Handsoap Life Cycle Assessment

HANDSOAP COMPARISON OF THE LIFE CYCLES OF VARIOUS RECIPES AND PROCESSING METHODS

DATE:

Author: Kimi Ceridon 61 Arlington Street Medford, MA 02155 857.523.0804 kceridon@kalepa-tech.com

21-December-2009

1

INTRODUCTION

Commonly, choices for improving a consumer’s environmental sustainability tend to focus on big ticket items such as vehicle purchases or major lifestyle changes such as selecting local, organic food supplies. The cost and effort associated with these changes may be discouraging or simply not feasible to implement due to time or budget constraints. However, many everyday choices offer opportunities to make small improvements in personal sustainability while involving no additional effort or cost to implement. The barrier to making such choices is typically a lack of consumer information and communication allowing them to compare the environmental impacts of the everyday products they consume. These are products consumers readily and conveniently access and interact with everyday without much thought to their origins including items like personal hygiene products, home cleaning products and everyday disposables and durables. One such everyday product consumers interact with multiple times a day is soap used for handwashing. The following study takes a closer look at the environmental performance two types of hand soap alternatives – bar soap and liquid soap.

There is large variation in hand soap products available on the market. Differences in the ecological impact associated with these products can be attributed to everything from variations in the basic formulation to differences in packaging methods to size of manufacturing scale to dispenser methods to how a customer uses the product. This initial survey focuses on studying and comparing the ecological impacts of a few versions of these products. The goal is to examine broad product categories to evaluate the degree of disparity between the environmental impacts of the products, evaluate hotspots that offer opportunities for decreasing the disparity and, through a brief sensitivity assessment, guide future studies in focusing on important environmental issues associated with hand soap formulation, packaging, use and disposal. The study subsets are as follows: Comparison of environmental impacts due to of ingredients, packaging and manufacturing for basic formulas of bar and liquid hand soap Sensitivity of recovering one of the main byproducts of soap manufacturing – glycerin.

Comparison of environmental impacts when water usage and disposal scenarios are considered.

Sensitivity to alternative water usage scenarios.

The study summarized here uses one methodology to evaluate multiple scenarios. The goal is to determine the best path to pursue for future studies and provide preliminary guidance for formulating or purchasing future products.

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SOAP – THE BASICS

In their most basic form, all soaps are made of three basic of ingredients – fats or oils, a caustic and water.

Blending these ingredients at an elevated temperature causes a chemical reaction called saponification to occur.

1 This is represented as a simple chemical formula shown in Equation 1 . fat + 3NaOH → glycerine + 3 soap

Equation 1

The general chemical formula for soaps is RCOOX, where the X represents an element from the first column in the periodic table or an alkali metal, the R represents a hydrocarbon chain with 8 to 22 carbon elements surrounded

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2

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by hydrogens. Since soap is a salt, it partially ionizes in water where one end of the RCOO ion attracts water, the other attracts oils. This gives soap its unique cleansing properties.

The raw ingredients used give soap different properties. The type of fat or oil used determines the length of the resulting hydrocarbon chain. Examples of fats and oils used for soap are animal tallow and lard or plant oils such as palm oil, coconut oil and soybean oil. Soaps may include a single fat or oil or a combination of many fats and oils. This initial exploration is limited natural vegetable and animal oils and fats and synthetic oils and fats are not considered. Although it is not necessary, it is common to make hard bar soap from fats that are solid at room temperature and ‘soft’ liquid soap from oils that are liquid at room temperature. Whether hard bar soap or ‘soft’ liquid soap results is determined from the type of caustic used. Sodium hydroxide (NaOH) produces a bar soap and potassium hydroxide (KOH) produces a liquid soap. It is also suggested that deionized water be used to minimize contaminates in the final product.

Manufacturing soap involves one of two methods for processing soap – cold processing (also called kettle or batch processing) and hot processing (also called continuous processing). Continuous processing is typically used for large scale manufacturing operations and due to additional steps such as salt precipitation, it is more forgiving of impurities and imperfect ratios of fat to caustic. In all cases, the basic process can be described as heating the fat 3 or oil with warm caustic dissolved in water to temperatures between 175°F to 212°F. Depending on the reduction of lye to fat ratio, glycerin is also produced in this process. When some bar soaps are manufactured, the excess glycerin is incorporated into the bar for added moisturizing properties. This is especially true for homemade and specialty soaps. On the other hand, it is common for larger scale manufacturing operations to settle the warm mixture and remove the excess glycerin. From a literature search, ten to twenty percent by volume of the mixture may be recoverable byproduct glycerin.

While processes such as precipitation, compaction, cutting and forming consume energy, it is assumed this consumption is marginal compared to that of heating the fats, oils and lyes. Additionally, while energy savings likely result from large scale manufacturing, the literature indicates continuous processing is employed to ensure consistent product quality rather than for reduced energy consumption. For these reasons, the difference between these processes is not addressed in this study.

Energy consumption is a large contributor to environmental impacts of soap during the manufacturing process.

From the literature, the amount of energy required to make soap was not clearly indicated. Energy consumption is estimated through a two methods. First, manufacturers of soap making equipment indicate the amount of time required to heat a batch of soap. Using this value and the equipment wattage, the approximate energy consumption per batch is determined. The second method used tabulated thermal properties to evaluate the amount of energy required to heat ingredients. Thermal property values for a general category of ‘fats’ are readily available, but values for specific fats is not. An average value was used for estimates. Caustic solutions have highly temperature dependent enthalpies even at low concentrations. So, an average value was used for this estimate.

Since a thorough thermal analysis of a soap making system is time prohibitive for this study, the resulting values are estimate meant to roughly validate the first method.

The use-phase of hand soap includes the need for packaging as well as the consumption of municipal water during product use. These are significant contributors to the ecological impacts of hand soaps. User behavior also differs Page 3

between the type of product used. In the study “Comparing the Environmental Footprint of Consumer Products: 4 The Relevance of Different Life Cycle Phases,” Annette Koehler estimates the amount of soap used in each case as well as the corresponding amount of hot water consumed during a single hand washing. That study summarizes the differences in user behavior as follows: Amount of soap product • Bar soap: 0.35 g • Liquid soap: 2.3 g Water use for hand washing • Bar soap: 0.91 liters (0.24 gal) • Liquid soap: 0.64 liters (0.17 gal) • Water temperature 38°C (100.4°F) • Light fuel oil boiler for warm water supply The above values are used for a baseline in this study, but some modifications to the assumptions used by Koehler are used.

Many consumers do not think much about the end of life of their hand soaps. It simply goes down the drain with the water. In this study, treating the soap at a municipal water treatment facility is considered. The end-of-life of the packaging is compared for a few alternative scenarios. For this study, it is assumed bar soap is typically packaged in coated paperboard packaging. For the liquid soap, it is assumed an 8-ounce polyethylene terephthalate (PET) plastic bottle with pump that includes a small steel spring is used for packaging. While it is not uncommon to recycle these bottles which are labeled with resin identification code ‘1’ for ease of sorting, alternatives to ‘Waste scenario/US U’ are not considered in this particular study.

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STUDY DEFININTION

Methodology For this study, a faculty version of SimaPro 7.1.8 was used. While it does not impact the outcomes from the methodology or datasets, it should be noted that as a faculty version, a few features, such as editing the specifics of ‘Data Quality Requirements’, are disabled. Impact 2002+ and the EcoInvent Unit process library are the primary life cycle methodology and library used for this study. This methodology allows the results to be presented as both mid-point characterizations as well as end-point damage assessments. Both end-point and mid-point results are discussed when appropriate.

Goal and Scope This study evaluates the ecological impacts of various formulations of hand soaps. Each step of this study builds the evaluation on previous phases through the end of life. In addition sensitivity analysis of a few of the phases is conducted to evaluate impacts beyond the initial study baselines.

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The study first compares the ingredients used for some basic formulations of handsoap including a sensitivity analysis of a few recipes. Building on this comparison, product life cycle phases are added to the study. The impacts are compared for a few product recipes through manufacturing and packaging. This includes a sensitivity analysis of recovering glycerin byproduct. Finally, the impacts of usage and disposal are included.

In this case, the baselines provided by the Koehler study are first applied with some modified assumptions, but additional scenarios are explored to evaluate the sensitivity of impacts related to water usage.

Functional Unit The Koehler study utilized a unit of a “one-time hand washing of approximately 30 seconds” for its functional unit. For this study, it is preferred to use one thousand times this unit or 1000 hand washing lasting approximately 30 seconds each. This selection over that of the Koehler study is arbitrary based purely on preference. Ultimately, it is mere a matter of scaling. For the purposes of this study, the choice of “Light fuel oil boiler for warm water supply” is modified to “Electricity, production mix US/US U” for warm water supply.

In calculating the energy necessary to heat the water, an initial tap water temperature of 14°C is used where a change in temperature of 25°C is used for a baseline.

System definition and boundaries As this study builds the system definition and boundary expand to include a new phase in the product life cycle. Early phases, including resource extraction and manufacturing, are considered independently. Later phases are built on these initial comparisons and evaluations.

The first part of this study examines the ingredients used to make soaps including various alternative recipes.

The EcoInvent Unit Process library offers three options for solid fats - tallow, coconut oil and palm oil - and one option for a liquid fat – soybean oil. All studies use caustics from the technosphere and deionised industrial water for processing. The data is country specific and there are some recognized inconsistencies in the information included in the data. These uncertainties and inconsistencies are noted, but not treated in this study. This is left for later, more in-depth studies. In this case, the following basic recipes are considered: Bar Soap made from 100% Animal Fat (Tallow, at Plant/CH U) Bar Soap made from 100% Coconut Oil (Crude Coconut Oil, at plant/PH U) Bar Soap made from 100 % Palm Oil (Palm Oil, at oil mill/MY U) Bar Soap from 50% Palm Oil and 50% Coconut Oil Bar Soap from 50% Palm Oil and 50% Animal Fat Liquid Soap from 100% Soybean Oil (Soybean Oil, at oil mill/US U) The manufacturing process is added to these recipes for this evaluation. Using data for soap making equipment and some order of magnitude thermal calculations, the amount of energy to make 128 ounces (1 gallon) of soap was used. Less energy is required to heat liquid fats to the necessary temperatures. The EcoInvent Unit Process library includes ‘Soap, at plant/RER U’ as a material process. This process is not used for this study as it does not include caustics in the process, the stated energy usage agrees well with the values calculated for this study.

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In addition to the manufacturing process, the packaging for the products is included as follows: Bar Soap Packaging: A single bar is typically 4.5 ounces (2.75 bars for 1000 uses) 2 2 Package is 8in x 4-n (32in ) 110 # paper (385g/m ) for 7.9g/box 21.8g of coated paperboard for 1000 uses Liquid Soap Packaging A single bottle holds 8 ounces of soap (10 bottles for 1000 uses) Packages are PET body, PET pump with a steel spring 3 Density PET of 1.37g/cm , so it is approximately 125g of PET (bottle = 80g, pump= 45g) 3 The spring is a 0.060-in diameter x 4 inches long steel (7.85g/cm ) for 2g of steel 1250g of PET and 20g of steel for 1000 uses Examining the impacts associated with the manufacturing of the soaps of interest, but the most significant impacts come from the water used during the handwashing phase of the life cycle. Since no user surveys were completed in association with this study, the values presented by the Koehler study are used to evaluate this phase. In addition to this baseline, some alternative scenarios are presented to evaluate the sensitivity of these results to the user behaviors during handwashing. In the interest of remaining brief while exploring the use phase fully, the disposal scenarios are incorporated into the handwashing lifecycle evaluation. As is later shown, the disposal scenarios do not impact the overall comparisons.

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RESULTS

Recipe Comparisons - Raw Ingredient While Equation 1 can be used to create recipes based on chemical formulas of fats, it was determined that online recipes for homemade soaps and other literature provided sufficient details to construct SimaPro processes. Notable, the websites for the Majestic Mountain Sage (www.thesage.com), Willow Way (www.soapequipment.com), The Original Soap Dish (www.thesoapdish.com), About Candle and Soap Making (www.candleandsoap.about.com) and Snow Drift Farm Inc (www.snowdriftfarm.com) were examined to obtain a ratio of fats to caustics to water for bar and liquid soap.

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100% Animal Fat 100% Coconut Oil 100% Palm Oil 50% Palm / 50% Coconut 50% Palm / 50% Animal

Figure 1 – Mid-point comparison of bar soap recipes

The mid-point characterization results for various bar soap recipes are shown in Figure 1. As can be seen, the entire plant base oils result in negative impact values for a non-carcinogens, aquatic ecotoxicity and terrestrial ecotoxicity. This is due to the fact these oils are derived from terrestrial based plants that commonly produce other useful byproducts/effluents which results in negative impacts that improve the ecological impacts. In the case of coconut oil, the Life Cycle Inventory shows byproducts/effluents such as ‘Protein peas, IP at farm/CH U’ and ‘Palm Fruit Bunches, at farm/MY U.’

100% Animal Fat 100% Coconut Oil 100% Palm Oil 50% Palm / 50% Coconut 50% Palm / 50% Animal

Figure 2 – End-point comparison of bar soap recipes

While the negative impacts presented in Figure 1 appear significant in a midpoint result, the end-point damage assessment result shown in Figure 2 reveal a different scenario. Despite the negative impacts in certain categories, the damage assessment shows that overall, the bar soap from 100% Animal Fat has lower overall impacts. This is due to the fact that in the EcoInvent Unit Process Library, only the energy input to render tallow is considered. Tallow is a byproduct of meat packing where ‘The animal husbandry and the process of slaughtering are not included, since the raw material is considered as waste.’

On a volumetric basis of 128 ounces, Figure 3 shows a comparison of the ingredients of bar soaps with those

Page 7 100% Animal Fat 50% Palm / 50% Coconut 50% Palm / 50% Animal Liquid 100% Soybean

Figure 3 – Comparison of bar soap and liquid soap recipes

of liquid soaps. Comparing bar soaps to liquid soaps on a volumetric basis is moot since a different amount of each is used during later phases. However, the information is presented for edification.

Manufaturing- Processing and Packaging Baseline The manufacturing of soap primarily includes the energy input for heating and blending the ingredients. While other equipment, such as compactors, cutters and conveyers, are necessary for large scale process, their energy consumption is marginal compared to the energy required for heating the fats/oils, caustic and waters to sufficient temperature. The calculated values for energy input agree well with the values that appear in the EcoInvent Unit Process ‘Soap, at plant/RER U’. While this pre-defined unit process uses ‘Heat, unspecific, in chemical plant/RER U’ as the energy source for heating, this study uses ‘Electricity, production mix US/US U’ instead. While a chemical plant may use sources such as spent process heat, ‘unspecific’ appeared too generalized so a specific energy source was selected for all manufacturing processes. This is uniformly applied and the ecological impacts of specific manufacturing methods are not considered, thus the comparisons should hold.

The distance traveled for each product is assumed equivalent. For the purposes of this study, this assumption is valid because the scope is broadly defined spanning general categories of handsoap. For example, if a manufacturer were considering comparing co-located product lines to determine which is more ecologically friendly, this study would be applicable. However, if the scope were instead meant to compare the environmental performance homemade soaps to manufactured soaps or the environmental performance of different sources of raw ingredients, this assumption insufficiently captures that scope. The study does not capture the transportation differences between small batch and large batch processing or differences between raw ingredients sourced from different global locations. As will be shown in the use-phase

100% Animal Fat 50% Palm / 50% Animal 50% Palm / 50% Coconut Liquid 100% Soybean

Figure 4 –Damage assessment comparison of bar and liquid

comparison, this assumption is also valid considering transportations ecological impacts are small relative to other ecological impacts over the entire life cycle.

The impacts due to product packaging are included in the following graphs. Figure 4 compares the damage assessment of three bar soap recipes and one liquid soap recipe used for one functional unit of ‘1000 hand washing lasting approximately 30 seconds each.’

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From Figure 4, it appears Liquid Hand Soap has larger impacts relative to any bar soap at this stage in the product life cycle. While single score assessment is not sufficient for ISO14040, Figure 5 is shown to emphasize the disparity between bars soaps and liquid soaps through manufacturing phase for 1000 handwashes.

4 3.8 3.6

Human Health

3.4 3.2

Ecosystem Quality

3 2.8

Climate Change

2.6 2.4

Resources

mPt

2.2 2 1.8 1.6 1.4 1.2 1 0.8 0.6 0.4 0.2 0

Bar Hand Soap (100% Animal Fat)

Bar Hand Soap(50/50 Palm/Animal) Human health

Bar Hand Soap(50/50 Palm/Coconut) Ecosystem quality

Climate change

Liquid Hand Soap (Soybean Oil)

Resources

Figure 5 – Single score comparison of bar and liquid

Figure 6 examines the relative contributions to the ecological impacts of liquid soap. It is notable that liquid soap has large contributions from packaging and soap manufacturing. The disparity between liquid soap and bar soap is due to the quantity of product per functional unit. While 2.75 packages of bar soap are required, 10 packages of

Manufacturing Transport Waste Packaging

Figure 6 – Damage assessment for liquid soap manufacturing phases.

liquid soap are required for 1000 handwashes. This represents a significant difference in raw materials input.

Manufacturing - Glycerin Byproducts Investigation Glycerin is a byproduct of soap manufacturing. In some cases, the glycerin is left in the soap to improve the skin conditioning properties of the product. However, glycerin is an economically profitable product commonly used in products such as explosives. For this reason, a sensitivity analysis evaluating the recovery of 10% and 25% glycerin by volume is completed.

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Since this sensitivity analysis is meant to evaluate the relative reductions in ecological impacts, the comparison is completed on a per volume basis. This choice is sufficient for evaluating the avoided impacts due to recovering glycerin. On a volumetric basis, the differences between bar soap and liquid soap are not relevant, but Figure 7 shows a comparison for both bar and liquid soaps on a single plot. This is done in the interest of space rather than relevance between the product types. As can be seen, recovery of 10% glycerin results in a 2% discount in human health impacts, a <1% discount in ecosystem quality, a 3% discount in climate change and a 6% discount in resource depletion impacts.

120 115

Bar Soap (50/50 Palm/Coconut)

110 105 100

Bar Soap + 10% Glycerin Byproduct

95 90

Bar Soap + 25% Glycerin Byproduct

85 80

Liquid Soap (100% Soybean)

75 70 %

65

Liquid Soap + 10% Glycerin Byproduct

60 55

Liquid Soap + 25% Glycerin Byproduct

50 45 40 35 30 25 20 15 10 5 0

Human health

Ecosystem quality

Climate change

Resources

Figure 7 – Sensitivity analysis for glycerin byproducts

a Manu of Bar Soap (50/50 Palm/Coconut) c Manu of Liquid Soap (100% Soybeam Oil)

Bar Soap + 10% Glycerin (50/50 Palm/Coconut) Liquid Soap + 10% Glycerin (50/50 Palm/Coconut)

Bar Soap + 25% Glycerin (50/50 Palm/Coconut) Liquid Soap + 25% Glycerin (50/50 Palm/Coconut)

Cumulatively these values are significant in the manufacturing phase of the product, but as will later be shown, they are not as significant when the use phase is considered. Formulations using glycerin byproducts are not used for the remainder of this study.

Use Phase – Handwashing Baseline As has been indicated in the previous discussions, the use phase contributes significantly to the ecological impacts of handwashing. From the previous discussions, the impacts due to liquid handsoap manufacturing and packaging are significantly higher than that of bar soap. For this part of the assessment, the values presented in the Koehler study are used.

Per functional unit, handwashing consumes water at a rate of 2600 times the mass of bar soap and 260 times the mass of liquid soap. While relative ecological impacts of materials are not equated to their relative mass in a life cycle, this does represent significant disparity in this particular study. This is especially true when comparing the usage of bar soap to liquid soap. The affect is compounded when the energy required to heat the water is included. In this case, it is assumed ‘Tap water, at user/RER U’ is heated using ‘Electricity, production mix US/US U’ from 14°C to 28°C. To demonstrate the contributions water usage and water heating have on the total life cycle of handsoap products, Figures 8 and 9 show the damage assessment contributions per product phase for 100% soybean oil liquid soap and 50% animal fat/50% palm oil bar soap respectively. In both plots, the water and heat usage is 120 115 110 105 100 95 90 85

Manufacturing

80 75

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Transport

70 %

65

Waste

60 55 50

Water + Heat in Use Phase

45 40

Packaging

35 30 25 20 15 10 5 0

Figure 8 – Damage assessment usage of liquid soap.

Ecosystem quality per phase including Climate change Resources

Human health

the largest contributor to the impacts. In the case of liquid soap, the packaging and manufacturing phases do show notable contributions as well.

Figure 10 compares damage assessment for the life cycle of these two products as well as two additional bar soaps. In this view, the comparison of these two products is not as obvious which product offers the better ecological impact. Figure 11 presents the same information in a single factor comparison. The differences Manufacturing between bars soaps is moot which is largely attributed to the fact the use phases are equivalentTransport and the Waste largest contributor to the impacts. The liquid soap yields a 20% improvement over bar soap which, even with Packaging the larger manufacturing and packaging impacts, is attributed to the lower quantities of water and heat during Water + Heat in Use Phase use phase. To evaluate these comparisons closer, earlier assumptions about raw material sourcing, transportation, energy sources and additional manufacturing processes needs to be included.

120 115 110 105 100

Figure 9 – Damage assessment per phase including usage of bar soap.

95 120 85 115 80 110 75 105 70 100 95 65 90 60 85 55 80 50 75 70 45 65 40 60 35 55 30 50 25 45 40 20 35 15 30 10 25 5 20 0 15 10 5 0 -5 -10 -15

Bar Saop – 100% Animal Fat Bar Soap – 50/50 Palm/Animal Bar Soap – 50/50 Palm/Coconut Liquid Soap – 100% Soybean Oil

%

%

90

Human health

Ecosystem quality

mPt

Resources

Handwashing with Bar Hand Soap(50/50 Palm/Animal) Bar Hand Soap(50/50 Palm/Coconut) Figure 10 – Damage assessment of bar soap versusHandwashing liquidwithsoap.

Human health

31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0

Climate change

Handwashing with Bar Hand Soap (100% Animal Fat) Handwashing with Liquid Hand Soap (Soybean Oil)

Ecosystem quality Manufacture of Bar Soap (50/50 Palm/Animal) Bar Packaging

Climate change Transport, lorry 16-32t, EURO5/RER U Water + Heat For Bar Soap

Resources Waste scenario/US U

Human Health Ecosystem Quality Climate Change Resource Depletion

Handwashing with Bar Hand Soap (100% Animal

Handwashing with Bar Hand Soap(50/50 Palm

Handwashing with Bar Hand Soap(50/50 Palm/Coconut

Handwashing with Liquid Hand Soap (Soybean

health Ecosystem quality Climate change Resources Figure 11 – SingleHuman score comparison bar soap and liquids soap

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Use Phase – Handwashing Water Usage Investigation Since it was not clear from the Koehler report how they arrived at the water usage scenarios, a sensitivity analysis is applied to the use phase for handwashing. Since the bar soap scenarios result in nearly identical impacts, only one bar soap is used for this comparison. To evaluate the sensitivity to water usage, the following two additional water usage scenarios are included: • •

Bar soap: 0.64 liters (0.17 gal) Liquid soap: 0.91 liters (0.24 gal)

Figure 12 and presents results similar to those of Figures and 11. In this view, it is obvious that the overall impact of handwashing is largely dependent on the user’s behavior. Without a study to carefully evaluate users behaviors, it is difficult to say which product has the lower impact.

34 32 30 28 26

Human Health

24

Ecosystem Quality

22

Liquid 0.91 l/use

mPt

20 18 16 14

Bar 0.91 l/use

Bar 0.64 l/use

Liquid 0.64 l/use

Climate Change Resource Depletion

12 10 8 6 4 2 0

Handwashing with Bar Hand Soap(50/50 Palm

Handwashing with Bar Hand Soap(Less Water Human health

Handwashing with Liquid Hand Soap (Soybean Ecosystem quality

Climate change

Handwashing with Liquid Hand Soap (xMore Water Resources

Figure 12 – Single score comparison bar soap and liquids soap

In Figure 12, it is interesting that when the same amount of water is used for both bar and liquid, the bar soap has lower ecological impact. In this case, the manufacturing and packaging impacts constitute the differences in impacts. From the perspective of a manufacturer, the formulation of the soap itself has less influence on the ecological impacts than how the manufacture may influence behaviors.

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CONSLUSIONS AND RECOMMENDATIONS

The previous discussion highlights some interesting aspects about the ecological impacts of handwashing. At the initiation of this study, it was thought that bar soap is the more environmental choice when it comes to handsoap.

This initial assumption was based on the fact far more liquid soap product is used and, on a per use basis, more packaging is required for each handwashing.

The results presented in this report for the raw ingredients were presented on a volumetric basis not related to the functional unit. From this perspective, the sourcing of raw materials did not reveal a large disparity between the two products. However, using a volume related to the functional unit, the ecological intensity of the liquid soap ingredients is much higher due to larger volumes. The initial

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assumption that liquid soap has larger ecological impacts held through the manufacturing and packaging phases. As suspected, this was largely due to the difference in volume of product necessary for 1000 handwashes. However, as the study built through the life cycle phases, the differences in contributions between the two products is minimized compared to the contributions of the use phase. Additionally, exploring different scenarios for use phase, shows that the ‘best choice’ of product is largely dependent on the user’s interaction with the product.

There are lessons in this study for both users and manufactures of hand soaps. For users, to reduce their impacts during handwashing, they should note that is less about the product used and more about the amount of warm water used. Users might consider ways to reduce the amount of water and amount of heat used while handwashing. While heat can kill bacteria on skin, the temperatures required is commonly intolerable to humans, so the use of warm water does not necessarily contribute to improving hand cleanliness. Additionally, a soap’s cleaning function is commonly related to the time the soap is in contact with a surface and bacteria in order to disrupt the function of bacteria. In this case, some liquid soaps can be spread on a surface and lathered without the use of water. Employing a method of spreading and lathering soap with little or no water then rinsing with cool water after lathering while keeping running water off when not in use can reduce the water and heat usage during hand washing.

As is common with many products, the use phase is more difficult for a manufacturer to influence as opposed to changing a manufacturing process. However, the lesson for manufacturer is that they may consider exploring ways to improve the user interaction with hand soap products. Recently manufactures introduce ‘foaming’ liquid soap dispensers. Through this innovation, manufacturers were able to impact user behaviors and encourage reductions in product usage while only marginally increasing product packaging. This innovation did not, however, change the amount of water used. Judging from the results of this study, this innovation did little to improve the overall ecological impacts of the product through all life cycle phases. Perhaps for future innovations, manufacturers might focus on ways to influence users to reduce water use.

For future work, it is recommended that the scope of this study be re-examined to evaluate more specific product categories. This may include comparing homemade or specialty soaps compared to manufactured soap or sourcing raw materials from different locations or operations or comparing foaming and liquid soaps. An exploration of specific soap recipes may also be considered including additives such as softeners, perfumes and dyes. These additional studies should include a better examination of transportation and manufacturing processes.

Overall, this study proved more complex that initially expected. It is likely that evaluating of many other personal hygiene products will result in similarly complex issues.

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REFERENCES 1.

2.

Online pamphlet “Soap and Detergent Manufacture” from New Zealand Institute of Chemistry located at http://nzic.org.nz/ChemProcesses/detergents/ Online source “Soap - The History Of Soap, What Is Soap?, How Is Soap Made?, How Does Soap Work?” located at http://science.jrank.org/pages/6214/Soap.html

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3.

4.

Online source “Soap” located at http://en.wikipedia.org/wiki/Soap A. Koehler, C. Wildbolz & S. Hellweg “Comparing the Environmental Footprint of Consumer Products: The Relevance of Different Life Cycle Phases,” ETH Zurich, Institute of Environmental Engineering (IfU), Group for Ecological System, presented October 1, 2008 at LCA VIII, Seattle, WA.

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