Rüdel et al. Environ Sci Eur (2020) 32:5 https://doi.org/10.1186/s12302-019-0286-x COMMENTARY Open Access Persistent, mobile and toxic substances in the environment: a spotlight on current research and regulatory activities Heinz Rüdel1* , Wolfgang Körner2, Thomas Letzel3, Michael Neumann4, Karsten Nödler5 and Thorsten Reemtsma6,7 Abstract Certain persistent and polar substances may pose a hazard to drinking water resources. To foster the knowledge exchange in this feld the Working Group Environmental Monitoring of the German Chemical Society (GDCh) Divi- sion Environmental Chemistry and Ecotoxicology discussed at their meeting in December 2018 the signifcance and relevance of persistent, mobile and toxic chemicals (PMT substances) in the environment. Five oral contributions highlighted not only various aspects such as the identifcation of potential PMT substances based on certain proper- ties and their possible regulation under the European REACH regulation, but also current developments in the analy- sis of PMT substances and results from environmental monitoring. The data presented prove that many persistent and mobile substances can be detected in surface waters. Once detected, it can be complex and costly to identify sources and reduce inputs, as a case study on 1,4-dioxane in Bavarian surface waters shows. The same applies to the removal of polar substances from raw water for drinking water production. Today, scientifc advances in analytical methods make it easier to identify and quantify even very polar substances in water samples. In addition to the targeted analy- sis of critical chemicals, non-target screening is playing an increasingly important role. This opens up the possibility of detecting substances in water samples that have not previously been investigated in routine monitoring and testing their relevance for humans and the environment. However, the list of potentially occurring PM substances that have not yet been investigated is still very long. Further methodological improvements seem necessary here. In view of the evidence for the presence of PMT substances in the environment (e.g., trifuoroacetic acid and 1,4-dioxane) and the potential risks for drinking water abstraction, it seems important under consideration of the precautionary principle to identify and prioritise relevant REACH-registered substances. The assessment should be based on the intrinsic proper- ties and the emission potential of the compounds. The implementation of a detailed proposal made at European level to regulate PMT and very persistent and very mobile (vPvM) substances in the context of REACH would ensure that chemicals identifed as being substances of very high concern according to the PMT and vPvM criteria are subject to authorisation in future. Keywords: Persistence, Mobility, Toxicity, Water resources, Drinking water, Water production, Risk assessment, REACH regulation, Polar compounds, Non-target analysis Background Substances with a specifc combination of intrinsic sub- stance properties might pose a hazard to drinking water *Correspondence: [email protected] resources. Te combination of the two intrinsic substance 1 Fraunhofer Institute for Molecular Biology and Applied Ecology properties persistence (P) and mobility (M) increases the (Fraunhofer IME), Auf dem Aberg 1, 57392 Schmallenberg, Germany Full list of author information is available at the end of the article probability for PM substances to pass natural barriers © The Author(s) 2020. This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creat iveco mmons .org/licen ses/by/4.0/. Rüdel et al. Environ Sci Eur (2020) 32:5 Page 2 of 11 like river banks and artifcial barriers in water treatment substances registered under REACH already today can facilities. Especially critical are substances that have pose a signifcant risk to drinking water quality. toxic properties, too (PMT substances). Consequently, a A chemical substance emitted into the environment contamination potentially becomes irreparable. In addi- poses a threat to the drinking water resources, if it is tion, substantial analytical challenges exist related to the transported from the point of emission through soil lay- detection and quantifcation of mobile (polar) substances ers, river banks, aquifers, and other natural or even arti- in water samples during routine monitoring. fcial barriers. Te time scales for this transport can vary Te Working Group Environmental Monitoring of the from a few days in the case of surface water sources, to German Chemical Society (GDCh) Division Environ- 1 or 2 weeks for river bank fltration, or few years for mental Chemistry and Ecotoxicology discussed at their remote groundwater extraction wells. Important factors meeting in December 2018 the signifcance of persis- are the scale of environmental emissions, and whether tent, mobile and toxic chemicals (PMT substances) in the substance, or its transformation products, are suf- the environment. To gather information on the current ciently persistent in the environment and enough mobile knowledge on PMT substances experts were invited to in the aquatic environment. Te German Environment present results from analytical research, environmen- Agency (UBA) proposes to name such substances in tal monitoring and regulation. Five oral contributions the regulatory context of REACH persistent, mobile highlighted various aspects spanning from chemical risk and toxic (PMT) substances or very persistent and very assessment to analytical approaches regarding the detec- mobile (vPvM) substances [2–5]. tion of PMT substances. Te same intrinsic substance properties that lead to persistence in the environment and mobility in the PMT and vPvM substances under REACH (M. aquatic environment might lead to a breakthrough in Neumann, UBA) drinking water treatment facilities. Tey may not be Te EU REACH Regulation (EC) No. 1907/2006 is in removed by flters or by technical degradation proce- force since 2007. REACH intends to ensure a high level dures. Persistent and mobile substances can circulate of protection for human and environment health. Under in the water cycle and cause irreparable contamination. REACH, industry must demonstrate in their registration Terefore, it seems no sustainable solution to rely on ret- dossiers the safe use of substances over their entire life rospective and costly advanced water treatment technol- cycle. Tis includes to take into account the precaution- ogy to protect or remediate drinking water, particularly ary principle and to substitute substances of very high because even costly treatments are not completely efec- concern (SVHCs) and critical uses of chemicals. To date, tive in removing persistent and mobile substances. approx. 22,400 substances have been registered under A substantial analytical challenge exists related to REACH by over 14,800 enterprises. In contrast, authori- the detection and quantifcation of mobile substance in ties have to date identifed 197 substances as SVHCs of water samples. Conventional methods using gas chro- which 43 substances already entered the authorisation matography (GC) and reversed phase liquid chroma- regime under REACH. By now, restrictions were imple- tography (RPLC) are not able to detect and quantify the mented for 69 substances under REACH. most mobile substances, such as those that are very polar, Ensuring that the drinking water sources are secure ionisable or ionic, resulting in high water solubility and from any threats caused by chemicals is of the utmost low n-octanol–water partition coefcients (KOW), or low importance. Te EU Drinking Water Directive (98/83/ pH-dependant n-octanol–water distribution coefcients EC) and the EU Groundwater Directive (2006/118/EC) (DOW). Tis has recently been described as the analytical explicitly demand protection against chemical contami- and monitoring gap [6], and is illustrated in the third con- nation. In contrast, an increasing number of chemicals tribution (see “Protection of water resources from traces are detected in the aquatic environment. A literature of mobile substances” section). review (25 studies from 2000 to 2018; [1]) showed that Te hazard posed by persistent chemicals that are already 333 chemicals were detected in groundwa- mobile in the aquatic environment has been well known ter and/or drinking water. Of these 333 chemicals, 142 since decades. REACH currently lacks criteria for intrin- (43%) corresponded to substances that were registered sic substance properties that indicate a potential drinking under REACH (as of May 2017) of which 32 were also water contaminant. Consequently, there is a regulatory used as pharmaceuticals and fve were also used as pes- gap between the requirements of the drinking water ticides. Te proportion of substances registered under directive