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Environmental and health aspects of corrosion– importance of chemical speciation
KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.ORCID iD: 0000-0003-2145-3650
2010 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

During the last decades, the interest in corrosion of metals and alloys from an environmental and health perspective has increased rapidly as a consequence of stricter environmental and human exposure legislations, their extensive use as implant materials and an increasing understanding related to occupational and/or daily exposure to airborne particles. Corrosion-induced metal release, however, needs to be understood in detail and to include knowledge related to chemical speciation, i.e. the oxidation state, complexation and chemical form of released metals, parameters of high importance when considering toxicity.

In this licentiate work, corrosion-induced metal runoff from roofing materials (copper, zinc, and chromium(III)-, and chromium(VI) surface treated galvanized steel) has been investigated from an environmental perspective with focus on chemical speciation of released metals (Papers I-II). From these papers it was evident that the total concentration measured in the runoff water is not sufficient for any environmental risk assessment. The environmental fate including changes in chemical speciation and hence metal precipitation has to be considered. For example, it was shown that the copper concentration decreased by three orders of magnitude already in the internal drainage system of a shopping centre with a copper roof, to a concentration lower than storm water collected from a nearby parking space (Paper I). Also, speciation measurements can explain corrosion, metal release and surface processes of chromium surface treated galvanized steel at different sites (urban and marine). Any environmental risk assessment has to be done by considering all metal species released, and compared with ecotoxic values. For example, when most chromium(VI) (the most toxic species) was released, significantly less zinc was released at the same time which decreased the overall ecotoxicity of the runoff water significantly (Paper II).

When assessing environmental risks by standard laboratory tests, it is important to understand all mechanisms which are possibly influenced by individual experimental parameters and which often are different for different test substances. Some metals released, as seen in the case of iron, may precipitate with time and be pH-, solution- and buffering dependent. This behavior can lead to strongly underestimated measured metal concentrations (Paper III).

When particles of metals or alloys are to be investigated (Papers III-VI), it is essential to conduct a thorough particle characterization, since the surface properties cannot be defined. In addition, the surface properties (oxide layer properties) change with varying particle size (Paper VI) and with other experimental parameters such as dispersion (Paper VI).

All iron-, and chromium-based particles investigated (Papers III-VI) revealed large differences between alloy particles and pure metals. Particles of pure iron and nickel released significantly more metals compared with particles of the investigated alloys, whereas particles of pure chromium released less metals compared with the alloys. Particles of stainless steel (AISI 316L), ferro-chromium and ferro-silicon-chromium released very low amounts of metals (Papers III-VI). The released quantity increased with increased acidity (Papers III-VI) and also in the presence of complexing agents (ongoing research). The manufacturing process is of high importance, as observed for stainless steel particles when compared with a side product from stainless steel production with similar composition that released significantly more metals (Paper III). Particles of metal oxides, i.e. chromium(III)oxide and iron(II,III)oxide, released very low amounts of metals due to their thermodynamic stability.

Ongoing research activities focus on the specific influence of complexing agents and proteins on the metal release process from massive sheet and particles of metals and alloys. The applicability and the possibility to use different analytical tools are investigated and elaborated for small-sized particles. A detailed understanding of the correlation between material and particle characteristics, the metal release process, the chemical speciation in interaction with proteins and/or cells, and the particle/cell interaction is essential to enable any correlation between material/particle characteristics and toxicity.

The aim of this licentiate summary is – in contrast to the six included scientific papers – to explain the importance of chemical speciation for corrosion processes from a health and environmental perspective in a popular way to reach a broad non-academic audience. The summary is hence written as a guidance document for stakeholders and the regulatory community working with environmental and health risk assessment.

Place, publisher, year, edition, pages
Stockholm, Sweden: KTH , 2010. , xvi, 36 p.
Trita-CHE-Report, ISSN 1654-1081 ; 32
URN: urn:nbn:se:kth:diva-24701ISBN: 978-91-7415-716-1OAI: diva2:352874
2010-10-28, conference room 3, YKI, Drottning Kristinas väg 49A, Stockholm, 10:00 (English)
QC 20101006Available from: 2010-10-06 Created: 2010-09-23 Last updated: 2010-12-14Bibliographically approved
List of papers
1. Storm water runoff measurements of copper from anaturally patinated roof and from a parking space. Aspects on environmental fate and chemical speciation
Open this publication in new window or tab >>Storm water runoff measurements of copper from anaturally patinated roof and from a parking space. Aspects on environmental fate and chemical speciation
2009 (English)In: Water Research, ISSN 0043-1354, E-ISSN 1879-2448, Vol. 43, 5031-5038 p.Article in journal (Refereed) Published
Abstract [en]

Release of copper from a naturally aged copper roof on a shopping centre building in a suburban site of Stockholm has been measured during different rain events after its interaction with the internal drainage system and storm drains made of cast iron and concrete. Concentrations of copper removed by means of urban storm water from a nearby parking space have been determined for comparison. Predictions and measurements of the chemical speciation of released copper are discussed compared to the total concentration, and to threshold values for freshwater and drinking water. The results clearly illustrate that the major part of the released copper from the roof is readily retainedalreadyduringtransport throughthe internal drainage systemof the building, a pathway that also changes the chemical speciation of released copper and its bioavailable fraction.Most copper,not retainedby cast ironandconcrete surfaces,wasstronglycomplexed to organic matter. The median concentration of free cupric ions and weak copper complexes was less than, or within the range of reported no effect concentrations, NOECs, of copper in surface waters. The parking space contributed with significantly higher and time-dependent concentrations of total copper compared to measured concentrations of copper fromthe roof after the interaction with the drainage system. Most copper in the surface runoff water was strongly complexed with organic matter, hence reducing the bioavailable fraction significantly to concentrations within the NOEC range. Dilution with other sources of urban storm water will reduce the released concentration of copper even further. The results illustrate that already the internal drainage system and the storm drains made of cast iron and concrete act as efficient sinks for released copper which means that any installation of additional infiltration devices is redundant.

National Category
Physical Chemistry
urn:nbn:se:kth:diva-24692 (URN)10.1016/j.watres.2009.08.025 (DOI)000274724700005 ()2-s2.0-70849124889 (ScopusID)

QC 20101006

Available from: 2010-09-22 Created: 2010-09-22 Last updated: 2016-05-25Bibliographically approved
2. Chromium(III) and Chromium(VI) Surface Treated Galvanized Steel for Outdoor Constructions: Environmental Aspects
Open this publication in new window or tab >>Chromium(III) and Chromium(VI) Surface Treated Galvanized Steel for Outdoor Constructions: Environmental Aspects
2010 (English)In: Environmental Science and Technology, ISSN 1086-931X, Vol. 44, no 11, 4322-4327 p.Article in journal (Refereed) Published
Abstract [en]

The long-term degradation of chromium(III) (Zn-Cr(III)) and chromium(VI)-based (Zn-Cr(VI)) surface treatments on galvanized steel and their capacities to hinder the release of zinc induced by atmospheric corrosion at non-sheltered urban and marine exposure conditions for two years are investigated.

Compared to bare zinc sheet, both surface treatments revealed high corrosion protection abilities and capacities to hinder the release of zinc, still evident after two years of exposure. The zinc barrier properties of the thinner Zn-Cr(VI) (10 nm) treatment were during the first 100 days of urban exposure slightly improved compared with Zn-Cr(III) (35 nm). However, their long-term protection capacities were inversed. 

Released concentrations of total chromium correspond to annual release rates less than 0.000032 (Zn-Cr(III)) and 0.00014 g Cr m-2yr-1 (Zn-Cr(VI)) after one year of urban exposure. Ageing by indoor storage of the surface treatments prior to outdoor exposure reduced the released Cr concentrations from the surface treatments. No Cr(VI) was released from the aged surfaces but from the freshly exposed Zn-Cr(VI).  

Marine exposure conditions resulted in a faster reduction of chromate to chromium(III)oxide compared with urban conditions, and a significantly lower amount of both chromium(III) and chromium(VI) released from Zn-Cr(VI) at the marine site compared with the urban site.

Barrier properties, Chromium oxides, Cr concentration, Environmental aspects, Galvanized steels, Indoor storage, Marine exposure, Outdoor exposure, Protection capacity, Release rate, Total chromium, Urban conditions, Urban exposure, Urban site, Zinc sheets, Atmospheric corrosion, Chromates, Galvanized metal, Galvanizing, Zinc
National Category
Chemical Sciences Other Environmental Engineering
urn:nbn:se:kth:diva-24693 (URN)10.1021/es1003022 (DOI)000278003500047 ()2-s2.0-77952893663 (ScopusID)
QC 20101006Available from: 2010-09-22 Created: 2010-09-22 Last updated: 2011-01-17Bibliographically approved
3. Transformation /dissolution studies on the release of iron and chromium from particles of alloys compared with their pure metals and selected metal oxides
Open this publication in new window or tab >>Transformation /dissolution studies on the release of iron and chromium from particles of alloys compared with their pure metals and selected metal oxides
2012 (English)In: Materials and Corrosion, ISSN 0947-5117, Vol. 63, no 6, 481-491 p.Article in journal (Refereed) Published
Abstract [en]

Transformation/dissolution (T/D) data for different Cr- and Fe-based alloys (a FeCr alloy, stainless steel AISI 316L, an alloy side product (SP) from stainless steel production) compared with their pure metals (Cr, Fe) and selected metal oxides (Cr2O3, Fe3O4) was generated and is used throughout the entire REACH assessment documentation of chromium metal and ferrochromium alloys to derive conclusions regarding their acute and chronic ecotoxicity hazard classification. Short and long term tests were conducted to assess data for acute and chronic aquatic toxicity following the recognized standardized T/D protocol. Tests were performed in media of different pH (pH 6.0 and pH 8.0), time periods, and solution composition, also investigating the effect of different experimental parameters. Generated data elucidates the complexity of the metal release process and its dependence on many interacting material-, surface-, and experimental factors as well as on the chemistry of the metalwater system being metal species specific. It is evident that the extent of metal release cannot be predicted by either the bulk or the surface composition, and that metal speciation measurements of released metals are essential to assess aquatic toxicity induced by metal/alloy particles. Observed released Fe and Cr concentrations were significantly lower than reported acute and chronic ecotoxicological endpoints.

Place, publisher, year, edition, pages
Wiley-VCH Verlag, 2012
ferrochromium alloy; hazard assessment; metal particles; metal release; transformation; dissolution
National Category
Other Chemistry Topics
urn:nbn:se:kth:diva-24696 (URN)10.1002/maco.201005943 (DOI)000305392600004 ()2-s2.0-79954425453 (ScopusID)

QC 20120718

Available from: 2010-09-23 Created: 2010-09-23 Last updated: 2016-04-26Bibliographically approved
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5. Particles, sweat, and tears: A comparative study on bioaccessibility of ferrochromium alloy and stainless steel particles, the pure metals and their metal oxides, in simulated skin and eye contact
Open this publication in new window or tab >>Particles, sweat, and tears: A comparative study on bioaccessibility of ferrochromium alloy and stainless steel particles, the pure metals and their metal oxides, in simulated skin and eye contact
2010 (English)In: Integrated Environmental Assessment and Management, ISSN 1551-3793, ISSN 1551-3793, Vol. 6, no 3, 456-468 p.Article in journal (Refereed) Published
Abstract [en]

Ferrochromium alloys are manufactured in large quantities and placed on the global market for use as master alloys (secondary raw materials), primarily for stainless steel production. Any potential human exposure to ferrochromium alloy particles is related to occupational activities during production and use, with 2 main exposure routes, dermal contact and inhalation and subsequent digestion. Alloy and reference particles exposed in vitro in synthetic biological fluids relevant for these main exposure routes have been investigated in a large research effort combining bioaccessibility; chemical speciation; and material, surface, and particle characteristics. In this paper, data for the dermal exposure route, including skin and eye contact, will be presented and discussed. Bioaccessibility data have been generated for particles of a ferrochromium alloy, stainless steel grade AISI 316L, pure Fe, pure Cr, iron(II,III)oxide, and chromium(III)oxide, upon immersion in artificial sweat (pH 6.5) and artificial tear (pH 8.0) fluids for various time periods. Measured released amounts of Fe, Cr, and Ni are presented in terms of average Fe and Cr release rates and amounts released per amount of particles loaded. The results are discussed in relation to bulk and surface composition of the particles. Additional information, essential to assess the bioavailability of Cr released, was generated by determining its chemical speciation and by providing information on its complexation and oxidation states in both media investigated. The effect of differences in experimental temperature, 30 °C and 37 °C, on the extent of metal release in artificial sweat is demonstrated. Iron was the preferentially released element in all test media and for all time periods and ironcontaining particles investigated. The extent of metal release was highly pH dependent and was also dependent on the medium composition. Released amounts of Cr and Fe were very low (close to the limit of detection, <0.008% of particles released or dissolved as iron or chromium) for the alloy particles (ferrochromium alloy and stainless steel), the pure Cr particles, and the metal oxide particles. The released fraction of Cr (Cr/[Cr + Fe]) varied with the material investigated, the test medium, and the exposure time and cannot be predicted from either the bulk or the surface composition. Chromium was released as noncomplexed Cr(III) and in addition in very low concentrations (<3 mg/L). Nickel released was under the limit of detection (0.5 mg/L), except for ultrafine stainless steel particles (<10 mg/L). It is evident that media chemistry and material properties from a bulk and surface perspective, as well as other particle characteristics, and the chemical speciation of released metals have to be considered when assessing any potential hazard or risk induced by sparingly soluble metal or alloy particles.

Bioaccessibility, Chemical speciation, Dermal contact, Ferrochromium alloy, Metal particles
National Category
Physical Chemistry
urn:nbn:se:kth:diva-14307 (URN)10.1002/ieam.66 (DOI)20821707 (PubMedID)2-s2.0-77954692674 (ScopusID)

QC 20100803

Available from: 2010-08-03 Created: 2010-08-03 Last updated: 2014-04-11Bibliographically approved
6. Bioaccessibility, bioavailability and toxicity of commercially relevant iron- and chromium-based particles: in vitro studies with an inhalation perspective
Open this publication in new window or tab >>Bioaccessibility, bioavailability and toxicity of commercially relevant iron- and chromium-based particles: in vitro studies with an inhalation perspective
Show others...
2010 (English)In: Particle and Fibre Toxicology, ISSN 1743-8977, Vol. 7, no 23Article in journal (Refereed) Published
Abstract [en]


Production of ferrochromium alloys (FeCr), master alloys for stainless steel manufacture, involves casting and crushing processes where particles inevitably become airborne and potentially inhaled. The aim of this study was to assess potential health hazards induced by inhalation of different well-characterized iron- and chromium-based particles, i.e. ferrochromium (FeCr), ferrosiliconchromium (FeSiCr), stainless steel (316L), iron (Fe), chromium (Cr), and chromium(III)oxide (Cr2O3), in different size fractions using in vitro methods. This was done by assessing the extent and speciation of released metals in synthetic biological medium and by analyzing particle reactivity and toxicity towards cultured human lung cells (A549).


The amount of released metals normalized to the particle surface area increased with decreasing particle size for all alloy particles, whereas the opposite situation was valid for particles of the pure metals. These effects were evident in artificial lysosomal fluid (ALF) of pH 4.5 containing complexing agents, but not in neutral or weakly alkaline biological media. Chromium, iron and nickel were released to very low extent from all alloy particles, and from particles of Cr due to the presence of a Cr(III)-rich protective surface oxide. Released elements were neither proportional to the bulk nor to the surface composition after the investigated 168 hours of exposure. Due to a surface oxide with less protective properties, significantly more iron was released from pure iron particles compared with the alloys. Cr was predominantly released as Cr(III) from all particles investigated and was strongly complexed by organic species of ALF. Cr2O3 particles showed hemolytic activity, but none of the alloy particles did. Fine-sized particles of stainless steel caused however DNA damage, measured with the comet assay after 4 h exposure. None of the particles revealed any significant cytotoxicity in terms of cell death after 24 h exposure.


It is evident that particle and alloy characteristics such as particle size and surface composition are important aspects to consider when assessing particle toxicity and metal release from alloy particles compared to pure metal particles. Generated results clearly elucidate that neither the low released concentrations of metals primarily as a result of protective and poorly soluble surface oxides, nor non-bioavailable chromium complexes, nor the particles themselves of occupational relevance induced significant acute toxic response, with exception of DNA damage from stainless steel.

National Category
Metallurgy and Metallic Materials
urn:nbn:se:kth:diva-24699 (URN)10.1186/1743-8977-7-23 (DOI)000282502100001 ()2-s2.0-77956491106 (ScopusID)
Knut and Alice Wallenberg FoundationSwedish Research Council

QC 20101006

Available from: 2010-09-23 Created: 2010-09-23 Last updated: 2014-04-14Bibliographically approved

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