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Assessing the Greenness of Chemical Reactions in the Laboratory Using Updated Holistic Graphic Metrics Based on the Globally Harmonized System of Classification and Labeling of Chemicals M. Gabriela T. C. Ribeiro,*,† Santiago F. Yunes,‡ and Adélio A. S. C. Machado§ †

REQUIMTE, Departamento de Química e Bioquímica, Faculdade de Ciências da Universidade do Porto, Porto 4169-007, Portugal Departamento de Química, Universidade Federal de Santa Catarina, 88040-900 Florianópolis, Santa Catarina, Brasil § Departamento de Química e Bioquímica, Faculdade de Ciências da Universidade do Porto, Porto 4169-007, Portugal ‡

S Supporting Information *

ABSTRACT: Two graphic holistic metrics for assessing the greenness of synthesis, the “green star” and the “green circle”, have been presented previously. These metrics assess the greenness by the degree of accomplishment of each of the 12 principles of green chemistry that apply to the case under evaluation. The criteria for assessment were based on the hazards symbols used in the system established by the European Union, directive 67/548/EEC, obtained from the safety data sheets of chemicals. Meanwhile, the Globally Harmonized System of Classification and Labeling of Chemicals (GHS) replaced that system and introduced a new classification of hazards and new symbols. The objective of this work is to present new criteria for the construction of the metrics based on the GHS system. A brief presentation of this system is included. The present upgrade also includes an improvement of the graphic presentation of the green star to facilitate the visual assessment of the degree of accomplishment of each green chemistry principle. KEYWORDS: High School/Introductory Chemistry, First-Year Undergraduate/General, Second-Year Undergraduate, Safety/Hazards, Green Chemistry, Reactions, Synthesis n previous articles, two graphic holistic metrics, “green star” and “green circle”,1−5 for assessing the greenness of synthesis were presented. These metrics assess the greenness by evaluating the accomplishment of each of the 12 principles of green chemistry that apply to the case under evaluation. For assessment of the greenness of synthesis reactions, the construction of the metrics begins by an inventory of all the substances involved−feedstock, products, byproducts, solvents, catalytic reagents, and so forth. Next, information is collected on the hazards to human health, the environment and the potential chemical accident for each substance, as well as information to assess whether the substances are renewable and break down to innocuous degradation products. To construct the metrics, the hazards of the substances involved are generally obtained from safety data sheets (SDS), and scores are attributed to the hazards according to predefined criteria. The criteria were based in the hazards symbols used in the system established by the European Union, directive 67/548/EEC,6 commonly included in SDS. Meanwhile, the Globally Harmonized System of Classification and Labeling of Chemicals (GHS),7 established by international mandate in the 1992 United Nations Conference on Environment and Development, started to be used. GHS introduced a new classification of hazards and new symbols and prescribed a more systematic lay-out of SDS (under 16 headings) to transmit the hazard information.7 To adapt the metrics to this change, they were now revised as reported here.

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© 2014 American Chemical Society and Division of Chemical Education, Inc.

New criteria to score the accomplishment of the principles according the new classification of hazards of substances had to be defined because a “direct translation” between the systems in the two regulations is not possible. The objective of this communication is to present these new criteria and examples of their use. The utilization of GHS for the construction of these metrics presents advantages such as (i) a more systematic assessment of the hazards of chemicals for use in evaluation criteria, due to the increased systemization of hazards in GHS, which makes easier the construction of the metrics; (ii) increased contact with GHS in the laboratory context,8,9 following its recent legal adoption in the U. S.;10 and (iii) further contact with SDS, that acquired increased importance as a consequence of their prominent role in REACH (Registration, Evaluation, Authorization, and Restriction of Chemicals)11 for transmission of hazards. At the present stage of adoption, GHS is probably still poorly used by U. S. teachers. The next section provides a brief overview of its most relevant practical contents to make easier its use in the academic context.

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GHSAN OVERVIEW GHS is a result of the 1992 United Nations Conference on the Environment and Development where a resolution was agreed to protect environment and the human health regarding Published: August 25, 2014 1901

dx.doi.org/10.1021/ed400421b | J. Chem. Educ. 2014, 91, 1901−1908

Journal of Chemical Education

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Table 1. Hazard Classes and Categories (GHS) Hazards Physical Hazards

Hazard Classes Explosives

Flammable gases (including chemically unstable gases)

Aerosols Oxidize gases Gases under pressure

Flamable liquids Flamable solids Self-reactive substances and mixtures

Pyrophoric liquids Pyrophoric solids Self-heating substances and mixtures Substances or mixtures, which in contact with water emit flammable gases Oxidize liquids Oxidize solids Organic peroxides

Hazard Categories

Hazards

Unstable explosives Divisions 1.1, 1.2, 1.3, 1.4, 1.5, 1.6 Categories 1, 2 Health Hazards

Category A (chemically unstable gases) Category B (chemically unstable gases) Categories 1, 2, 3 Category 1 Compressed gas Liquified gas Refrigerated liquified gas Dissolved gas Categories 1, 2, 3, 4 Categories 1, 2 Type A

Hazard Classes

Corrosive to metals Acute toxicity

Skin corrosion/irritation Serious eye damage/eye irritation Respiratory sensitizer Skin sensitizer Germ cell mutagenicity Carcinogenicity Toxic to reproduction

Type B Type C and D Type E and F Type G Category 1 Category 1 Categories 1, 2

Environmental Hazards

Specific target organ toxicity following single exposure Specific target organ toxicity following repeated exposure Aspiration hazard Hazardous to the aquatic environment, short-term (acute)

Categories 1, 2, 3 Hazardous to the aquatic environment, long-term (chronic) Categories 1, 2, 3 Categories 1, 2, 3 Type A Type B

Hazards to ozone layer

Hazard Categories Type C and D Type E and F Type G Category 1 Categories 1, 2, 3, 4, 5 (oral) Categories 1, 2, 3, 4, 5 (dermal) Categories 1, 2, 3, 4, 5 (inhalation) Categories 1, 2, 3 Categories 1, 2, 2A, 2B Categories 1, 1A, 1B Categories 1, 1A, 1B Categories 1, 1B, 2 Categories 1, 1B, 2 Categories 1, 1B, 2 Additional category for effects on or via lactation Categories 1, 2, 3 Categories 1, 2 Categories 1, 2 Acute 1 Acute 2 Acute 3 Chronic 1 Chronic 2 Chronic 3 Chronic 4 Category 1

the difficulties of the task, confirmed by several revisions since then, the last being the fifth, in 2013 (for the history of GHS see ref 12). This situation is due to several factors, for instance, the complexity of the field of chemical hazards, the number of the prevailing different national and intranational systems around the word, the requirement of a certain extension of compatibility with these to make acceptable the adoption of the new system, and so forth. GHS is a recommendation, not a legal requirement, and its implementation has to be voluntarily agreed by the countries. To facilitate the adoption, the regulation consists of a set of blocks that can be adopted globally or individually (if the national legislation on those not adopted is compatible with GHS).9 Information on countries that have already adopted the regulation may be found in ref 13. The GHS regulation document7 is very long and complex (529 pages) and this is also true for national adoption regulations (for instance, the EU document,14 including appendices with detailed information, contains 1355 pages; in contrast, the U. S. legislation is comparatively shorter, 324 pages10).These documents are obviously only suitable for specialists, but more palatable information on GHS and its development can be found in refs 8,9, and 15−17. The impact of GHS on laboratory safety was discussed by Hill,8 that pointed the advantages and opportunities of its implementation, as well as the challenges and barriers that have to be overcome (for instance the conflict of the GHS and NFPA

Figure 1. Examples of hazard statements to show what the codes represent.

chemical substances and mixtures.12 The aim was to achieve a uniform system with global scope across the world for chemical hazard identification and communication and to replace the various systems used by different countries (or even by the different bodies that are responsible for different aspects of the problem in each countryenvironment, occupational health, transport, etc.). Besides facilitating the protection purpose, the uniform system allows eliminating part of the commercial barriers in the international chemical business. The elaboration of the system was slow, the final version being published only in 2002. This long gestation period shows 1902



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Figure 2. GHS pictograms and hazard classes and categories.

Diamond hazard rating systems, that use inverse scalesthere will be a mental barrier against the new scale for those that have used the Diamonds for a long time).18 Another problem is the difficulty of classification of chemicals with respect to health effects (toxicity), where discrepancies appear to be frequent.19 A recent paper18 refers the challenges of the changes with reference to the human behavior but presents results of a study that suggests that some of the identified potential problems may not be as insurmountable as it was thought (however, the authors remark that the samples of individuals inquired in the study were limited in scope).

The main purpose of this section is to provide a practical description, addressed to nonspecialist teachers and to students, on how the GHS information assembled on chemical hazards is transmitted in labels and SDS. Brief presentations of hazards classification, hazard symbols (pictograms), and signal words, and hazard and precautionary statements are provided. The relevant material about these items prescribed by GHS was collected in a spreadsheet included in the Supporting Information for easy reference when necessary, for instance, when students have to read labels and interpret the information provided in the laboratory or when they collect information from SDS to construct the greenness metrics discussed below. 1903



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Figure 3. Example of a precautionary statement to show what the codes represent.

GHS regulation classifies substances and mixtures according to their physical, health and environmental intrinsic hazards. For each of these, hazard classes are established which define the nature of the hazard. Each hazard class is divided in several hazard categories according to the severity (see Table 1).20 For instance, the class “skin corrosion/irritation” includes three hazard categories with decreasing hazard severity as shown (responses of tissue skin accordingly to defined time of exposure adopted for each category). To each hazard class and category are assigned hazard statements used to characterize the hazards (phrases that describe the nature and degree of the hazard). Hazard statements21 are represented by hazard codes, composed by a letter H and a number beginning with a figure indicating the hazard type (2 for physical, 3 for health, and 4 for environment hazards) followed by two figures corresponding to sequential numbering of hazards inside the class, as exemplified in Figure 1. The hazard code is intended to be used for reference purpose and should not be used to replace the hazard statement. Additional hazard statements, represented by hazard codes composed by the letters EUH and a number, are used in countries within the European Union (EU).22

Figure 4. Hazards (GHS) for copper(II) sulfate pentahydrate; data obtained from Sigma-Aldrich.25

Hazard symbols (pictograms−graphic elements intended to succinctly convey information) and signal words (a word, danger or warning, which indicates the relative level of severity of the hazards) are also defined. In Figure 2, the GHS pictograms and the hazard classes and categories to which they are assigned are presented. All the hazardous substances or mixtures are assigned with hazards statements, but not always with pictograms or signal words.20 Precautionary statements21 may be also assigned to the substances. These are phrases that describe recommended measures that should be taken to minimize or prevent adverse effects (resulting from exposures, improper handling, or storage) caused by hazardous substances or mixtures.20 Precautionary statements are represented by codes composed

Table 2. Example of the Information Provided about Hazard Communicationsα

α

Complete information is provided in the Supporting Information. 1904



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Table 3. Scores To Classify the Hazards of Substances, Using GHS Regulation To Classify the Hazards Hazards Physical

Hazard statements

Additional hazards statements, only used in EU

Health

Hazard statements


Environmental

Hazard statements


Score, Green Star

Hazard Codes

Classification, Green Circle

H200, H201, H202, H203, H205, H220, H222, H224, H225, H228 (category 1), H230, H270, H271, H272 (category 2), H240, H241, H242 (Type C and D), H250, H251, H260, H261 (category2) H204, H221, H223, H226, H227, H228 (category 2), H229, H231, H272 (category 3), H242 (Type E and F), H252, H261 (category3), H280, H281, H290 No indication EUH001, EUH 006, EUH 014, EUH 018, EUH 019, EUH044, EUH 209

3

High

2

Moderate

1 3

Low High

EUH209A No indication H300, H301, H304, H310, H311, H314, H318, H330, H331, H334, H340, H341, H350, H351, H360, H361, H370, H371, H372, H373 H302, H305, H312, H315, H317, H319, H332, H335, H336, H362 No indication EUH029, EUH031, EUH032, EUH070, EUH071, EUH201, EUH202, EUH206, EUH207

2 1 3

Moderate Low High

2 1 3

Moderate Low High

EUH066, EUH201A, EUH203, EUH204, EUH205, EUH208 No indication H400, H401, H410, H411, H420 H402, H412, H413 No indication EUH059

2 1 3 2 1 3

Moderate Low High Moderate Low High

No indication

1

Low

by a letter P and a number beginning with 1 for general, 2 for prevention, 3 for response, 4 for storage, and 5 for disposal precautionary statements (Figure 3). A guide to GHS by OSHA (Occupational Safety and Health Administration)23 provides useful information but seems rather long for beginners. The Excel file included in the Supporting Information, aimed at these, contains all the hazard statements and respective hazard classes and categories, hazard pictograms, signal words, and a list of the precautionary statements; pictograms for transport14,24 are also presented. It was decided to include also the pictograms commonly referred as labels in transport regulations prescribed by the “UN Model Regulations on the Transport of Dangerous Goods”20 because these pictograms may be confused by teachers and students with the GHS pictograms (Table 2 includes an example of the information provided). To increase the usefulness of Excel and facilitate its use, it includes also relevant figures and tables from this text. An example of the hazards for copper(II) sulfate pentahydrate, together with precautionary statements as they appear in SDS, is presented in Figure 4.

Table 4. Criteria To Classify Substances Regarding Degradability and Renewability Score (S), Green Star

Characteristics

Criteria

Degradability

Not degradable and may not be treated to render the substances degradable to innocuous products Not degradable but may be treated to render the substances degradable to innocuous products Degradable and breakable to innocuous products Not renewable

3

Renewable

1

Renewability

Classification, Green Circle Not degradable

2

1

Degradable

3

Not renewable Renewable

P3, P5, and P9) and of potential chemical accidents (P12) of all the substances involved (raw materials/feedstocks, products, byproducts, solvents and other auxiliary substances such as catalytic reagents, solvents, separation agents, etc.) and wastes; (iv) renewability of raw materials/feedstocks and tendency to break down into innocuous degradation products (P7 and P10); and (v) the use of derivatizations or similar operation (P8).4 Then, to evaluate the hazards to human health and the environment and of potential chemical accident, every substance is classified in a scale from 1 to 3 (for green star) or from having low to high hazards (for the green circle), by criteria in Table 3, where all the relevant information gathered from the original document7 is systematized. This table shows the scores attributed to the several hazard codes (hazard statements) in the construction of the metrics. Additionally,

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NEW CRITERIA FOR CONSTRUCTION OF THE METRICS The metrics are constructed accordingly to criteria to assess the accomplishment of each of the 12 principles relevant for the situation under analysis. The assessment of greenness begins by examining the protocol of the experiment to obtain information about: (i) stoichiometric reagents in excess (information is used to assess the accomplishment of principle P2); (ii) the conditions of pressure and temperature (accomplishment of P6); (iii) hazards to human health and to the environment (P1, 1905



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Table 5. Scores (S) To Construct the Green Starα Green Chemistry Principle P1Prevention

P2Atom Economy

P3Less Hazardous Chemical Synthesis

Criteria

S

Waste is innocuous (S = 1, Table 3) Waste involves a moderate hazard to human health and environment (S = 2, Table 3, for at least one substance, no substances with S = 3) Waste involves a high hazard to human health and environment (S = 3, Table 3, for at least one substance) Reactions without excess of reagents (≤10%) and without formation of byproducts Reactions without excess of reagents (≤10%) and with formation of byproducts Reactions with excess of reagents (>10%) and without formation of byproducts Reactions with excess of reagents (>10%) and with formation of byproducts All substances involved are innocuous (S = 1, Table 3)

Substances involved with moderate hazard to human health and environment (S = 2,Table 3, for at least one substance, no substances with S = 3) Substances involved with high hazard to human health and environment (S = 3, Table 3, for at least one substance) P5Safer Solvents and Auxiliary Solvents and other auxiliary substances are not used, but if used are innocuous (S = 1, Table 3) Substances Solvents or other auxiliary substances are used with moderate hazard to human health and environment (S = 2, Table 3, for at least one substance, no substances with S = 3) Solvents or other auxiliary substances are used with high hazard to human health and environment (S = 3, Table 3, for at least one substance) P6Increase Energy Efficiency Room temperature and pressure Room pressure and temperature between 0 and 100 °C when cooling or heating is needed Pressure different from room pressure and/or temperature >100 °C or less than 0 °C P7Use Renewable Feedstocks All raw materials/feedstocks are renewable (S = 1, Table 4) At least one raw material/feedstock is renewable, water is not considered (S = 1, Table 4) None of the raw materials/feedstocks are renewable, water is not considered (S = 3, Table 4) P8Reduce Derivatives Derivatizations or similar operations are not used Only one derivatization or similar operation is used More than one derivatization or similar operations are used P9Catalysts Catalysts are not used and if used are innocuous (S = 1, Table 3) Catalysts are used with moderate hazard to human health and environment (S = 2, Table 3) Catalysts are used with high hazard to human health and environment (S = 3, Table 3) P10Design for Degradation All substances involved are degradable and break down to innocuous products (S = 1, Table 4) All substances involved not degradable may be treated to render them degradable to innocuous products (S = 2, Table 4) At least one substance is not degradable or it may not be treated to render it degradable to innocuous products (S = 3, Table 4) P12Safer Chemistry for Substances used with low hazard to cause chemical accidents (S = 1, Table 3, considering health and physical hazards) Accident Prevention Substances used with moderate hazard to cause chemical accidents (S = 2, Table 3, for at least one substance considering health and physical hazards, no substances with S = 3) Substances used with high hazard to cause chemical accidents (S = 3, Table 3, for at least one substance considering health and physical hazards) α

3 2 1 3 2 2 1 3 2 1 3 2 1 3 2 1 3 2 1 3 2 1 3 2 1 3 2 1 3 2 1

Original version published in ref 2.

in Table 5. These criteria involve three levels of accomplishment of the principles, used in the green star. The green circle uses a simpler binary criterion−accomplishment/no accomplishment of each principle, assessed by the criteria defined before in ref 4 and presented in Table 6. The green star is represented in an Excel radar chart1 and the green circle in an Excel pie chart;4 the colors green/red are used to identify the accomplishment/no accomplishment of the principles (green circle) or the degree of their accomplishment, 1 to 3 (green star). A visual inspection provides an indication of the global greennessthe greener is the chart, the higher is the degree of greenness. For comparison of different green stars, a Green Star Area Index (GSAI) can be calculated as a percentage (100 × green area of the green star/area of the green star of maximum greenness). GSAI varies between 100 (maximum greenness) and 0 (minimum greenness). Similarly, for comparison of different green circles the Accomplishment of Principles Index (API) may be calculated as the percentage of principles accomplished (100 × number of principles accomplished/total

information to identify whether the substances are renewable and break down to innocuous degradation products is collected. This information is used to classify the substances following the criteria in Table 4. The information above can be obtained from the SDS available online in the sites of several manufacturers of chemistry products; when there is no information, the worst score is chosen. In the Supporting Information, to facilitate the management of the information in the construction of the metrics, a simplified alternative to Table 3 in this text (Supporting Information Table S1) presents the scores attributed to all hazard codes for this purpose, with the hazard codes listed and sorted by the number of code; colors are used to differentiate the type of hazards. Information about how the scores in Table 3 were fixed is also provided in the Supporting Information.

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GREEN STARS AND GREEN CIRCLES The green star is constructed giving the scores 1, 2, or 3 (the maximum value of greenness) to each of the 12 principles following the criteria defined before1−3 and presented in detail 1906



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Table 6. Criteria To Assess the Accomplishment of the Principles of Green Chemistry To Construct the Green Circleα Green Chemistry Principle P1Prevention P2Atom Economy P3Less hazardous chemical synthesis P5Safer solvents and auxiliary substances P6Increase energy efficiency P7Use renewable feedstocks P8Reduce derivatives P9Catalysts P10Design for degradation P12Safer chemistry for accident prevention α

Criteria for Accomplishment of the Principle No waste is produced or, if produced, has low hazard to human health and the environment (Table 3) Reactions without excess of reagents (≤10%) and without formation of byproducts (water not considered) All the substances involved have low hazards to human health and the environment (Table 3) Neither solvents nor other auxiliary substances are used or, if used, have low hazards to human health and the environment (Table 3) Environmental pressure and temperature All raw materials/feedstocks involved are renewable (Table 4) Derivatizations or similar operations are not used Catalysts not necessary or they have low hazards to human health and the environment (Table 3) All substances involved are degradable and break down to innocuous products (Table 4) All the substances involved have low hazards of chemical accident, considering the health and physical hazards (Table 3)

Original version published in ref 4.

number of principles that apply). When all the principles are accomplished API = 100, if none is, API = 0. Due to different criteria used for green star and green circle, the green star uses three levels of evaluation of the principles, whereas for the green circle the criterion is binaryaccomplishment/no accomplishment. For this reason, it is not possible to compare the greenness of two different syntheses using GSAI for one and API for the other. The present revision included not only the use of the GHS system but also an improvement of the graphic look of the green star to facilitate the vision of the individual evaluation of the principles. Now, when the principle is fully accomplished the color is green, when it is partially accomplished, part of the corner is green and part is red, and when it is not accomplished it is completely red. The same system of colors is used in both the green star and the green circle, and in the first allows an easier visual assessment of the degree of accomplishment of the principles than before. Moreover, with this new format, it is possible to represent the principles not subjected to assessment (Figure 5C and D). In Figure 5, the green star (Figure 5A and C) and the green circle (Figure 5B and D) for the synthesis of tetraamminecopper (II) sulfate monohydrate are presented.3,4 These new metrics have replaced with success the old ones in our teaching green chemistry activities. The green star is used by university students in our chemistry courses to assess the greenness of the syntheses, to choose the greenest ones between several protocols available in the literature for assigned cases, and also to assess how greenness changes when improvements are introduced. They are also being used in ten secondary schools in Portugal (Oporto region) in a project under development with the goal of introducing green chemistry to secondary schools that involves more than 1000 of students (10th grade, about 400 students; 11th and 12th grades, more than 300 students each). The green circle is used in the 10th and 11th grades as it is easier to construct, but in the 12th, the green star is used instead. Students are using the new metrics with increased success; in particular, the new

Figure 5. Green star and green circle for the syntheses tetraamminecopper(II) sulfate monohydrate; (A) and (B) show only the principles that apply; (C) and (D) also show that principles P4 and P11 are not assessed. Green Star Area Index (GSAI) = 100 × green area of the star/green area of the star of maximum greenness. Accomplishment of Principles Index (API) = 100 × number of principles accomplished/total number of principles that apply. Only the principles that apply to the situation are considered in these calculations. The numbers 1, 2, and 3 define the radial scale of the green star plot.

graphics of green star facilitates the reading of the greenness, allowing easier interpretation of results and further discussion of improvements of synthesis protocols. Moreover the use of these new versions of the metrics is a good opportunity for a presentation of GHS to students, as well as for calling increased attention to the importance of safety in the use of chemicals.

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CONCLUSIONS GHS provides a more detailed assessment of the hazards of chemicals than the previous system based in the hazards symbols and, although being more complex and requiring additional work, it supports a better evaluation of greenness by these revised versions of the metrics. The new graphics of green star makes its reading by visual inspection easier, thus providing a more precise assessment of the level of greenness.

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ASSOCIATED CONTENT

S Supporting Information *

Three files are provided: (i) Excel file with all the hazard statements and respective hazard classes and categories, hazard pictograms, signal words, pictograms for transport, and a list of the precautionary statements. (ii) Information for the 1907



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548/EEC and 1999/45/EC, and amending Regulation (EC) No 1907/2006, 2008. http://eur-lex.europa.eu/LexUriServ/LexUriServ. do?uri=OJ:L:2008:353:0001:1355:EN:PDF (accessed Aug 2014). (15) Winder, C.; Azzi, R.; Wagner, D. The Development of the Globally Harmonized System (GHS) of Classification and Labeling of Hazardous Chemicals. J. Hazard. Mater. 2005, 125 (1−3), 29−49. (16) Silk, J. C. Development of a Globally Harmonized System for Hazard Communication. Int. J. Hyg. Environ. Health 2003, 206 (4−5), 447−452. (17) Pratt, I. S. Global Harmonization of Classification and Labeling of Hazardous Chemicals. Toxicol. Lett. 2002, 128 (1−3), 5−15. (18) Black, T.; Wood-Black, F. Challenges of Going Global Complying with the New Global Harmonization Standard. J. Chem. Health Saf. 2013, 20 (6), 19−23. (19) ChemWatch Briefing Notes, GHS Busters. https://www. swiftpage6.com/speasapage.aspx?X=2Y0RSDXNI9G1KQ0R00YEWW (accessed Aug 2014). (20) United Nations Economic Commission for Europe (UNECE), Globally Harmonized System of Classification and Labelling of Chemicals (GHS), 5th revised ed., Annex 1, 2013. http://www. unece.org/fileadmin/DAM/trans/danger/publi/ghs/ghs_rev05/ English/05e_annex1.pdf (accessed Aug 2014). (21) United Nations Economic Commission for Europe (UNECE), Globally Harmonized System of Classification and Labelling of Chemicals (GHS), 5th revised ed., Annex 3, 2013. http://www. unece.org/fileadmin/DAM/trans/danger/publi/ghs/ghs_rev05/ English/07e_annex3.pdf (accessed Aug 2014). (22) The European Parliament and The Council, Regulation (Ec) No 1272/2008 on Classification, Labelling and Packaging of Substances and Mixtures, amending and repealing Directives 67/ 548/EEC and 1999/45/EC, and amending Regulation (EC) No 1907/2006, 2008, Part 5, p 141. http://eur-lex.europa.eu/LexUriServ/ LexUriServ.do?uri=OJ:L:2008:353:0001:1355:EN:PDF (accessed Aug 2014). (23) Occupational Safety & Health Administration (OSHA), A Guide to the Globally Harmonized System of Classification and Labelling of Chemicals (GHS). https://www.osha.gov/dsg/hazcom/ ghs.html (accessed Aug 2014). (24) United Nations Economic Commission for Europe (UNECE), GHS pictograms. http://www.unece.org/trans/danger/publi/ghs/ pictograms.html (accessed Aug 2014). (25) Sigma-Aldrich, MSDS for Copper(II) Sulfate Pentahydrate. http://www.sigmaaldrich.com/MSDS/MSDS/DisplayMSDSPage. do?country=US&language=en&productNumber=209198&brand= SIAL&PageToGoToURL=http%3A%2F%2Fwww.sigmaaldrich. com%2Fcatalog%2Fproduct%2Fsial%2F209198%3Flang%3Den (accessed Aug 2014).

construction of green star and green circle, including tables presenting the scores attributed to hazard codes and how the scores were fixed and also tables with criteria to score the principles to construct the green star and green circle. (iii) Excel file to obtain the green star and calculate GSAI. This material is available via the Internet at http://pubs.acs.org/.

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AUTHOR INFORMATION

Corresponding Author

*E-mail: [email protected]. Notes

The authors declare no competing financial interest.

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ACKNOWLEDGMENTS M.G.T.C. Ribeiro’s work has been supported by Fundaçaõ para a Ciência e a Tecnologia through grant no. PEst-C/EQB/ LA0006/2011. S.F.Y. thanks CAPES Foundation for a posdoctoral grant under a cooperation program awarded by CAPES (Brasil)/FCT (Portugal).

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REFERENCES

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