가솔린첨가제 MTBE 의인체및생태영향 안윤주, 이우미 J. ENVIRON. TOXICOL. Vol. 21, No. 2, 93~102 (2006) 건국대학교환경과학과 Effects of Gasoline Additive, Methyl tert-butyl Ether (MTBE) to Human Health and Ecosystem Youn-Joo An and Woo-Mi Lee Department of Environmental Science, Konkuk University, Seoul 143-701, Korea ABSTRACT Methyl tert-butyl ether (MTBE), an octane booster that is added to the reformulated gasoline, has been a widespread contaminant in aquatic ecosystem. MTBE is a recalcitrant pollutant having low biodegradability. Due to its higher water solubility and low octanol-water partition coefficient, it can be rapidly transported to the surrounding water environment. Also, MTBE is a known animal carcinogen, and is classified as a possible human carcinogen by U. S. Environmental Protection Agency. The adverse effect of MTBE to aquatic biota was widely reported. In Korea, the recent detection of MTBE in groundwater near gasoline filling stations has drawn concern to public health and ecosystem. To address this concern, the effect of MTBE to human health and ecosystem was discussed in this review. Also, ecotoxicity data of MTBE for fish, invertebrates, and algae were extensively compared to estimate the hazard concentration 5 (HC 5) of MTBE as a screening level. Key words : methyl tert-butyl ether (MTBE), gasoline additive, human health, ecosystem, ecotoxicity, HC 5 MTBE 의특성및환경매체내분포 1. MTBE 사용역사와오염실태 Methyl tert-butyl Ether (MTBE) 는 Methanol 과 Isobutylene 으로합성된화학물질로연료의완전연소를위한가솔린첨가제로사용되고있다. MTBE 는가솔린구성성분중단독성분으로는최다량 (10~15% v/v) 함유되어있으며, 자동차로인한대기중의일산화탄소와오존농도를감소시키는등 To whom correspondence should be addressed. Tel: +82-2-2049-6090, E-mail: anyjoo@konkuk.ac.kr 대기보전에일조를해왔다. MTBE 는 1970 년대말미국에서사용되기시작하였고, 1990 년대기정화법 (Clean Air Act) 이개정되면서그사용량이증가하였으며, 1998 년경에는미국내 Bulk Chemical 생산량으로 4 위를기록하였다 (Johnson et al., 2000). 1990 년대초반이후미국뿐아니라유럽등지에서광범위하게사용된 MTBE 는대기오염저감물질이지만, 이와동시에지하수및지표수오염에대한문제점이제기되기시작하였다. 지하수가주요식수원인미국에서는 1993 년이후로지하수와지표수에서 MTBE 가검출되었고 (Newman, 1995), 1995 년캘리포니아주 Santa Monica 지하수에서이취미물질인 MTBE 오염이발견됨으로써위해성에관한 93
94 J. ENVIRON. TOXICOL. Vol. 21, No. 2 논란이일어나기시작하였다. MTBE 는지하저장탱크 (Underground Storage Tank, UST) 의누유로인해환경매체로누출되며, 지표수의경우 Boating 과같은여가활동이주요오염원이될수있다 (An et al., 2002). 미국환경청 (U. S. Environmental Protection Agency) 은 MTBE 를잠재적인체발암물질 (Possible Human Carcinogen) 로규정하는등인체발암성이제기되면서 MTBE 에대한우려와사용규제에대한필요성이부각되고있다. 미국은연방차원에서의규제기준은없지만일부주 ( 예 : 캘리포니아 ) 는주정부차원의규제기준을설정하고있다. 유럽에서도 1995 년부터 1999 년까지가솔린에서의 MTBE 사용량은 23% 증가했다. 독일의최근연구에의하면독일내 50 개도시로부터정수처리를마친음용수시료에서 MTBE 를분석한결과 (DL 10 ng/l), 46% 의시료에서 MTBE 가검출되었고, 농도범위는 17~712 ng/l 로조사되었다 (Kolb and Püttmann, 2006) 우리나라는 1993 년무연휘발유공급이의무화되면서연료에 MTBE 를사용하기시작하여약 11% (v/v) 까지첨가되어왔다. 2003 년국정감사에서 MTBE 오염과관련한실태조사필요성이제기되었고, 국내지하수및토양에도분포되었을것으로추정되면서, 환경부는최근 2 년간에걸친 MTBE 국내오염실태조사사업을수행하였다. 그결과, 주유소인근지하수에서 MTBE 오염이확인되었으며, 지속적인추가모니터링을통해체계적인관리방안을마련하겠다고발표한바있다. CH 3 CH 3 O C CH 3 CH 3 Fig. 1. Molecular structure of methyl tert-buthyl ether. Table 1. Physical and chemical properties of MTBE at 25 C 1) Property MTBE CH 3OC (CH 3) 3 Molecular weight 88.15 Specific gravity (g/cm 3 ) 2) 0.7404 Water solubility (mg/l) 42000 Vapor pressure (Pa) 33500 Henry s law constant (Pa m 3 /mol) 70.31 Log K ow 0.94 3) Log K oc 1.05 % Volume in gasoline 3),4) 10~15 Water solubility in gasoline mixture (mg/l) 4300 4), 4700 5) Biodegradation rate (% per day) 3) 0.01~0.1 Odor Threshold (ppbv) 3) 95 Taste Threshold (µg/l) 3) 10~130 1) Data from Mackay et al. (Mackay et al., 1999) unless otherwise noted, 2) measured at 20 C, 3) Day (Day, 2000), 4) Based on gasoline containing 10% MTBE, 1% benzene, 5% toluene, 1% ethylbenzene, and 8% total xylenes (Day, 2000), 5) MTBE solubility is from reformulated gasoline containing 11% MTBE and BTEX solubility from conventional gasoline containing 1% benzene, 5% toluene, 1.5% ethylbenzene, and 10% total xylenes at 20 C (Johnson et al., 2000) 2. MTBE 의물리화학적특성 MTBE 는분자구조에 Ether 기를가지고있는난분해성물질로 (Fig. 1), 생분해성이낮고환경매체내의잔류기간이길다 (Johnson et al., 2000). MTBE 는가솔린의기타구성성분 (Benzene, Toluene, Ethylbenzene, Xylenes 등 ) 에비해높은수용해도 ( 약 40,000 mg/l), 낮은 Kow 값 (log Kow 약 1,24) 을가지고있다 (Andrews, 1998; An et al., 2002). 이러한성질로인해 MTBE 는토양입자에잘흡착되지않고, 지하수로유입될경우지하수흐름을타고단시간내에광범위한지역으로확산될가능성이높다. 또한 MTBE 는이취미물질로사람에따라단맛, 쓴맛이있다고알려져있으며, 맛과냄새는각 각 2.5~680 µg/l, 2.5~190 µg/l 으로사람에따라 MTBE 를감지할수있는범위가광범위하다 (Keller et al., 1998). 1. MTBE 의발암효과 MTBE 의인체독성 MTBE 의동물발암성은실험연구를통해이미규명이되었으며, 미국환경청 (US EPA) 은 MTBE 를잠재적인체발암물질로규정하는등인체발암성이의심되고있다. 국제암연구센터 (International Agency for Research on Cancer, IARC) 에의하면 MTBE 는
June 2006 An and Lee : MTBE 의인체및생태영향 95 Group 3 carcinogen (not classifiable as to its carcinogenicity to humans) 로분류되어있다. Table 2 는 MTBE 에대한설치류의급성독성자료로, Rat 을대상으로섭취, 흡입, 그리고피부접촉의경로로 4 시간동안 MTBE 를노출시켰을때 LD50 와 LC50 를나타낸것이다 (ECB, 2000 위해성평가보고서에서인용 ). 동물실험을통해 MTBE 가체내 Table 2. Acute toxicity of MTBE to animals (Rodents). (Adapted from ECB, 2002) Exposure route Exposure duration LD50/LC50 Oral 4 hours 3,800 mg/kg Oral 4 hours 3,866 mg/kg Oral 4 hours 4,000 mg/kg Oral 4 hours 2,000 mg/kg Inhalation 4 hours 85 mg/l Inhalation 4 hours 120~140 mg/l Dermal 4 hours 10,200 mg/kg Dermal 4 hours 10,000 mg/kg Dermal 4 hours 2,000 mg/kg *Tests were conducted based on OECD guideline 401 or 402 study 로흡수될경우영향을받는기관은간과신장인것으로나타났다 (Burleigh-Flayer et al., 1992). 설치류를이용한독성실험에서흡입의경우 3,000 ppm 이상일때, 섭취의경우 250 mg/kg 이상섭취시켰을때종양이발생하였다. 72 주동안 CD-1 mouse 에 MTBE 흡입실험결과 8,000 ppm 을흡입시킨수컷의 16% 에서간암이발생했고, 33% 는간세포에서양성종양과악성종양이함께발견되었다. 대조군에서간암발생률이 4% 인것에비하면약 4 배정도암발생률이높은것으로나타났다. 또한암컷의경우같은농도에서간암발생이 2% 로수컷이암컷보다 MTBE 에더영향을받는것을연구되었다. 동물실험에서 MTBE 의흡입에대한 NOAEC 은 400 ppm, 섭취에대한 LOAEC 은 250 mg/kg 으로산출되었다. 설치류에대한장기간의실험에서 MTBE 는잠재적인발암을나타냈는데, 암컷에고용량 (29,000 mg/m 3 ) 의 MTBE 를흡입시켰을때간세포에 Adenoma 발생률이증가한것으로나타났다 (WHO, 2005). Table 3 은설치류를 MTBE 에장기간노출 Table 3. Chronic toxicity of MTBE to animals (rodents) (Adapted from ECB, 2002) Test species Duration/route Doses NOAEL/LOAEL Effects at LOAEL Sprague-Dawley 357~1,428 14d-oral 357/357 mg/kg 1) Depressed Lung weight Rat mg/kg 1) Sprague-Dawley 90~1,750 1) Increased kidney weight, hyaline 28d-oral 90/440 mg/kg Rat mg/kg 1) droplet formation in kidney pct Sprague-Dawley 250~1,500 28d-oral 250/250 mg/kg 1) Kidney protein droplet nephropathy Rat mg/kg Sprague-Dawley 100~1,200 90d-oral 300/900 mg/kg 1) Increased liver weight, AST2), Rat mg/kg 1) increased cholesterol Sprague-Dawley 200~1,200 3) Increased liver weight, Signs of 90d-oral Rat mg/kg 1) 200/200 mg/kg1) morphological changes to hepatocyte cell structures in electron microscopy Fisher-344 Rat 28d-inhalation 400~8,000 mg/kg 400/3,000 ppm Proliferation of the kidney proximal tubuli epithelial cells CD-1 Mouse 28d-inhalation 400~8,000 mg/kg 400/3,000 ppm Liver cell proliferation Depressed lung weight (females), CD-rat 31w-inhalation 250~1,000 ppm 500/1,000 ppm increased hemoglobin, blood urea nitrogen and LDH 4) (males) Abnormalities in kidney pct morphology, Fisher-344 Rat 13w-inhalation 800~8,000 ppm 800/4,000 ppm changes in hormone levels, Alterations in red blood cell parameters 1) Gavage administration applied, 2) aspartate amino transferase, 3) LOEL, 4) lactate dehydrogenase
96 J. ENVIRON. TOXICOL. Vol. 21, No. 2 시켰을때 NOAEC/LOAEC 값을제시하고있는데 (ECB, 2000 위해성평가보고서에서인용 ), Fisher-344 와 Sprague-Dawley Rat 의정소세포에서 Adenoma 가발생하였다. 대부분악성종양은고농도에서발생하였고 MTBE 에대한유전독성은관찰되지않았다 (ECB, 2002). 2. MTBE 의비발암효과 MTBE 는미국환경청의통합위해도정보시스템 (Integrated Risk Information System, IRIS) 하에서평가된바있으며, 호흡경로에의한비발암참고치는 3 mg/m 3 로알려져있다. 미국환경청의 National Health and Environmental Effects Research Laboratory (NHEERL) 에서수행된인체노출평가실험에의하면지원자 ( 남자 19 명, 여자 18 명 ) 을대상으로 1.39 ppm 의 MTBE 를한시간동안흡입시킨결과별다른영향을받지않는것으로나타났고, 2 명의지원자를대상으로혈액을채취하여분석한결과 TBA 로신속하게대사되는것으로조사되었다. 미국알라스카주의 Fairbanks 에서연료에 MTBE 를사용하기시작한이후로거주민들이두통, 현기증, 그리고구역질등의증상을호소했다. 또한 MTBE 노출이있는작업장에서근무하는노동자를대상으로조사한결과목이타는듯함, 기침, 메스꺼움또는구토, 현기증, 방향감각상실이나혼미한증상이나타났고또한설사, 열, 식은땀, 피부염증, 근육통, 피로, 실신, 호흡곤란증상이관찰되었다 (ECB, 2002). 근무자들의혈액검사결과작업전에는 0.013 µmol/l 로, 작업후에는 0.02 µmol/l 로증가하였으며, 채취한혈액중 MTBE 는최대 0.42 µmol/l 까지측정되었다. 또한몇몇근무자에서는 MTBE 의대사산물인 TBA 가고농도로검출되었다. 그리고자동차를이용하여통근하는사람을대상으로혈액내 MTBE 를측정하였을때통근전에는 0.002 µmol/l 였으나작업장에도착하였을때에는혈액내농도가 0.011 µmol/l 로약 6 배가증가하였다 (ECB, 2002). 한편 1~76 µg/l 의 MTBE 와 0.2~14 µg/l benzene 이함유된수돗물을 5~8 년동안섭취한 60 명의환자에서명백히설명할수없는다양한증상이나타났는데이는혈액림프구주변에서세포괴사로인한것으로밝혀졌다 (Vojdani et al., 1997). MTBE 의생태영향 MTBE 에대한생태영향은현재까지대부분수생태계를대상으로연구되어있다. MTBE 는휘발성을가지는유기오염물질이므로수생태계에서의독성자료는거의급성독성자료이며, 생활사가다른생물종에비해짧은조류 (Algae) 에대해서만만성노출에의한영향이보고되어있을뿐이다. 본연구에서는수생태계에대한 MTBE 의영향을파악하기위해영양단계별 ( 어류, 무척추동물, 조류등 ) 로구분하여각생물종에대해독성자료를토대로심도있게고찰하였다. 1. 어류독성 Table 4 는 MTBE 에대한어류의독성자료이다. 독성시험종중가장많이이용된종은 Pimephales promelas 이다. 어류에대한독성종말점은대부분이 LC50 이었고동일노출기간이라하더라도어종에따라그값의차이가현저하였다. 또한동일어종, 동일노출시간이라하더라도실험자에따른독성값은차이가있는것으로나타났다. MTBE 에대한어류독성의최저값과최고값은상당한차이가나타났는데최저독성값은 를 7 일간노출시켰을때성장에대한 NOEC 값으로제시된 234 mg/l 이다 (Hockett, 1997). 최고값은 Longo (1995) 가수행한 Oryzias latipes 을 8 일간노출시켜얻은 LOEC 값 (2600 mg/l) 으로발달장애를측정한값이다. Wong et al. (2001) 은 Lepomis macrochirus 를이용한실험에서 96 시간의 LC50 와평형상태에대한 EC50 측정결과두가지독성종말점모두 1,054 mg/l 로관찰되었다. 또한 NOEC 은 767 mg/l 로 100% 의치사율을나타낸농도는 1,450 mg/l 으로측정되었다. P. promelas 에대한 31 일간의만성독성실험결과독성종말점에따라독성값의차이가크게는약 3 배정도나타났다 (Wong et al., 2001). 어류의 MTBE 에대한민감도를살펴보면 P. promelas O. mykiss L. macrochirus O. latipes 의순으로앞에서언급한최저독성값을나타낸 P. promelas 가가장민감하였고, 최고독성값을
June 2006 An and Lee : MTBE 의인체및생태영향 97 Table 4. Toxicity of MTBE to fish Species Duration Endpoint Type Conc. (mg L -1 ) Reference 24h LC50 flow through 1045 Hockett, 1997c 72h LC50 flow through 1026 Hockett, 1997c 96h LC50 flow through 980 Hockett, 1997c Geiger et al., 96h LC50 flow through 672 1981 Veith et al., 96h LC50 706 1983 BenKinney et al., 96h LC50 static, renewal 929 1994 7d NOEC (growth) static renewal 234 Hockett, 1997c 7d LOEC (growth) static renewal 388 Hockett, 1997c 31d IC20 (fry growth-dry wt) flow through 279 Wong et al., 2001 31d NOEC (fry growth-length) flow through 299 Wong et al., 2001 Pimephales promela s 31d LOEC (fry growth-length) flow through 450 Wong et al., 2001 31d NOEC (embryo/egg mortality) flow through 720 Wong et al., 2001 31d NOEC (time to hatch) flow through 299 Wong et al., 2001 Pimephales promela s 31d LOEC (time to hatch) flow through 450 Wong et al., 2001 31d NOEC (hatch mortality) flow through 720 Wong et al., 2001 31d NOEC (posthatch fry mortality) flow through 450 Wong et al., 2001 31d LOEC (posthatch fry mortality) flow through 720 Wong et al., 2001 Lepomis macrochirus (Bluegill sunfish) 96h LC50 (mortality) flow through 1054 Wong et al., 2001 Lepomis macrochirus (Bluegill sunfish) 96h EC50 (equilibrium) flow through 1054 Wong et al., 2001 Alburnus alburns Bengtsson and 96h LC50 1000 (Bleak) Tarkpea, 1983 Onchorhynchus mykiss (Rainbow trout) 96h LC50 flow through 887 Hockett, 1997a Onchorhynchus mykiss BenKinney et al., 96h LC50 1237 (Rainbow trout) 1994 Oryzias latipes (Medaka) 8d LOEC (development) 2600 Longo, 1995
98 J. ENVIRON. TOXICOL. Vol. 21, No. 2 Table 5. Toxicity of MTBE to invertebrates Species Duration Endpoint Type Conc. (mg L -1 ) Reference 48h EC50 651.4 Huels AG, 1991a 48h EC50 flow through 472 Wong et al., 2001 48h LC50 static, renewal 542 Hockett, 1997b BenKinney et al., 96h LC50 681 1994 Hockett, 1997b 96h LC50 static, renewal 542 Hernando et al., 96h EC50 720 2003-96h EC25 57 Hockett, 1997b 21d MATC (mortality) flow through 117 Wong et al., 2001 21d NOEC (growth) flow through 50 Wong et al., 2001 21d LOEC (growth) flow through 100 Wong et al., 2001 Ceriodaphnia dubia 48h LC50 static, renewal 340 Hockett, 1997b Ceriodaphnia dubia 5d LOEC (survival) static, renewal 580 Hockett, 1997b Ceriodaphnia dubia 5d NOEC (survival) static, renewal 342 Hockett, 1997b Ceriodaphnia dubia 5d LOEC (Reproduct) static, renewal 342 Hockett, 1997b Ceriodaphnia dubia 5d NOEC (Reproduct) static, renewal 202 Hockett, 1997b Brachionus calyciflorus Werner and 24h LC50 960 (rotifer) Hinton, 1998 Nitocra spinipes Bengtsson and 96h LC50 1000 (copepod) Tarkpea, 1983 Physa gyrina (snail) 96h EC50 flow through 559 Wong et al., 2001 Physa gyrina (snail) 96h LC50 flow through 1036 Wong et al., 2001 Hyallela azteca (amphipod) 96h EC50 flow through 473 Wong et al., 2001 나타낸 O. latipes 가가장둔감한종으로나타났다. P. promelas 에대한 96h-LC50 인 980 mg/l 와 31d- IC20 (growth) 인 289.4 mg/l 를이용하여 ACR (Acute-Chronic Ratio) 을산정한결과 3.4 로계산되었다 (Wong et al., 2001). 2. 무척추동물독성 Table 5 은 MTBE 에대한무척추동물의독성자료이다. Hockett (1997) 은 C. dubia 를 5 일간노출실험하여생존율과번식에대한 NOEC 과 LOEC 값을
June 2006 An and Lee : MTBE 의인체및생태영향 99 Table 6. Toxicity of MTBE to Microalgae Species Duration Endpoint Type Conc. (mg L -1 ) Reference Selenastrum carpricornutum (green algae) 96h IC20 103 API, 1999 Selenastrum carpricornutum (green algae) 96h IC25 134 API, 1999 Selenastrum carpricornutum (green algae) 96h IC50 static 491 Wong et al., 2001 Selenastrum carpricornutum (green algae) 96h EC50 184 BenKinney et al., 1994 Selenastrum carpricornutum Rousch and Sommerfeld, 5d NOEC (growth) 2400 (green algae) 1998 Navivula pelliculosa Rousch and Sommerfeld, 5d NOEC (growth) 1920 (diatom) 1998 Synechococcus leopoliensis Rousch and Sommerfeld, 3d NOEC (growth) 1920 (Blue-green algae) 1998 Scenedesmus subspicatus (green algae) 72h NOEC 470 Huels AG, 1991b 측정하였다. 생존에대한 NOEC 과 LOEC 은 342 mg/l, 그리고 580 mg/l 으로측정되었고번식에대한 NOEC, LOEC 은 342 mg/l, 202 mg/l 로측정되었다. Hernando et al. (2003) 은 OECD Guideline 202 와 ISO 6341 method 를이용하여 D. magna 의유영장애 EC50 를관찰한결과 720 mg/l 로나타났다. 이값은 D. magna 에대해다른시험자들에의해수행된독성값중가장높은값으로 BenKinney et al. (1994) 나 Hockett (1997) 이반수치사량을측정한것보다높은농도였다. Hockett (1997) 이수행한 C. dubia 의 48h-LC50 와 D. magna 의 48h-LC50 를비교하면 C. dubia 의독성값이 (340 mg/l) 이 D. magna 의독성값 (542 mg/l) 보다더낮아 C. dubia 가 D. magna 에비해 MTBE 에더민감하게반응하였다. Wong et al. (2001) 이수행한, Physa gyrina 그리고 Hyallela azteca 에대한 MTBE 독성시험에서가장민감한반응을나타낸것은 였다. MTBE 에대한갑각류의민감도는 C. dubia D. magna H. azteca P. gyrina 순으로가장민감한종은 C. dubia 로나타났다. 3. 조류독성 (Algal Toxicity) 앞에서언급한바와같이조류에대한만성독성 은어류나무척추동물에비해노출기간이짧은것이특징이다. 조류의경우 96 시간동안에여러세대에걸친분열이일어나기때문에 96 시간노출에의한시험은만성독성으로평가하였다. MTBE 의조류독성자료는 Table 6 에정리되어있다. Wong et al. (2001) 은 S. carpricornutum 에대해 Cell density 의 50% 감소를측정한결과 491 mg/l 로나타났다. S. carpricornutum 를이용한다른시험에서 5 일간의생장감소를측정한결과 4,800 mg/l 로상당히높은농도로측정되었다 (Rousch and Sommerfeld, 1998). 생물종에따른 MTBE 독성의차이는 MTBE 의소수성 (lipophilic) 성질과도연관이있는데, 이는생물체의지방함유량에따라흡수될수있는 MTBE 의양이영향을받기때문이다. 예를들면 N. pelliculosa 이 S. carpricornutum 보다 MTBE 독성에더민감한데, N. pelliculosa 저장산물로기름성분을가지고있다 (Rousch and Sommerfeld, 1998). 그러나지방함유량뿐아니라형태적인특성도독성과관계가있다. S. leopoliensis 는 S. carpricornutum 보다 MTBE 독성에더민감한데, 그원인은 Membranebound organelle 이없는 S. leopoliensis 가 MTBE 에더쉽게노출될수있기때문이다 (Rousch and Sommerfeld, 1998).
100 J. ENVIRON. TOXICOL. Vol. 21, No. 2 Table 7. Toxicity of MTBE to other aquatic organisms Species Duration Endpoint Type Conc. (mg L -1 ) Reference Hexagenia limbata (mayfly) 96 h EC50 flow through 581 Wong et al., 2001 Chronomos temtams (midge) 48 h EC50 flow through 1742 Wong et al., 2001 Rana temporaria (amphibian) 96 h LC50 2500 Paulov, 1987 4. 기타수서생물 Table 7 은어류, 물벼룩류, 그리고조류를제외한기타수서생물에대한 MTBE 의독성자료이다. Rana temporaria 는앞에서제시한다른수서생물에비해가장독성에둔감한것으로나타났고그다음으로둔감한종은 Chronomos tentans 이었다. 본연구에서수집된 MTBE 의수서독성자료중 MTBE 에대한결정론적생태위해성평가를수행할경우가장민감한값으로제시할수있는것은최저값인 S. carpricornutum 의 96h-IC20 인 103 mg/l 이다. 5. Acute-Chronic Ratio ACR (Acute-Chronic Ratio) 은같은물질과비슷한조건의급성독성값과만성독성값의비를이용하여산정된다. Wong et al. (2001) 은 P. promelas 와 D. magna 에대한 ACR 을산출하였다. P. promelas 대한 96h-LC50 인 980 mg/l 와 31d-IC20 (growth) 인 289.4 mg/l 를이용하여 ACR 을산정결과 3.4 로계산되었다. 또한 D. magna 의경우급성독성값인 472 mg/l (48h-EC50) 와만성값인 41.6 (IC20) 를이용하여 11.3 로제시하고있다. 본연구에서는위에서수집된자료를이용하여각생물종별 ACR 을산출하였다. ACR 의산출기준은 SMAV (Species Mean Acute Value) 와 SMCV (Species Mena Chronic Value) 을산출하고 SMAV 와 SMCV 의비를이용하여결정하였다. P. promelas 의 SMCV 와 SMCV 는 879.6, 455.8 로산정되어어류의 ACR 은 1.9 로산출되었다. D. magna 의경우 SMCV 와 SMCV 순으로 594.8, 70.7 로 ACR 은 8.4 로계산되었다. 위의값을이용하여 MTBE 에대한수서생물의 ACR 값을산정한결과 4 로결정되었다. 그러나 HC 5 산정시수서생물의보호를위하여 ACR 이 10 이하일경우기본값으로 10 을적용한다 (ANZECC, 2000). Table 8. Toxonomically different types of organisms (Aldenberg and Slob, 1993) Major subdivisions of organisms Fish Invertebrates Plants Others Types of organisms that are considered as being taxonomically different for AF Method Fish Crustaceans, insect, mollusks, annelids, echinoderms, rotifers, hydra Green Algae, blue algae, red algae, macrophytes Blue-green algae (cyanobacteria), amphibians, bacteria, protozoans, coral, fungi and others 6. MTBE 에대한수서생물의 HC 5 수서생물에대한 HC 5 를종민감도분포 (Species Sensitivity Distribution, SSD) 를적용하여산출하였다. 5 종이상의다양한데이터를이용한수학적인계산결과산출된농도가큰차이를나타내지않았기때문에 5 종에대한 NOEC 자료는독성데이터세트로충분하다고할수있다 (Pedersen et al., 1994). 이러한근거를바탕으로위에서제시한독성값을생물종별로분류한후전체적인수생태계의영향을예측하기위하여분류학적으로다른 4 개의그룹에서 5 개종이상의독성데이터를이용하였다 (Table 8 참조 ). 독성자료를급성값과만성값으로분류한후, 비교적자료가풍부한급성독성값을토대로생물종별기하평균값를이용하여종민감도분포를구축하고 MTBE 에대한수생태계의 HC 5 를산정하였다. 그결과 MTBE 에대한수생태계의 HC 5 는 311.88 mg/l 로 (50% confidence) 계산되었고, 만성효과로외삽하기위하여 ACR 10 을적용했을때최종적으로 31.18 mg/l 로예측되었다. 결 론 MTBE 는환경다매체에널리분포되어있는환
June 2006 An and Lee : MTBE 의인체및생태영향 101 경오염물질로다양한경로를통해인체나생태계에노출되고있다. 특히높은수용해도, 낮은생분해성과같은물리화학적인특성은 MTBE 의빠른확산과잔존성과크게연관이있으며, 동물발암물질로확인된물질인만큼, 현시점에서인체발암성여부는규명되고있지않으나, 추후계속적인연구와모니터링이필요한오염물질이다. 특히미국이나유럽국가에서음용수오염이보고되고있고, 최근국내에서도환경중 MTBE 오염이확인된만큼이물질의노출로인한인체및생태영향에대한파악이필요하다고사료된다. 특히매우저농도이기는하지만음용수에서의검출은만성노출의가능성을시사하므로따라서 MTBE 만성노출에대한연구가필요하다. 수생태계에서도대부분의연구는급성연구에집중되어있으나, 난분해성인 MTBE 에수서생물이지속적으로노출될때발생하는생태독성, 그리고위해성에대한연구가추후수행되어야할것으로사료된다. 참고문헌 Aldenberg T and Slob W. Confidence limits for hazardous concentrations based on logistically distributed NOEC toxicity data. Ecotoxicology and Environmental Safety 1993; 25: 48-63. An Y-J, Kampbell DH and Cook ML. Co-occurrence of methyl tert-butyl ether and benzene, toluene, ethylbenzene and xylene compounds at marinas in large reservoir. J Environ Engr -ASCE 2002; 128: 902-906. An Y-J, Kampbell DH and Sewell GW. Water quality at five marinas in Lake Texoma as related to methyl tertbutyl ether (MTBE). Environ Pollut 2002; 118: 331-336. Andrews C. MTBE-A long-term threat to ground water quality. Groundwater 1998; 36: 705-706. ANZECC. National Water Quality Management Strategy Water Quality and Monitoring Guidelines. 2002. API. Toxicity of methyl tertiary-butyl ether (MTBE) to Selenastrum capricornutum under static test conditions: ENSR Environment Toxicology Laboratory for American Petroleum Institute. 1999. Bengtsson BE and Tarkpea M. The acute aquatic toxicity of some substances carried by ship. Marine Pollut. Bulletin 1983; 14(6): 213-214. BenKinney MT, J.F. B, J.S. G and P.A. N (1994). Acute toxicity of methyl-tertiary-butyl ether to aquatic organisms. Abstract 15th Annual SETAC Meeting 30 October-3 November 1994 Denver. Co. USA. Burleigh-Flayer HD, Chun JS and Kintigh WJ. (1992). Methyl Tertiary Butyl Ether: Vapor Inhalation Oncogenicity study in CD-1 Mice: Bushy Run Research Center. Day MJ. Fate and Transport of fuel components below slightly leaking underground tanks. Soil Sediment & Groundwater 2000; MTBE special issue: 21-24. ECB. Tert-Butyl Methyl Ether. European Union Risk Assessment Report. 2002 Geoger DL, Call DJ and Brooke LT. Acute toxicities of Organic chemicals to Fathead Minnows (Pimephales promelas), Vol. IV. Center for lake Superior Environmental Studies, University of Wisconsin, Superior, WI, USA. 1981. Hernando MD, M. E, A.R. F-A and Y. C. Combined toxicity effects of MTBE and pesticides measured with Vibrio fischeri and bioassays. Water Res 2003; 37: 4091-4098. Hockett JR. Acute Toxicity of MTBE to the Under Static-renewal Test Conditions (Study Number 0480-378-003-001). ENSR. Fort Collins, Co. USA. (1997a). Hockett JR. Acute Toxicity of MTBE to the Under Static-renewal Test Conditions (Study Number 0480-378-003-001). ENSR. Fort Collins, Co. USA. (1997b). Hockett JR. Short-term Sub-chronic toxicity of MTBE to the Fathead Minnow () under static-renewal test conditions (Study Number 0480-378- 005-001). ENSR. Fort Collins, Co. USA. (1997c). Huels AG. Bestimmung der Auswirkungen von MTB-Ether auf das Schwimmverhalten von (nach EG 84/449, Nov, 1989). Marl. 1991a. Huels AG. Bestimmung der Auswirkungen von MTB-Ether (Driveron) auf das Wachstum von Scenedesmus subspicatus 86.81.SAG. 1991b. Johnson R, Pankow J, Bender D, Price C and Zogorski J. MTBE-To what extent will past releases contaminate community water supply wells? Environ Sci Technol 2000; 34: 210A-217A. Keller A, Froines J, Koshland C, Reuter J, Suffet I and Last J. Health & Environmental Assessment of MTBE. Report to the governor and legislature of the State of California: University of California. 1998. Kolb A and Püttmann W. Methyl tert-butyl ether (MTBE) in finished drinking water in Germany. Environmental Pollution 2006; 40: 294-303.
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