Analysis of Alternatives

ANALYSIS OF ALTERNATIVES

Substance Name: Sodium chromate (Na2CrO4) EC Number: 231-889-5 CAS Number: 7775-11-3/10034-82-9

Substance Name: Potassium chromate (K2CrO4) EC Number: 232-140-5 CAS Number: 7789-00-6

Submitting Applicant: SAES Getters S.p.A.

Use title 1: Use of Sodium and Potassium chromate in the fabrication of alkali metal dispensers for production of photocathodes

Use title 2: Use of alkali metal dispensers containing sodium and potassium chromate for production of photocatodes

Use number: 1 & 2

Report status Confidential report Report date 07/04/2017

The information in this document is the property of SAES Getters S.p.A.. It may not be copied without the express written consent of SAES Getters S.p.A.. The information is given in good faith based upon the latest information available to SAES Getters S.p.A.. EC number: CAS number: SODIUM CHROMATE 231-889-5 7775-11-3/10034-82-9 POTASSIUM CHROMATE 232-140-5 7789-00-6

CONTENTS 1. SUMMARY ...... 6 2. ANALYSIS OF SUBSTANCE FUNCTION...... 6 2.1. Task performed by the substance and process description ...... 6 2.2. Critical properties and quality criteria ...... 10 3. ANNUAL TONNAGE ...... 12 4. IDENTIFICATION OF POSSIBLE ALTERNATIVES ...... 12 4.1. List of possible alternatives ...... 12 4.1.1. SAES Getters studied alternatives (chemical) ...... 12 4.1.2. SAES Getters studied alternatives (technological) ...... 13 4.1.3. Other alternatives tested in SAES ...... 14 4.1.4. Other players proposed alternatives ...... 14 4.1.5. External alkali dispenser ...... 15 4.1.6. Digital detectors ...... 15 4.1.7. Thermal or IR imaging ...... 16 4.2. Description of efforts made to identify possible alternatives ...... 19 4.2.1. Research and Development ...... 19 4.2.2. Data searches ...... 20 4.2.3. Consultations ...... 20 5. SUITABILITY AND AVAILABILITY OF POSSIBLE ALTERNATIVES...... 21 5.1. Molybdate salts: Green AMD ...... 21 5.1.1. Substance ID and properties ...... 21 5.1.2. Manufacturing process description ...... 21 5.1.3. Green AMD working principle ...... 23 5.1.4. Technical feasibility: differences between Green and Chromate based AMD ...... 23 5.1.5. Economic feasibility ...... 25 5.1.6. Reduction of overall risk due to transition to the alternative ...... 25 5.1.7. Availability ...... 25 5.1.8. Conclusion on suitability and availability for Molybdate salts ...... 25 5.2. Digital detectors ...... 26 5.2.1. General description ...... 26 5.2.2. Technical feasibility / comparison with Image Intensifiers ...... 28 5.2.3. Economic feasibility ...... 29 5.2.4. Reduction of overall risk ...... 29 5.2.5. Availability ...... 29 5.2.6. Conclusion on suitability and availability for digital detectors ...... 30 5.3. New generation of photocathodes ...... 30 6. OVERALL CONCLUSIONS ON SUITABILITY AND AVAILABILITY OF POSSIBLE ALTERNATIVES FOR USE 1 ...... 31 6.1. Ranking of alternative ...... 31 6.2. List of actions ...... 32 7. ANNEX – JUSTIFICATIONS FOR CONFIDENTIALITY CLAIMS ...... 33

07-04-2017 ANALYSIS OF ALTERNATIVES 2 EC number: CAS number: SODIUM CHROMATE 231-889-5 7775-11-3/10034-82-9 POTASSIUM CHROMATE 232-140-5 7789-00-6

Tables: Table 1: Overview of evaluation of alternatives ...... 17 Table 2: Differences between Chromate and Molybdate ...... 24 Table 3: Feature Comparison table of II/TV and FPD Systems ...... 29 Table 4: Ranking of alternatives ...... 31

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EC number: CAS number: SODIUM CHROMATE 231-889-5 7775-11-3/10034-82-9 POTASSIUM CHROMATE 232-140-5 7789-00-6

LIST OF ABBREVIATIONS

AfA Application for Authorisation AMD Alkali Metal Dispenser ATEX ATmosphères EXplosibles (1999/92/EG & 94/9/EG) AoA Analysis of Alternatives CAS Chemical Abstracts Service CBA Cost Benefit Analysis CLP Classification Labelling and Packaging (EC) 1272/2008 CMR Carcinogenic, Mutagenic or toxic to Reproduction CSR Chemical Safety Report DSD Dangerous Substance Directive 67/548/EEC DU Downstream User EC European Commission ECHA European Chemicals Agency EEA European Economic Area ES Exposure Scenario eSDS Extended Safety Data Sheet ERC Environmental Release Category EU European Union FPD Flat-Panel Detector GC-MS Gas Chromatography – Mass Spectrum II Image Intensifier LAD Latest Application Date LE Legal entity LoA Letter of Access LR Lead Registrant MOS Margin of Safety OC Operational Condition NVD Night Vision Device PPE Personal Protection Equipment PPM Parts Per Million PV Present Value R&D Research and Development RAC Risk Assessment Committee RCR Risk Characterisation Ratio REACH Registration, Evaluation, Authorisation & restriction of Chemicals RMM Risk Management Measures RPE Respiratory Protective Equipment SCOEL Scientific Committee for Occupational Exposure Limits SVHC Substance of Very High Concern SEA Socio Economic Analysis SOP Standard Operating Procedures VOC Volatile Organic Compounds WIPO World Intellectual Property Organisation WTP Willingness To Pay WWTP Waste Water Treatment Plant

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EC number: CAS number: SODIUM CHROMATE 231-889-5 7775-11-3/10034-82-9 POTASSIUM CHROMATE 232-140-5 7789-00-6

1. SUMMARY

The Applicant, SAES Getters S.p.A., has been producing Alkali Metal Dispensers (AMDs) for over 30 years, the basic constituent to produce Image Intensifiers and photomultiplier tubes, which main applications are Medical Devices, Scientific Equipment, Defence and Research Facilities, Telecom industry and Avionics, Consumer Electronics and Domotic.

Due to the well known hazard connected to the Cr(VI) salts the whole production process has always been conducted in very strictly controlled conditions to reduce emissions and exposure at the minimum.

In the meantime SAES Getters S.p.A. kept in researching and developing potential alternatives in order to substitute Chromate salts into the production process, but the research still doesn’t reach an acceptable point, neither for the Applicant or the competitors.

Due to the fact that potential alternatives are still under development and didn’t reach a satisfying efficacy level, hexavalent chromium in alkali dispensers used to create photocathodes in X-ray image intensifiers has been exempted by RoHs until 31 December 2019 and in spare parts for X-ray systems placed on the EU market before 1 January 2020 with Commission Delegate Directive 2014/11/EU of 18 October 2013.

In the following report all potential considered alternatives have been described and the analysis has highlighted that there is no indication of an existing valid alternative up to now. The alternative research program is proposed in section 6 of this document. In the meantime, also the evaluation of potential alternative technologies has been evaluated. A prevision of a minimum of 6 to a maximum of 10 years has been estimated to find a valid chemical substitution or technology.

2. ANALYSIS OF SUBSTANCE FUNCTION

2.1. Task performed by the substance and process description

Image intensifiers (used with X-ray imaging equipment) and photomultiplier tubes (used for measurement of electromagnetic radiation) and other similar devices use a component known as a photocathode which converts visible light (from an input phosphor) into electrons. An image intensifier or image intensifier tube is a vacuum tube device for increasing the intensity of available light in an optical system to allow use under low-light conditions, such as at night, to facilitate visual imaging of low-light processes, such as fluorescence of materials in x-rays or gamma rays (x-ray image intensifier), or for conversion of non-visible light sources, such as near-infrared or short wave infrared to visible. They operate by converting photons of light into electrons by a photocathode, amplifying the electrons, and then converting the amplified electrons back into photons for viewing.

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EC number: CAS number: SODIUM CHROMATE 231-889-5 7775-11-3/10034-82-9 POTASSIUM CHROMATE 232-140-5 7789-00-6

A Night Vision Device (NVD) is an optoelectronic device that allows images to be produced in levels of light approaching total darkness. The image may be a conversion to visible light of both visible light and near- infrared, while by convention detection of thermal infrared is denoted thermal imaging. The image produced is typically monochrome, e.g. shades of green. NVDs are most often used by the military and law enforcement agencies, but are available to civilian users. The term usually refers to a complete unit, including an image intensifier tube, a protective and generally water-resistant housing, and some type of mounting system.

A photocathode is a negatively charged electrode in a light detection device such as a photomultiplier or phototube that is coated with a photosensitive compound. When this is struck by a quantum of light (photon), the absorbed energy causes electron emission due to the photoelectric effect. Photocathodes operate in a vacuum, so their design parallels vacuum tube technology; they are divided into two broad groups; transmission and reflective. The effectiveness of a photocathode is commonly expressed as quantum efficiency, that being the ratio of emitted electrons vs. impinging quanta (of light). Photocathode is the key component of both image intensifiers and night vision tubes Although a plain metallic cathode will exhibit photoelectric properties, the specialized coating greatly increases the effect. A photocathode usually consists of alkali metals with very low work functions. The coating releases electrons much more readily than the underlying metal, allowing it to detect the low- energy photons in infrared radiation. The lens transmits the radiation from the object being viewed to a layer of coated glass. The photons strike the metal surface and transfer electrons to its rear side. The freed electrons are then collected to produce the final image. Although a plain metallic cathode will exhibit photoelectric properties, the specialized coating greatly increases the effect. A photocathode usually consists of alkali metals with very low work functions. The coating releases electrons much more readily than the underlying metal, allowing it to detect the low- energy photons in infrared radiation. The lens transmits the radiation from the object being viewed to a layer of coated glass. The photons strike the metal surface and transfer electrons to its rear side. The freed electrons are then collected to produce the final image.

They are fabricated by a process that uses the Alkali Metal Dispensers (AMDs). (AMDs) have been available from the SAES Group for over 30 years and offer an efficient and safe method of depositing ultrapure alkali metals. AMDs keep the alkali metal pure in the form of a stable salt. The procedure used is to first assemble the device with a coating of antimony metal on the photocathode support. The alkali dispenser is inserted inside the device with electrical connections and then the device is evacuated to remove all traces of air.

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EC number: CAS number: SODIUM CHROMATE 231-889-5 7775-11-3/10034-82-9 POTASSIUM CHROMATE 232-140-5 7789-00-6

The alkali dispenser is a sealed tube containing a mixture of an alkali metal chromate with a reducing agent, usually zirconium/aluminium (Zr/Al) alloy powder. Alkali metals are very reactive and will react extremely rapidly with minute traces of oxygen and moisture vapour and so the alkali antimony photocathode coating layer must be fabricated in-situ in the absence of air and moisture and kept permanently within a high vacuum.

AMDs are first connected to a joule effect heating system. The vacuum device in which the AMD is mounted is then pumped under turbo molecular pump vacuum ), and in some cases heated at 300 -600 °C for some hours, still under pumping, in order to remove gases and vapors (H2O, CO, CO2, H2) sorbed on the device walls. The AMD experience the same temperature as the whole system.

After this thermal process, the AMD is heated by Joule effect at about 400 -600 °C (corresponding to for min, with a current increase rate of A/min

After this degassing, the AMD is heated at least at its evaporation temperature

• About 600 -800 °C ( corresponding to A) (K) • About 650-850°C ( corresponding to A) (Na)

When the evaporation temperature is reached, evaporation starts according to following redox reaction, whose stoichiometry is not completely known because of the complex chemistry of Chromium, and can be approximated as

5 Na2CrO4 + Zr3Al2= 3 ZrO2 + Al2O3 + n Cr2O3 + 10 Na (vapour) 5 K2CrO4 + Zr3Al2= 3 ZrO2 + Al2O3 + n Cr2O3 + 10 K (vapour)

In order to obtain suitable photosensitive surface, the alkali metal must be evaporated at a constant flux. Both higher and lower fluxes can result in photosensitive surfaces with non-acceptable emissive properties.

This can be done both relying on previous experience, or by computer controlled feedback

At the end of the evaporation process, the exhausted AMD, whose content is made of St101 alloy, Zirconium and Aluminum Oxides, mixed Chromium Oxides, and theoretically possible Alkali Metal Chromate residuals can be either left into the final device or discarded, depending on the specific device and process features.

Traditional AMD configurations in wire shape release a few mg of alkali metal: compact sources of ultrapure vapors of Cesium, Potassium, Sodium, Rubidium and Lithium. They are directly inserted in the lamps like the one in the picture below

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EC number: CAS number: SODIUM CHROMATE 231-889-5 7775-11-3/10034-82-9 POTASSIUM CHROMATE 232-140-5 7789-00-6

2.2. Critical properties and quality criteria

The following specific performances are required:

• Very pure alkali metal films are required • The rate of evaporation of the alkali metal has to be strictly controlled • The tube must have a vacuum free of harmful gases during formation of photosensitive surfaces • No loose particles must be present within the tube • Rate of evaporation of the alkali metal must be reproducible • Dispenser must be available in different configuration (essentially with different wire lengths, which can fit in each tube and release different total quantities of alkali metals

The main critical point that is bound to the successful process is the activating temperature,

This temperature difference implies that

1. AMDs based on different salts, that works at lower temperature can undergo a degassing process, without activating the alkali metal evaporation, at lower temperatures than their Chromate counterparts, resulting in longer degassing times in the final device production process, needed to compensate the lower temperature, with obvious effect on the final device production cost. 2. Less effective removal of sorbed gases with impacts on the photosensitive surface quality7

The second critical point in substitution is the economical one, better described in the SEA document. In fact, SAES alkali metal dispensers are applicable to the manufacture of any alkali photocathode, ranging from the simplest type to complex types for image intensifiers and low light level vidicons. The main general applications of the alkali metal dispensers are:

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EC number: CAS number: SODIUM CHROMATE 231-889-5 7775-11-3/10034-82-9 POTASSIUM CHROMATE 232-140-5 7789-00-6

In the following industrial applications:

• Consumer Electronics • Medical Devices • Defence • Scientific Equipment and Research Facilities • Telecom industry

All the listed end users, before introducing any items in their production line, are forced to homologate them. Prior to marketing and sales of medical, electronic, avionic devices, all systems and their components need to have type approvals according to the official standards of their destination countries. These standards aim at improving active and passive device safety, environmental protection as well as the quality of products and production process. The approval process is very long and consists of several steps:

• Component approval (lamps, mirrors, tires etc) • Component fitting to the device (electric/electronic sub assemblies, etc) • System approvals (breaking, exhaust emission etc) • Whole machinery type approval

For each item, the European authority chosen by the manufacturer will issue a system approval according to each applicable directive. Those approvals are based on test reports prepared by an officially recognized testing organisation. Once all approvals are collected, the testing organisation issues the report for the approval as a basis for the homologation certificate.

In this respect, then, any changes in the production process of a component is subject as a consequence at the re-homologation process, which implies high investment in costs, timing, and can result in the non- acceptance of the new system.

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EC number: CAS number: SODIUM CHROMATE 231-889-5 7775-11-3/10034-82-9 POTASSIUM CHROMATE 232-140-5 7789-00-6

3. ANNUAL TONNAGE

Confidential average annual tonnage for use: (aggregated Sodium and Potassium salt< 20 kg/year)

4. IDENTIFICATION OF POSSIBLE ALTERNATIVES

4.1. List of possible alternatives Studies have been performed for many years and efforts in finding possible alternatives for chromates. The alternatives have been evaluated according to different approaches, either chemical or technological.

4.1.1. SAES Getters studied alternatives (chemical)

The following alternative salts have been evaluated up to now:

Within SAES Getters the R&D department since 30 years is trying to evaluate any potential alternative to Chromates. In developing the actual most promising alternative they went through the testing of several other salts:

Vanadate salts The same mixture has been produced to be applied within some meters of wire and evaluate the behaviour in comparison with the Chromate. The technological problem in using this kind of salts has letting loose the release control of the metal, resulting in unpredictable signal precision.

Tungstate salts The release temperature for the metal was too low, letting therefore the chamber full of undesired impurities.

than Vanadate, therefore this salt has been excluded from the R&D program.

Silicate salts Silicate salts have been completely discarded due to the high quantity of produces gases during use and the appearance of the sample in the air, demonstrating quick degradation of the system.

Titanate salts Titanate demonstrated a strange and unmanageable behaviour to humidity,

Molybdate salts It is the alternative actually studied by SAES and developed for further implementation. The proposal can be promising, but several problems still need to be solved, better explained in detail in Section 5.113.

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EC number: CAS number: SODIUM CHROMATE 231-889-5 7775-11-3/10034-82-9 POTASSIUM CHROMATE 232-140-5 7789-00-6

4.1.2. SAES Getters studied alternatives (technological)

Gallium Arsenide

Within SAES getters different generations of devices have been developed with the time and based on their records the following “generations” can be identified:

It can be noticed that the last generations of devices are based on Gallium/Arsenide salts. Several considerations need to be made on the classification of the salts: Gallium Arsenide is classified by ECHA as carcinogenic 1B, and its preparation requires the use of AsH3 and Ga(CH3)3, both with a high impact on the environment. The application of this kind of devices is very limited due to the high increase of the price and in many cases it need to be associated to the classical composition based on chromates as well, even if from a strict technological point of view the efficiency of the system can be considered as higher and a new generations of devices have been presented. GaAs suffers from a limited

This promising research field that generated the so called “third generation” of photocatodes has already been overcome due to its limitations and more different technologies are actually contributing in generating a complex system with the best performances.

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EC number: CAS number: SODIUM CHROMATE 231-889-5 7775-11-3/10034-82-9 POTASSIUM CHROMATE 232-140-5 7789-00-6

4.1.3. Other alternatives tested in SAES

Li-In and Na-Ga alloys

Two samples of alloys provided by a partner )have been tested in order to check if these alloys could be actually considered a possible sources of metal vapours and to measure the operating temperatures. The samples consisted of small spheres They were packed in sealed glass vials under inert atmosphere.

The aim of those preliminary tests was to give a preliminary information on the ability to release alkali metal upon heating, this was not sufficient to assess their practical exploitability, since many other characteristics needed to be first investigated and deepened, like outgassing, reproducibility, manufacturing costs, flammability, toxicology etc. ) According to preliminary tests, the ability of the dispensers to release Na and Li has been confirmed.

Some perplexities on the potential development of the systems are reproducibility of the system.

SAES Getters S.p.A. did not further investigate this approach since the synthesis of proven to be non-reproducible, and the partner was not able to supply further samples.

4.1.4. Other players proposed alternatives

Bismuth compounds An Austrian manufacturer, Alvatec, produces and supplies alkali dispensers that do not contain hexavalent chromium . These contain intermetallic compounds of bismuth with the alkali metal such as BiCs3. A review of patents identified gold, aluminium and silicon as possible alloying elements with alkali metals that release the alkali metals on heating. However, none of these are available commercially. Based on the R&D background of SAES, none of those proposals can potentially successfully pass the preliminary development steps

Indium based One manufacturer of photomultiplier tubes (PMT) has evaluated Indium based alkali dispensers and found two problems. Most PMT designs are fairly small and are made of glass that is sealed by melting the glass after the parts including the alkali dispenser are assembled. The dispenser is hermetically sealed with a low melting point metal and indium is chosen as it melts at a low temperature, forms a good gas-tight seal and is non-toxic. No other metals would have all of these properties. However the glass melting temperature is much higher than the melting point of indium so that the indium melts when the PMT is sealed and some of the alkali metal escapes before it can be used. This leaves insufficient alkali remaining to form the photocathode. The second problem is that a high current is needed to activate the alkali dispenser mixture. This current is passed from outside of the device into the PMT via wires that bond to the glass. The high

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EC number: CAS number: SODIUM CHROMATE 231-889-5 7775-11-3/10034-82-9 POTASSIUM CHROMATE 232-140-5 7789-00-6 current however causes the wire temperature to rise and this causes the wire to expand and can crack the glass which would then leak destroying the vacuum. This problem would also occur with larger image intensifiers that are made of metal, usually steel and glass to metal (steel) seals. The heater wires must be insulated from the metal with a glass hermetic seal to maintain the vacuum. Resistance heating of the alkali dispenser wires could cause the glass seal to crack compromising the vacuum. This has not been an issue with traditional alkali dispensers containing hexavalent chromium. Because of the design of the dispensers, they found that the alkali metal is produced at a very different rate to Cr(VI)-type dispensers so that the image quality was very poor. Also, many loose particles are formed which remain in the image intensifier and are unacceptable as they appear randomly in images and could give misleading or incorrect diagnoses. Another issue is the indium seal. Image intensifiers are baked at about 200°C to remove contamination while they are evacuated. Indium melts at well below 200°C so that the mixture could react prematurely releasing the alkali metal vapour during vacuum baking so that it is lost.

4.1.5. External alkali dispenser

In the context of the RoHS request of exemption the following alternative has been considered. Most current Image Intensifiers designs use internal alkali dispensers although it is possible to connect an external alkali dispenser to the Image Intensifiers or PMT and then to remove the dispenser after fabrication of the photocathode and creation of the vacuum seal. This however requires a significant design change and current designs cannot be adapted to use this approach. There are also technical disadvantages with external alkali dispensers as explained below. The cost of design change to move to an external dispenser would be very high because new designs of Image Intensifiers would have to be built with new production lines. Existing production lines could not be used as these would still be needed to build replacement Image Intensifiers that will continue to be used as spare replacement parts for existing pre- 2014 X-ray imaging equipment (and so would not need to comply with RoHS). As the market for Image Intensifiers is declining, manufacturers would not invest in redesigning their Image Intensifiers or build new production lines and so the availability of Image Intensifiers would very significantly decline. This would leave only a few models from one supplier who would dominate the market, removing competition. This would severely restrict the availability of Image Intensifiers in the EU and insufficient to supply EU hospitals with the number of lower-end imaging systems that they currently purchase. With very little competition, prices of Image Intensifiers would inevitably rise and this will also impact on healthcare providers in the EU. This alternative that has been studied to have a RoHS compliant system cannot be considered in the context of this Application for Authorisation, since it doesn’t solve the problem of the use of sodium/potassium chromate, to produce the alkali metals, in any case necessary

4.1.6. Digital detectors

Image intensifiers can be replaced by digital array detectors but these presents either advantages as disadvantages and actually they are used only in high-end imaging systems, being much more expensive (at list twice as much expensive). The best performing digital semiconductor detectors contain Cd, Pb or Hg and so should not be considered as suitable substitutes. Silicon digital array detectors is the most common type used in high end systems. Digital detector is the most promising alternative to Image Intensifiers, but in the light of various aspects better explained in Section 5.2 they do not sufficiently cover the full application range, as is demonstrated by the fact that at present, in the EU, about 45% of new X-ray systems sold, still use image intensifiers.

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EC number: CAS number: SODIUM CHROMATE 231-889-5 7775-11-3/10034-82-9 POTASSIUM CHROMATE 232-140-5 7789-00-6

4.1.7. Thermal or IR imaging

Image-intensifier technology has most widely been associated with use in night-vision goggles (NVGs). Another major technology, unrelated to image intensification, yet referred to as night vision, is that of thermal or IR imaging. Image intensification and thermal imaging each have comparative strengths and weaknesses. Thermal imagers are quite good at detecting heat sources in total darkness, such as body heat of personnel or engine heat; however, they do not have as high a resolution as do image intensifiers (at equivalent fields of view). Such is because thermal imagers provide an electronic output and the pixel size of the focal plane array (FPA) is much greater than the “effective” pixel size of the direct view optical output of the image intensifier tube. Additionally, thermal imagers had for many years been impractical for user-mounted applications, like NVGs, because of their greater size, weight and power (SWaP) consumption. Advances in recent years with uncooled thermal imagers such as vanadium oxide and amorphous silicon, have greatly improved these features making them more suitable for head-mounted applications. This technology is in any case limited to the night vision devices for Defence and no implementation in the radiographic sector has been developed up to now.

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EC number: CAS number: SODIUM CHROMATE 231-889-5 7775-11-3/10034-82-9 POTASSIUM CHROMATE 232-140-5 7789-00-6

Other alternatives tested in This alternative is technologically very different, at a very early SAES development stage

Li-In and Na-Ga alloys19 Technical feasibility: no. During the first phase, the capability of release has been tested up to now. Some perplexities are arisen from the microscopical analysis of the samples, which pose many doubts on the capability of reproducibility of the system. No solution has been found up to now.

Economical feasibility: to be verified. Apart from raw materials and market availability, costs will also needed to be considered bound to the whole development and adaptation process ,

Availability: no, none of those alternative are actually available in the market20

Overall reduction of risk: yes

Other players proposed Those are proposals indicated by potential competitors alternatives Technical feasibility: verified. Both have already been tested Bismuth salts without success for further development Indium sealing system Economical feasibility: to be verified. Most of them have not been evaluated for economical feasibility because of failing the technical performance.

Availability: no, none of those alternative are actually available in the market

Overall reduction of risk: yes

Different location of alkali This alternative has been considered as a proposal in the context dispenser of RohS directive, but not in the context of this Application for Authorisation, since it doesn’t involve the substitution of Chromate salts

Technical feasibility: not applicable.

Economical feasibility: not applicable.

Availability: not applicable

Overall reduction of risk: not applicable

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EC number: CAS number: SODIUM CHROMATE 231-889-5 7775-11-3/10034-82-9 POTASSIUM CHROMATE 232-140-5 7789-00-6

Digital detectors Most of them use dangerous substances like Cd, Pb or Hg. Just silicon based array detectors can be an option for development

Technical feasibility: to be verified. The process is not applicable to any kind of device because of the low resolution of the image

Economical feasibility: to be verified. big investment need to be performed in time and technology to improve the whole system and adapt it to all the needing applications. For the time being the digital detectors are much more expensive than the Image Intensifiers

Availability: to be verified. Not for all systems

Overall reduction of risk: to be verified, three over four present overall no significant risk reduction Thermal or IR imaging Use limited to the night vision sector

Technical feasibility: limited. The process is not applicable to any kind of device

Economical feasibility: to be verified. To obtain the same performances the development of complex system still has to be finalised

Availability: yes. With limited applicability

Overall reduction of risk: yes

4.2. Description of efforts made to identify possible alternatives

4.2.1. Research and Development

The project started well before the coming into force of the REACH Regulation and Chromate salts were not subject to authorization; several alternatives have been studied in order to find the best compromise between performance and risks and the outcome is the subject of this document, while the description of the investment costs and time are describes in the SEA document. The project started with the goal of replacing Chromates with non-toxic alkali salts, having the constraint to keep the same product geometry, alkali metal load, and as much as possible, evaporation conditions. For this reason, the project has been focused form the beginning on mixed alkali metal oxides (Vanadates, Titanates, Molybdates, Niobates)21. The screening has been made on 1. Toxicity 2. Cost

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EC number: CAS number: SODIUM CHROMATE 231-889-5 7775-11-3/10034-82-9 POTASSIUM CHROMATE 232-140-5 7789-00-6

Mixture of salt in wire configuration. On the basis of the preliminary test

Molybdates have been selected as the most promising candidates based on their relatively high evaporation temperature, even if lower than to the Chromate one23. Tests have then been repeated in wire format, leading to the results reported in section 5.1.4.

4.2.2. Data searches

Data sources are listed below:

Following databases were searched to recover information on chemicals or guidance in composing the present document:

CCRIS (Chemical Carcinogenesis Information); http://toxnet/nlm.nih.gov ChemIDplus (Chemical Identification/Dictionary); http://toxnet/nlm.nih.gov CHRIS (Chemical Hazards Response Information System); http://www.nisc.com/cis/qcis1.asp CPDB (Carcinogenic Potency Database); http://toxnet/nlm.nih.gov DART (Developmental Toxicology Literature) http://toxnet/nlm.nih.gov European Chemical Agency http://echa.europa.eu/web/guest European Environment Agency http://www.eea.europa.eu/themes/chemicals GENETOX (Genetic Toxicology Data); http://toxnet/nlm.nih.gov Haz-Map (Occupational Exposure/Toxicology); http://www.haz-map.com/refernc.htm. HSDB (Hazardous Substances Data Bank); http://toxnet/nlm.nih.gov IRIS (Integrated Risk Information System); http://toxnet/nlm.nih.gov NTP (National Toxicological Program) http://ntp.niehs.nih.gov/ RTECS (Registry of Toxic Effects of Chemical Substances); http://toxnet/nlm.nih.gov TSCA (Toxic Substances Control Act). http://www.epa.gov/oppt/existingchemicals/pubs/tscainventory/ United States Environmental Protection Agency http://www.epa.gov/

4.2.3. Consultations

To complete this document and collect all information about the Analysis of Alternatives several companies and company-functions have been involved: The most involved team has been the participant to the R&D project within SAES Getters S.p.A., who developed the devices in their actual shape and constitution, tested the first alternative and finalise the process in the minimal details. Within SAES Getters S.p.A. the same R&D group who developed the first and actual used devices begun working on alternatives.

Selected customers were dedicated to the application of the first new devices and the development of the best conditions for applications. No clear feedback is available up to now, but the company is keeping in developing and proposing the alternative to substitute the Chromate salts.

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EC number: CAS number: SODIUM CHROMATE 231-889-5 7775-11-3/10034-82-9 POTASSIUM CHROMATE 232-140-5 7789-00-6

5. SUITABILITY AND AVAILABILITY OF POSSIBLE ALTERNATIVES

In this section only the most promising developing alternative have been described, compared with the existing implemented solutions.

5.1. Molybdate salts: Green AMD

5.1.1. Substance ID and properties

The Molybdate salts have the formula Me2(MoO4)

Na2(MoO4): CAS 7631-95-0 – EC 231-551-7 – Not classified according to CLP Regulation. The substance has been registered as a monoconstituent in its an-hydrate and hydrate form according to REACH Regulation in a tonnage band > 1000 tons/Year by several EU producers/importers.

K2(MoO4): CAS 13446-49-6 – EC 236-599-2 – Some notifications indicate the substance as irritant for skin, eye and respiratory tract, nevertheless no confirmation with real data has ever been provided. It has still not been registered It is not expected to have a different toxicological /risk profile than the analogous sodium salt

5.1.2. Manufacturing process description

The manufacturing process, which is mostly identical for Na and K dispensers,

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EC number: CAS number: SODIUM CHROMATE 231-889-5 7775-11-3/10034-82-9 POTASSIUM CHROMATE 232-140-5 7789-00-6

5.1.3. Green AMD working principle

Green AMDs function is to release the Alkali Metal (Na o r K) in vacuum devices, during photosensitive surface formation. Green AMDs are first connected to a joule effect heating system. The vacuum device in which the AMD is mounted is then pumped under turbo molecular pump vacuum and in some cases heated at 400 -600 °C for some hours, still under pumping, in order to remove gases and vapors sorbed on the device walls.

After this thermal process, the AMD is heated by Joule effect at about 450-650° C ( corresponding to A 1) for 30 min, with a current increase rate of A/min in order to remove as much as possible sorbed vapors and gases, which could affect the purity of the evaporated metal.

After this degassing, the AMD is heated at least at it evaporation temperature • About 500-700° ( corresponding to A) (K) • About 450-650° °C ( corresponding to A) (Na)

When the evaporation temperature is reached, evaporation starts according to following redox reaction

9 Me2(MoO4) + Zr3Al2 →18 X(gas)↗ + 3Zr(MoO4)2 +Al2(MoO4)3 where Me is the alkali metal, and Zr3Al2 is the stoichiometric formula of , used a reducing agent in the process. In order to obtain suitable photosensitive surface, the alkali metal must be evaporated at a constant flux. Both higher and lower fluxes can result in photosensitive surfaces with non-acceptable emissive properties. In order to keep a constant evaporation rate it is typically needed to increase the AMD temperature during the evaporation procedure by increasing the passing current. This can be done both basing on previous experience, or by computer controlled feedback based on alkali metal flow measure by Atomic Adsorption. At the end of the evaporation process, the exhausted AMD, whose content is made of Zirconium and Aluminum Molybdates, and possible Alkali metal Molybdate residuals, 27can be either left into the final device or discarded, depending on the specific device and process features.

5.1.4. Technical feasibility: differences between Green and Chromate based AMD

The main difference between Chromate based AMDs and their green counterparts is the initial evaporation temperature, which is higher for Chromates. This temperature difference implies that Green AMDs can undergo a degassing process , at lower temperatures o Longer degassing times in the final device production process, with obvious effect on the final device production cost.

1 The actual current needed to reach the degassing and evaporation temperature is a function of the specific device in which the AMD is operated, and of the AMD length. Current data reported are valid for test in SAES evaporation bench, for a AMD.

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EC number: CAS number: SODIUM CHROMATE 231-889-5 7775-11-3/10034-82-9 POTASSIUM CHROMATE 232-140-5 7789-00-6

AND/OR Less effective removing of sorbed

• AMD users must completely re-design their alkali metal dispensing procedure, in order to to obtain effective photosensitive surface.

The differences are summarized in the following table28

Table 2: Differences between Chromate and Molybdate Initial evaporation current (A) Sodium AMD Chromate Molybdate Potassium AMD Chromate Molybdate

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EC number: CAS number: SODIUM CHROMATE 231-889-5 7775-11-3/10034-82-9 POTASSIUM CHROMATE 232-140-5 7789-00-6

5.1.5. Economic feasibility

Approval by the customers of the new formulation

Raw material cost: Molybdate salts are more expensive than Chromate, but the raw material cost has a very low impact on the overall economical feasibility of the project

Research & implementation of the new process SAES Advanced Technologies SpA invested development, implementation, and sampling of Green AMDs. Costs are related to manpower and chemicals for testing. The development leveraged on previous studies carried out by the group R&D labs ( SAES Getters SpA),

. More details can be found in the SEA document

Plant modification investment

Approval by the customers of the new formulation An estimate cost for new product development is based on the need for 3 months of qualified and experienced personnel plus two weeks of machine time which must be subtracted to standard production

5.1.6. Reduction of overall risk due to transition to the alternative

The overall reduction of risk is very high, since the molybdate salts are no classified for the human health or the environment

5.1.7. Availability

Molybdate salts are available on the market in sufficient quantity for this production and with an affordable price. Development and implementation of suitable devices has still to be finalised and accepted by customers

5.1.8. Conclusion on suitability and availability for Molybdate salts

The Molybdate salts can be considered as valid alternatives from a technical and a Risk assessment point of view for chromate salts.

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EC number: CAS number: SODIUM CHROMATE 231-889-5 7775-11-3/10034-82-9 POTASSIUM CHROMATE 232-140-5 7789-00-6

5.2. Digital detectors

5.2.1. General description

(Pediatr Radiol. 2006 Sep; 36(Suppl 2): 173–181. Flat-panel detectors: how much better are they? J. Anthony Seibert)

History Real-time fluoroscopic imaging has been available for medical diagnostic purposes since the beginning of X- ray applications in medicine, before the turn of the 20th century (Eisenberg RL (1992) Radiology, an illustrated history. Chapter 10: dark adaptation and image intensification. Mosby Year Book, St. Louis, pp 149–55). A light image derived from the conversion gain of X-rays into visible light photons formed the real- time display for the diagnostician. Technical advances through the next 40 years improved the X-ray to light conversion factor of a standard Patterson fluoroscopic screen, a scintillator without any secondary gain, but light levels were still low, requiring dark adaptation of the human visual response and high radiation dose per frame. In this situation, the diagnostician had to render a diagnosis with less visual acuity, using the dark-sensitive rods of the eye as opposed to the higher acuity cones of the eye that function only in higher intensity light. A breakthrough in fluoroscopy technology occurred with the introduction of the X-ray image intensifier (II), introduced in the late 1940s; the II eventually revolutionized real-time X-ray fluoroscopic imaging as we know it. This device provided an output of non-limiting brightness and smaller (‘minified– image size, achieved by conversion of X-rays to light to electrons to light, with the key being the acceleration of electrons and minification of the image for signal amplification. Finally, the radiologist was able to do work without dark adapting to low light levels, thus improving acuity and image information transfer. Subsequent improvements were the optical coupling of the output image to a television (TV) camera and closed-circuit viewing system for real-time video image display in the fluoroscopy room. Even though the image was significantly degraded by the limited resolution and bandwidth of the TV system, the convenience of viewing, adjusting contrast, and storing images on videotape were significant. Incremental improvements in image quality and image size occurred throughout the 1960s and 1970s. Revolutionary change in fluoroscopy occurred in the mid-1970s with the introduction of high-speed digitization of the analog video signal. Using rapid image processing, real-time subtraction of pre- and postcontrast images led to the implementation of digital subtraction angiography (DSA), certainly a very important event in the history of interventional angiography. In the late 1990s, the monetary and technological investments in flat-panel displays led to the implementation of the flat-panel detector (FPD) for radiography by many manufacturers. Soon after, FPD fluoroscopy operation soon began, and with several years of refinement and technological advances, is now poised to compete with the II in the clinical marketplace. The questions regarding its capabilities, however, have not been completely answered, and FPD implementations for fluoroscopy thus far have had a mixed review, particularly as it pertains to image quality at low exposure levels.

Description Amorphous silicon (a-Si) thin-film-transistor (TFT) arrays represent the technological research and monetary investment in the creation of compact displays for laptop computers, begun in the late 1980s. In the mid-1990s, feasibility studies for producing an X-ray detector demonstrated that the same technology could be used for acquiring a two-dimensional (2D) projection X-ray image, and subsequently a ‘real-time– fluoroscopy sequence. Currently, in 2006, the technology has advanced to clinical mainstream applications in both radiography and fluoroscopy. Clinical radiography results have demonstrated the clear superiority of FPD systems over screen-film radiography and other digital radiography devices, but the question of how much better the FPD is for fluoroscopic applications still requires investigation. Some reports of FPD fluoroscopy capabilities are reviewed below. Common to both the indirect and direct X-ray conversion technologies, the basic architecture of an a-Si TFT

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EC number: CAS number: SODIUM CHROMATE 231-889-5 7775-11-3/10034-82-9 POTASSIUM CHROMATE 232-140-5 7789-00-6 device is arranged as a row and column array of detector elements.

Within each detector element are the TFT, a charge collection electrode and a charge collection capacitor. Interconnecting each element via the TFT and capacitor are ‘gate–and ‘drain–lines. By keeping the TFT switch closed during the exposure, incident X-rays interact with the converter and produce a corresponding charge that is stored in the local capacitor. When the X-ray exposure is terminated, one gate line at a time is set high to activate all connected TFTs along the row, where the charge flows from the local capacitors through the transistors and down the drain lines in parallel to the output charge amplifiers at each column of the matrix. Digitization of the output signal occurs and the digital image is built up one row at a time. Deactivating the gate line resets the TFTs for the next exposure, and the adjacent gate line is activated for the next row of data, with the process continuing until the whole array is analyzed. For real-time fluoroscopic imaging, the readout procedure must occur fast enough to acquire data from all detector elements over a period of 33 ms or 30 frames per second, which places high demands on the switching characteristics of the TFTs, charge/discharge rate of the capacitors, and the speed of the charge amplifiers and digitizers of the output stage.

Various types of semiconductors are used depending on the type of imaging technique and the performance that is required, but types based on silicon were the first to be introduced and are the most common. Amorphous silicon photodiode or CMOS detectors are used, but as silicon is a light element, it adsorbs X-radiation inefficiently. Silicon detectors, therefore, usually have a coating of an X-radiation sensitive phosphor, based on heavy metals that efficiently adsorb radiation and convert it into visible light that is detected by the silicon. Thallium doped caesium iodide is the most common type of phosphor used to convert X-radiation into visible light that can be detected by silicon. Thallium is very toxic and this type of phosphor is used only in digital silicon detectors.

Recently, more efficient types of digital detector such as cadmium zinc telluride (CZT) have been developed. These are more sensitive than silicon detectors so that lower radiation doses can be used, but they contain cadmium which is a RoHS restricted substance. Other types of digital detectors based on silicon but without thallium do not efficiently adsorb radiation because silicon is a low atomic mass element. Gallium arsenide detectors are used for non-medical applications only, but arsenic is toxic and a carcinogen and it also has a lower sensitivity than heavy metal semiconductor detectors such as CZT detectors. Some types of silicon detectors require cooling and so consume more energy. Overall silicon detectors have lower sensitivity than CZT and so require higher radiation doses than CZT.

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EC number: CAS number: SODIUM CHROMATE 231-889-5 7775-11-3/10034-82-9 POTASSIUM CHROMATE 232-140-5 7789-00-6

5.2.2. Technical feasibility / comparison with Image Intensifiers

The benefits for FPD image quality include lack of geometric distortion, little or no veiling glare, a uniform response across the field-of-view, and improved ergonomics with better patient access in radiographic devices. Better detective quantum efficiency indicates the possibility of reducing the patient dose in accordance. Furthermore digital detectors exhibit very limited image degradation and over a much longer period of use than an image intensifiers A fact of using an Image Intensifier is the need to collimate down for higher magnification. More detail becomes visible, but the field of vision is reduced with each step up in magnification. On the other hand, magnification on a FPD system doesn't reduce scale at all.

These detectors have proved very successful for high-exposure interventional procedures but lack the image quality of the II/TV system at the lowest exposure levels common in fluoroscopy. However, first-generation FPD devices have been implemented with less than adequate acquisition flexibility (e.g., lack of tableside controls/information, inability to easily change protocols) and the presence of residual signals from previous exposures, and additional cost of equipment and long-term maintenance have been serious impediments to purchase and implementation.

Another aspect concerns devices used for mobile applications. Mobility is a potential risk to the more fragile digital detectors compared to the actual Image Intensifiers.

Digital detectors give good images compared to image intensifiers; in general Image Intensifiers systems and digital systems use similar X-ray doses but there are some treatments where digital detectors require slightly higher doses which will have a negative health impact on patients.

Quantitatively, from detection efficiency metrics, the FPD holds up quite well at high exposures encountered in cine-radiography and interventional DSA studies. Detective quantum efficiency (DQE), a measure of a detector’s ability to preserve information in the image relative to the incident X-ray information presented at the phosphor, is higher for the FPD relative to the II except at low exposures typically encountered in continuous fluoroscopy (30 frames per second). At higher exposure levels typical of radiography and DSA, the relatively large signal produced by the absorbed X-rays allows the gain of the output charge amplifiers of the FPD to be low. However, at fluoroscopy exposure levels, the necessary low exposure per image requires significant gain amplification to achieve a reasonable signal level for digitization. Not only is the signal amplitude increased, but electronic and other noise sources from the FPD are increased, as well, resulting in an image with low signal-to-noise ratio. The output image is no longer ‘quantum noise limited–(X-ray statistics are not the dominant noise source in the image), low contrast resolution is reduced, and image quality suffers. At low exposure levels, detector lag also plagues these detectors during readout

Restricted to the field of night vision, despite some manufacturers’ advertising claims that their digital night vision is the most superior product available, digital night vision is still a few years from being on a par with the best Image Intensifiers devices. Digital doesn’t work in total darkness and no digital night vision device can also be used as a weapon sight, nor of any which approaches the latest “premium” Gen 3 II devices.

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EC number: CAS number: SODIUM CHROMATE 231-889-5 7775-11-3/10034-82-9 POTASSIUM CHROMATE 232-140-5 7789-00-6

Table 3: Feature Comparison table of II/TV and FPD Systems Feature Digital Flat Panel Conventional II/TV Dynamic range Wide, about 5,000:1 Limited by TV, about500:1 Geometric distortion None Pin-cushion and ‘S-distortion Detector size (bulk) Thin profile Bulky, significant with large FOV Image area FOV 41 x 41cm 40cm diameter (25% less area) Image quality Better at high dose Better at low dose From Pediatric Radiology. Vol36(s2).p185. By Seibert, J. A., (2006)

5.2.3. Economic feasibility

Typically, an image intensifier based imaging system costs from less than €100,000 to up to ~€200,000, whereas a digital detector based system ranges from €200,000 - 300,000 or more. But even if digital detectors are considerably more expensive than image intensifiers they are gaining an increasing market share in the EU. In Nordic countries, most new systems have digital detectors whereas some new image intensifier systems are sold in France, Germany and the UK. Hospitals in southern and eastern European countries currently buy more image intensifier systems than digital systems.

5.2.4. Reduction of overall risk

The best performing digital semiconductor detectors contain Cd, Pb or Hg and so should not be considered as suitable substitutes. Silicon digital array detector is the most common type used in high end systems. Various types of semiconductors are used depending on the type of imaging technique and the performance that is required, but types based on silicon were the first to be introduced and are the most common. Amorphous silicon photodiode or CMOS detectors are used, but as silicon is a light element, it adsorbs X-radiation inefficiently. Silicon detectors, therefore, usually have a coating of an X-radiation sensitive phosphor, based on heavy metals that efficiently adsorb radiation and convert it into visible light that is detected by the silicon. Thallium doped caesium iodide is the most common type of phosphor used to convert X-radiation into visible light that can be detected by silicon. Thallium is very toxic and this type of phosphor is used only in digital silicon detectors.

5.2.5. Availability

In the framework of the RohS exemption request and discussion (2013) an assumption is put forward that by 2018, most new X-ray systems sold in the EU will use digital detectors if the current technical issues can be resolved. Manufacturers estimate that this work may be completed by ~2017 or possibly a few years later, so after this date, image intensifiers will no longer be used in new x-ray imaging systems although

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EC number: CAS number: SODIUM CHROMATE 231-889-5 7775-11-3/10034-82-9 POTASSIUM CHROMATE 232-140-5 7789-00-6 image intensifiers will continue to be used for up to 20 years more as replacement spare parts in systems placed on the EU market before this date. As research cannot guarantee results, 2017 may be optimistic and 2020 may be a more realistic date.

Further support for the foreseen phase-out of image intensifiers with innovative digital detectors can be found in the 2006 ERA report, reviewing the need for exemptions for category 9 and 9 applications (Goodman, P. (2006) Review of Directive 2002/95/EC (RoHS) categories 8 and 9 – Final Report. ERA Report 2006-0383, July 2006, amended September 2006, http://ec.europa.eu/environment/waste/pdf/era_study_final_report.pdf).

Actually, based on the state of art, the research efforts of manufacturers did not manage up to now to resolve all technical issues to allow for the development of commercial substitutes

5.2.6. Conclusion on suitability and availability for digital detectors

In general it can be stated digital detectors are a potential technological substitute for Image Intensifiers, but in many fields their development is at an early stage and with lower applicability. They still present technical and safety issues to be solved.

5.3. New generation of photocathodes

No valid alternative can be actually proposed to develop a new generation of photocathodes

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EC number: CAS number: SODIUM CHROMATE 231-889-5 7775-11-3/10034-82-9 POTASSIUM CHROMATE 232-140-5 7789-00-6

6.2. List of actions

It is demonstrated that no valid alternative is available up to now; nevertheless a number of activities will be put forwards in order to further evaluate all potential alternatives to the use of Chromate salts.

Tier 1 Within SAES R&D reached an acceptable level and just a few more months / one year will be dedicated. Most of the development has to be dedicated in the cooperation with the customer for implementation. This activity will then follow time of implementation from the beginning until the complete acceptance by the customer in adapting their process and solving the incoming issues: from 5 to 10 years.

Tier 2 A technological and commercial campaign has to be organised and realised, preparing advertising and presenting it during congresses, exhibitions and directly by the customers This activity can take from 2 to 5 years

Tier 3 By some customer the use of the new material has to pass through a homologation procedure. The finalisation of a homologation process can take up to 5 years and will be initiated after the fine tuning of the specific application.

In total a substitution plan will last from a minimum of 6 to10 years.

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EC number: CAS number: SODIUM CHROMATE 231-889-5 7775-11-3/10034-82-9 POTASSIUM CHROMATE 232-140-5 7789-00-6

7. ANNEX – JUSTIFICATIONS FOR CONFIDENTIALITY CLAIMS

Blanked out Justification for blanking Page item number reference Demonstration of Commercial Interest Demonstration of Potential Harm Limitation to Validity of Claim

g 7 g

9 g

10 g g y

13 g

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EC number: CAS number: SODIUM CHROMATE 231-889-5 7775-11-3/10034-82-9 POTASSIUM CHROMATE 232-140-5 7789-00-6

17 g

20 g

21 g

25 g

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