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Deltares, June 2020 22 Clearer picture of substances of concern 'Emerging substances' sound quite innocent. But they are not only new: they can also be a threat to people and the environment. New substances are registered on a daily basis without us knowing exactly what effect they have. Deltares will provide provide clear answers in a European research network: what substances in the soil should we really be worried about? Which substances are involved exactly? The range is very wide: it includes substances in, for example, medicines, plastics, care products, cleaning solu- tions, impregnating agents and paint. More and more of them are ending up in the environment, where they are hardly degraded, if at all, and spread easily through water. One result is problems with soil quality. Hilde Passier: 'Because more and more substances are emerging and we can make better and better measure­ ments, we see new substances pop- ping up in our measurements of soil and water in recent years. So we are establishing a more detailed and ac- curate picture. The next question is: should we be worried?' What is the danger? The uncertainty about the level of the threat posed by these dangerous sub- stances is a problem. Some substances are so new that we still don't know how they behave in the environment. Passier: 'There are a lot of questions indeed. Are these substances broken down, do they accumulate some­ where deep in the subsurface or do they actually pass through the system very quickly before being taken to the sea by a large river?' Whatever the answers, recent research by the Council for the Environment and Infrastructure has shown that the spread of hazardous substances is not declining enough. The decrease in concentrations of chemical sub­ stances has come to a standstill in surface water and the air. Particles of new substances are also being found in human and animal tis- sue, and in blood, and these may be toxic. Passier: 'We know that PFAS, a collective name for a group of chemi- cal additives in things like textiles, fire extinguishing agents and cosmetics, accumulate in living tissue. Some types of PFAS may be carcinogenic in high concentrations. Standards have been set for many substances and these are also beingmonitored. But By Saskia Klaassen /Photo Vincent Boon Deltares, spring 2020