We mainly owe the water and dirt repellent properties in our textiles to special chemicals. Some remain for an extremely long period of time in the environment and are now found nearly everywhere. These moderately volatile compounds spread beyond national borders and are transported long distances mainly through the air. More and more new persistent organic pollutants (POPs) are coming on the market. It only becomes clear with time that these substances degrade very poorly, accumulating in the fatty tissue of living organisms and along the food chain. As a result, they are also incredibly toxic to higher organisms and can severely disrupt the immune and endocrine systems. Below is a discussion with Prof Ralf Ebinghaus, head of the Environmental Chemistry Department at the Helmholtz-Zentrum Geesthacht, Centre for Materials and Coastal Research. We’re talking with him about the spread, risk and “global distillation” of these substances.
1. Do we have an overview here in Germany of the POP quantities that have been emitted in the past?
Prof Ralf Ebinghaus: It is generally difficult to obtain spatially and temporally resolved emissions data. The manufacturers are also not really keen on being observed too closely. To make matters more difficult, the emissions are usually a mixture of substances that may vary in composition. Buyers also usually don’t know the exact chemical composition they are obtaining from the manufacturer because they aren’t purchasing a chemically defined substance mixture, but rather a functionality. This functionality can, for example, ensure the fire resistance of a piece of furniture or to what degree an outdoor jacket is water resistant. How this is achieved, of course, is a trade secret.
2. Where do you obtain your data on chemicals from past time periods?
Ebinghaus: The Arctic is a wonderful archive. Here we can see for ourselves that the Roman Empire minted copper coins. We also observe that not only platinum group elements from catalytic convertors or lead from gasoline but also rare Earth elements in the Arctic are to some extent detectable in increasing concentrations. We know that the cryosphere – that is, the ice deposits on Earth – serve as an archive for past emissions into the atmosphere. We could show this in an entire array of classical as well as newer pollutants in our own analyses. You can also use the snow cores in the Alps as an archive. Or archived seal liver specimens. There have been specimens at the FTZ in Büsum since the great seal distemper outbreak in 1985. These specimens help other scientists today. The Natural History Museum of Stockholm also houses seal liver specimens. These time series go back to the fifties. Such biological “archives” supply us with highly valuable data. Furthermore, the German Environment Agency’s Environmental Specimen Bank is also, of course, essential.
3. What makes POPs so special? Why are they such a great danger for humans and the environment?
Ebinghaus: The classical persistent pollutants possess a certain volatility while they also have a certain tendency to adhere to particles. Their so-called moderate volatility is what makes them so special. It is for this reason that they are found in the gaseous phase, on air particles, in sediments and in living organisms (biota). In addition, they are also dissolved in water or found on water particles. They are potentially everywhere. This is precisely what makes these POPs so dangerous. I’ll give you another example. There are the notorious chlorofluorocarbons (editor’s note: coolants and solvents that have meanwhile been banned). These are extremely persistent, “living” hundreds of years. They are, however, not POPs because they are only found in the air. Or methane. It is extremely persistent, with an atmospheric half-life of approximately twelve years, but does not spread to other compartments. POPs are really characterised by the fact they spread across all environmental compartments. The health consequences of POP accumulation in the human body are diverse.
4. Through our own behaviour – for example, through our diet – can we influence POP absorption? Are people, especially those who eat a great deal of fish or meat, more at risk?
Ebinghaus: Unfortunately, that can’t be answered in an entirely general sense because these substances or substance mixtures have a tremendously wide spectrum of physiochemical properties and can therefore also be distributed in a wide variety of ways in nature as well as in food. Food is certainly a particularly important input pathway for adults, but for small children, house dust, for example, can be of greater importance. Generally speaking, it is safe to say that very fatty fish at the upper end of the food chain contain higher concentrations. Marine mammal offal is also highly contaminated. This presents a real problem for the Inuit as they still eat a traditional diet. Those of us who live in Europe have the choice and could eat a diet without fish.
5. Why are POPs so toxic for some aquatic life forms?
Ebinghaus: Of course that’s a very vital question because the concentrations in seawater are, in fact, very low – only a few billionths of a gram per litre. To explain how such a low concentration can be problematic, let me use an example. Imagine a tiger and a cat: which of the two is more dangerous to humans in your opinion? Clearly, it’s the tiger. However, if I ask you which one presents a higher risk to humans, then things get more complicated. Deaths in the European Union by tigers are zero; deaths by asthma, which can also be triggered by cats, however, amount to more than 10,000 per year.
The link between danger and the resulting risk is exposure. Humans come across cats more frequently. Now to return to marine animals: they are exposed to these pollutants their entire lives, twenty-four hours a day. Then also add the immense accumulation while going up the food chain: two nanograms per litre in seawater become two hundred milligrams per kilogram in sea mammals – this is almost a visible quantity. And at the very end of the food chain are humans!
6. There are studies that show that POPs contained in Arctic ice and in the Alps are now being released again in large quantities due to the warming planet. Are we experiencing a second surge of toxins from these POPs?
Ebinghaus: Yes, that’s right and it’s a problem that we must quite certainly adjust to. The “cold condensation” functions not only if we look at the Arctic region, but also at the Earth’s high-altitude areas—in the Alps, for example, or in the highlands of Tibet. Substances accumulate there, degrade more slowly due to the lower temperatures and are deposited in the ice and snow. If the ice and snow thaw, these compounds are then released again. We can observe this in the short-term along the eastern coast of Greenland, where the level of atmospherically transported pollutants in the seawater is increasing due to melting snow. The same of course applies to older archives, which again release the conserved pollutants during thaw. Incidentally, this applies not only to organic pollutants or POPs, but also, for example, to the lead formerly used in gasoline, plutonium from above-ground nuclear weapons testing or, as recently proven, mercury. This is also just temporarily stored, as long as the ice archive remains intact.
9. But sometimes the provocative question is posed: Isn’t it good that our pollutants don't accumulate here in Europe but far away, in the Arctic?
Ebinghaus: That would be very short-sighted thinking. The persistent pollutants initially wind up in the Arctic. This process of slow but continuous drifting of POPs toward the Arctic (as well as the Antarctic) is referred to as “global distillation” or “cold condensation”. There, the POPs are already responsible for immense problems because they accumulate in the food chain. After all, we also undertake fishing in the Arctic. The pollutants in the meantime, have remained virtually undegraded in the extremely cold conditions. While they slowly but surely degrade in temperate latitudes, they remain unchanged in the polar regions. If the ice thaws again, we would have an archive that exists only for a limited time.
10. What consequences does the release of POPs in Europe and North America have for other regions of the planet and especially for those who live in the Arctic?
Ebinghaus: Inuit are particularly at risk because they traditionally consume marine mammal offal. Currently the most problematic compound – due to its high concentration – is what is known as a novel pollutant, which has recently been included in the Stockholm Convention. This is the perfluorooctane sulfonic acid (PFOS), which was used, for example, in making textiles, carpets and paper waterproof. The highest concentration of PFOS in blood plasma was in a male Inuit from Nunavik, with nearly five hundred micrograms per litre. We can also say rather pointedly, that what we profit from in Europe and North America becomes a detriment far away from us, most clearly in the Arctic. This is really not fair at all.
7. What do you find particularly striking?
Ebinghaus: Well, the dimensions: fifty-six million people die globally every year according to World Health Organisation calculations and nine million of those are from chemical pollution. In comparison: 3.4 million individuals die from tuberculosis, malaria and AIDS combined. Some dimensions become clear here. We need to ask ourselves why chemical pollution isn’t as vital a topic as climate change or fighting malaria?
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