As an environmental toxicology student, I often cringe when I hear news reports or documentaries warning of disturbing facts regarding daily exposure to toxic substances. The more extreme headlines typically read something along the lines of, “What chemicals are lurking in your home?”, “Is your purse slowly poisoning you?”, and, “What you don’t know about the chemicals on your pajamas”.
We live out our days suffocated by alleged facts thrown at us from all angles, claiming that your lipstick, your toothpaste, the insulation in your home, and even the water you drink all pose toxic hazards and is essentially contributing to your health’s downward spiral into the disease-ridden abyss.
I’m not sure which is more upsetting – the lack of proof to support otherwise outlandish claims, or the public’s gullibility in not always questioning the reliability and credibility of such statements, and automatically vowing to never wear lipstick or brush their teeth ever again.
History has proven that concern over toxic substances in our homes or and in our environment is extremely important. On the larger environmental scale, the dumping of millions of tonnes of sludge into our drinking water sources, and remediation of toxic sites such as the Sydney Tar Ponds in Nova Scotia (read the success story here) are generally agreed upon as real threats to humans and wildlife health. I am not challenging or denying the risks of dangerous substances that may be found in our homes, workplaces, and the general environment, for which serious health effects are readily documented (such as asbestos and even insulation still installed today; read the Treehugger series here). This is really just my attempt at ranting (but disguised as an article) about this seemingly increasing trend of using borderline ‘scare tactics’ to make people believe that all unfamiliar chemicals are automatically dangerous to the environment and to your health.
The goal of this article is not to investigate specific instances where products or substances promoted as toxic are in fact shown to not adversely affect human health to a great degree using intense toxicological inquiry. The purpose is to explore how these terrifying reports may, in general, be stretching the truth or exaggerating, and why you might not want to necessarily believe everything you hear or read about toxins in the environment. I hope to provide the tools to allow you to evaluate such claims for yourself, which can be awfully tricky while being bombarded by excessive amounts of information from our friends, our neighbours, NGOs, and the 6 o’clock news. Here, I present to you my first big issue with scientific communication, as it is relevant to toxicology.
Issue #1. The First Law of Toxicology.
Paracelsus, the founder of toxicology, gave us the first, and most important rule of the discipline: “All things are poison, and nothing is without poison; only the dose permits something not to be poisonous”. In other words, and the phrase that we use today – the dose makes the poison. At a high enough dose, most, if not all, substances will reach a level of toxicity to elicit adverse health effects.exposure
In some cases, the combination of all these elements may necessitate a push towards chemical regulation, including a ban on a particular substance. But the topic of dangerous chemicals in our environment makes quite the news story – and I don’t blame them. Omit the technical details like the necessary exposure required for toxic effects to take place, and you have a scary, poisonous substance that people will pay attention to. ‘Toxic’ is a scary word; mention that a chemical is toxic, and soon enough there will be hundreds of Facebook groups and organizations dedicated to banning it.actually
1) ‘Toxic’ has somehow become known as a precursor to ‘cancer’. But, not all toxic chemicals are carcinogenic; they may affect reproduction and development, among other physiological processes, but not all toxic chemicals cause cancer, as some people I’ve spoken to seem to believe.
2) If it’s toxic to rats, it must be toxic to humans. Not necessarily. Obviously, though, it is unethical to inject or feed certain quantities of a particular chemical to humans to observe what response it elicits, if any. Therefore, much toxicological research is conducted in laboratories, where a common measurement of toxicity is the LD50 or (LD meaning ‘lethal dose’, and the subscript 50 meaning ‘50%’) which essentially means the dose of a chemical (typically administered orally or injected) required to cause mortality in half of the population studied, whether it be rats, mice, or monkeys. Sometimes, these doses can be at very high levels that humans would not typically be exposed to. Also, consider the fact that humans are much larger organisms than rats. Essentially, you would expect humans, being much larger than laboratory animals, to require exposure to a higher concentration of a substance before toxic effects would occur. But, if this information is communicated to the public in an irresponsible way that directly relates LD50 values in rats to that in humans without actually mentioning the assumptions made, alarm bells automatically go off.
3) The need to reiterate that the dose makes the poison. I would like to very briefly bring the childhood vaccination argument to attention here, but without discussing the entire issue at hand. I’ll focus on mercury specifically: vaccines have trace amounts of mercury. That probably sounds really scary, right? It shouldn’t. Why? Because there are also trace amounts of mercury in our environment in general that we are exposed to on a daily basis – mercury is a naturally occurring element. I’d imagine that a single portion of seafood such as tuna would have many, many times more mercury than you would ever be exposed to from all childhood vaccines combined – never mind the amount of seafood you eat over your lifetime (thanks for that, bioaccumulation). Though we know about high concentrations of mercury in seafood, exposure to trace concentrations of mercury through vaccinations has been used by anti-vaccination groups as a scare tactic to further their agendas.
Yes, there are a lot of bad chemicals out there. But I don’t think it needs to be as scary as they are portrayed to be. Some popular examples of chemicals that have been receiving a lot of attention include:
· polyurethane in spray foam insulation,
· polybrominated diphenyl ethers (PBDEs; flame retardants),
· perfluorooctanic acid (PFOA; a surfactant found in some frying pans),
· perfluorooctane sulfonic acid (PFOS; also a surfactant),
· bisphenol A (BPA; used to make tough plastics), and
· phthalate esters (plasticizers).There is more general agreement surrounding the risks associated with these compounds, largely as a result of more extensive scientific research regarding their potential hazards.
So, when an article in your local newspaper claims that there are toxins hiding in your lipstick (note: I’m focusing away from the environment directly for a bit, but bare with me because it remains applicable), one must first consider the to these chemicals. This can be measured in terms of the concentration (the amount of the substance in question within the volume of the entire lipstick; typically either evaluated per lipstick bottle, or an estimated lifetime use of lipstick). Sometimes, it takes extremely high doses of these types of chemicals to elicit any sort of physiological response – doses that the average lipstick use over one’s lifetime would not meet or exceed. Two other important variables in toxicology – bioaccumulation and persistence – are also key factors that address the tendency for a chemical to build up in an organism over time and the amount of time it takes for a chemical to be eliminated, respectively. Therefore, it is not as simple as recognizing that a substance may be toxic in some quantities, but involves also evaluating PBT (persistence, bioaccumulation, and toxicity) in its entirety, and really investigating whether overall exposure is high enough to warrant real public concern. But at what point do we have to take it down a notch? I believe that we need to do one of two things: either accept that we have, as a society, completely surrounded ourselves with plastics, persistent contaminants, and other miscellaneous synthetic materials of which the dangers are still largely unknown, or find a way to report this information more responsibly.So, the important question is: Are the doses (and cumulative doses) of these toxic chemicals we’re exposed to a legitimate concern at standard doses, or is this a form of borderline propaganda?Below, I’ve listed a few of my biggest pet-peeves regarding reports on chemicals: These compounds in particular are all on the radar of environmental and personal health – many, like PFOA and PFOS, are now considered environmentally ubiquitous, found even in remote regions of the Arctic where such chemicals are neither produced nor used.
In no way am I advocating for the widespread use of chemicals that have the potential to be hazardous to human and wildlife health. There have been many, many, cases where the harm caused by exposure to toxic substances outweighs the benefits of their use (except, maybe, for extreme case like the continued use of DDT in tropical countries in the attempt to combat malaria). I just hope that you can be critical with the information that is thrown at rapid speeds in our direction day in and day out, and to not live in a world of fear that every object surrounding you or that every environmentally foreign compound is destructive to your health.