Are we really unnecessarily panicking about nanograms?

The late medieval alchemist and physician Paracelsus made the pronouncement: ‘All things are poison and nothing is without poison. Only the dose makes whether something is toxic.’ Simon Rozendaal takes this statement as the starting point of his latest book, Paniek om niets (Panic About Nothing).

This principle of Paracelsus is also the foundation of (eco)toxicology. It means simply that there is a boundary between no toxicity and actual toxicity. You can comfortably consume 100 grams of sugar per day (you will only develop problems after years), but you would not want to try that with table salt. With cyanide, the ‘classic’ poison, the toxicity threshold is around a few hundred milligrams. With strychnine, as little as 30 mg can be lethal. The more toxic the substance, the lower the dose a human being can no longer tolerate. Paracelsus therefore acknowledges no lower limit for toxicity — that is something Rozendaal has invented himself!

Ingesting a toxic quantity of PFAS will not kill you immediately. However, at just a few hundred nanograms per ml of blood, you begin to experience problems with your liver, your cholesterol levels rise, and your immune system is compromised. There is therefore genuine toxicity involved, and it can certainly lead to a premature death. According to Simon Rozendaal, 0.2 micrograms (200 nanograms) is so minute that it cannot possibly be toxic. In an interview with de Volkskrant, he claims that the absolute threshold is 1 ppm, or 1 microgram. Yet PFOA (perfluorooctanoic acid), for example, is demonstrably toxic below that supposed magic threshold.

Misconception

He repeatedly asserts that the standard for a substance is set so low that at such low concentrations it will not actually kill you outright. He thus presents a ‘standard’ as though it were a toxicity threshold at which immediate death occurs. This is, incidentally, a widespread misconception. An environmental or health standard must, however, guarantee safety and therefore be protective of both the environment and the individual. A standard is thus the highest concentration at which, according to current scientific knowledge, harm is ruled out.

Rozendaal gives further evidence that he does not know what he is talking about. He attempts to offer a (pseudo)scientific explanation for why perfluoro compounds cannot be particularly toxic. He points out that carbon-fluorine compounds are chemically very stable, do not readily react with other substances, and are therefore of low toxicity.

Biochemical research established decades ago that the functioning of enzymes and proteins is linked to their three-dimensional structure. Associative binding of PFAS, without any chemical reaction, alters this three-dimensional structure and thereby the functioning of an enzyme or protein. It is likely that the extremely electronegative fluorine atoms cause such a chemically inert substance to bind enormously strongly to crucial protein structures — so strongly that even at environmental concentrations far below 1 ppm, the substance becomes bound and health thresholds are exceeded.

It is also worth bearing in mind that PFAS, precisely because of this strong binding, accumulates in both humans and animals. Relative to PFAS concentrations in water, the concentration in fish is considerably higher. In a person who eats fish frequently, that concentration can rise still further. This is why there are (low) standards for fish, as well as for drinking water and eggs, simply in order to protect people over the long term against the harmful effects of years of consumption.

Fish

Standards are revised because science continually generates new knowledge, not because analytical measurement techniques are becoming ever more refined. The European Food Safety Authority (EFSA), for instance, has established new health-based threshold values for PFAS. This new standard-setting prompted the RIVM to review the Dutch standards as well. This in turn led to a health-based threshold value based on the safe lifelong consumption of fish from surface water with a PFAS concentration of 0.3 ng/l. The value is in fact defined as a PFAS concentration in fish and then converted to the corresponding concentration in water, because the resulting concentration in water (that 0.3 ng/l) can no longer be reliably measured. Here, then, standard-setting is clearly running ahead of measurement capabilities — whereas Rozendaal repeatedly claims that standards are being set ever lower simply because we are able to measure ever more precisely.

In his book, Rozendaal regularly casts doubt on findings that are scientifically established, such as the effect of PFAS on the immune system. He writes, for example (on page 108): ‘There is a weak relationship between PFAS and a reduced immune response… There is a tentative epidemiological association, a so-called correlation. But epidemiological research is the lowest rung on the scientific ladder. If you find an association within a particular group of people, it could have an entirely different cause.’

The United States Environmental Protection Agency (EPA) identified 50 epidemiological studies, of which one was classified as ‘highly reliable’ and 29 as reliable. When so many reliable studies reach the same conclusion, causality becomes highly probable. Furthermore, 13 animal toxicology studies were identified, of which 3 were classified as highly reliable and 9 as reliable. Causality established.

The procedure by which standards are derived at all these institutions is designed to reach a scientifically sound consensus as objectively as possible. That process always begins with a comprehensive review of the literature. Of the publications identified (for the EPA’s PFOA standard alone, 4,802 papers), the scientific quality of each is first assessed against a set of objective criteria. A standard is then derived for each effect category, following a rigorous protocol, that protects the population (or the environment).

Pulled up short

The report is subsequently submitted to an independent committee, and sometimes a public consultation round is also held. Hundreds of scientists are involved in this process. If anyone were to attempt to introduce a standard lower or higher than is scientifically warranted, they would be immediately pulled up short.

It is therefore all the more incomprehensible that a science journalist — particularly one with a background in the exact sciences — should entirely disregard this whole process and maintain a wholly personal opinion, simply because he believes that whatever is just barely measurable will invariably become the standard. To the layperson it may appear to be science; in reality, it is deception. It undermines the credibility of standard-setting, the willingness to comply with standards, and public trust in government. ‘Panic about nothing’ — when we know that PFAS are so persistent that if we were to halt every emission today, in a hundred years’ time there would still be just as much PFAS in the environment?