human health risk assessment?



What is a chemical?



Over 500 years ago, Paracelsus, the father of toxicology recognized that, “The poison makes the dose”. What this means is that all chemicals have properties that can harm us. The key to figuring out whether a chemical will actually harm us lies in the amount or dose we are exposed to. Here are two examples to illustrate this point:


  • Warfarin has been used for years to kill rodents like rats and mice. At high doses warfarin is also lethal to humans. Yet, at much lower doses, warfarin is used in people as a blood thinner.
  • Caffeine is something some of us consume daily. But in a small number of cases, even caffeine taken in massive amounts can cause or contribute to death in humans.


The above examples show that the same chemical can be friend or foe depending on the dose. Different chemicals vary widely in their potency for causing harm. For example, tetrodotoxin a neurotoxin present in several types of fish such as the pufferfish can be lethal to humans in doses as low at 2 mg (Noguchi T, J Toxicol Toxin Rev 2001:20:1-10). This is an extremely small amount, when you consider that a teaspoon of sugar or salt weighs between 4000 and 6000 mg. On the other hand, large numbers of fats, carbohydrates, proteins and food additives, cause no ill effects even if consumed in multi- gram quantities daily.

Since chemicals differ widely in the amounts and potencies at which they cause harm, it’s important set limits for them. Human health risk assessment is the process by which these limits are set.