Use of the Threshold of Toxicological Concern (TTC) approach for deriving target values for drinking water contaminants

Thresholds of Toxicological Concern for cosmetics-related substances: New database, thresholds, and enrichment of chemical space

“…Application of the TTC approach has also been proposed for, or extended to, the risk assessment of other types of substances. These include substances present in consumer products (Antignac et al, 2011;Blackburn et al, 2005;SCCS, SCHER and SCENIHR, 2012;SCCS NfG, 2016): micropollutants, drug residues, pesticide metabolites and other impurities in drinking water (Brüschweiler, 2010;EFSA, 2016;Houeto et al, 2012;Laabs et al, 2015;Melching-Kollmuß et al, 2010;Mons et al, 2013); genotoxic impurities in human pharmaceuticals (EMEA, 2006); herbal preparations (EMEA, 2008); homeopathic medicines (Buchholzer et al, 2014); and human pharmaceutical substances carried over in multiproduct manufacturing facilities (Bercu and Dolan, 2013;Stanard et al, 2015). It has also been used as a first-level screening tool to prioritize for review a large number of substances identified as needing an assessment under the Canadian Environmental Protection Act (Health Canada, 2016).…”

Drinking Water in Germany: A Case Study of High Quality Drinking Water

“…For some of these compounds, the concentrations are below the level that will threaten human health (i.e. 10-170 ng/L) (Van Genderen et al 2000;Stan et al 1994;Zuccato et al 2000;Ternes 2001;WHO 2011;Christensen 1998;Schulman et al 2002;Webb 2001;Mons et al 2003;Mons 2003;Versteegh and Dik 2007). Table 12.1 presents an overview of concentrations of some of the pharmaceuticals detected in treated water in the Netherlands, in comparison with their safe drinking water levels (SDWLs) and their minimum therapeutic doses.…”

“…To achieve an impeccable drinking water quality, as a part of the Q21, target values (i.e. acceptable/tolerable concentrations) for those emerging contaminants have been proposed as an addition to the regulatory standards (Mons et al 2013). The derivation of these target values is mainly based on the approach called Threshold of Toxicological Concern (TTC), (Mons et al 2013).…”

“…Thus, a TTC of 0.15 mg per person per day has been determined as a 6 As the EU Drinking Water Directive (1998) noted, "for the purposes of the minimum requirements of this Directive, water intended for human consumption shall be wholesome and clean if it is free from any micro-organisms and parasites and from any substances which, in numbers or concentrations, constitute a potential danger to human health". 7 Toxicological information reveals that the emerging substance is present in drinking water at a concentration below the level that will threaten human health (Mons et al 2013). …”

A note of caution: the threshold of toxicological concern (TTC) is unsuited as a decision rule for deciding whether mixture risk assessment is necessary

“…Its basic idea is to use the toxicological information from a pool of well tested chemicals to draw conclusions on acceptable levels for untested but chemically similar compounds. The TTC concept has been applied or is under evaluation for a range of different chemicals in different exposure scenarios, for example chemicals in food [2], pesticide metabolites [3], drinking water contaminants [4] and cosmetics [5]. In detail, NOAELs (No Observed Adverse Effect Levels, the highest tested concentration at which no statistically significant adverse effects were observed in an animal experiment) are compiled for a specific group of chemicals, so-called Cramer classes, and a specific toxicological endpoint.…”