PM₁₀-bound arsenic emissions from the artistic glass industry in Murano (Venice, Italy) before and after the enforcement of REACH authorisation

Highlights

• 3077 PM10 samples collected in Murano and analysed for arsenic at multiple sites.

• Before the Sunset Date, As concentration was 88-folds higher than the EU standards.

• The Island of Murano was the main arsenic source in the area.

• Significant drop of As concentrations were detected after the REACH Sunset Date.

• Good practice in the regulation enforcement led to successful mitigation effects.

Abstract

The island of Murano (Venice, Italy) is famous worldwide for its artistic glass production. Diarsenic trioxide was a main ingredient of the raw glass mixture until 2015, when the authorisation process of European REACH Regulation (Registration Evaluation Authorisation of Chemicals) entered into force, effectively forbidding the use of arsenic. A total of 3077 PM₁₀ samples were collected across the Venice area in 2013–2017. This period included the REACH Sunset Date (May 2015). High arsenic concentrations were recorded in Murano before the Sunset Date (average 383 ng/m³), representing a serious concern for public health. Other sites in Venice complied with the EU target value. In 2013, concentrations were 36-folds higher than model estimation computed over the maximum-allowed emission scenario. Polar plot analysis indicated Murano as the major source of arsenic contamination. The concentration significantly dropped after the REACH implementation, thus meeting the European target values. However, high peaks of arsenic were still detected; inspections on raw and finished glass materials confirmed that some factories were still using arsenic. Results reported serious airborne arsenic pollution in Murano before the REACH implementation. This work represents an interesting case study on the effectiveness of the European REACH process.

Introduction

The artistic glass production in Venice (Italy) has a thousand-year history, dating back to the VII century BC. In 1291, all the workshops in the city centre were moved to the island of Murano (Fig. 1) in order to prevent outbreaks of fires due to the glassmaking activity, moreover, there was the aim to isolate and preserve “secret recipes” of glass composition, engineering and manufacturing. From that moment onward, the glass production was strictly confined to Murano, contributing to the technological development through centuries of research and experimentation (Tagliapietra, 1996, Toninato, 2003, Zecchin, 2003). The artistic glass sector in Murano underwent a serious decline during the last century due to market globalisation, the illegal competition of the counterfeit market, and the technological developments that has made this ancient artisan technique basically uncompetitive. Consequently, many factories decided to move their glass production to the mainland or other countries. Despite the rapid decline of the glass sector, Murano still hosts a large number of studio-workshops and small factories scattered on the highly populated island (~4500 inhabitants over 1.2 km²).

The main raw materials used in the art glass production include silica sand (SiO₂), alkali feldspars, borax (Na₂B₄O₇⋅10H₂O), and aluminium oxide (Al₂O₃). The glass mixture is mixed with alkali carbonates (Na₂CO₃, K₂CO₃) aiming to drop the melting temperature of the glass. Stabilisers (e.g., dolomite (CaMg(CO₃)₂), Pb₃O₄, and ZnO) are present to reinforce the glass structure and to improve its chemical and physical properties along with several dye elements added in different oxidation states (e.g. Ti, Cr, Mn, Fe, Co, Ni, Cu, Se, Ag, Cd, Au). The melted glass mixture generally presents gas bubbles originating from the decomposition of raw materials (e.g., added carbonates and dolomite) which release CO₂ to form CaO and MgO. Gas bubbles are then eliminated by adding the so-called refining agents (e.g., As₂O₃, Sb₂O₃, CaF, NaNO₃). Historically, every factory conserved a “secret recipe” to produce its own glass, however, arsenic trioxide was widely used (Apostoli et al., 1998, Rampazzo et al., 2008, Constantinescu et al., 2018). The transition between As(III) and As(V) at ~1200 °C releases oxygen stripping gases out from the glass mixture. Refining agents can be also added for secondary purposes, such as producing a more transparent glass, obtaining specific colours, or helping to remove unwanted colours of the raw glass after the addition of additives (Vogel, 1994).

For centuries, emissions from traditional furnaces were uncontrolled. Exhaust gases were released directly into the open air from the melting ovens through chimneys that were relatively low and had no abatement devices. The adoption of higher chimneys and stricter safety and security criteria started in the ’50-’70s of the last century. The European Directives on air quality were implemented and local authorities were able to propose incentives for investing in new technologies since the early 2000s. However, these changes were difficult to implement, due to a unique urban structure with a high density of population, and without separation between residential and productive activities. Also, local cultural/artistic heritage constraints caused the use of suboptimal technical solutions (Spagnolo et al., 2018).

Consequently, arsenic contamination was found in water, sediment and biota surrounding Murano Island (Giusti and Zhang, 2002), and atmospheric pollution was pointed out in several studies (Guerzoni et al., 2005, Rossini et al., 2010, Stortini et al., 2009, Masiol et al., 2014, Valotto et al., 2014). The geochemical fingerprint of the glassmaking industry, made up of As, Cd and Se, was widely detected in atmospheric depositions across the Venice Lagoon (Guerzoni et al., 2005), PM₁₀ (Rampazzo et al., 2008, Rossini et al., 2010), PM_2.5 (Stortini et al., 2009, Masiol et al., 2014), and PM₁ (Valotto et al., 2014). This pollution was also detected over a wide area encompassing the historic city centre of Venice, the mainland and the coastal area (Masiol et al., 2014). Generally, high concentrations of arsenic were reported in PM₁₀ collected daily in the surrounding area of Murano (60–181 ng/m³) (Rampazzo et al., 2008, Rossini et al., 2010) as well as in biological fluids of glassworkers (Apostoli et al., 1998).

Results of these studies raised serious concerns for public health since arsenic is classified as a “carcinogenic to humans” (group I) by the International Agency for Research on Cancer (International Agency for Research on Cancer IARC, 2009). As₂O₃ is also classified as carcinogenic for skin and lungs according to the European Classification, Labelling and Packaging Regulation (CLP EC Regulation 1272/2008) (European Commission EC, 2018). The World Health Organization reports an excess lifetime risk level of 1:10000 with an air concentration of about 66 ng/m³ (World Health Organization WHO, 2000). These concentrations were comparable to previous studies in Murano (Rampazzo et al., 2008, Rossini et al., 2010). Following the biological evidence of adverse health effects due to airborne arsenic exposure, a target year average of 6.0 ng/m³ arsenic in PM₁₀ was fixed as a European air quality target value (Directive 2004/107) to be met by December 31, 2012 (European Parliament and Council of the European Union, 2004).

During 2013–2017, the Environmental Protection Agency for the Veneto Region (ARPAV) carried out some monitoring campaigns to investigate the impacts of the local glass industry on the air quality in Murano. In the meantime, the ban of As₂O₃ came into force in compliance with the European REACH Regulation EC 1907/2006. The REACH Regulation (Registration Evaluation Authorisation of Chemicals; EC 1907/2006) (The Comission of the European Communities, 2006) was implemented in 2006 aiming to assure a high- level protection of human health and the environment; it also aims to achieve earlier identification of the intrinsic properties of chemicals. The process included registration, evaluation, authorisation and eventual restrictions of certain substances in use. It also aimed to enhance the innovation and competitiveness of the EU chemical industry. Before any authorisation, a potential chemical substance was inserted in the so-called “Candidate List” for prioritisation and defined as Substances of Very High Concern (SVHC). Arsenic was classified as SVHC, thus the As₂O₃ use was limited while suitable alternatives were proposed and tested (Giubilato et al., 2016). The deadline for the use of arsenic, also legally referred to as the “Sunset Date”, was set on May 21, 2015.

This study aims to: (i) estimate the dispersion of exhaust fumes from the authorised glass workshops and factories in Murano before the Sunset Date established by the application of the REACH authorisation through the implementation of an advanced non-steady-state air dispersion modelling system; (ii) compare the model results with the arsenic concentrations experimentally quantified in 3077 PM₁₀ samples collected in 4 sites before and after the Sunset Date; (iii) investigate the source location of As by using polar plot analyses to detect the major source areas; (iv) to estimate the background As concentration in the area and understand the real impact of the glassmaking industry; (v) to verify the drop of concentrations after REACH authorisation implementation; and (vi) detect potential unauthorised use of As after the Sunset Date.