‘Our’ scandal was, of course, just one in a long line. In those years ‘poison dumps’ were discovered everywhere, homes were evacuated, products were withdrawn from the market (dioxin chickens! Seveso!), sites were closed off and the media constantly reported on exotic-sounding chemicals that would ruin our food or drinking water. ‘Can you rule out the possibility that people will get cancer from this?’ as a radio reporter, did I ask a professor of toxicology? He said, ‘No, I can’t rule that out’. Of course he couldn’t rule that out, but by adding a few seconds of silence behind that statement, the whole thing took on a threatening character and the listeners understood that something very creepy was going on here! Scaremongering, therefore, factless but effective. I don’t have hard numbers, but I think the majority of the Dutch are convinced that we are all being poisoned with industrially produced cancer-causing chemicals. This is chemophobia, needless fear of chemical substances and I have enthusiastically encouraged it over the years. I have now come to very different insights, so here is a kind of dummy guide to better understand when the media scare you about hazardous, often carcinogenic, substances. How do they get there? When is a substance carcinogenic and how afraid should you be? What happens if you ingest a carcinogenic substance? And are we perhaps taking science TOO seriously?
This story would have been much shorter if we all remembered this 500 year old lesson from the Swiss physician Philippus Aureolus Theophrastus Bombastus von Hohenheim also known as Paracelsus: Dosis Sola Facit Venenum. That means: it is the amount that determines whether a substance is toxic. You need a few grams of table salt per day to stay healthy, but 10 times as much is deadly. You need air with 20% oxygen, 100% oxygen destroys your lungs, without water you die but drinking 3-4 liters in a few hours is lethal too. None of this is news and this wisdom is universal, and in 99 out of 100 poison scandals you can shrug your shoulders just because it involves a tiny amount of a certain substance, it is the dose that determines the danger. But instead of shrugging there is panic, because you are intimidated by a scientific haunted house full of rattling skeletons and shaking gravestones. Cancer! Cancer! Cancer!
The bogeyman du jour is now PFAS, a collective name for thousands of per- & polyfluoroalkyl substances . They repel both water and grease and thus ensure the smooth bottom of pizza boxes, non-stick pans, waterproof clothing and much more. They are called Forever Chemicals because supposedly they never break down (that’s not true, but it does take years) and they are found in small quantities in humans, animals and the environment. They are suspected of causing all sorts of health problems. In the Netherlands advice has already been given not to eat too much self-caught fish (from the Western Scheldt). The organization Toxicowatch worries about PFAS in face masks and the Dutch government tries to limit the use of PFAS. Even a newspaper that is known for its critical attitude towards green scares (De Andere Krant), ran the headline: ‘Toxic substances are flooding our living environment’. And in a subsequent issue a concerned immunologist Dr Carla Peeters said: ‘ We have made 100,000 chemicals in the last fifty years that did not exist before. We don’t know what the long-term effects will be.’
I am willing to believe that chemists have developed 100,000 chemical substances in the past half century, but it seems difficult to rule out the possibility that nature beat them to it. How to know on a planet with 177 million different more or less identified chemicals ; I understand that chemists are still regularly surprised. Nature is a chemical factory. Substances are added 24/7/365 and undoubtedly disappear again. People also contribute to this, through industry and through the kitchen. A cooked potato is a chemical product and its composition varies, depending on whether it is an Eigenheimer or a Bintje, fried in oil or butter, on induction or on gas, on a low burner or full fire. We cook beans to make them less toxic, we try to neutralize the oxalic acid in spinach with eggs, or we make the meat more toxic because a little bit burnt is quite tasty. Chemistry! A person ingests 200,000 different chemicals every day, of which we know nothing.
Fear of poison is of all times. Kings used to employ “poison tasters” who took the first bite, but today we fear not so much that we won’t wake up the next day, but that we will get cancer half a century later. And this is not about a whole plate of food, but about a few milligrams of, for example, a pesticide or another substance that does not ‘belong’. Science now has the role of poison taster and it must meet high standards: if you can prove that Substance X causes cancer in only 1 in a million people, then measures must be taken.
1 in a million people, that sounds very safe, but to discover something like that you have to set up a study with two million people. Half get Substance X and the other half you keep ‘clean’ and that during several for decades – cancer is a slow disease – and then count tumors. That is of course impossible (and also unethical because you are not allowed to administer potentially dangerous substances to people) and nobody wants to wait that long.
Science therefore opts for laboratory animals, usually rats or mice, but an experiment with two million rats will probably be considered an environmental problem by the authorities. The Mega Mouse study in the 1950s once counted 200,000 mice, it has never been repeated.
So they take 1000 rats, or even less, but that has the disadvantage that you can only calculate a chance of 1 in 1000, not 1 in a million.
This is ‘solved’, more or less, by giving the animals a dose that is a thousand times higher than what an average consumer would ingest.
This is a caricature of things but essentially correct. In such research, the test animals are given megadoses that are thousands of times higher than that pesticide residue in that salad on your plate. It is therefore not surprising that in such research half of all tens of thousands (?) investigated chemicals, whether natural or artificial, do cause cancer in laboratory animals. ‘If you give enough, you can cause cancer with any substance,’ says chemist Jaap Hanekamp of University College Roosevelt in Middelburg, the Netherlands. Much of the fuss about carcinogens is based on this type of animal experiments, rarely on human research. After all, that is much more complex.
This approach assumes that a large amount of a substance will have more or less the same effect as a smaller amount. The effect is said to be ‘linear’ and only a ZERO dose has no effect. In everyday life, outside of science, everyone has known for a long time that this is not true, but science doesn’t seem that far yet. I will come back to this under the heading Hormesis .
And what to do if it turns out that the test animals get cancer in their tails or their forestomach from such a mega dose of Substance X? People don’t have those. Rats and mice make their own Vitamin C, humans don’t, what does that mean? And what should you do if it turns out that animal species react differently?
‘Dioxin is a good example of this,’ says Hanekamp. ‘ In the 1980s they called it a super poison , but now people joke that dioxin is the most toxic substance for hamsters . They underwent the first tests and they fell over ‘immediately’. Then they tested it on rats and you could stuff them with dioxin and they wouldn’t give a damn.’
Humans are surprisingly insensitive to dioxin. The substance is carcinogenic only in super high doses, and even then…. In 2004, then-Ukrainian President Yuschenko was poisoned with 5 million times the permitted amount of TCDD, supposedly the most dangerous type of dioxin. He suffered from chloracne, a nasty skin disease, for many years, but recovered. In 2021 he was still alive. Years ago it was also discovered that humans can also produce dioxins, albeit at a very low level.
According to the German specialist Prof. Mueller from Braunschweig, the dioxin standard is a thousand times too strict . In small doses, it seems, dioxin can even reduce the risk of cancer . Incidentally, dioxins have more or less disappeared from the scene because nature is an extensive source of these and similar substances.
These animal experiments have also been carried out with some PFAS substances – there are thousands of them. Dr Hanekamp: ‘I have worked through the fundamental literature for a number of PFAS substances for the ‘norm’, so I know how the toxicology was done. Then you do indeed see that rats and mice with high exposures are being investigated and then I think, well, what can I do with that, it is much too high, often a million times higher than what we have in terms of exposure and then the question is of course: can I do something with that? It’s not very exciting yet’.
Many people opt for organic unsprayed fruit and vegetables in the firm expectation that they will consume fewer pesticides. They are fooling themselves. A head of lettuce does not have the ambition to end up on a consumer’s plate as pure as possible, it just wants to make small heads of lettuce and see them grow. That doesn’t happen automatically because insects, mites, fungi and other scum lurk and to ward them off, the head of lettuce can only make chemicals, natural pesticides. In the case of lettuce, it is the carcinogenic caffeic acid. Your entire organic greengrocer’s shop is full of similar natural carcinogens, totally comparable to their industrial competitors. Piperine in pepper, d-limonene in oranges, catechol in coffee, hydrazine in mushrooms, flame retardants in sea vegetables and much more. Hanekamp: ‘PFAS really is a wimp compared to those substances, especially when you consider that more than 10,000 different halogenated hydrocarbons of natural origin have already been found in the world, almost all of them highly reactive substances!’
The use of commercial spray products is very limited by law, so you only ingest a few milligrams of those products; of the equally dangerous natural pesticides 10,000 times as much. Grams!  None of this is a reason to radically change your diet, but rather a warning not to expect everything from science.