Pollutant released by industrial facilities impact on humans and the environment. The seriousness of global warming or health and ecological consequences can be underestimated if only the quantity of pollutants is used17. The global warming potential is strongly dependent on the chemicals’ radiative efficiency, in other words their ability to absorb energy and how long they stay in the atmosphere, known as their lifetime. The health consequences at the societal level depend also on the release media, length of exposure and population density18. Our results are presented here in terms of global warming impact potential, human toxicity and ecotoxicity impact potentials of point source emissions in Europe by major pollutants in the E-PRTR regulation, by industries and across regions. Impact potentials are measured in carbon dioxide equivalents (CO2eq) for the global warming potentials, in Comparative Toxic Units for human health (CTUh) and ecotoxicity (CTUe), respectively. It should be noted that CTUh and CTUe values, calculated by the USEtox model, cannot be directly compared, as they are measured on different scales and in different units.

Global warming and toxicity impact potentials by pollutants and industries

The global warming potential is expressed in carbon dioxide equivalents (CO2eq) and allows comparisons of different gases in terms of climate change impact potential. It measures how much energy per unit weight (kg or ton) the gas can absorb over a certain period of time, compared to the unit weight of carbon dioxide. This way emissions can be added and compared across gases, sectors, regions, times or greenhouse gases. The characterization factor for human toxicity impacts (human toxicity potential) is expressed in comparative toxic units (CTUh), which estimates the increase in morbidity in the total human population. Its unit [CTUh per kg emitted] is defined as the disease cases per kg emitted. For ecotoxicity, impact potentials are expressed in comparative toxic unit for freshwater ecosystem (CTUe), which provides an estimate of the potentially affected fraction of species (PAF) integrated over time and volume per unit mass of a chemical emitted.

The global warming potential impact from industrial point source emissions is mostly related to carbon dioxide (CO2) releases of the facilities (96% of the total) in the EU Member States, in 2017, (Table 2). Methane emission is the second largest contributor with 2%. Above average share of Methane in greenhouse gases are reported in Ireland (5%), Malta (16%), Luxembourg (8%), Poland (7%), Slovenia (9%). Emissions of certain greenhouse gases (Sulphur hexafluoride (SF6), Perfluorocarbons (PFCs), Hydro-fluorocarbons (HFCs)) are reported by a smaller fraction of EU Member States.

Human toxicity impacts are dominated mostly by mercury compounds in the EU as a whole, accounting for 76% of the total impact potential in 2017 (Table 2). An important risk of further mercury emissions has been already highlighted by earlier research due to mercury’s bio-accumulation properties in organisms and humans during their lifetime19. Hence, mercury concentrations usually increase when moving up the food web. Our trend analysis in a later section of this study shows that mercury’s annual emission was stable in the period from 2001 to 2017.

Table 2 Human toxicity, ecotoxicity and global warming impact potentials by major pollutants (in % of the total CTUh, CTUe and CO2 equivalent, respectively, 2017).

The World Health Organization (WHO) includes mercury in its list of chemicals of major public health concern20. There is some degree of variation across Member States in terms of toxicity impacts of pollutants, but in general zinc and lead compounds are being the pollutants with considerable, 9–10% impact potential of the total on average.

The pollutants with the largest contribution to ecotoxicity was zinc in 2017 (68% of the total) together with some other metals confirming earlier results1,3.

On the industrial level the largest estimated human toxicity footprint was estimated for the Production of electricity (46%) followed by Manufacturing of basic iron, steel, and ferro-alloys (20%) and Manufacturing of cement (10%) in 2017 (Table 3). As for ecotoxicity, Sewerage (50%) is the industry with the largest estimated chemical footprint. Beyond having large chemical footprint, electricity production is the sector with the largest global warming potential (50% of the total). This result highlights the importance of managing the electricity production sector’s environmental footprint. It should be added, however, that electricity is a major input to other sectors’ production and therefore impact potentials are indirectly caused by the electricity demand from companies in other sectors. In the same vein, the ecotoxicity impact of the sewerage sector is dependent on activities in other industrial sectors.

Table 3 Human toxicity, ecotoxicity and climate change impact potentials by NACE sectors (2017, % based on CTUh, CTUe and CO2 equivalent)

There is obvious variation of the results on the Member State level in the European Union, partly due to differences of national economic structures, in particular in case of ecotoxicity. The largest contribution to ecotoxicity is calculated for Manufacture of paper and paperboard (33%) and Manufacture of pulp (33%) in Sweden, while for Mining of other non-ferrous metal ores in Poland (49%) and Romania (31%). The largest emitter facilities are further discussed in a later section of this study.

The USEtox model allows differentiation between cancer and non-cancer characterisation factors, assuming equal weighting between cancer and non-cancer due to a lack of more precise insights into this issue. We decomposed the results similarly to an earlier study on Sweden10, and found that non-cancer human toxicity dominated the aggregated human toxicity impact potentials in Europe. Non-cancer human toxicity impact potential was 59,200 CTUh of the total 61,400 CTUh in 2017 calculated with USEtox 2.12, and cancer related CTUh was only a fraction of the total, 2200 CTUh, (Fig. 1). When filtering our cancer toxicity results with the USEtox 2.12 model by pollutants and industries, we found that Chromium compounds and Polycyclic aromatic hydrocarbons (PAHs), Mercury compounds and PCDD + PCDF (dioxins + furans) have the largest cancer toxicity impact potential in Europe. The production of electricity, mining of hard coal, sewerage, manufacture of other inorganic basic chemicals are the industries with the largest cancer toxicity impact potential. Using a sample of 52 mobile phones manufactured between 2000 and 2013, it was demonstrated with the USEtox model that toxicity increased with technology innovation and chromium showed the most significant risk for both cancerous and non-cancerous diseases21.

Figure 1
figure 1

Contribution of substances to cancer, non-cancer and total human toxicity (CTUh), emitted from point sources reported under E-PRTR to air and water (2017), characterized with USEtox 2.12. Only the total contribution and the four substances with largest contributions are shown.

Regional mapping of European toxicity and global warming potentials

The E-PRTR database contains important information for regional assessment, as companies shall report the geographic coordinates and addresses of facilities together with their country codes. By combining this information with the pollutant release data, we can draw maps of facilities with the largest human toxicity, ecotoxcity and global warming impact potentials (Fig. 2). There are clusters of global warming and toxicity impact potentials in the industrialized regions of Northern England, Northern Italy, the German Ruhr-area, Southern Poland, in the Benelux states, and in coastal areas of Spain, Portugal and the Nordic countries. There is some overlap of areas with the largest toxicity and global warming footprints. In a later section of this study we present findings on the correlation of the different types of impact potentials.

Figure 2

The human toxicity (CTUh, panel a), ecotoxicity (CTUe, panel b) and global warming ((CO2eq, panel c) impact potentials of substances emitted from largest European point sources to air and water in 2017 characterized with USEtox 2.12 and IPCC values. Observations are visualized with QGIS 3.28, Firenze, (https://qgis.org, 2022 version), and point-source releases are sized as a function of the toxicity and global warming impact potentials. Notes The outlier data point for Chromium compounds reported by Delimara Power station is corrected as suggested by the European Environmental Agency (693 kg instead of 69,300 kg).

Facility rankings

An important innovation of our research is that we drill down to the company facility level to investigate which facilities have the largest global warming and toxicity impact potentials in Europe. This way we target stakeholders in sustainable finance and in sustainability in general. Investors, public policy experts and consumers, all need metrics and quantitative information so as to measure sustainability and make informed investment, regulatory and consumption decisions. Current environmental finance data providers (Refinitiv, MSCI, etc.) base their company level sustainability information on reports of listed companies which mainly focus on energy and greenhouse gas emission data and lack the disaggregated geographic, facility level information on human toxicity and ecotoxicity risks.

The facility with the largest contribution to human toxicity and to global warming impact potential is PGE Górnictwo Bełchatów (Table 4). PGE Górnictwo Bełchatów is part of Poland’s largest energy sector company with respect to sales and revenues. The Bełchatów Power Station is a coal-fired power station near Bełchatów, It is one of the largest coal-fired power plants in the world. Hence, it is also among the largest emitters of greenhouse gases. Eight of the top ten polluter facilities in terms of human toxicity are in the Electricity production sector. Most of the largest emitters release mercury compounds in the air.

Several top-ranked facilities in our toxicity assessment are ranked on the top of the 2016 ranking of industrial air pollution by the European Environmental Agency (PGE Górnictwo Bełchatów Nr 1, RWE Power AG Nr 2, LEAG; Kraftwerk Jänschwalde Nr 4, Kraftwerk Boxberg Nr 5, etc.)22, which confirms the robustness of our approach. The EEA applied a value-of-life-year (VOLY) estimation technique and calculated marginal damage costs of air pollution. Marginal damage costs for impacts on health have been calculated for heavy metals and organic pollutants.

Presumably it is not surprising that seven of the top ten ranked facilities with the largest contribution to ecotoxicity are in the sewerage and water collection and treatment sector (Table 3). However, he emissions of waste water companies stem from other sectors as well. Furthermore, facilities in the sector of manufacturing other inorganic basic chemicals (Solvay Chimica IT S.P.A.) and in the metal mining sector (Zakłady Górniczo-Hutnicze) released pollutants with the biggest ecotoxicity footprint. Largest emitters in the sewerage sector release mainly zinc compounds, cadmium compounds and nickel compounds into water.

Table 4 The facilities with the largest contribution to human toxicity (CTUh), ecotoxicity (CTUe) and global warming potential (CO2eq Kt), emitted from E-PRTR point sources to air and water in 2017, characterized with USEtox 2.12 and IPCC global warming potential values. Only the 10 facilities with the largest impact potentials are shown. Assumptions made in toxicity characterisation are given in the Methods section, and follow Sörme et al. (2016). Calculations were based on the sub-compartment level for toxicity.

Correlation analysis—Global warming potential versus toxicity potential

In LifeCycle Impact Assessment (LCA) the pollutant releases cannot be directly compared after the characterization step, as impact potentials for global warming (CO2eq) and toxicity (CTUe or CTUh) are expressed in different metrics2. Thus, a normalization step is needed to convert values into a directly comparable common scale, based on the relative value of the observations to the minima and maxima in the distribution of the characterized values for each year and industry (NACE, Nomenclature of Economic Activities).

Table 5 presents the pairwise correlation ratios of the normalized indicators in our research. Here, we used the lowest, facility level observations for the correlation calculations, but the toxicity and global warming impact potentials were aggregated onto the facility level from the pollutant level. Pairwise correlation ratios of human toxicity, ecotoxicity and global warming potentials are positive in the range of 0.25–0.42, although not very strong.

In general, an important policy lesson from the weak correlation across different impact potentials is that the global warming potential is an important measure of climate change risks, but not a sufficient or complete measure of the overall environmental performance of industrial activities and organizations. We split the sample and calculated correlations for the facilities in the industrial sectors which were identified with the largest toxicity and global warming impacts (electricity production and sewerage) in the subsection of the results on industrial analysis. The correlation ratios in the ’Production of electricity’ sector confirm our earlier results that the association between global warming impact potentials and human toxicity impact potentials is positive and moderately strong (0.57), and therefore in this this sector GHG emission is a better proxy for chemical footprint than in the overall economy. The correlation between the global warming impact potentials and ecotoxicity is, however, weak and negative in the ’Sewerage sector’ giving a further example for the limits of using CO2 data for the overall assessment of environmental performance.

Table 5 Cross-correlation (Facility level observations by all sectors and sectors with the largest impact potentials)

Trends in GHG and toxic emissions

We conducted time-series analysis of the substances with the largest contribution to toxicity as suggested by an earlier paper on Sweden9. In the sample period from 2001 to 2017, the first reporting year under the European Pollutant Release and Transfer Register (E-PRTR) was 2007. The E-PRTR followed the European Pollutant Emission Register (EPER) under which reporting was required every three years, first in 2001 and later in 2004. The EPER data is part of the E-PRTR dataset published by the European Environmental Agency, and hence covered in our trend analysis. The slope of the trend of total human toxicity is negative in the early 2000s (Fig. 3a), although became again positive in the last years of the sample in 2016 and 2017. Total human toxicity in the sample decreased by 28%. Human toxicity of zinc was reduced monotonously and radically, while human toxicity of mercury compounds was unchanged.

Although our study focuses on human and freshwater ecotoxicity, mercury can have a wide range of negative health effects on many types of terrestrial animals. Toxic effects include reduced fertility, impaired development of embryos, changes in behaviour and negative effects on blood chemistry19.

Earlier research with USEtox 1.01 found that zinc and copper were the substances with the largest contribution to ecotoxicity impact potential in Europe in 2004 (70%, and 30% respectively)3. Our calculations confirm the importance of zinc and copper compounds, and shows the increasing and threefold ecotoxicity impact potential for copper. Contrary to the downward trend of human toxicity, ecotoxicity remained unchanged from 2001 to 2017 (Fig. 3b). Another research on the Canadian National Pollutant Release Inventory (NPRI) calculated ecotoxicity potential with the USEtox model in Nova Scotia and showed that copper (51.06%) accounted for the largest share of ecotoxicity potential8.

Figure 3
figure 3

Trend of contribution of substances to human toxicity (CTUh), ecotoxicity (CTUe) and global warming (CO2) impact potentials emitted from European point sources to air and water (2001–2017), characterized with USEtox 2.12. Only the total contribution and the five substances with largest contributions are shown. Assumptions made in characterization are given in the table footnotes. Under the European Pollutant Emission Register (EPER), data was reported every three year, first in 2001 and later in 2004. After 2007 data has been reported every year.

Point source greenhouse gas emissions of industrial facilities increased by 5% from 2001 to 2017. Carbon dioxide releases increased by 7%, while Nitrous oxide releases dropped by 65%, Hydro-fluorocarbons releases by 23% and Sulphur hexafluoride by 83%.

Time trends could be used as a measure of data quality, as substantial dispersion across years could indicate errors in data if assuming no significant change in production or technology4. The slopes of the curves were more-or-less stable suggesting stability of data quality except for Chromium. Here, we mention again the reporting error of Chromium releases by the Delimara Power station, highlighted by the European Environmental Agency during the preliminary discussions of the draft paper on Research Square.

Measurement quality

In this subsection, we investigate the quality of the information in the E-PRTR reports. First we deal with the measurement methods. Second, we analyze the standards used for the reported measurements and calculations.

Facilities are required to report for each pollutant and compartment pair whether releases were measured (“M”), calculated (“C”) or estimated (“E”). “M” is reported when the releases of a facility are derived from direct monitoring results, based on actual measurements of pollutant concentrations for a given release route. “C” is reported when the releases are based on calculations using activity data (fuel used, production rate, etc.) and emission factors or mass balances. “E” is reported when the releases are determined by best assumptions or expert guesses that are not based on publicly available references, or in case of absence of recognised emission estimation methodologies or good practice guidelines. It follows that in general, “M” is considered superior to “C” and “C” superior to “E”.

In the EU-28, about three quarters of the toxic releases are measured, no matter whether impact potentials are calculated as human toxicity impacts or ecotoxicity impacts (Table 6). There is, however, great variation within countries. In Ireland, Italy and Malta a higher share of toxic pollutant releases are estimated by best assumptions or expert guesses that are not based on publicly available references, recognised emission estimation methodologies or good practice guidelines (in terms of ecotoxicity 94%, 29% and 63%, respectively). Four fifth of greenhouse gas emissions are calculated on the basis of fuel used, production rate, etc.

As a consequence, measurement quality may have an effect on data quality and on decisions based on the EPRTR data.

Table 6 Shares of measured, calculated and estimated pollutant releases in% of total impact potentials by country (2017)

Operators should prepare their data collection in accordance with internationally approved methodologies, where such methodologies are available23. CEN (Comité Européen de Normalisation, European Committee for Standardization) and ISO (International Organization for Standardization) standards are considered as internationally approved measurement methodologies for toxic releases, For greenhouse gases the “Guidelines for the monitoring and reporting of greenhouse gas emissions under the Emission Trading Scheme”, the “IPCC—Intergovernmental Panel on Climate Change Guidelines” and the “UN-ECE/EMEP Atmospheric Emission Inventory Guidebook” can be reported as calculation methodologies. The operator may only use “equivalent” methodologies other than internationally approved methodologies, if they fulfil one or more of certain criteria: (i) the methodology is already prescribed by the competent authority in a licence / permit for the facility (PER), (ii) A national or regional binding measurement, calculation or estimation methodology is prescribed by legal act for the pollutant and facility concerned (NRB), (iii) the operator has shown that the alternative measurement methodology used is equivalent to existing CEN/ISO measurement standards (ALT), (iv) the operator uses an equivalent methodology and demonstrated its performance equivalence by means of Certified Reference Materials (CRMs), (v) the methodology is a mass balance method (e.g. the calculation of NMVOC releases into air as difference from process input data and incorporation into product) and is accepted by the competent authority MAB), (vi) the methodology is a European-wide sector specific calculation method, developed by industry experts, which has been delivered to the European Commission, to the European Environment Agency, and the relevant international organisations.

Table 7 presents the share of pollutant released by standard types in terms of human toxicity, ecotoxicity and CO2 equivalents. About one third of toxic releases are reported according to the most robust CEN/ISO standards and about one fifth according to the least preferred other methods. Half of the greenhouse gas releases are calculated according to the ETS norms.

Table 7 Shares of pollutant released by measurement/calculation standard types in% of the total (in 2017).

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