Human Health Impact as a Boundary Selection Criterion in the Life Cycle Assessment of Pultruded...

R E S E A R C H A N D A N A LYS I S

Human Health Impact as a BoundarySelection Criterion in the Life CycleAssessment of Pultruded Fiber ReinforcedPolymer Composite MaterialsJohn P. Basbagill, Michael D. Lepech, and Subhan M. Ali

Keywords:

carcinogensindustrial ecologylife cycle inventory boundarypultrusion industrytoxicityworkplace exposure levels

Summary

The human health impact of fiber reinforced polymer (FRP) composite materials manufac-tured by the pultrusion industry is not fully understood. In particular, it is unclear whetherthe human health impact of toxic chemicals present in low concentrations in fire retardantpultruded FRP materials is disproportionately high. This impact may be an important crite-rion when making boundary selection decisions in the life cycle assessment (LCA) of thesematerials. The North American pultrusion industry was surveyed to determine resin mixconcentration levels and workplace inhalation toxicity exposure levels. LCAs were thenconducted on three building panel resin mixes to determine whether the human healthimpact of toxic chemicals used in the mixes was low enough to exclude the chemicals fromthe life cycle inventory (LCI) boundary. The first resin mix represented a typical pultrudedproduct, the second mix removed toxic chemicals present in small concentrations, and thethird mix replaced toxic chemicals present in small concentrations with a nontoxic chemical.Results showed that toxicity levels fell below exposure limits and no significant difference inhuman health impact existed among the LCAs. The research concludes that human healthimpact is a useful criterion when defining an LCI boundary. Toxic chemicals present in smallconcentrations in pultruded FRP materials may be excluded from the LCI boundary, astheir human health impacts are low. Because these levels are marginal in North Americanpultrusion factories, no changes in resin mixes are recommended for the pultrusion industry.

Introduction

Background on Pultrusion

Pultrusion is a process first developed in the 1950s for themanufacturing of fiber reinforced polymer (FRP) compositeproducts. Two types of pultrusion methods are commonly used:wet bath and injection (figures 1 and 2). In wet bath pultrusion,strands of fibers are pulled from a creel through a resin bath

Address correspondence to: John P. Basbagill, Stanford University, 473 Via Ortega, Room 233, Stanford, CA 94305. Email: [email protected]

c© 2012 by Yale UniversityDOI: 10.1111/j.1530-9290.2011.00416.x

Volume 16, Number 2

containing polymer resin, fillers, catalysts, and pigments. Typi-cal fillers used are calcium carbonate and kaolin. The resin-richfiber system is then guided through custom tooling and arrangedinto the desired shape before being drawn into a heated die. Asthe material moves through the die, the resin cures, and theprofile exiting the die is a finished FRP composite product. Ininjection pultrusion, the resin bath is replaced with a machinedcavity attached to the die. The fibers are continuously pulled

266 Journal of Industrial Ecology www.wileyonlinelibrary.com/journal/jie


Figure 1 Wet bath pultrusion process.

into the die, and resin is injected at high pressure into thecavity and fiber bundle. The material is then pulled through amultizone heating region in the die where the resin cures.

Workplace Human Health Effects of Chemicals Usedin Pultrusion

The resin mix, or composition of the finished pultrudedproduct, used in pultrusion contains potentially toxic chemi-cals. These chemicals may yield elevated inhalation exposurelevels for those working near the open resin bath. In particular,wet bath pultrusion uses three potentially harmful chemicals inthe open resin bath: styrene and two fire retardants, decabro-modiphenyl oxide (decaBDE) and antimony trioxide (ATO).Styrene is used to reduce viscosity and pull loads in the die. TheInternational Agency for Research on Cancer (IARC) classi-fies styrene as “possibly carcinogenic to humans” (2002, 522),the health effects of which include respiratory effects at acuteexposure levels and central nervous system effects at chronicexposure levels (USDHS 2010). DecaBDE, ATO, and aluminatrihydrate (ATH) are critical for fire suppression, yet the firsttwo chemicals yield halogenated combustion products. The ad-verse effects on human health of decaBDE and ATO at highexposure levels include chloracne and impairment of the im-mune, nervous, endocrine, and reproductive systems (Jandacekand Tso 2001). Dioxins and furans are also two environmentalpollutants formed during combustion (Chen and Wang 2010).Although the U.S. Department of Health and Human Servicesdoes not comment on the broad category of dioxins, it does clas-sify 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) as a “knownhuman carcinogen” and furans and styrene as “reasonably an-

ticipated to be a human carcinogen” (USDHS 2009). The U.S.Environmental Protection Agency says decaBDE has “sugges-tive evidence of carcinogenic potential” (USEPA 2008, 43) un-der the Guidelines for carcinogen risk assessment (USEPA 2005),and the IARC (1989) classifies ATO as a possible human car-cinogen. Because of these potential human health risks, workerexposure limits for styrene and fire retardants have been set bythe Occupational Safety and Health Administration (OSHA).

Human Health Impact as a Criterion in LCI BoundarySelection

Recent research has established the importance of usingLCA to better understand the human health risks of indoor oc-cupational exposure to chemicals (Hellweg et al. 2005, 2009).In addition, Raynolds and colleagues (2000) acknowledge theimportance of having a practical, repeatable, and quantitativeLCA system boundary selection methodology. A cutoff ratio,defined as the percentage of mass of a unit process mass input,of 0.05 or 0.10 is typically used to cut system boundaries. Yetinputs present in very small mass quantities may have signifi-cant upstream environmental impacts (Raynolds et al. 2000).Studies have failed to consider using the human health impactof these quantities as a boundary criterion in LCAs of productsand manufacturing processes (Ahmadi et al. 2003; Nagai et al.2000; Ryszard 2003; Schischke et al. 2001).

As a recent example, Song and colleagues (2009) performedan LCA of trucks and buses made with steel, aluminum, or FRPcomposite materials. The study analyzed energy consumptionin the material production and manufacturing stages of thepultrusion process, but potential human health risks of FRP

Figure 2 Injection pultrusion process.

Basbagill et al., Human Health Impact of Pultruded FRP Materials 267


pultruded materials were not evaluated. The products’ energyuse and raw material consumption were shown to be low, butthe research did not examine whether chemicals used in lowconcentrations have a low enough human health impact to beexcluded from an LCI boundary.

International Organization for Standardization (ISO) stan-dard 14040 also supports the role that human health may play inLCI boundary definition. The standard states that mass, energy,and environmental relevance are typically used as decision cri-teria for defining LCI boundaries, but “making the initial iden-tification of inputs based on mass contribution alone may resultin important inputs being omitted from the study” (ISO 1997a,628). The research presented herein fills this gap by consideringhuman health as a criterion for defining an LCI boundary forthe entire life cycle stream of the pultrusion industry.

Motivation

Quantifying human health impacts of pultruded FRP ma-terials is important because human exposure to halogenatedcompounds is ubiquitous. Exposure during the manufacturingphase may be especially harmful due to the proximity to activechemicals in the open resin bath. The scope was intention-ally limited to North American pultrusion companies so as todevelop a North American dataset. Practical recommendationscould also be offered to these companies, such as using alternatechemicals in the resin mixes.

An additional motivation for this research involved improv-ing decision making in LCA, specifically when defining theLCI boundary. As ISO 14041 states, “Resources need not beexpended on the quantification of such [environmental] inputsand outputs that will not significantly change the overall con-clusions of the study” (ISO 1997b, 629). In addition, LCA prac-titioners have limited time to quantify all material inputs, high-lighting the importance of streamlining LCI boundary decisionmaking. Because 100% system completeness is both impossibleand unnecessary, a good system boundary selection method isimportant to fairly compare systems (Raynolds et al. 2000). Thisresearch uses human health impact as an LCI boundary selec-tion method in an attempt to achieve streamlined and rationalLCA comparisons.

Methodology

The research was broken down into two steps: (1) determinethe human health impact of pultruded FRP composite materials,and (2) perform LCAs on three pultruded building panel typesto validate whether human health impact is a useful criterionfor defining an LCI boundary in a pultruded FRP system.

The first step—determining the potential harm of pultrudedFRP composite materials—focused on the manufacturing phaseof these materials. As mentioned, styrene and fire retardantswere believed to pose the most harm to humans in this phase.A survey was distributed in three parts to industry producers ofpultruded products to obtain two pieces of information: (1) con-

centrations of toxic chemicals in pultruders’ resin mixes and (2)inhalation exposure levels in pultrusion factories. The surveywas distributed to the Pultrusion Industry Council (PIC), a sub-group of the American Composites Manufacturers Association(ACMA). The ACMA is a trade association serving the com-posites industry, with more than 850 North American manufac-turers or suppliers as members. PIC members are those ACMAmembers who manufacture or supply products used specificallyin the pultrusion process. PIC membership currently includes16 pultruders, all of whom are located in North America. Theirproducts include beams, rods, and sheets used in window anddoor frames, structural building components, decking, seawalls,cooling towers, and other infrastructure applications.

The first part of the survey was an initial screening sent totwo large pultruders asking for detailed information on resinmixes. The intention of this screening was to obtain a generalidea of the chemicals that comprise pultruded products beforesurveying the entire industry.

The second part of the survey asked all 16 PIC members toprovide information on components of their resin mixes: resinpaste, fibers, filler, fire retardants, styrene, pigment, mold releaseagent, and catalysts. Each member was requested to provide aprecise breakdown of the material inputs for the manufacturingof their products. A percent range (by mass) for each materialwas requested in order to account for the variation in mate-rial percentages across each member’s products. If a range wasnot available, members were asked to provide bills of materi-als for specific products detailing quantities of materials goinginto their products. Pultruders were asked to use a represen-tative range of their products. The chemicals were classifiedinto two groups: group A represented chemicals with concen-trations greater than 5% of the total resin mix, and group Brepresented chemicals with concentrations usually less than orequal to 5% of the resin mix. The 5% threshold was chosenbased on Raynolds and colleagues’ (2000) discussion of 0.05as a lower boundary for a mass cutoff ratio. Table 1 showsthat group A consisted of resin (typically unsaturated polyesterresin), styrene, fibers, and fillers. Group B consisted of fire re-tardants, pigment, mold release agent, and catalysts. It is alsoimportant to note that not all pultruders’ resin mixes containeda fire retardant or pigment. Styrene required careful attention indetermining its precise percentage in the resin mix. The chemi-cal is present in the resin itself as well as added separately to theresin mix. Therefore pultruders were asked to provide percentranges for both locations.

Part three of the survey was then sent to those PIC mem-bers who responded to the second part. Pultruders were askedto provide inhalation workplace exposure levels for chemicalsclassified as having potential workplace human health risks:styrene, decaBDE, and ATO. Pultruders hired industrial hy-giene specialists to take measurements of concentration levelsof toxins in the air. Pultruders provided reports from the special-ists showing the dates the measurements were taken, analyticalmethod, sampling instruments, chemicals sampled, number ofsamples, sample time, sample duration, sample location, andconcentration results. The oldest measurements were taken in

268 Journal of Industrial Ecology


Table 1 Percentage ranges of chemicals used in pultruded products

Percent of mix design Possible humanChemical CAS numbera (range by mass) carcinogen?b Group

Unsaturated polyester resin 092230-55-2 15–37 Yes AGlass fiber 065997-17-3 50–65 No AFiller 4.0–15 No A

Kaolin 001332-58-7Calcium carbonate 000471-34-1

Fire retardant 0–18 BDecabromodiphenyl oxide 001163-19-5 0–6 YesAntimony trioxide 001309-64-4 0–3 YesAlumina trihydrate 021645-51-2 0–18 No

Styrene 000100-42-5 8.0–13 Yes APigmentc 0–2 No BMold release agentc 0.2–0.6 No BCatalyst 0.2–0.6 No B

Percadoxd 015520-11-3Trigonoxd 000686-31-7Tert-butyl perbenzoate 000614-45-9

Other chemicals BLight absorber 000131-53-3 0–0.1 NoCoathylenee 0–0.5 No

aCAS refers to Chemical Abstracts Service.bAs classified by the International Agency for Research on Cancer (IARC).cAll material safety data sheets (MSDSs) claim proprietary content.dProprietary content claimed by Akzo Nobel Polymer Chemicals.eBinder/thermoplastic powder additive. Proprietary content claimed by DuPont Polymer Powders Switzerland Srl.Note: Group A indicates the chemical is typically present in concentrations greater than 5% of the resin mix; Group B indicates the chemical’sconcentration is typically less than 5%.

2007. A consistent measurement protocol was observed withineach pultruder’s facility as well as from pultruder to pultruderregarding sampling methods (gas chromatography), number ofsamples (between 4 and 11), locations of samples (various op-erator workstations), and sample duration (between two andfive hours), thus ensuring the quality and relevance of the mea-surements. Exposure levels from all datasets received were ag-gregated to produce a representative range of workplace toxinlevels for the pultrusion industry. These levels were then com-pared with work exposure limits set by OSHA.

LCAs were then performed on three pultruded building pan-els, each manufactured with a different resin mix, in order toassess the impact of these industry findings. Resin mix A con-tained fire retardant chemicals present in concentrations typicalof pultruded products, resin mix B removed these fire retar-dants and scaled up the remaining chemicals so the volumes ofresin mixes A and B were equal, and resin mix C replaced thebrominated fire retardants with ATH, a nontoxic fire retardant.The life cycle impact assessment (LCIA) software SimaPro wasthen used to determine whether carcinogenicity differences—asmeasured in disability-adjusted life years (DALY), or a measureof years lost due to poor health, disability, or premature death—were noticeable among the three resin mixes (PRe Consultants2010). The software was also used to determine whether thehuman health impact of resin mix A was disproportionate tothe concentration levels of its fire retardant toxic chemicals.

Respiratory organics and respiratory inorganics were also exam-ined as human health indicators. The impact of these airborneparticles was also measured in DALY.

The LCIA software has a few limitations. European aver-aged datasets, not North American datasets, were used. Theamount and type of equipment and fuel used to extract, pro-cess, and transport raw materials are likely different betweenthe two continents, and this limitation would affect the im-pact assessment results. SimaPro also did not contain all thepultrusion chemicals in its database, so surrogates were chosenfor the missing chemicals. It was assumed that these surrogatesyielded results reasonably close to those of the actual chemical.Matches were found in SimaPro for two of the potentially toxicchemicals under scrutiny in this study (styrene and decaBDE),but “antimony” was substituted for ATO. It was assumed thatthese limitations did not have a significant effect on the results.

Industry Survey

The pultruders who responded to the survey produced37 million kilograms (kg)1 of pultruded products in 2008. Thisamount represented more than 50% of the total yearly output ofthe pultrusion industry (ACMA 2010). Data from an additionalNorth American pultruder that was not a PIC member were re-ceived and included in the results. Pultruders either provideda precise percentage of each chemical’s concentration in an



Table 2 Resin mixes for three pultruded composites containingtoxic and nontoxic fire retardants

Percent of resin mix(by mass)

Resin Resin ResinChemical mix A mix B mix C

Resin 22 23.7 21Fibers 52 55.9 51Filler 8 8.6 8Fire retardant 7 0 9

Decabromodiphenyl oxide 5 0 0Antimony trioxide 2 0 0Alumina trihydrate 0 0 9

Styrene 9 9.7 9Pigment 1 1.1 1Mold release agent 0.5 0.5 0.5Catalyst 0.5 0.5 0.5

overall resin mix or a range of percentages for each chemical.Resin mix data were given for as few as one product or as many asten products. Table 1 presents the reported percentage rangesof each chemical concentration in pultruded products’ resinmixes. The table also shows whether the chemical is consid-ered a possible human carcinogen and typically present in highconcentrations (group A, greater than 5%) or low concentra-tions (group B, less than or equal to 5%). This determinationwas made by averaging the concentration percentage values foreach chemical. When only a range of percentages was available,the average value within each range of concentration percent-ages was used.

Table 1 shows that fibers are the primary component of FRPpultruded products, typically accounting for more than 50% ofthe resin mix’s mass. Resin and filler make up most of the restof the mixture, followed by styrene (total, including styrenein the resin), fire retardants, pigments, a mold release agent,catalysts, and small amounts of other chemicals. Resin, styrene,and two of the fire retardants are classified as possible humancarcinogens, and the two fire retardants are the only chemicalspresent in small concentrations classified as a possible humancarcinogen.

The amounts of potentially toxic chemicals present in theresin mixes varied. Styrene’s average concentration level was9%, decBDE’s average concentration level was 5%, and ATO’saverage concentration level was 2%. Although all resin mixeshad styrene present, some resin mixes had no fire retardants,some had just one fire retardant, and some had a mixture of twofire retardants. Table 2 shows the average percentages of all thechemicals in the three resin mixes investigated in this study.Resin mix A and C were equivalent in all respects, except thattoxic fire retardants in mix A were replaced with a nontoxic fireretardant in mix C. Resin mix B contained no fire retardants.

Table 3 shows the results of part three of the survey: inhala-tion exposure levels of styrene, decaBDE, and ATO at variousworkstations in pultrusion factories. These levels were com-pared with exposure limits reported by OSHA in order to de-

Table 3 Inhalation exposure levels of potentially harmful chemicalsused in the pultrusion industry

Reported Occupationaloccupational exposureexposure level limits

Chemical range (mg/m3)a (mg/m3)a,b,c

Styrene 21–81 425/850d/2,550e

Decabromodiphenyl oxide 0–1.4 5f

Antimony trioxide 0–1.2 0.5

aTo convert from parts per million (ppm) to milligrams per cubic meter(mg/m3): threshold limit value (TLV; mg/m3) = molecular weight (MW)× TLV (ppm)/24.45.bOccupational Safety and Health Administration (OSHA) Limits, Title29, Code of Federal Regulations, Part 1910, Subpart Z, Section 1910.1000,Table Z-1, “Limits for Air Contaminants.”cTWA = time-weighted average exposure for an 8-hour work shift.dCeiling limit = instantaneous exposure limit that shall not be exceededduring any time of the work day except for the permissible “5-minute” peakin any 3 hours.ePeak = 5-minute “peak” concentration once in any 3 hours.f Not established by OSHA/American Conference of Governmental In-dustrial Hygienists (ACGIH). American Industrial Hygiene Association(AIHA) Workplace Environmental Exposure Limit (WEEL) establishedin 1981 at 5 mg/m3 (8-hour time-weighted average [TWA8]).

termine whether pultrusion workers are exposed to unsafe levelsof toxic chemicals.

Table 3 shows that the human health impact of styrene andfire retardants in the workplace is generally small and belowOSHA exposure limits. One data point of 1.2 milligrams per cu-bic meter (mg/m3)2 was reported, which was over the 0.5 mg/m3

OSHA limit for ATO. This data point was interpreted as anoutlier, as all other values were well below the exposure limit.Because toxicological assessment of the workplace risk posedby acute and chronic exposure to these chemicals is outsidethe scope of this work, based on these results, inhalation ex-posure levels of chemicals used in the manufacturing phase ofthe pultrusion process were considered to pose minimal risksto human health. Whereas OSHA standards are health protec-tive, it should also be understood that they do not assure zerorisk and do not necessarily equate with zero DALY. Althoughthe probability is small, occupational risk may be present wheninterpreting the results in table 3. This risk may be significant,despite the reported exposure levels falling below OSHA limits.Measuring the degree of this risk was beyond the scope of thisresearch. The next step was to use a case study to look at the en-tire life cycle of pultruded products in order to evaluate humanhealth impact as a criterion in defining the LCI boundary.

Validation of LCI Boundary Using a Life CycleAssessment Case Study

An attributional LCA was performed on resin mixes A, B,and C in order to describe the environmental properties of thepultrusion process over its entire life cycle. Changes withinthe life cycle were not considered, otherwise a consequentialLCA may have been more suitable (Finnveden et al. 2009).



Eco-indicator 99 was the impact assessment method chosen,as this method provides human health impact indicators rele-vant to this research. For example, Eco-indicator 99 has devel-oped damage models for respiratory and carcinogenic effects andlinked these health effects to DALY (Goedkoop and Spriensma2000).

The goal of the LCA was to determine whether the pres-ence of toxic chemicals in low concentrations in pultrudedFRP materials has a human health impact disproportionate tothe chemicals’ concentration levels. A disproportionate impactwould mean the toxic chemicals should be included in LCIboundaries. The analysis was also performed to demonstratehuman health’s role as an impact category when defining anLCI boundary for pultruded products. A 5% cutoff ratio wasused to determine which toxic chemicals to remove from resinmix A (Raynolds et al. 2000). Table 2 shows that decaBDEand ATO fell below the 5% rule and therefore were removed.Styrene’s concentration in resin mix A was 9% and thereforewas not removed. Styrene is also essential to the manufacturingprocess and therefore cannot be removed.

An LCA case study was conducted on pultruded claddingpanels made from resin mixes A, B, and C. Currently claddingpanels are being installed on the Pacific Health Services Hos-pital (PHSH) in San Francisco’s Presidio Park. The PHSH isa certified historic structure undergoing a transformation fromhospital to luxury apartments. Built in 1931, the hospital wasabandoned from 1988 to 2009. Renovation has recently be-gun to transform the 220,000 square foot (ft2) building into 154Leadership in Energy and Environmental Design (LEED) Silverapartments. Historic windows and facades are being refurbished.An ACMA member that manufactures composite building ma-terials is replacing the old limestone cladding material with anFRP material. The closest pultruder to the site is 95 kilometers(km) away in San Jose, California. The functional unit is a1 foot (ft) × 1 ft panel. The thickness of the panel is 0.50 ft.

The scope of the LCA included the following three phases:(1) raw material extraction, production, and transportation tothe manufacturing site; (2) manufacturing and transportation tothe building site; and (3) end-of-life. Use phase was not consid-ered because a finished pultruded product is chemically inert,and finished plastics yield negligible toxic emissions (Hiladoand Huttlinger 1981). Human health impacts during the usephase—excepting combustion scenarios—were therefore as-sumed to be minimal. As far as combustion scenarios, researchhas found that health hazards from the combustion of productscontaining styrene (Sumi and Tsuchiya 1971) and phosphate-free fire retardants (Hartzell 1992) (such as decaBDE, ATO,and ATH) are no greater than products not containing thesechemicals. Therefore human health impacts of resin mixes A, B,and C were assumed to be similar during the use phase, furthervalidating exclusion of the use phase from the LCA.

Raw Material Extraction, Production,and TransportationRaw material extraction was the first phase of the LCA.

Raw materials for resin mixes A, B, and C were processed then

transported from supplier locations to the pultruder for fabri-cation. Potential suppliers were chosen based on proximity tothe site, under the assumptions that suppliers should be chosenbased on cost minimization, and the closer a supplier is to thesite, the lower the transportation costs. The suppliers chosenfor the LCA do not necessarily represent the actual suppliersused by the ACMA member manufacturing the panels. Table 4shows quantity, supplier location, and distance from supplierto pultruder for each material used in the production of onefunctional unit of resin mix A, B, and C.

Table 4 shows that the mass functional unit, or total quan-tity of material in each panel design, is 17.48 kg for resin mixA, 16.41 kg for resin mix B, and 17.28 kg for resin mix C.These quantities were derived from industry data, as describedabove. The volume of each panel type was kept constant at1 ft × 1ft × 0.5 ft, or one functional unit. All suppliers were onthe West Coast of the United States except for one catalyst sup-plier in Chicago in the midwestern United States. Surrogatesused in the LCA software are noted.

Manufacturing and TransportationThe primary energy requirement for the manufacturing

phase was electricity to operate the pultrusion machinery. Ma-terial inputs for this phase were the chemicals used to make thepultruded building panels, as shown in table 2. Energy inputs tothe manufacturing phase included the electricity to operate thepultrusion machinery. Following a model being developed byAli and colleagues (2011) for determining energy requirementsof pultruded products during the manufacturing phase, equation(1) was used to calculate the electricity required to manufactureone functional unit of pultruded building panel made of eitherresin mix A, B, or C. This equation is a model and does notnecessarily represent the actual electricity used by the ACMAmember to manufacture the panels. Independent variables werebuilding panel cross-sectional area, building panel weight, andline speed.

Electricity Consumption = 0.011333 − 0.06599 × Area

+ 0.078928 × Weight

+ 3.46086 × Speed (1)

The weight of the resin mixes was assumed to be the sum ofthe weights of each of the individual chemicals, or the weightof one functional unit building panel. Pull speed was set at12.2 meters per hour (m/hr),3 which Ali and colleagues (2011)obtained by averaging industry values. Based on these threeinputs, the resulting electricity consumption was 1.44 kilowatt-hours (kWh)4 for resin mix A, 1.36 kWh for resin mix B, and1.43 kWh for resin mix C. Outputs for the manufacturing phasewere the finished pultruded building panels and scrap material.The scrap rate used was 2%, which Ali and colleagues (2011)also obtained by averaging industry values.

After the panels were manufactured by the pultruder, theywere transported 95 km from the pultruder to the Presidiobuilding site. The mass functional unit was multiplied by



Table 4 Chemicals used in resin mix A, resin mix B, and resin mix C: quantities, location, and distance from supplier to pultruder

Quantity per 1 ft2 panel (kg)Distance from

Density Resin Resin Resin supplier toChemical (kg/m3) mix A mix B mix C Supplier Location pultruder (km)

Unsaturated polyester resin 2000 3.85 3.89 3.63 Huntsman AdvancedMaterials

Los Angeles, CA 623

Glass fiber 2540 9.09 9.17 8.81 Owens Corning Compton, CA 649Filler (kaolin) 405 1.40 1.41 1.38 Wintersun Chemical Ontario, CA 679Fire retardant

Decabromodiphenyl oxide 3360 0.87 0 0 Wintersun Chemical Ontario, CA 679Antimony trioxidea 5200 0.35 0 0 Wintersun Chemical Ontario, CA 679Alumina trihydrateb 2420 0 0 1.56 Spectrum Chemical

ManufacturingGroup

Gardena, CA 642

Styrene 909 1.57 1.59 1.56 Silver Fern Chemical Seattle, WA 1,308Pigment 62 0.17 0.18 0.17 Ishihara San Francisco, CA 85Mold release agentc 656 0.09 0.09 0.09 Maverix Solutions Tustin, CA 678Catalystd 910 0.09 0.09 0.09 Akzo Nobel Polymer

ChemicalsChicago, IL 3,450

Mass functional unit 17.48 16.41 17.28

a “Antimony” used as a surrogate.b “Aluminum, fume or dust” used as a surrogate.c “Paraffin” used as a surrogate.d “Organic chemicals” used as a surrogate.Note: ft2 = square foot; kg = kilogram; kg/m3 = kilograms/cubic meter; km = kilometer.

transportation distance for a diesel truck to yield1,661 kilogram-kilometers (kg · km)5 for resin mix A, 1,559 kg ·km for resin mix B, and 1,642 kg · km for resin mix C. All threepanel types were attached to the building facade with stainlesssteel rods and epoxy, and these materials were also modeled.The panels were light enough to be installed by hand. The en-ergy to operate the hand tools during the installation phase wasassumed to be negligible.

End-of-Life PhaseBecause of the physical equivalency of the three resin mixes,

the building panels were assumed to have an equal life span.Justification for this assumption was based on data from table 2,which shows that the only significant difference in the makeupof the resin mixes was the fire retardants. As the literaturedoes not discuss the impact of fire retardants (decaBDE, ATO,or ATH) on the life span of FRP composites, equal life spanwas assumed. It was also assumed all three panel types wouldbe demolished along with the rest of the building and trans-ported 23 km from the building site to a landfill, the Marin Re-source Recovery Center. This phase required fuel for transporta-tion, and it was assumed that none of the building panels wererecycled.

Assembly of LCA ModelsLCA models were then assembled in SimaPro for the three

panel types based on data collected from the three phases. “Car-cinogens” was the primary Eco-indicator 99 impact category

recorded from the results, in order to determine whether toxicchemicals present in low concentrations in the resin mixesof pultruded FRP materials have a noticeable human healthimpact throughout the life cycle. “Respiratory organics” and“respiratory inorganics” were two additional impact categoriesconsidered from Eco-indicator 99. The results also determinedthe usefulness of human health impacts as a criterion in LCIboundary selection in addition to conventional criteria such asmass concentration or environmental impact.

Results and Discussion

Figure 3 shows the impact assessment results. The chartindicates that the presence of potentially toxic fire retardantsin FRP pultruded materials does not have a noticeable humanhealth impact throughout the entire life cycle.

The DALY impact due to carcinogens was negligible andnearly equal for the three resin mixes for each of the threephases. The processes contributing the most to DALY wereextraction of materials to manufacture polyester unsaturatedresin (raw material extraction phase), transportation of all resinmix materials from the supplier to the pultruder (manufac-turing phase), and transportation of the demolished buildingpanels from the site to the landfill (end-of-life phase). Thesethree processes were the greatest contributors to DALY for allthree resin mixes. Resin mix A’s cumulative health impact was1.65E–06 DALY, resin mix B’s cumulative health impact was1.66E–06 DALY, and resin mix C’s cumulative health impact



Figure 3 Impact assessment of pultruded composite building panels containing toxic and nontoxic fire retardants. Note that “end of life” istoo small to appear.

was 1.58E–06 DALY. Therefore DALY actually increased by0.6% when fire retardants were removed from the resin mix.This slight increase was likely due to the fact that the styreneconcentration increased in resin mix B and Eco-indicator 99weighted the health impacts of the fire retardants less thanstyrene. The respiratory organics and respiratory inorganics cat-egories were nearly equal and had very small impacts for all threeresin mixes. Therefore the results indicate that the presence oftoxic chemicals—specifically styrene, decaBDE, and ATO—insmall concentrations in pultruded products does not notice-ably impact human health. The DALY of pultruded compositesis small and nearly the same with or without the presence ofpotentially toxic fire retardants.

Figure 3 reinforces results from the industry survey. As men-tioned, workplace inhalation levels of toxic chemicals used inpultrusion were all below OSHA exposure limits. Results fromthe figure show that the human health impact of styrene andfire retardants appears to be minimal in pultrusion factories andthroughout the life cycle of pultruded composites. The work-place human health risk of chemicals used in pultruded materi-als also appears to be the same with or without the presence ofpotentially toxic chemicals present in small concentrations. Inother words, exposure to styrene and fire retardants in the resinbath in pultrusion factories has minimal human health risk.

Results also show that the human health impact is useful as aboundary selection criterion in LCAs of pultruded composites.This criterion can be used in addition to mass or environmentalimpact—criteria traditionally used when determining LCI sys-tem boundaries—when potentially toxic chemicals are presentin the resin mix. In the case study presented herein, both massand human health impact were used to draw LCI system bound-aries. Results showed that fire retardants—pultrusion chemicalspresent in resin mixes in small concentrations—did not have adisproportionately high human health impact. From a humanhealth perspective, LCAs involving pultruded FRP compositematerials can exclude fire retardants present in small concentra-tions from the LCI boundary. The use of both mass and human

health impact as boundary selection criteria results in a morerational, streamlined LCA and ensures that exclusions to theLCI boundary do not have a disproportionately high humanhealth impact.

Conclusions

A survey of the pultrusion industry shows that workplaceinhalation exposure levels of chemicals with known humanhealth risks fall below established exposure limits. The LCAs ofbuilding panels containing three resin mixes—one containingtoxic fire retardants, one without fire retardants, and one with anontoxic fire retardant—show that their human health impactsare nearly the same, and small for each individual life cyclephase as well as cumulatively across the entire life cycle. Inparticular, human health impacts for the manufacturing phasewere less than the raw material extraction phase. These resultssuggest that the human health risk of resin additives and fireretardants used in pultrusion is minimal in manufacturing plantsas well as at all locations throughout the life cycle of pultrudedproducts. From a human health perspective, no changes in resinmix are recommended for the pultrusion industry.

A second conclusion is that human health impact is usefulas a boundary selection criterion in LCAs. This criterion ap-plied to pultruded FRP composite resin mixes found that fireretardants may be excluded from LCIs without worry that theirhuman health impact is disproportionate to mass concentra-tion. Use of traditional LCI boundary criteria, such as mass orenvironmental impact, does not provide this assurance. It ispossible that these traditional criteria may exclude from theLCI boundary chemicals whose human health impact is dispro-portionately high when compared to mass concentration. As aresult, the LCA would not provide an accurate picture of thehuman health implications of products.

These conclusions are reached with several considerationsin mind that provide points for future research. First, bioaccu-mulation may result from chronic exposure to additives such



as brominated fire retardants, particularly in the occupationalphase. The health impacts of bioaccumulation may be signifi-cantly greater than when considering only air exposure levels.Additional toxicological research is needed in this area. The pu-rity of the chemicals used in the pultrusion industry is anotherconsideration. Pure chemicals were assumed in this study, al-though impure chemicals may be more toxic and have a greaterhuman health impact. Another consideration is the chemicalcombination of carbon-based additives, which may produce aheightened human health impact greater than the individualimpacts. Finally, other LCIA models on human toxicity couldbe used as a basis of comparison with the method used here.Comparison of different LCIA methods (such as USEtox) onthe human health impacts of potentially toxic chemicals hasshown little or no agreement (Pizzol et al. 2011). It would beinsightful to see which other LCIA methodologies, if any, yieldresults similar to those here.

Acknowledgments

Thanks are expressed to the National Science Foundationfor providing funds for this research, award number 0956523.Appreciation is given to ACMA, PIC, and those pultrusioncompanies that provided primary data necessary for this re-search. Gratitude is also expressed to David Lipiro of Envi-ronmental Compliance & Risk Management Inc. for providingcounsel on developing a life cycle inventory for the pultrusionindustry, John Busel of ACMA and Cheryl Richards of PPGIndustries for providing help with data acquisition and servingas liaisons with pultrusion companies, and Dr. Marcia Hardy ofAlbemarle Corporation for serving as an invaluable referencefor toxicological information and risk assessment. Finally, themany helpful comments of the reviewers are much appreciated.

Notes

1. One kilogram (kg, SI) ≈ 2.204 pounds (lb).2. One milligram (mg, SI) = 10−3 grams (g) ≈ 3.53 × 10−5 ounces

(oz). One cubic meter (m3, SI) = 103 liters (L) ≈ 264.2 gallons(gal).

3. One meter (m, SI) ≈ 3.28 feet (ft).4. One kilowatt-hour (kWh) ≈ 3.6 × 106 joules (J, SI) ≈ 3.412 × 103

British thermal units (BTU).5. One kilometer (km, SI) ≈ 0.621 miles (mi).

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About the Authors

John P. Basbagill and Subhan M. Ali are Ph.D. students inthe civil and environmental engineering department at Stan-ford University in Stanford, CA, USA. Michael D. Lepech isan assistant professor of civil and environmental engineering atStanford University in Stanford, CA, USA.


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http://www.epa.gov/iris/toxreviews/0035tr.pdf

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