Screening-Level Estimates of Environmental Release Rates, Predicted Exposures, and Toxic Pressures of Currently Used Chemicals

Abstract

We describe a procedure to quantify emissions of chemicals for environmental protection, assessment, and management purposes. The procedure uses production and use volumes from registration dossiers and combines these with Specific Environmental Release Category data. The procedure was applied in a case study. Emission estimations were made for chemicals registered under the European Union chemicals regulations for industrial chemicals (Registration, Evaluation, Authorisation and Restriction of Chemicals [REACH]) and for the active ingredients of medicines and crop protection products. Emissions themselves cannot be validated. Instead, emission estimates were followed by multimedia fate modeling and mixture toxic pressure modeling to arrive at predicted environmental concentrations (PECs) and toxic pressures for a typical European water body at steady state, which were compared with other such data. The results show that screening-level assessments could be performed, and yielded estimates of emissions, PECs, and mixture toxic pressures of chemicals used in Europe. Steady-state PECs agreed fairly well with measured concentrations. The mixture toxic pressure at steady state suggests the presence of effects in aquatic species assemblages, whereby few compounds dominate the predicted impact. The study shows that our screening-level emission estimation procedure is sufficiently accurate and precise to serve as a basis for assessment of chemical pollution in aquatic ecosystems at the scale of river catchments. Given a recognized societal need to develop methods for realistic, cumulative exposures, the emission assessment procedure can assist in the prioritization of chemicals in safety policies (such as the European Union REACH regulation), where "possibility to be used safely" needs to be demonstrated, and environmental quality policies (such as the European Union Water Framework Directive), where "good environmental quality" needs to be reached. Environ Toxicol Chem 2020;39:1839-1851. © 2020 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Keywords: Chemical safety; Emission; Environmental quality; Environmental release category; Exposure; Mixture toxic pressure.

Figure 1

Graphical illustration of the Van Straalen–Aldenberg convolution integral (Equation 2). Probability of exceedance of critical effect concentrations in water is obtained by evaluating the product of the probability density function of exposure concentrations (dotted line) and the cumulative distribution function of critical effect concentrations (black line) at all possible values of the standardized concentration z.

Figure 2

Registered amounts of chemical substances used in Europe (A) and estimated amounts of chemicals emitted to the environment (B). Black = pharmaceuticals; gray = pesticides; white = monoconstituent organics. Use volumes and releases range over 12 orders of magnitude: from as little as kg/yr (pharmaceuticals) to over a million tons/yr (monoconstituent organics).

Figure 3

Expected steady‐state concentrations of chemical substances in a “typical European Union water body,” as defined in European Chemicals Agency (2016; A, present study), compared with the average aquatic log median effect concentration (EC50; acute) for the studied chemicals (B, from Posthuma et al. 2019b). Note the small overlap between the 2 types of distributions, as in Figure 1. Black = pharmaceuticals; gray = pesticides; white = monoconstituent organics.

Figure 4

Distribution of expected toxic pressures (TPs) of chemicals used in Europe, calculated from the overlap of the exposure and (median effect concentration [EC50]) effect distributions established for each chemical according to Figure 3. Black = pharmaceuticals; gray = pesticides; white = monoconstituent organics. msPAF = multisubstance potentially affected fraction.