un«ed States • DRAFT Environmental Protection ECA6-CIN-U029 December, 1987 v°/EPA Research and Development DRINKING WATER HEALTH ADVISORY-FOR 1.2.4-TRIMETHYLBENZENE Prepared for OFFICE OF DRINKING WATER Prepared by Environmental Criteria and Assessment Office Office of Health and Environmental Assessment U.S. Environmental Protection Agency Cincinnati, OH 45268 DRAFT: 00 NOT CITE OR QUOTE NOTICE This document I* a preliminary draft. It has not been formally released by the U.S. Environmental Protection Agency and should not at this stage be construed to represent Agency policy. It Is being circulated for comments on Its technical accuracy and policy Implications. ------- DISCLAIMER reP°r* ^s an external draft for review purposes only and does not constitute Agency policy. Mention of trade 'names or commercial products not constitute endorsement or recommendation for use. Repository Material Permanent Collection Cs. ' " US ERA -Headquarters and Chamic?"? Libraries EPA West Bldg Room 3340 Ma'lcode 3-?04T 1301 Constitution Ave - Washington DC 20004 • 202-5SS-C55S 11 ------- PREFACE This Drinking Water Health Advisory was prepared for the Office of Drinking Water by the Office of Health and Environmental Assessment, Environmental Criteria and Assessment Office, Cincinnati. OH. These non- regulatory Health Advisories derive 1-day. 10-day, longer-term and lifetime health advisory levels for noncardnogens, and carcinogenic potency values for known carcinogens. In the development of this Health Advisory, the scientific literature has been Inventoried and key studies ha-ve been evaluated. Both the published literature and Information obtained from Agency program offices have been evaluated. The literature search Is current through 1985. Hore recent Information may have been added during the review process. The first draft of this document was prepared by Syracuse Research Corporation under EPA Contract No. 68-03-3228. This document was subse- quently revised after reviews by staff within the Office of Health and Environmental Assessment and the Office of Drinking Water, and outside experts. This Health Advisory will become part of the EPA drinking water docket. 111 ------- 1,2,4-Trlmethylbenzene -1- February 12, 1988 I. INTRODUCTION The Office of Drinking Water's nonregulatory Health Advisory Program provides Information on health effects, analytical methodology and treatment technology that would be useful In dealing with contamination of drinking water. Health Advisories also describe concentrations of contaminants In drinking water at which adverse effects would not be anticipated to occur. A margin of safety Is Included to protect -sensitive members of the popu- lation. Health Advisories are not legally enforceable Federal standards. They are subject to change as new and better Information becomes available. The Advisories are offered as technical guidance to assist Federal, State and local officials responsible for protection of the public health when emergency spills or contamination situations occur. The Health Advisory numbers are developed from data that describe noncarclnogenlc endpolnts of toxldty. They do not Incorporate quantita- tively any potential carcinogenic risk from such exposure. For those chemi- cals that are known or probable human carcinogens according to the proposed Agency classification scheme, nonzero, 1-day, 10-day and longer-term Health Advisories may be derived, with attendant caveats. Health Advisories for lifetime exposures may not be recommended. For substances with a carcino- genic potential, chemical concentration values are correlated with carcino- genic risk estimates by employing a cancer potency (unit risk) value together with assumptions for lifelong exposure and the IngestIon of water. The cancer unit risk Is usually derived from a linearized multistage model with 95% upper confidence limits providing a low-dose estimate of cancer risk. The cancer risk Is characterized as being an upper limit estimate, that 1s. the true risk to humans, while not Identifiable, Is not likely to exceed the upper limit estimate and In fact may be lower. While alternative risk modeling approaches may be presented, for example One-hit, Welbull, Loglt or Problt, the range of risks described by using any of these models has little biological significance unless data can be used to support the selection of one model over another. In the Interest of consistency of approach and In providing an upper-bound on the potential carcinogenic risk, the Agency recommends using the linearized multistage model. ------- 1.2,4-TMmethylbenzene -2- February 12, 1988 II. GENERAL INFORMATION AND. PROPERTIES Synonyms Asymmetrical tMmethylbenzene; uns-trlmethylbenzene; psl-cumene; pseudocumene; pseudocumol; as-trlmethylbenzene Uses 1,2,4-Trlmethylbenzene Is used In the manufacture of trlmellltlc anhydride, dyes, Pharmaceuticals, perfumes, resins and pseudocumldlne (Ulndholz. 1983). It 1s a component of gasoline (Verschueren, 1983). Properties Chemical Structure CAS f Chemical formula Molecular weight Physical state (at 25°C) Melting point Boiling point Vapor pressure (25*C) Specific gravity (20/4°C) Hater solubility (25°C) Octanol/water partition coefficient (log Kow) Conversion factor (25°C. 760 mm Hg) CH, I CH3 CH, 95-63-60 C9H12 120.19 liquid -43.78-C 170°C 2.03 mm Hg 0.8761 57 mg/L 3.78 1 mg/m8 = 4.91 ppm Ulndholz. 1983 Ulndholz. 1983 Ulndholz. 1983 Mackay and Sh1u. 1981 Ulndholz. 1983 Mackay and Sh1u, 1981 Hansch and Leo. 1985 ------- 1,2,4-Trlmethylbenzene -3- February 12, 1988 Taste threshold (water) Odor threshold (water) Odor threshold (air) 0.2 mg/m3 Verschueren, 1983 Occurrence In methodology reports (I.e., no mention was made of efforts to ensure representative samples), 1,2,4-tMmethylbenzene was reported 1n single samples of drinking water In Cincinnati, OH at a concentration of 0.127 yg/L (Coleman et al., 1984) and In drinking water from Kltakyushu, Japan at a concentration of 3.3 pg/L (Shlnohara et al.. 1981). Concentrations ranging from 0.002-0.540 jig/L have been detected In seawater from the Narragansett Bay (Wakeham et al., 1983). The mean atmospheric concentration of 1,2,4-trlmethylbenzene In various urban/suburban areas In sthe United States Is reportedly 1.2 ppb (5.9 yg/m8), and the mean concentration Is reportedly 0.580 ppb (2.8 yg/m8) In rural/remote areas (Brodzlnsky and Singh. 1982). 1,2,4-Trlmethylbenzene Is emitted In the exhaust from highway vehicles (Hampton et al.. 1982). Environmental Fate • Based on experimental equilibrium data (Hlne and Hookerjee, 1975), the Henry's Law constant for 1,2,4-trlmethylbenzene at 25°C Is 0.00563 atm-ma/mole. Given this value and using the method of Lyman et al. (1982). the volatilization half-life of 1,2,4-trlmethylbenzene from a river 1 m deep flowing 1 m/sec with a wind velocity of 3 m/sec Is estimated to be 3.4 hours. Thus, 1,2,4-trlmethylbenzene Is expected to be highly volatile from water. The rate of blodegradatlon of 1,2,4-trlmethylbenzene In natural water cannot be predicted from the available data. In combination with the other water soluble compounds of petroleum oil. 1,2,4-trlmethylbenzene was blodegraded using a seawater Inoculum (van der Linden, 1978) and a groundwater Inoculum (Kappeler and Wuhrmann, 1978). Perry (1979) reported the co-oxidation of 1,2,4-trlmethylbenzene by Nocardla coralllna V-49. Various strains of Pseudomonas are capable of blodegradlng 1,2,4-trlmethylbenzene (Kunz and Chapman, 1981; OmoM and Yamada, 1969). ------- 1,2,4-Trlmethylbenzene -4- February 12, 1988 III. PHARNACOKINETICS Absorption Alkylbenzenes In general are absorbed Into the blood from various portals of entry {Gerarde, 1959), with Inhalation and percutaneous absorption being the most Important routes of Industrial exposures. Wkulskl and VMglusz (1975) as well as Cerf et al. (1980) demonstrated the uptake of 1,2.4- trlmethylbenzene after oral administration In rats and rabbits. Sandmeyer (1981) listed the systemic toxlclty of 1,2,4-trlmethylbenzene via Inhalation In mice, Indicating that absorption of this chemical does occur. Distribution Gerarde (1959) reported that due to their high llpophlllclty, ~85X of alkylbenzenes 1n blood are bound to red blood cells. Alkylbenzenes generally accumulate In tissues with high Upld content. Metabolism In general, alkylbenzenes are metabolized by side chain oxidation to form alcohols or carboxyllc acids. These compounds are then conjugated with glucuronlc acid or glyclne for urinary excretion. These reactions probably occur primarily 1n liver mlcrosomes (Gerarde, 1959). Mlkulskl and Wlglusz (1975) reported that after a single oral dose of 1200 mg/kg of 1,2,4-trlmethylbenzene to male Wlstar rats, a total of 62.5X of the dose was excreted In the urine as glyclne, sulfuMc acid and glucuronlc acid conjugates. The elimination half-lives for these conjugates were 9.5 hours for glyclne conjugates, 22.9 hours for glucurmlde and 37.6 hours for organic sulfates. Cerf et al. (1980) administered 0.5 mL/kg/day (438 mg/kg/day) 1,2,4-trlmethylbenzene by gavage to male albino rabbits for 5 days. The two principal metabolites found -1n urine were 2,4-d1methylbenzo1c acid and 3,4-d1methylh1ppuMc acid. Bakke and Schellne (1970) reported that the only phenolic metabolite detected In the urine of two rats within 48 hours after an oral dose of 1,2,4-trlmethylbenzene was 2,4,5-tr1- methylphenol. This metabolite amounted to only a fraction (0.05X) of the original dose of 1,2,4-trlmethylbenzene. ------- 1,2,4-Trlmethylbenzene -5- February 12, 1988 Excretion Gerarde (1959) reported that alkylbenzenes In general are eliminated unchanged through the lungs or as blotrans- format Ion products In the urine. The urinary metabolites (glyclne and glucuronlde conjugates) are water soluble. A small amount of the parent compound may be excreted In urine, but this Is limited--by-Us Tow water solubility. The amount of the parent compound eliminated through the lungs In exhaled air depends on the concentration In the blood and the vapor pressure. Mlkulskl and Wlglusz (1975) reported the Following elimination half-times for 1,2,4-trlmethylbenzene metabolites 1n male Wlstar rats: 9.5 hours for glyclne conjugates; 22.9 hours for glucuronlde and 37.6 hours for organic sulfates. IV. HEALTH EFFECTS Humans Short-Term Exposure No data on short-term exposures to humans by 1,2,4- trlmethylbenzene were located In the available literature. Lonqer-Term Exposure The only published report of human exposures (Baettlg et al.( 1958) describes an occupational health Investigation of 27 painters working 1n a plant using the solvent Fleet-X DV 99. Chemical analysis of this solvent showed that It consisted of 97.5X aromatic hydrocarbons and 2.5X of parafflnlc and napthenlc hydrocarbons. Spectography Identified >50% of the solvent to be 1,2,4-trlmethylbenzene and >30% to be 1,3,5-trlmethylbenzene. Rough quantltatlon of the exposure levels to the solvent, using Indicator tubes for benzene and Us homologs, demonstrated air concentra- tions between 10 and 60 ppm. If these vapors were exclu- sively tMmethylbenzenes. this would correspond to a concen- tration range of 2.0-12.2 mg/ma. Compared with 10 unexposed unskilled workers as controls, clinical findings In the exposed Included: subjective complaints of central nervous system characteristics (vertigo, headaches, drowsi- ness), chronic asthma-like bronchitis (classification criteria not specified), hyperchromlc anemia (<4.5 million erythrocytes/mm2) and disturbances In blood clotting. ------- 1.2,4-Trlmethylbenzene -6- Febroary 12, 1988 Animals Short-Term Exposure After absorption Into the blood, alkylbenzenes In general have two principal toxic effects In tissues; Irritation and Injury of endothellal tissue and central nervous system depression (Gerarde, 1959). Gerarde (1959) reported that 2.5 ml of a mixture of tMmethylbenzene Isomers In olive oil (1:1 v/v) administered by gavage to rats weighing 250 g caused death 1n 7/10. No other details were reported. Given an average density of 0.87 for the trlmethylbenzene mixture (Hlndholz. 1983), the average trlmethylbenzene dose was -4.4 g/kg. Cameron et al. (1938) conducted short-term Inhalation exposures to rats and mice with a sample from coal tar fractional distillation containing -70% crude aromatlcs of the 1,2,4-tr1methylbenzene-l,3,5-tr1methylbenzene type. No pathological changes were noted In the major organs of rats (n=8) and mice (n=10) exposed to 1800-2000 ppm of this sample (8852-9836 mg/m3 assuming exclusive trlmethylben- zene content; experiments were performed at 20°C and 760 mm Hg Is assumed) for 48 and 12 continuous hours to rats and mice, respectively. No adverse effects were noted 1n six rats exposed to the same sample at 1800-2000 ppm for 14 exposures of 8 hours each. Dermal/Ocular Effects Gerarde (1959) reported that direct skin contact with liquid alkylbenzenes causes vasodllatlon, erythema and Irritation. Longer-Term Exposure Bernshteln (1972) reported that Inhalation of trlmethyl- benzene (mixture of 1,2,3-, 1,2,5- and 1,3,5-lsomers) at 1000 mg/ma, 4 hours/day for 6 months Inhibited phagocytlc activity of leukocytes 1n rats. Baettlg et al. (1958) exposed male rats (n=8) by Inhalation 8 hours/day, 5 days/week to an approximate concentration of 1700 ppm of the solvent Fleet-X 0V 99 (see chemical analysis description under human longer-term exposure section) for 4 ------- 1,2,4-Trlmethylbenzene -7- February 12, 1988 months. Rats (sex and number not specified) were also exposed to 500 ppm of the solvent for 70 days. Assuming the solvent content to be exclusively tMmethylbenzenes, these exposures correspond to 8360 and 2459 mg/m3, respective- ly. Differences between exposed rats and controls were determined for the following: mortality, behavior, weight, drinking water and food Intakes, urine dilution and concen- tration tests, urinary phenol excretion and red and white differential blood cell counts. Four of the 8 rats exposed to 8360 mg/m3 died within the first 2 weeks whereas none died In the 2459 mg/m3 exposure group. Body weight was decreased In both exposure groups but the effect was confounded by a decrease In food Intake. Severe excitation with subsequent narcosis and ataxla toward the end of the dally exposure period was exhibited In the high exposure group but only Indicated In the 2459 mg/ma group. These phenomena receded within a few hours postexposure. Increases In water Intake, urinary diuresis and excretion of free, total and bound phenols were noted In the exposed rats. Blood analysis also revealed a relative lymphopenla and neutrophlUa In the exposed rats. Hlstologlc examination of the kidney, liver, spleen and lungs was performed only on five animals (those that Initially died were replaced) of the high exposure group. Pathologic changes Included cloudy swelling and fatty Infiltration In the kidney, peripheral fatty Infiltration In the liver, an Increase In secondary nodules In the spleen, and marked congestion of the pulmonary capillaries with alveolar wall thickening. Reproductive Toxldtv • Data regarding the reproductive toxlclty of 1,2,4-trl- methylbenzene .could not be located In the available literature. Developmental Toxldtv Data regarding the developmental toxlclty of 1,2,4-tM- roethylbenzene could not be located In . the available literature. HutaqenUUv Data regarding the mutagenlclty of l,2,4-tr1m°thylbenzene could not be located In the available literature. ------- 1,2.4-Trlmethylbenzene -8- February 12. 1988 Carclnoqenlcity Data regarding the carclnogenlclty of 1,2,4-trlmethyl- benzene could not be located In the available literature. The chemical has not been selected for carclnogenlclty testing (NTP. 1987) - V. QUANTIFICATION OF TOXICOLOGICAL EFFECTS Health Advisories are based upon the Identification of adverse health effects associated with the most sensitive and meaningful noncarclnogenlc endpolnt of toxlclty. The Induction of this effect Is related to a particu- lar exposure dose over a specified period of time, most often determined from the results of an experimental animal study. Traditional risk charac- terization methodology for threshold toxicants Is applied In HA development. The general formula Is as follows: (NQAEL OR LOAEL) (BW) [UF(s)l ( L/dav) where: NOAEL = No-Observed-Adverse-Effect Level (the exposure dose In rag/kg bw/day) or LOAEL = Lowest-Observed-Adverse-Effect Level (the exposure dose In mg/kg bw/day) BM = Assumed body weight of protected Individual (10 kg for child or 70 kg for adult) UF(s) = Uncertainty factors, based upon quality and nature of data (10, 100, 1000 or 10,000 1n accordance with NAS/ODW or Agency guidelines) L/day - Assumed water consumption (1 L/day for child or 2 L/day for adult) 1-Day Health Advisory Data were not sufficient for derivation of a 1-day HA for 1,2,4-trlmethylbenzene. 10-Day Health Advisory Data were not sufficient for derivation of a 10-day HA for 1,2,4-trlmethylbenzene. ------- 1.2,4-Trtmethylbenzene -9- February 12. 1988 Longer-Term Health Advisory Data were not sufficient for derivation of a longer-term health advisory. Although significant results were Indicated In both the Bernshteln (1972) and the Baettlg et al. (1958) studies, the exposures were to mixtures of trlmethylbenzenes. which makes quantUatlon of single components equivocal. Additional deficits Include the lack of more than one exposure level and detail (e.g., number of ar7lmals not specified, degree of Inhibition not quantUated) In the Bernshteln (1972) study. The Baettlg et al. (1958) animal Investigations lacked proper reporting of results (I.e.. statistical analyses either not done or not specified) and techniques, was not comprehensive In scope (I.e., hlstologlc examination performed on a limited number of animals In the high exposure group only) and used small numbers of animals. The human study also lacked quantification of symptoms/effects, was performed on a small number and lacked appropriate follow-up. Lifetime Health Advisory The lifetime HA represents that portion of an Individual's total exposure that Is attributed to drinking water and Is considered protective of noncarclnogenlc adverse health effects over a lifetime exposure. The lifetime HA Is derived 1n a three step process. Step 1 determines the Reference Dose (RfD), formerly called the Acceptable Dally Intake (ADI). The RfD Is an estimate (with uncertainty spanning perhaps an order of magnitude) of a dally exposure to the human population (Including sensitive subgroups) that Is likely to be without appreciable risk of deleterious health effects during a lifetime, and 1s derived from the HOAEL (or LOAEL), Identified from a chronic (or subchronlc) study, divided by an uncertainty factor(s) times an additional uncertainty factor. From the RfD. a Drinking Water Equivalent Level (DUEL) can be determined (Step 2). A DWEL Is a medium-specific (I.e.. drinking water) lifetime exposure level, assuming 100X exposure from that medium, at which adverse, noncarclnogenlc health effects would not be expected to occur. The DUEL Is derived from the multiplication of the RfD by the assumed body weight of an adult and divided by the assumed dally water consumption of an adult. The lifetime HA In drinking water alone Is determined In Step 3 by factoring In other sources of exposure, the relative source contribution (RSC). The RSC from drinking water Is based on actual exposure data or, 1f data are not available, a value of 20X Is assumed for synthetic organic chemicals and a value of 10% Is assumed for Inorganic chemicals. If the contaminant Is classified as a known, possible or probable carcinogen, according to the Agency's classification scheme of carcinogenic potential (U.S. EPA, 1986), then caution must be exercised In making a decision on how to deal with possible lifetime exposure to this substance. The risk manager must balance this assessment of carcinogenic potential and the quality of the data against the likelihood of occurrence and significance of health effects related to noncarclnogenlc endpolnts of toxlclty. In order to assist the risk manager In this process, drinking water concentrations associated with estimated excess lifetime cancer risks ------- 1,2,4-TMmethylbenzene -10- Febroary 12, 1988 over the range of 1 In 10,000 to 1 in 1,000,000 for the 70 kg adult drinking 2 L of water/day are provided In the Evaluation of Carcinogenic Potential Section. Data were not sufficient for derivation of a lifetime health advisory for the same reasons specified for the longer-term health advisory. Evaluation of Carcinogenic Potential Pertinent data regarding the carclnogenlclty of 1,2,4-trlmethyl- benzene could not be located In the available literature. This chemical has not been scheduled for carclnogenlclty testing (NTP, 1987). IARC has not evaluated the carcinogenic potential of 1.2,4-trlmethylbenzene. Applying the criteria described 1n the U.S. EPA's Guidelines for Carcinogen Risk Assessment (U.S. EPA, 1986a), 1,2,4-trlmethylbenzene may be classified 1n Group D: Not classified. This category signifies that the evidence Is Insufficient to assess the agent's carcinogenic potential. VI. OTHER CRITERIA. GUIDANCE AND STANDARDS ACGIH (1980, 1985) recommended a TLV of 25 ppm (-5 mg/m3) and a STEL of 35 ppm (~7 mg/ma) for mixed trlmethylbenzenes. These numbers are based largely on human experience with trlmethylbenzenes. VII. ANALYTICAL METHODS Analysis of 1,2,4-tr1methylbenzene 1s by a purge-and-trap gas chromatographlc procedure used for the determination of volatile aromatic and unsaturated organic compounds In water (U.S. EPA. 1985a). This method calls for the bubbling of an Inert gas through the sample and trapping volatile compounds on an adsorbent material. The adsorbent material 1s heated to drive off compounds onto a gas chromatographlc column. The gas chromatograph Is temperature programmed to separate the method analytes. which are then detected by the photolnonlzatlon detector. This method 1s applicable to the measurement of 1,2,4-tr1methylbenzene over a concentration range of 0.06-1500 yg/L. Confirmatory analysis Is by mass spectrometry (U.S. EPA. 1985b). The detection limit for confirmation by mass spectrometry has not been determined. VIII. TREATMENT TECHNOLOGIES Very little Information Is available on treatment technologies capable of removing 1,2,4-trlmethylbenzene from water. ------- 1,2,4-TMmethylbenzene -11- February 12, 1988 Muller et al. (",381) presented mass transfer coefficients for non- polar volatile organic compounds. Including 1,2,4-tr1methylbenzene. They concluded that In bubble aeration systems mass transfer rates for volatile compounds depend on mass transfer rate coefficients as well as the degree of saturation of the exit gas. U.S. EPA (1986b) estimated the feasibility of removing 1.2.4-tr1methy1benzene from water by alrr stripping. employing the engineering design procedure and cost model presented at the 1983 National ASCE Conference on Environmental Engineering. Based on chemical and physical properties and assumed operating conditions, 90X removal efficiency of 1,2,4-trlmethylbenzene was reported by a column with a diameter of 5.8 ft and packed with 15 ft of 1 Inch plastic saddles. The air-to-water ratio required to achieve this degree of removal effectiveness Is 25. Actual system performance data, however, are necessary to realistically determine the feasibility of using air stripping for the removal of 1,2,4-trlmethylbenzene from contaminated drinking water. In summary, the amenability of 1,2,4-trlmethylbenzene to air stripping has been clearly established. Selection of air stripping to attempt 1,2,4-trlmethylbenzene removal from contaminated drinking water must be based on a case-by-case technical evaluation and an assessment of the economics Involved. IX. REFERENCES ACGIH (American Conference of Governmental Industrial Hyglenlsts). 1980. Documentation of the Threshold Limit Values. 4th ed. Cincinnati, OH. p. 415-416. ACGIH (American Conference of Governmental Industrial Hyglenlsts). 1985. TLVs. Threshold Limit Values and Biological Exposure Indices for 1985-86. Cincinnati. OH. p. 32. Baettlg, K., E. Grandjean, L. Rossi and J. Rlckenbacher. 1958. Toxlkologlsche Untersuchungen Ueber Trlmethylbenzol. (Toxlcologlcal Investigations of trlmethylbenzene.) Archlv Fuer Gewerbepathologle und Gewerbehyglene. 16: 555-566. (English translation available.) Bakke, O.M. and R.R. Schellne. 1970. Hydroxylatlon of aromatic hydro- carbons In the rat. Toxlcol. Appl. Pharmacol. 16(3): 691-700. Bernshteln. L.N. 1972. Phagocytosis reaction In experimental animals on chronic poisoning by vapors of benzene and Its methyl derivatives. Vop. Gig. Tr. Profzabol., Hater. Nauch. Konf. 1971, 53-4 (Russ.) Edited by Fllln, A-P. Kaz. Nauch. - Issled. Inst. Gig. Tr. Profzabol.: Karaganda, Ussr. Chem. Abstracts Vol. 81, 146520 p. 1974. (Cited In Sandmeyer. 1981) English abstract available. ------- 1,2,4-TMmethylbenzene -12- Febrtfary 12, 1988 Brodzlnsky, R. and H.B. Singh. 1982. Volatile organic chemicals In the atmosphere: An assessment of available data. Atmospheric Science Center. Henlo Park, CA. SRI International. Contract No. 68-02-3452. p. 179. Cameron, G.R., J.L.H. Paterson, G.S.H. de Saram and J.C. Thomas. 1938. The toxlclty of some methyl derivatives of benzene with special reference to pseudocumene and heavy coal tar naphtha. J. Pathol. Bacterlol. 46: 95-107. Cerf, J.. H. Potvln and S. Laham. 1980. Acidic metabolites of pseudocumene In rabbit urine. Arch. Toxlcol. 45(2): 93-100. Coleman, W.E., J.W. Hunch, R.P. Strelcher, H.P. Rlnghand and F.C. Kopfler. 1964. The Identification and measurement of components In gasoline, kero- sene, and No. 2 fuel oil that partition Into the aqueous phase after mix- Ing. Arch. Environ. Contam. Toxlcol. 13: 171-178. Gerarde, H.W. 1959. Toxlcologlcal studies on hydrocarbons. III. The b1o- chemorphology of the phenylalkanes and phenylalkenes. Am. Med. Assoc. Arch. Ind. Health. 19: 403-418. Hampton, C.V., H.R. Plerson, T.M. Harvey, W.S. Updegrove and R.S. Marano. >1982. Hydrocarbon gases emitted from vehicles on the road. I. A qualita- tive gas chromatography/mass spectrometry survey. Environ. Sd. Technol. 16: 287-298. Hansch, C. and A.J. Leo. College, Claremont, CA. 1985. Hedchem Project. Issue No. 26. Pomona, H1ne. J. and P.K. Hookerjee. 1975. The Intrinsic hydrophlllc character of organic compounds. Correlations In terms of structural contributions. J. Org. Chem. 40: 292-298. Kappeler, Th. and K. Uuhrmann. 1978. Hlcroblal degradation of the water soluble fraction of gas oil. I. Water Res. 12: 327-333. Kunz, D.A. and P.J. Chapman. 1981. Catabollsm of pseudocumene and 3-ethyl- toluene by Pseudomonas put Ida (arvllla) mt-2: Evidence for new functions of the TOL (pUWO) plasmld. J. Bacterlol. 146: 179-191. (CA 95: 3155b) Lyman, H.J., W.F. Reehl and D.H. Rosenblatt. 1982. Handbook of Chemical Property Estimation Methods. McGraw-Hill, NY. p.15-21 to 15-29. Mackay, 0. and H.Y. Shlu. 1981. A critical review of Henry's Law Constants for chemicals of environmental Interest. J. Phys. Chem. Ref. Data. 10(4): 1175-1199. Mlkulskl, P.I. and R. Wlglusz. 1975. The comparative metabolism of mesl- tylene, pseudocumene, and hemlmellltene In rats. Toxlcol. Appl. Pharmacol. 31: 21-31. ------- 1,2,4-Trlmethylbenzene -13- February 12, 1988 Mullen, C.M., H. Gujer and W. Glger. 1981. Transfer of volatile substances from water to the atmosphere. Water Research. 15(11): 1271-1279. NTP (National Toxicology Program). 1987. Toxicology Research and Testing Program. Management Status Report 10/13/87. NTP, Research Triangle Park, NC. OmoM, T. and K. Yamada. 1969. Utilization of hydrocarbons by micro- organisms. XIII. Oxidation of m-xylene and pseudocumene by Pseudomonas aeruqlnosa. AgMc. Blol. Chem. 33: 979-985. (CA 11: 057883k) Perry, J.J. 1979. Mlcroblal cooxldatlons Involving hydrocarbons. Hlcro- blol. Rev. 43: 59-72. Sandmeyer, E.E. 1981. Aromatic hydrocarbons. In: Patty's Industrial Hygiene and Toxicology. Vol. 26. 3rd ed., G. Clayton and F.E. Clayton, Ed. John H1ley and Sons, Inc., NY. p. 3300-3302. Shlnohara, R., A. Kldo. S. Etot T. Horl, M. Koga and T. Aklyama. 1981. Identification and determination of trace organic substances 1n tap water by computerized gas chromatography-mass spectrometry and mass fragmentography. Water Res. 15: 535-542. U.S. EPA. 1985a. Method 503.1, Volatile Aromatic and Unsaturated Organic Compounds In Water by Purge and Trap Gas Chromatography. Environmental Monitoring and Support Laboratory, Cincinnati, Ohio 45268, June 1985. (Revised November 1985). U.S. EPA. 19B5b. Method 524.1, Volatile Organic Compounds In Water by Purge and Trap Gas Chromatography/Mass Spectrometry. Environmental Monitoring and Support Laboratory, Cincinnati, Ohio 45268, June 1985." (Revised November 1985). U.S. EPA. 1986a. Guidelines for Carcinogen Risk Assessment. Federal Register. 51{185):33992-34Q03. U.S. EPA. 1986b. Economic Evaluation of 1,2,4-Trlmethylbenzene Removal from Water by Packed Column Air Stripping. Prepared by Office of Water for Health Advisory Treatment Summaries. van der Linden, A.C. 1978. Degradation of oil In the marine environment. Dev. Blodeg. Hydrocarbons. 1: 165-200. Verschueren, K. 1983. Handbook of Environmental Data on Organic Chemicals, 2nd ed. Van Nostrand Relnhold Co., New York. p. 1163. Wakeham, S.G., J.T. Goodwin and A.C. Davis. 1983. Distributions and fate of volatile organic compounds In Narragansett Bay, Rhode Island. Can. J. F1sh Aquatic Sc1. 40(Suppl.J: 304-321. ------- 1,2,4-Trlmethylbenzene -14- February 12, 1988 VMndholz. H.. Ed. 19B3. The Merck Index, 10th ed. Herck and Co., Inc., Rahway. NJ. p. 1141. ------- |