When we first learn about toxic substances or chemicals in our environment, the first response can often be fear, which can lead to stress and worry. But if you’re anything like me, though, you probably grew up using the same conventional products and eating the same conventional foods you see on store shelves without batting an eye. That’s because most of us probably won’t take action or see the need to change our lifestyle unless we absolutely have to - am I right? Either you or someone you love gets his by a chronic disease or illness like cancer, Alzheimer’s, heart problems, or gut issues that makes you take a step back and really think about how you live. It’s more often than not the idea that we could lose someone we love or end up suffering the same fate if we don’t change ASAP that lights a fire under us to take action.
The thoughts I had when I realized something was really off with my health were, “How could the air, food, water, and products I love be causing my disease and health issues? I’m a young, healthy person. This can’t be happening!” Even though I was an expert on toxicity, my perspective was skewed because I was used to studying carcinogens and extremely toxic chemicals in the lab. I was also of the mindset that, “I’ve been living the same way my whole life and I was always fine so why change now?” Sadly, this is how a lot of people think and it keeps them stuck.
Just how important are these environmental factors? A groundbreaking 2016 study found that up to 90% of cancers are caused by external factors such as diet, lifestyle, UV radiation, ionizing radiation, and carcinogens (Wu et al, 2016). This means that cancer is almost entirely preventable and it’s not all about genetics like we once thought. We actually have control over our health! This is just more evidence that little exposures, let’s say daily, over a lifetime or chronic exposures, may go unnoticed but are leaving an imprint on the molecular and cellular level possibly contributing to your overall toxic burden. To make things worse, chronic diseases often don’t show up until later in life, so then people end up kicking themselves for not reducing their toxic burden and supporting detoxification earlier. For instance, Alzheimer’s onset is typically around 65 years of age (National Institute on Aging, 2021) and likely didn’t happen overnight.
The question really becomes, “How do I find the sources of environmental toxicants?”
Believe it or not, there’s an entire field of study dedicated to answering that very question! It’s called toxicology and is basically the science of safety. According to the Society of Toxicology, “Toxicology is the study of the adverse effects of chemical, physical, or biological agents on living organisms and the ecosystem, including the prevention and amelioration of such adverse effects.”
It might sound extremely technical, which it can be, but everyone can benefit from understanding some key toxicology concepts that will help us make sense of environmental exposures so we can navigate through our daily lives with confidence, clarity, and actually enjoy life!
- Exposure and toxicity are two distinct concepts and exposure doesn’t always mean that you’ll have a toxic response or effect. This is because every chemical has its own unique set of characteristics that will determine if it actually gets into our bloodstream, which is what matters. Plus, our bodies are equipped with a detoxification system to protect us, but the efficiency depends on our lifestyle and genetics.
- Not all substances are toxic at the doses or concentrations we are exposed to in our daily lives. An example is water, which is a necessary substance for our survival that won’t kill us at the doses we actually need. However, you can still overdose on it.
- Toxic effects depend on the type of substance and the routes by which we’re exposed. The main routes that are important to consider for everyday exposure in order of sensitivity are: inhalation > oral > dermal > ocular. Things that we inhale can more easily and readily enter the bloodstream than those we ingest through the oral route or products we put on our skin.
How do know if a material or substance will be toxic to me or my family?
This may seem like a monumental feat, but with a systematic and rational approach we can identify hazards in our environment. There are some key pieces of information that are needed to make a safety judgement call or risk assessment based on toxicology principles.
1. Chemical or substance identity
The first fundamental piece of information we need to know is the chemical or substance identity. This is pretty straightforward when dealing with individual or single chemical ingredients, but most of what’s in our environment is a complex mixture. In this case, we need to know the relative amount of each component in the mixture in order to weigh out the potential toxic effects.
2. Physical and chemical properties
Next, we need to know the physical and chemical properties of the material to determine the possible routes of exposure. Is the material solid, liquid, gas, or able to form vapors or aerosols? Is it easily vaporizing or volatile? Generally speaking, the more volatile the compound, the more chemically reactive, and therefore more toxic.
3. Route(s) of possible exposure
For example, in the case of cookware, this is what we know: it’s a solid that can be exposed to heat that can potentially leach into food that we eat and also generate vapors during the cooking process. The main routes of exposure we need to consider are oral since we’ll eat the foods prepared in the cookware but also inhalation since vapors are generated during the cooking process.
4. Will the substances in mind remain bound in the matrix or released?
When it comes to performing a risk assessment for anything food-related it’s extremely important to understand if the substance(s) in question are matrix-bound or able to be liberated and therefore released. Let’s use cookware as an example again, if the inside of a pan is a metal like aluminum that is coated with a nonstick surface containing perfluorooctanoic acid (PFOA) we must consider the possibility that not only the coating could degrade at high temperatures liberating fumes that could be inhaled and also directly transfer into the food, but whether the aluminum could leach is also a factor. In other case, such as chewing gum, additives are likely not released in sufficient quantities since they remain bound within the matrix.
Materials & chemicals that remain bound in the matrix, and therefore, don’t leach into food, for example, are not relevant for toxicological consideration since we wouldn’t be exposed to them anyway.
5. Duration & frequency of exposure
There are 4 types of exposure: acute (single episode), sub chronic (repeatedly for several weeks or months), and chronic (repeatedly for many months or years). An acute exposure to a chemical that is rapidly absorbed may likely produce immediate effects, but could also result in delayed toxicity, which is sometimes totally different than the effects from the same chemical with chronic exposure. For example, acute exposure to cadmium causes nausea, vomiting, and abdominal pain. Whereas, chronic cadmium toxicity includes kidney injury, obstructive pulmonary disease, osteoporosis, and cardiovascular diseas (ATSDR, 2012a).
6. ADME
We know that simply being exposed to a chemical doesn’t mean that we’ll experience toxicity, which can be explained by the concept of ADME, or absorption, distribution, metabolism, and excretion. Simply put, even if a chemical is in our environment it has to be absorbed into the bloodstream at high enough quantities and be distributed within the body and actually reach target cells to cause toxicity. Then factor in the amount that would be metabolized and detoxified by excretion into the urine or feces to and what’s left can be used to determine if it will be toxic or not.
To be specific, if a chemical is metabolized and excreted more rapidly then the frequency at which we’re exposed to it then there won’t be enough of it in the body to cause harm. On the other hand, if we’re frequently exposed to a chemical that is metabolized slowly then it has the potential to bioaccumulate. This is typically how metals and persistent pesticides cause toxicity.
7. Tox Data
The last, and likely the most important piece of the puzzle, is toxicity data. Of course, in an ideal world, we would have toxicity data for every substance, but that’s impossible. In reality, the vast majority of chemicals have not been tested for safety. This is because the gold standard is human data, but we would never intentionally test on humans because it’s entirely unethical. However, human data exist mainly from occupational exposures, which is a tragedy in and of itself, especially since workers are often exposed to high concentrations of chemicals. This is why protecting occupational workers from toxicity is so critical.
Toxicity data from animal studies comprises the majority of what we know on the health effects of chemicals although this is being phased out too. Due to ethical, financial, time, and other constraints animal testing will no longer be the standard. In fact, lab animals like rats and mice, often have different responses to chemical exposures that don’t translate into humans so it doesn’t make sense to solely rely on this data.
An emerging and promising field is in vitro toxicology or the study of toxic effects on cells and lab-created or reconstructed tissue models. There are even models for skin, liver, heart, ovaries, and many other tissue types. Using these technological advances, we can avoid animal testing altogether and more government agencies are accepting these types of data.
Another method to complement in vitro data is computational toxicity which uses structure-activity relationships to compare toxic effects based on how similar a chemical is to one that has human or animal data. Taking all these types of data together we can formulate a rational and scientifically-sound safety/toxicity assessment.
Long story short - the low dose, chronic exposures that can be inhaled, ingested, and absorbed through the skin are the ones to be most concerned about. By taking consistent, daily actions to switch to healthier products you’ll reap lifelong benefits and reduce your overall toxic burden and risk of chronic disease. So don’t pressure yourself to make the switch all at once or be perfect because perfection is the enemy of progress. The truth is, we’re living longer than ever before so make sure you’re doing the best you can now to avoid chronic diseases later in life.
References
ATSDR. Toxicological Profile for Cadmium. Atlanta, GA. Agency for Toxic Substances and Disease Registry; 2012a. https://www.atsdr.cdc.gov/toxprofiles/tp5.pdf
National Institute on Aging. Alzheimer's Disease Fact Sheet. 2021. https://www.nia.nih.gov/health/alzheimers-disease-fact-sheet. Accessed 03 October 2021.
Wu S, Powers S, Zhu W, Hannun YA. Substantial contribution of extrinsic risk factors to cancer development. Nature. 2016 Jan 7;529(7584):43-7. doi: 10.1038/nature16166. Epub 2015 Dec 16. PMID: 26675728; PMCID: PMC4836858.
