Extra! Extra! Toxic chemicals found in...
It is quite common to see headlines screaming “Toxic Chemicals Found in [insert everyday product]”. Or along similar lines.
Unfortunately, such headlines can cause unwarranted alarm by perpetuating a common misconception: that the presence of a chemical means that it will cause harm.
Not necessarily – amounts matter!
FACT: “All substances are poisonous: there are none that are not. The dose alone differentiates a poison from remedy.” (Paracelsus, 1493-1541 – a Swiss physician, botanist and alchemist, known as the ‘father of toxicology’)
Any substance can be harmful in certain quantities, or in the wrong place, or if used in the wrong way.
Or, to put it in toxicology terms, the risk of harm depends on the hazard – the substance’s inherent ability to cause harm, and the dose – what quantity of the substance, in what concentration, and for what duration of contact.
All chemicals have the potential to cause harm at high doses, but there will be a level below which the chemical has no adverse effect. Of course, this applies to natural chemicals as well as man-made chemicals – their origin is irrelevant. And there is no such thing as ‘chemical free’.
Examples of right substance, wrong dose
FACT: How a substance comes into contact with the body is also important
Another important consideration is the route by which a substance contacts or enters the body. There are four major routes of exposure: oral – by mouth, dermal – applied to the skin, via inhalation – breathed into the lungs, and intravenous – injected into the bloodstream.
Substances that may cause harm via one route may have minimal effect via another. For example, the skin is a highly effective barrier to certain substances. Therefore, different routes of exposure may result in different rates of absorption into the body, or mean that a substance cannot reach a part of the body where it would cause harm.
Examples of right substance, wrong route of exposure
FACT: Just because a substance is found in the body does not mean that it causes adverse health effects.
Every day we are exposed to many chemical substances from both natural and man-made sources. This has been the case for thousands of years. For example, foods naturally contain carcinogens, allergens and other toxic substances, but because we consume low doses and a variety of foods, our bodies can deal with the quantities of these substances we ingest.
Indeed, our bodies are equipped to eliminate many substances that have the potential to cause harm, whether they enter the body via the oral route, through contact with the skin, via the lungs, or intravenously. The main way in which our body does this is by metabolising the substance (transforming it to other substances) in the liver or kidneys and excreting the metabolites from the body, primarily via urine or faeces. Individual characteristics, such as age, gender, lifestyle and health status, can play a part in how our bodies deal with different substances.
Health authorities consider factors such as hazard, dose, route of exposure and individual characteristics when considering the safety of products that we may come into contact with.
Considering all of these things together determines the risk – the likelihood of injury or disease resulting from exposure to a potential hazard. Click here for more information on product safety.
So, just because a substance can be detected in the body does not mean that it will have any negative impact.
The bottom line? “There are no 'safe' or 'dangerous' chemicals, just safe or dangerous ways to use them.”[1]
Sources
[1] Schwarcz, J. 2011, Right Chemistry: We need rational discussion about pesticides, without rhetoric, Montreal Gazette 10.09.2014. http://www.montrealgazette.com/health/Right+Chemistry+need+rational+discussion+about+pesticides+without+rhetoric/10280979/story.html
Unfortunately, such headlines can cause unwarranted alarm by perpetuating a common misconception: that the presence of a chemical means that it will cause harm.
Not necessarily – amounts matter!
FACT: “All substances are poisonous: there are none that are not. The dose alone differentiates a poison from remedy.” (Paracelsus, 1493-1541 – a Swiss physician, botanist and alchemist, known as the ‘father of toxicology’)
Any substance can be harmful in certain quantities, or in the wrong place, or if used in the wrong way.
Or, to put it in toxicology terms, the risk of harm depends on the hazard – the substance’s inherent ability to cause harm, and the dose – what quantity of the substance, in what concentration, and for what duration of contact.
All chemicals have the potential to cause harm at high doses, but there will be a level below which the chemical has no adverse effect. Of course, this applies to natural chemicals as well as man-made chemicals – their origin is irrelevant. And there is no such thing as ‘chemical free’.
Examples of right substance, wrong dose
- Vitamin A is essential to proper functioning of the human body, with our body obtaining vitamin A from the foods that we eat. However, over-consumption of this substance can cause poisoning and death. During their famous Antarctic journey, it is thought that Douglas Mawson and Dr Xavier Mertz ingested toxic levels of vitamin A as they resorted to eating the livers of their huskie dogs in order to survive. Dr Mertz died, but Mawson staggered 160 km to safety. Liver has since been found to be a very rich source of vitamin A.
- Or think about aspirin. One or two tablets every few hours has a beneficial effect in pain relief. However, 50 tablets all at once could cause acute kidney failure, coma, and heart failure.
FACT: How a substance comes into contact with the body is also important
Another important consideration is the route by which a substance contacts or enters the body. There are four major routes of exposure: oral – by mouth, dermal – applied to the skin, via inhalation – breathed into the lungs, and intravenous – injected into the bloodstream.
Substances that may cause harm via one route may have minimal effect via another. For example, the skin is a highly effective barrier to certain substances. Therefore, different routes of exposure may result in different rates of absorption into the body, or mean that a substance cannot reach a part of the body where it would cause harm.
Examples of right substance, wrong route of exposure
- Water is essential for life. But water can also kill, for example taken in large quantities into the lungs it causes asphyxiation.
- Touching a block of lead is not usually harmful because lead is not absorbed particularly well through the skin, but breathing or swallowing enough lead for a toxic dose can result in poisoning.
FACT: Just because a substance is found in the body does not mean that it causes adverse health effects.
Every day we are exposed to many chemical substances from both natural and man-made sources. This has been the case for thousands of years. For example, foods naturally contain carcinogens, allergens and other toxic substances, but because we consume low doses and a variety of foods, our bodies can deal with the quantities of these substances we ingest.
Indeed, our bodies are equipped to eliminate many substances that have the potential to cause harm, whether they enter the body via the oral route, through contact with the skin, via the lungs, or intravenously. The main way in which our body does this is by metabolising the substance (transforming it to other substances) in the liver or kidneys and excreting the metabolites from the body, primarily via urine or faeces. Individual characteristics, such as age, gender, lifestyle and health status, can play a part in how our bodies deal with different substances.
Health authorities consider factors such as hazard, dose, route of exposure and individual characteristics when considering the safety of products that we may come into contact with.
Considering all of these things together determines the risk – the likelihood of injury or disease resulting from exposure to a potential hazard. Click here for more information on product safety.
So, just because a substance can be detected in the body does not mean that it will have any negative impact.
The bottom line? “There are no 'safe' or 'dangerous' chemicals, just safe or dangerous ways to use them.”[1]
Sources
[1] Schwarcz, J. 2011, Right Chemistry: We need rational discussion about pesticides, without rhetoric, Montreal Gazette 10.09.2014. http://www.montrealgazette.com/health/Right+Chemistry+need+rational+discussion+about+pesticides+without+rhetoric/10280979/story.html
