Persistent, mobile and toxic substances in the environment: a spotlight on current research and regulatory activities

Abstract

Certain persistent and polar substances may pose a hazard to drinking water resources. To foster the knowledge exchange in this field the Working Group Environmental Monitoring of the German Chemical Society (GDCh) Division Environmental Chemistry and Ecotoxicology discussed at their meeting in December 2018 the significance and relevance of persistent, mobile and toxic chemicals (PMT substances) in the environment. Five oral contributions highlighted not only various aspects such as the identification of potential PMT substances based on certain properties and their possible regulation under the European REACH regulation, but also current developments in the analysis 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, scientific advances in analytical methods make it easier to identify and quantify even very polar substances in water samples. In addition to the targeted analysis 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., trifluoroacetic 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 properties 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 identified as being substances of very high concern according to the PMT and vPvM criteria are subject to authorisation in future.

Persistent, mobile and toxic (PMT) and very persistent and very mobile (vPvM) substances pose an equivalent level of concern to persistent, bioaccumulative and toxic (PBT) and very persistent and very bioaccumulative (vPvB) substances under REACH

“…1,4-dioxane has a plethora of uses. It is a solvent in the production of lacquers, varnishes, cleaning and detergent preparations, dyes, antifreeze, adhesives, cosmetics, deodorant fumigants, shampoos, emulsions and polishing compositions, polyester manufacturing, pulping of wood, extraction medium for animal and vegetable oils, laboratory chemical (eluent in chromatography), cassettes, plastic and rubber, insecticides as well as a stabilizer for 1,1,1-trichloroethane [7,50] 1,4-dioxane is prevalent in groundwater at industrial due to its historic use as a There is evidence that the general population can be exposed to HFPO-DA via several routes including drinking water, locally emitted air, home grown fruits and vegetables, plants and fish. Removal from water is very difficult and current methods are likely insufficient to achieve removal.…”

“…There are many recent research developments and monitoring studies that have bought persistent and mobile substances to the forefront of worldwide scientific discussion [5][6][7][8]. As early as the 1990s, the scientific community realized the real hazard posed by persistent chemicals that are mobile in the aquatic environment [9][10][11].…”

Mobility and adsorption of liquid organic hydrogen carriers (LOHCs) in soils – environmental hazard perspective

“…Since there is a concern that some LOHCs possess traits of PMT substances we have performed a PMT-screening using recently proposed cut-off values. 29,57,58 We have adapted these values to the data that are available for LOHCs, which means in most cases we have used screening-level data. This resulted in following threshold values: (a) log K oc < 4.0 for classification as mobile (M), (b) classification into aquatic toxicity acute category 1 or terrestrial toxicity category 1 for fulfilling the "toxic" criterion (T), and (c) less than 20% biodegradation in ready biodegradability test for classification as persistent (P).…”

“…Furthermore, low to moderate toxicity of the three quinaldines as well as H 2 -rich forms of alkylcarbazoles was observed, showing the effects categorised as "acute 2" or "acute 3" in aquatic 11 and "harmful" in terrestrial 28 organismsnone of which fulfils the 'T' criterion in current 'PMT' assessment approach (Table 5). 29,57,58 Based on this screening-level data Quin-2Me-H10 would be considered potentially "PM" ( persist-ent and mobile) substance. 29 Quin-2Me does not raise concerns at the moment due to its biodegradability, while the risk of Quin-2Me-ph to contaminate drinking water would be low because of the immobility.…”

Can a chemical be both readily biodegradable AND very persistent (vP)? Weight-of-evidence determination demonstrates that phenanthrene is not persistent in the environment

“…The potential of chemicals to exhibit environmental persistence is considered a key indicator of potential risk, associated with increased and poorly reversible exposure [3][4][5][6][7]. More recently, the environmental persistence of chemicals has been gaining increasing attention as an issue of concern in the absence of bioaccumulation potential and/or toxicity [4,8].…”