1-s2.0-S0304389407013805-mainRWRWWRW

Available online at www.sciencedirect.com

Journal of Hazardous Materials 153 (2008) 12621269

Toxicity assessment of volatile organic cooto

ann

n Uni-Lan

er 20er 200

Abstract

This study exhaEscherichia rcycwith imping r andmotorcycles ne (Xfrom motorc natebenzene (No eal cexhaust is si ratedshowed that two- 2007 Elsevier B.V. All rights reserved.

Keywords: Dosemortality curves; Volatile organic compounds; Polycyclic aromatic hydrocarbons; Escherichia coli

1. Introdu

Due toTaiwan, sigrisks to impeople fremetropolitamobility. Aand Commwere 13.2before De(ca. 452 vethe world.is apparenexhaust gais known(VOCs), pomatter and

CorresponE-mail ad

0304-3894/$doi:10.1016/jction

marked rises in congested traffic of metropolitannificant increases in waste gas have the inevitable

pact public health. In the highly populated Taiwan,quently use motorcycle as a common means ofn transportation due to their higher convenience andccording to the Taiwan Ministry of Transportationunications (http://www.motc.gov.tw/) [1], there

106 motorcycles officially reported in Taiwancember 2006. The motorcycle density in Taiwanhicles per square kilometer) almost ranked first inIn some cities, the exhaust gas from motorcycles

tly the primary source of mobile pollutants. Thes is presumed to be harmful to human health as itto contain a range of volatile organic compoundslycyclic aromatic hydrocarbons (PAHs) particulateother chemicals [2].

ding author. Tel.: +886 3 9357400x741; fax: +886 3 9357025.dress: [email protected] (B.-Y. Chen).

VOCs have been found to cause acute toxic effects (primar-ily neurological), cancer (such as leukemia), neurobehavioraleffects and adverse effects on the kidney [3]. The major volatilecomponents of motorcycle exhaust include benzene (B), toluene(T), ethyl benzene (E) and xylene (X) [4,5]. A portion of theabsorbed benzene is excreted in exhaled air unmetabolized; how-ever, a large portion of the absorbed compound is metabolizedto benzoic acid. This compound is conjugated with glycine inthe liver and eventually excreted in urine as hippuric acid [6,7].The acute health effects associated with exposure to benzeneinclude dizziness, muscle weakness, confusion and incoordina-tion. These effects generally occur only a high concentrationsand are not likely to be associated with motorcycle exhaust.The effects associated with exposure to benzene are similar tothe physiological response following exposure to most organicsolvents. With respect to chemicals, evidence for benzene leuke-mogenesis has been reported in both human populations [8,9]and in experimental animals [10].

In addition, ophthalmic effects of VOCs also have been noted;for instance, the injury of the optic nerves may have resultedfrom toluene as a metabolite [11]. Toluene has also been crim-inated as the cause of polyneuropathy in shoe factory workers

see front matter 2007 Elsevier B.V. All rights reserved..jhazmat.2007.09.091aromatic hydrocarbons in mChang-Tang Chang a, Bor-Y

a Department of Environmental Engineering, National I-Lab Department of Chemical & Materials Engineering, National I

Received 24 June 2007; received in revised form 4 SeptembAvailable online 29 Septemb

investigates the toxicity of various pollutant species from motorcyclecoli DH5. The toxicity evaluation of the major components of motoer, and polycyclic aromatic hydrocarbons (PAHs), collected with filte. The toxicity of benzene (B), toluene (T), ethyl benzene (E) and xyleycles. In addition, three types of reformulated gasoline (high oxyge. 2), and low oxygen and low benzene (No. 3) were prepared to revgnificantly more toxic than BTEX due to the highly toxic VOCs genethe toxicity, indicated as EC50, was approximately as follows: PAHs >mpounds and polycyclicrcycle exhaustChen b,

versity, I-Lan, 260 Taiwan, ROCUniversity, I-Lan, 260 Taiwan, ROC07; accepted 21 September 20077

ust via doseresponse analysis and margin of safety usingle exhaust volatile organic compounds (VOCs), collectedXAD-2, is essential to determine emission standards for) was selected for comparison as standard VOCs emitted

and high benzene content (No. 1), low oxygen and highombined toxicity of individual compositions. Motorcyclefrom incomplete combustion. Overall toxicity evaluation

stroke engines > four-stroke engines > BTEX.

C.-T. Chang, B.-Y. Chen / Journal of Hazardous Materials 153 (2008) 12621269 1263

[12]. Generally, toluene in vapor phase can be absorbed rapidlyfrom the lungs, and liquid toluene is taken up readily fromthe gastroiXylene is amembranescan be absThe euphoity is attracof sniffingter instancecase(s) [17are thus usin compariRegardingBTEX, thecategoriesAmong thetion reactiobenzene co

Motorcybe toxic anmutation rethose of soupon conceeasy to be afetta et al. [and bladdeassociatedadducts) anexposed toPAHDNAide (B[a]PDlung cance

Althougmotorcycleseriously dTherefore,determinatcrucial forcycle exha(e.g., Micrquantitativemethods arof assessmwe intentiomentally semicroorganVOCs andBTEX as swith econoopen policble alternatalso confirmwith costicity for gwere carrie(QA/QC).

2. Materials and methods

ested pollutants, engine and gasoline

Challenge pollutantsjor compositions of motorcycle exhaust are BTEX (ben-), toluene (T), ethyl benzene (E) and xylene (X)). First, to

bases for toxicity comparison, individual BTEX solventserially diluted with deionized water to obtain solutionserent concentrations. The VOCs analysis method was

to use of gas chromatography (GC)-flame ionisationr (FID) to analyze concentration of species. The HNU

le Gas Chromatography, model-311, with GC column0, 1.75% Bentonite 34, 6 in. 1/8 in. was used to ana-OCs composition. The sampling procedures composedparing and preheating the sampling system, connectingto-analysis system and combining the data-log system.mpligas ing thin thst ree, eth

s wd PAlid Pples

enginAD-s phat 1h twnd fi

mpliwere

. Thichroion pat 9

was

an d

centr-stro

nds

tert-b

ne

nzeneeeelbenz

imethntestinal tract, but poorly through the skin [13,14].powerful solvent, but is irritating to eyes, mucousand skin [15]. It can pass through intact skin or

orbed from lungs and the gastrointestinal tract [16].ria that is a typical response to ethyl benzene toxic-tive to certain individuals who have made a practiceglue, paint thinner, or ethyl benzene itself, the lat-resulting in a schizophreniform psychosis in some

,18]. As BTEX are well-characterized pollutants, theyed as standard pollutants of petroleum hydrocarbonsson with other pollutants (e.g., motorcycle exhaust).toxic metabolites and/or suspected carcinogens inir metabolic transformations are divided into four

oxidation, reduction, hydrolysis and conjugation.se, oxidation is the most common biotransforma-n mediated by microsomal enzymes. For example,nverts to phenol via hydroxylation.cle exhaust also contains PAHs which are known tod genotoxic. In addition, as Cerna [19] indicated thesponse of gaseous PAHs are more significant thanlid PAHs, and their toxicity are strongly dependentntration [20]. The reason is that the gaseous PAHs arebsorbed into blood than that of the solid PAHs. Bof-21] also demonstrated that cancer of the skin, lungsr can result from exposure to PAHs. PAHs have beenwith elevated levels of DNA adducts (e.g., AHDNAd p53 mutations in persons who smoke and/or arePAH in the either workplace or ambient air [22,23].adducts formed by the carcinogen B[a]P diol epox-E) have been strongly linked to an increased risk of

r.

h the concentration of highly toxic VOCs is low inexhausted waste gas, it might affect human health

ue to long-term exposure and/or bioaccumulation.from the perspective of air pollution control, the

ion of toxicity of VOCs and PAHs is extremelyhow to take actions of toxicity attenuation for motor-ust. As known, there are some standard methodsotox [24], Mutatox and Ames test) that can bely evaluated toxicity of pollutants. However, thesee not cost-effective to be a first screening protocolent upon suspected toxicants for public uses. Thus,nally selected a genetically defective and environ-nsitive strain Escherichia coli DH5 as a probingism [25] to reveal dosemortality relationships ofPAHs in motorcycle exhaust using well-known

tandards for comparison. With this plausible methodmic feasibility, industrial sectors can adopt a morey toward diverse waste sources to consider possi-ives for reduction, reuse or recycling. Results wereed with literature data, revealing the practicability

effectiveness as first screening assessment of tox-eneral use. Serial dilutionagar plating proceduresd out in duplicate for quality assurance and control

2.1. T

2.1.1.Ma

zene (Bobtainwere s

in diffrelateddetectoPortabSP-l20lyze Vof prethe auThe sawasteassessiVOCsThe tetoluen

PAHsampleand so

Samcycleand Xgaseoudrawnthrougticles agas safiltersiccatorwith dextractheated7.5 g)in a cle

Table 1The conwith two

Compou

MethylBenzenen-HeptaTolueneEthylbep-Xylenm-XylenO-XylenIsopropy1,2,4-Trng volume was about 1 L for each run. However, thenjected to GC was only 300 mL for analysis. Beforee toxicity of VOCs, the concentrations of main toxice motorcycle were measured and shown in Table 1.sults shows that the main toxic VOCs are benzene,yl benzene and xylene.ere also extracted from the motorcycle exhaust. TheHs can be classified into two phases, gaseous PAHs

AHs.of PAHs were taken from the exhaust gas of motor-e. Impactor sampling combined with quartz filter

2 adsorbent was used to collect solid phase andase PAHs and carried out in triplicate. The air was0 L/min first through a 2.5m cutoff cyclone, theno 47-mm quartz filters (Whatman) that collected par-nally through two XAD-2 resins (Supleco Co.) for

ng [26,27]. According to literatures [28,29], quartztreated after the humidity was removed in a des-

e XAD-2 was cleaned by Soxhlet extraction firstlomethane (24 h) and then with methanol (24 h). Therocedure was repeated twice. The XAD-2 was then0 C to remove moisture. The cleaned XAD-2 (ca.packed in a glass resin (6 cm 1.5 cm I.D.) and keptessicator until sampling. The filters and XAD-2 were

ation of main toxic VOCs components in the exhaust waste gaske engine

No. 1 gasoline(ppm-v)



utyl ether 14.4 14.2 13.6101.6 103.2 65.3

14.1 15.1 13.477.1 86.5 66.869.0 68.3 58.653.3 56.4 58.413.2 14.3 13.612.9 12.0 12.5

ene 1.2 1.1 1.5ylbenzene 1.6 1.8 1.3

1264 C.-T. Chang, B.-Y. Chen / Journal of Hazardous Materials 153 (2008) 12621269

analyzed with GCMS, Hp GCD. The instrumentation as wellas the analytical procedure was established and conducted asdescribed eR) containipurchased

2.1.2. ChaThe tox

assessed inreformulateand benzengasoline (hoxygen anand low beNote that aand benzencontent.

2.1.3. ChaTo have

cles in heaengine, twmodel engthe same afour-stroke

2.2. Dose

E. coliChang, Naan indicatoindicator stplate was pMiller, Difthe synchrotioning in tbroth was tculture wasphase (ca.culture wasile saline swith appropwas chosen

2.3. Biotox

Biotoxica modificaTo excludeall of the swere first s20 min) anized througconcentratichemicalswas postuldilutions o

Table 2The composition of gasoline

Volume %

etailed chemical analysis of gasolineffinsutane 4.82entane 3.62exane 1.75eptane 0.51ctane 0.30

11.00

hed paraffinsutane 1.14entane 10.26ethylpentane 4.39ethylpentane 2.59

-Dimethylbutane 1.83ethylhexane 1.39ethylhexane 1.39

-Dimethylpentane 0.84-Dimethylpentane 0.93,4-Trimethylpentane 5.51,4-Trimethylpentane 3.04,3-Trimethylpentane 2.87,3-Trimethylpentane 0.33-Dimethylhexane 1.00-Dimethylhexane 0.84-Dimethylhexane 0.98ethylheptane 0.90ethylheptane 0.71ethyloctane 0.30ethyloctane 0.30

,5-Trimethylhexane 0.72

42.26

paraffinsthylcyclopentane 0.921,3-Dimethylcyclopentane 0.30thylcyclohexane 0.30

1.52

sutene-2 0.49ntene-2 0.64

entene-2 0.33ethylpentene-l 0.48ethylpentene-2 0.78

2.72

aticszene 1.69

uene 3.99ylbenzene 1.69ylene 1.89ylene 4.79ylene 1.46ethyl,3-ethylbenzene 1.30ethyl,4-ethylbenzene 1.31

,4-Trimethylbenzene 2.72

20.84

Oxygenate content (%) Benzene content (%)xygenate and benzene content of gasolinegasoline 3.0 1.0gasoline 1.0 1.0gasoline 1.0 0.5lsewhere [30,31]. A standard PAH mixture (Z-014G-ng 17 compounds in CH2Cl2/benzene (1:1 v/v) wasfrom Supleco company for quantitative analysis.

llenge gasolinesicity of PAHs in different kinds of gasolines was also

the exhaust waste gas since the characteristics ofd PAHs was dependent on the content of oxygene [24]. Three types of reformulated gasolines, No. 1igh oxygen and high benzene), No. 2 gasoline (lowd high benzene), and No. 3 gasoline (low oxygennzene) (Table 2) were intentionally used for study.ccording to US CARB [26], the content of oxygene above 1.8 and 0.8, respectively are defined as high

llenge enginetoxicity figures for exhaust waste gas of motorcy-

vy traffic for city dwellers, two kinds of motorcycleo-stroke (2T) and four-stroke (4T), were used asines for assessment. The ages of the two-stroke arend are 3 years old. The powers of two-stroke andengines are 1.5 and 5.0 horse power, respectively.

mortality assessment

DH5 (generously provided by Professor Jo-Shutional Cheng-Kung University, Taiwan) was used asr strain for biotoxicity assessment. A loopful of therain seed taken from an isolated colony in LB-streakrecultured in 50 mL Luria-Bertani medium (LB broth,co) for 12 h overnight at 37 C, 200 rpm. To ensurenous growth activity and maximum metabolic func-

he same growth phase for bioassay, 5% (v/v) culturedhen inoculated to fresh sterile LB medium and a cellharvested at approximately mid-exponential growth

4 h) for further toxicity assessment. The 1.0 mL cellthen serially diluted and well mixed with 9.0 mL ster-

olution (SSS; NaCl 10.0 g L1) and only the diluentriate cell concentrations (ca. 150015,000 cells/mL)as the test seed (TS) for later uses.

icity assessment

ity assessment was specifically designated throughtion of doseresponse analysis [3239] as follows:

the presence of unwanted bacterial contaminants,olutions for sampled chemicals (e.g., BTEX, PAHs)terilized via moist-heat method (121 C at 15 psi ford then tested materials (e.g., BTEX, PAHs) steril-h 0.2m sterile filter were added. Thus, the sampleon defined herein was the concentration of testedand their serial diluents well mixed with SSS. Itated that the sodium chloride solution used for serialf various solution was the toxicity-free control. To

(a) The dn-Para

n-Bn-Pn-Hn-Hn-O

Total

BrancIsobIsop2-M3-M2,32-M3-M2,32,42,22,32,32,22,42,52,33-M2-M2-M3-M2,2

Total

CycloMecis-Me

Total

Olefint-Bt-Pec-P2-M2-M

Total

AromBenTolEtho-Xm-Xp-X1-M1-M1,2

Total

(b) The oNo. 1No. 2No. 3


exclude confounding interferences, phosphate buffered saline(PBS) solution, which is regularly used for biological assay,was not usbe formed dtoxicity tescriteria of mcentration. . ., 1/2n Ctested or itsresulted serfor use inseed (TS)count dilue1.0 mL frestoxicity-frethe control[34,35]. Stfollows: SPsampling, awere spreawould be amedium plcells in allat 37 C fomeration. Ostatisticallying proceduand controRSD can thcell count):

Cells per lit

To havedenoted as0 and 1 diretoxicity tosimply sugconcentratitoxicity). Ttoxicity ofThe concenin doserestoxicity (Tvide an obchemicals.less than thmore toxicdilution fachave zero

2.4. Dose

The con

Y = A + B

Schemunt m

.5{

(

B and inttratise (%r furma

latioC/V

hal cTo

espotrati.0, 3

ults

TEX

toxncentration (ECx) administered to the bacterial populationvoke x% response (e.g., x = 50 as EC50). The EC0 andcan be defined as the maximum concentration to have

ctable response (i.e., 0+%) and minimum concentratione 100% response, respectively. The discrepancy amongof effective concentrations at different levels (e.g., EC0,nd EC50) are response effect of each level. The highern be illustrated with lower toxicity of maximum concen-to have a detectable response. Whereas, the EC50 are theetectable response of the bacterial population. It is moreto use EC50 than to use EC20 as an indicator in regula-

he target compounds over and under their EC100 obviouslyn extinction and survival of viable cells, respectively. ECxtatively provides a more clear indication for toxicity com-

among chemicals; the smaller the ECx, the more toxiced here, since metallic phosphate precipitates mighturing serial dilution. The initial concentration C0 forts of all chemicals was appropriately chosen underaximal solubility. Serial-half dilution of initial con-

C0 (i.e., 1/2 C0, 1/4 C0, 1/8 C0, 1/16 C0, 1/32 C0,0) was carried out by using 50 mL solution to bederived diluents mixed with 50 mL SSS. The 9.0 mLial diluents (RSD) were all placed in sterile test tubesquantification of viable cells afterwards. The test

was then well mixed with RSD to form serial platents (SPCD) via serial dilution technique. Meanwhile,h TS mixed with 9.0 mL pure SSS was used as thee control. The numbers of viable DH5 in SPCD orwere estimated by the standard plate count method

andard plate count in LB medium was carried out asCD were serially diluted with SSS immediately afternd then appropriate volumes (ca. 0.20 mL) of SPCDd onto agar Petri plates. Note that all cells in SPCDssumed metabolically viable and culturable on LB-ates due to fresh preparation of fast-growing E. colisteps. The LB-medium plates were then incubatedr ca. 1624 h to form observable colonies for enu-nly plates with between 30 and 300 colonies wereappropriate for counting. Serial dilutionagar plat-res were carried out in duplicate for quality assurance

l (QA/QC). The microbial population in the originalen be calculated using the following formula (CC:

er of broth (CC) = number of coloniesamount plated dilution factor

(1)quantitative toxicity for comparison, CC0 was

the CC at zero-toxicity control. The ratio CC/CC0 ofctly indicated complete inhibition and no inhibitorybacterial cell, respectively. The unity of this ratiogests that the present toxicity of this diluent at thison is nearly equal to the toxicity of SSS (i.e., zerohe toxicity of SSS can be used to indicate the mainair pollutants that many species were mixed together.tration range for the ratio jumped from 1.0 to 0.0ponse curves [37] is defined here as the thresholdT) range. The comparison on TT range could pro-

vious diagram of toxicity ranking for various testedFor example, if the TT range for chemical A is muchat for chemical B, chemical A is inevitable muchthan chemical B and this indicated that much highertor must be carried out for chemical A in order to

toxicity as same as control (SSS) (Fig. 1).

response analysis

version formulae for doseresponse analysis were

log Z, (2)

Fig. 1.plate co

P = 0

erf(x)

wheretor) anconcen

responan erro

was no

sion re1 VCthe lettively.doserconcen

(e.g., 1

3. Res

3.1. B

Thetive coto proEC100a deteto havranksEC20 aEC0 catration50% dstrictlytion. Tresult iquantiparisonatic of toxicity assessment (dosemortality relationships) usingethod.

1 + erf( (Y 5)

2

)}, (3)

2

) x0

e2 d, (4)

dA denoted the Hill slope (i.e., steepness or slope fac-ercept of doseresponse relation, Z and Y were metalon (mg/L) and probit unit, respectively; P was the

) corresponding to administered metal, erf(x) wasnction. It should be noted that the response variablelized to be located between 0 and 1. The conver-n between the probit unit and provoked responseCC0 was calculated. The VCC and VCC0 denote

oncentration and initial lethal concentration, respec-consider the non-biased experimental design fornse analysis in log-normal distribution, pollutantons were approximately equally spaced on a log scale.16, 10, 31.6, 100, 316 mg/L).

and discussion

icity of a compound can be expressed by the effec-


Table 3Critical effective concentrations and related parameters of toxicity predicted from the probit model for BTEX

EC0 (mg/L) EC20 (mg/L)Benzene 8.18 102 9.65 101Toluene 9.52 103 5.63 101Ethyl benzene 5.74 102 7.89Xylene 1.66 101 1.42

the compound. As lower ECx clearly revealed higher toxic char-acteristics of pollutants in comparison, the toxicity ranking, inincreasing order, based upon EC20 and EC50 are listed as follows(Table 3; Fig. 2):

EC0: toluene > ethyl benzene > benzene > xylene,EC20: toluene > benzene > xylene > ethyl benzene,EC50: benzene > xylene > toluene > ethyl benzene.

Note that the difference in the ranking of ECx values was dueto diverse tolerance to the suspected toxic material to be tested.Moreover, the slope factor B of probit model for dosemortalitycurves (seeof a target chas a slopewere greatcharacterisorder, base

Slope B:

Note thresponse csusceptibilorganism.gests the smtolerance (FB for ethylto ethyl ben

Fig. 2. Dose(curves) (line

imum effecairbone eaused to esttially lethahttp://flora2doc for xylsame orderzene (5.46)US EPA (efor xylene)OM trendsethylbenze

ely vuldnts (

otornes

Diffratud arn thncen

Thealenrmorbenzlso snt thin Fasol

No.(S),: No(S),: No(S),

B(S) >Eqs. (2)(4)) is also another indicator to the toxicityompound. Note that a standard doseresponse curve

factorBof unity. Since all slope factorsBof the curveser than unity, steeper curves thus indicate the toxictics of all cases. The toxicity ranking, in increasingd upon slope B is listed as follows (Table 3; Fig. 2):

xylene > benzene > (1.0) > toluene > ethyl benzene.

at if the slope B (e.g., less than unity) of the doseurve is shallow, there is considerable variation inity to that particular chemical within probing micro-The largest value (1.675) of slope B for xylene sug-allest tolerance range from EC0 to EC100 for toxicityig. 2). In contrast, the smallest value (0.73) of slope

benzene simply implies the widest range of tolerancezene toxicity from the threshold dose (EC0) to a max-

relativand copolluta

3.2. Mgasoli

3.2.1.Lite

gen anrises iThe coFig. 3.naphthFurthesition,This aaugmeshownlated g

EC0:PAHsEC20PAHsEC50PAHsSlopePAHsmortality curve of BTEX toxicity predicted from the probit models indicated EC50 values).

These raincreasinglines. Thesince the mof No. 1 iserature [36EC50 (mg/L) Y=A + B log C3.64 Y= 4.183 + 1.456 log C5.07 Y = 4.380 + 0.880 log C

111.78 Y = 3.506 + 0.730 log C4.50 Y = 3.907 + 1.675 log C

t dose (EC100). As many chemicals do not becomesily, oral LD50 in acute dosemortality curve wasimate the quantity of chemical that would be poten-l for a human [36]. According to Taiwan EPA (e.g.,.epa.gov.tw/toxicweb/ToxicUC4/database/1330207.ene), oral LD50 (in g/kg) in rats were almost in theof magnitude (OM) (e.g., benzene (4.70), ethylben-, toluene (5.00), xylene (5.10 3.5)). According to.g., http://www.epa.gov/ttn/atw/hlthef/xylenes.html

, air LD50 (in g/m3) in mice almost followed identical(e.g., benzene (32.0), toluene (33.2), xylene (27.6),

ne (17.4)). Thus, this suggested that EC50 might beiable for parallel OM trends (except ethylbenzene)

be used to define the margin of safety for suspectedsee afterwards).

cycle exhaust using different reformulated

erent reformulated oxygen and benzene gasolinere [15,3739] indicated that increases in the oxy-omatic hydrocarbon (HC) contents lead to markede concentrations of PAHs in motorcycle exhaust.tration of PAHs composition profiles were listed inhighest mass concentration of the main composition,e, is approximately ranged from 45 to 80g/Nm3.e, the highest toxic concentration of the main compo-o(a)pyrene, is roughly ranged from 20 to 30g/Nm3.uggested that increases in these contents might alsoe toxicity of motorcycle exhaust to be generated. Asig. 4 and Table 4, toxicity rankings of these reformu-ines (in increasing order) were shown as follows:

1 PAHs(S) > No. 2 PAHs(S) > No. 3 PAHs(G) > No. 3

. 1 PAHs(S) > No. 3 PAHs(G) > No. 2 PAHs(S) > No. 3

. 1 PAHs(S) > No. 3 PAHs(G) > No. 2 PAHs(S) > No. 3

: No. 3 PAHs(G) > No. 1 PAHs(S) > No. 21.0 > No. 3 PAHs(S).nkings in toxicity seemed to be in parallel with anorder in oxygen and benzene in reformulated gaso-rankings can be also verified with the data in Fig. 3ost toxic compound, benzo(a)pyrene, concentration

larger than that of the other gasolines. In addition, lit-] indicated that PAHs may react with strong oxidative


Fig. 3. The mengine.

compoundsspecies. Mospecies prefrequency ttoxicity in

3.2.2. MotTo Con

in two-stroengine) weings (i.e., Eshowed thastraightforw

osemortality curve of toxicity of motorcycle exhaust using No. 1, No.o. 3 gasolines.

Table 4Critical effect

No. 1 PAHs(SNo. 2 PAHs(SNo. 3 PAHs(SNo. 3 PAHs(G

Table 5Critical effect

Two-stroke enFour-stroke enain composition of PAHs in the motorcycle exhaust with two-stroke

(e.g., O3, NOx) in air to form highly toxic pollutantreover, due to less mass transfer resistance, chemical

Fig. 4. D2 and Nsent in gas phase would have a significantly highero collide with species for reaction, leading to a highergas phase for No. 3 PAHs [40,41].

orcycle exhaust using different stroke enginessider evaluation upon practical cases, motorcycleske engine (2T engine) and four-stroke engine (4Tre used (Table 5 and Fig. 5). The toxicity rank-C0, EC20, EC50, slope B) of these two engines all

t 2T engine > 4T engine. The reasons of this result areard. Compared to 4T engine, 2T engine is relatively

Fig. 5. Dosemortality curve of toxicity of motorcycle exhaust using two-strokeand four-stroke engines.

ive concentrations and related parameters of toxicity predicted from the probit model for different motorcycle exhaust using reformulated gasoline

EC0 (mg/L) EC20 (mg/L) EC50 (mg/L) Y = A + B log C) 1.66 103 1.12 102 3.13 102 Y = 7.846 + 1.879 log C) 2.48 103 7.80 102 4.99 101 Y = 5.315 + 1.042 log C) 5.95 103 3.14 101 2.66 Y = 4.615 + 0.906 log C) 4.16 103 2.14 102 5.16 102 Y = 7.824 + 2.194 log C

ive concentrations and related parameters of toxicity predicted from the probit model for motorcycle exhaust using 2T, 4T engines

EC0 (mg/L) EC20 (mg/L) EC50 (mg/L) Y = A + B log Cgine 8.46 103 1.18 101 4.87 101 Y = 5.427 + 1.364 log Cgine 3.47 102 4.98 101 2.09 Y = 4.568 + 1.349 log C


Fig. 6. CompPAHs).

inexpensivsame size.plete combof engine oengine evidcity even toThis couldage 4T enregulations

3.3. Overa

The ranous pollut(1.879) > x(1.364) > 43 PAHs(S)In additionNo. 1 PAH(0.487) > N3 PAHs(S(5.07) etis significalikely duecombustionapparentlyoverall toxtoxicity serPAHs (ca. 0(No. 3 PAH

Reference

[1] Taiwan Iand Comturers in

[2] Lin, C.S., Study on the Influence of Oil and Engine Speed on Two-strokeMotorcycle Engine Exhaust Gases Toxicity, Masters Thesis, National SanYat-Sen University, 1997.

dwar. KaoWas

K. Jo,ociateor em

F. Oets of tWilcznal ex. Infancell tyviron.Aksod. 8 (Rithileuke

. Smting o. WaC emnage.. Ticcatalolko

anicprin

Fu, J.ir W

Broww Yor. We570

J. Tarcup. MCernCzec

Armsosure

viron.arison of toxicity potency for all tested pollutants (e.g., BTEX and

e to generate larger power output than 4T engine in theHowever, the 2T engine has disadvantages of incom-ustion and less efficiency due to mixed combustionil and gasoline. According to EC50, compared to 2Tently using 4T engine at least reduced fourfold toxi-xicity tolerance (i.e., slope B) seems to be identical.explain why Taiwan EPA tended to strongly encour-gine in place of 2T engine for new environmental[42].

ll toxicity comparison

king of toxicity tolerance (slope B) for vari-ants are No. 3 PAHs(G) (2.194) > No. 1 PAHs(S)ylene (1.675) > benzene (1.456) > 2T engine

[3] J. E[4] A.S

Air[5] W.

ass

vap[6] W.

ger[7] T.

tio[8] P.F

byEn

[9] M.Me

[10] K.in46.

[11] C.Mcoa

[12] R.AVOMa

[13] B.Avia

[14] P. Worgand

[15] L.J. A

[16] E.Ne

[17] B.L569

[18] M.Oc

[19] M.the

[20] B.expEnT engine (1.349) > No. 2 PAHs(S) (1.042) > 1.0 > No.(0.906) > toluene (0.880) > ethyl benzene (0.730)., the toxicity series based on EC50 (in mg/L) ares(S) (0.0313) > No. 3 PAHs(G)(0.0516) > 2T engineo. 2 PAHs(S) (0.499) > 4T engine (2.09) > No.

)(2.60) > benzene (3.64) > xylene (4.50) > toluenehylbenzene (111.78). Obviously, motorcycle exhaustntly more toxic than typical VOCs (e.g., BTEX)to highly toxic VOCs generated from incomplete. EC50s also indicated that all the pollutants weremore toxic than BTEX. Regarding margin of safety,icity evaluation upon all pollutants showed that theies (EC50 in mg/L) was approximately as follows:.050.5) >2T, 4T engines (0.52) >BTEX (3.65.0)s(s) and ethylbenzene excluded) (Tables, Figs. 26).

s

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Toxicity assessment of volatile organic compounds and polycyclic aromatic hydrocarbons in motorcycle exhaustIntroductionMaterials and methodsTested pollutants, engine and gasolineChallenge pollutantsChallenge gasolinesChallenge engine

Dose-mortality assessmentBiotoxicity assessmentDose-response analysis

Results and discussionBTEXMotorcycle exhaust using different reformulated gasolinesDifferent reformulated oxygen and benzene gasolineMotorcycle exhaust using different stroke engines

Overall toxicity comparison

References

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