Determination of Dimethylnitrosamine in Air, Water, and Soil by Thermal Energy Analysis: Measurements in Baltimore, Md. David H. Fine', David P. Rounbehler, Anna Rounbehler, and Arlene Silvergleid Thermo Electron Research Center, 85 First Avenue, Waltham, Mass. 02154
Eugene Sawicki, Ken Krost, and Gerard A. DeMarrais Environmental Protection Agency, National Environmental Research Center, Research Triangle Park, N.C. 277 1 1
Dimethylnitrosamine (DMN) is reported to be present as an air pollutant in Baltimore, Md. On the site of a chemical factory that is manufacturing unsymmetrical dimethylhydrazine for which DMN is an intermediate, average DMN levels are 11600 ng/m3. Average DMN levels in neighboring residential communities are 1070 ng/m3, with DMN levels in downtown Baltimore being between 30 and 100 ng/m3. Salt water from the Curtis Bay and Stonehouse cove area surrounding the chemical factory contains DMN a t the 35-940 ng/L level. H
Using a new sensitive and selective detector for N-nitrosamines ( I , 2), we recently reported dimethylnitrosamine (DMN) to be present as an air pollutant in Baltimore, Md., and Belle, W.Va., a t concentrations of between 40 and 300 ng/m3 ( 3 , 4 ) .The presence of DMN in air up to 36 000 ng/m3 has since been confirmed in four independent studies (5-a), including three which used GC-MS techniques for positive identification. Because DMN is a potent carcinogen in laboratory animals, its presence as an air pollutant a t concentrations in excess of that of other airborne carcinogens, such as benzo(a)pyrene ( 9 ) ,may be cause for concern. In Baltimore a source for DMN was traced to a chemical factory that was manufacturing unsymmetrical dimethylhydrazine (UDMH) for which DMN was produced as an intermediate. Because of the data reported here, production of UDMH in Baltimore ceased as of April 1976 (IO).This manuscript reports on nitrosamine data, mostly DMN, which were collected in Baltimore during the fall and early winter of 1975, and includes measurements of air, water, and soil, both on and off the UDMH factory site as well as in downtown Baltimore and other areas where the population density is relatively high.
Experimental Apparatus. For the analysis of air samples, the air sampling train was mounted inside a mobile, self-contained laboratory. Sample collection, work-up, and analysis were carried out on site in the mobile laboratory. A Thermal Energy Analyzer (Thermo Electron Corp., Waltham, Mass., Model 502), specially modified for field use, was used as the detector for an isothermal single-column gas chromatograph. The gas chromatograph column was prepared from a 6.5 X 2 mm i.d. stainless-steel tube packed with 15% FFAP on Chromasorb W (acid washed, DCMS treated, 80-100 mesh) and conditioned for 36 h a t 220 "C. Argon was used as the carrier gas a t a flow rate of 10-30 mL/min. The TEA cold trap was maintained a t -79 "C (dichloromethane-dry ice). Water samples were analyzed on similar TEA-GC equipment located a t the Research Center. For analysis of water samples, the TEA cold trap was maintained a t -150 "C. The high-performance liquid chromatograph was constructed by combining a Waters Associates (Milford, Mass.) Model 6000 high-pressure pump with a Waters Associates Model U6K injector. The liquid chromatograph was interfaced directly to the TEA. The TEA-HPLC was operated
isocratically with a 30-cm-long, 4-mm-i.d. fi Porasil or a fi Bondapak CN column (Waters Associates). For the fi Porasil the solvent system was a mixture containing 5% acetone and 95% isooctane a t a flow rate of 2 mL/min; for the fi Bondapak CN column, the solvent system was 1.5% acetonitrile and , 98.5% isooctane a t a flow rate of 1.5 mL/min. Materials. AnalaR grade acetone, acetonitrile, dichloromethane, and isooctane, which had been distilled from glass, were used. AnalaR KOH was used in the cold traps. Lowtemperature slush baths were made with technical grade solvents maintained a t their freezing point. Procedure. Air samples were collected by flowing 60-120 L of air through two successive cold traps, each containing 1 mL of 1 N KOH. The temperature of the two cold traps was maintained a t -79 to -95 "C. After collection the traps plus interconnecting tubing were washed with distilled water. The combined washings were made up to 60 mL and then extracted three times with 8 mL each of dichloromethane. The combined dichloromethane extracts were concentrated on a Kuderna Danish evaporator to a final volume of between 0.4 and 0.8 mL. The temperature of the Kuderna Danish was maintained a t 58-60 "C and contained 0.5 mL of isooctane as a keeper. Twenty microliters of the final concentrate was introduced into the TEA-GC and/or the TEA-HPLC. Water samples were collected in brown bottles and stored a t 4 "C. Water (500 mL) was extracted three times with 50 mL of dichloromethane. The combined extracts were dried over 75 g of sodium sulfate. The sodium sulfate was extracted twice with 35 mL of dichloromethane, and the combined dried extracts plus washings were concentrated on a Kuderna-Danish evaporator a t 52-53 "C to a final volume of approximately 0.5 mL. Soil samples were extracted three times with water, and the water in turn was extracted with dichloromethane, as above. Further details of the analytical techniques, as well as a description of the recovery procedures which were used, and a description of experiments which tested the validity of the procedures are described elsewhere ( 1 1 ) .
Results Figure 1 is the TEA-GC chromatogram of an air sample which was collected on the property of the UDMH facility on November 19, 1975, between 1:50 and 2 5 0 p.m. The chromatogram shows only two peaks following the solvent front, one corresponding to DMN a t the 36 000 ng/m3 level [a parallel Tenax sample ( 5 ) which was analyzed by GC-MS and showed 32000 ng/m3 of DMN] and a smaller peak. The smaller peak elutes close to the retention time of N-nitrosodipropylamine, but its TEA-HPLC retention time is different from that of N-nitrosodipropylamine. The same unknown peak has been observed to be present on several occasions but has not yet been identified. Table I summarizes the data collected on the site of the UDMH factory, close to the dimazine plant. The average DMN level found was 11 600 ng/m", with the highest value recorded being the 36 000 ng/m3 shown in Figure 1. Two stack measurements were made, one on the Volume 11, Number 6, June 1977
581
effluent from the dimazine thermal destructor which contained 1 2 000 ng/m3 of DMN, and the other on the effluent from the wet scrubber which contained 14000 ng/m3 of DMN. Table I1 summarizes data collected within 800 m (M mile) of the UDMH factory. Three samples taken a t the Patapsco Sewage Treatment Plant upwind of the chemical factory did not show DMN to be present, even a t the 1 ng/m3 level. A parallel Tenax-GC-MS study also showed DMN to be absent ( 5 ) .The remaining data points in Table I1 were all collected a t sites downwind of the UDMH factory. The average DMN value found was 1070 ng/m3. Two samples a t the Chessie Coal Pirs were collected during light rain on October 17, 1975. Table I11 shows data collected in the ambient community air of population centers in Baltimore and Arundel County (12). Much of the data presented in this table were taken several miles upwind of the UDMH site. The average DMN
content of the ambient community air of population centers was 100 ng/m3. DMN was found a t every site sampled, with the highest level of 760 ng/m3 being recorded on November 25, 1975, near Northbridge Avenue and Cannery Roads in Baltimore. Drinking water in Baltimore was examined for volatile N-nitrosamines (13), and none was found down to the detection limit of the technique (2 ng/L). Samples of salt water from the estuary comprising the Patapsco River, Curtis Bay, and Stonehouse Cove (see map in Figure 2 and Table 1V) were collected and screened for volatile N-nitrosamines. DMN could not be detected in the Patapsco River. The effluent from the sewage treatment plant contained 2 700 ng/L of DMN. At Pennington Avenue one mile south of the UDMH facility, the DMN level in the water was 90 ng/L. At the Chessie Coal Piers southwest of the UDMH facility, the aquatic DMN level was 140-250 ng/L. In Stonehouse Cove immediately adjacent to the UDMH facility, the DMN level in water samples collected from the shore ranged between 260 and 940 ng/L. Water samples from Stonehouse Cove taken both a t the surface and a t a depth of 6-20 ft all contained DMN. The DMN concentration a t the surface was always Y3 to of that below the surface. The highest levels of DMN were found a t the site of the UDMH factory. A drainage ditch on the east side of the property contained DMN a t the 5900 ng/L level. Two mud puddles immediately adjacent to the UDMH factory contained 200 000 and 6 000 000 ng/kg of DMN (moist basis). The concentration levels in the mud puddles are several orders of magnitude larger than previous findings of DMN in the environment. The identity of the DMN in the mud puddle was confirmed by GC-MS.
I
Discussion DMN has been shown to be carcinogenic in a wide variety of laboratory animals. For inhalation studies the lowest level tested and shown to be carcinogenic was 200 000 ng/m3 for rats and mice (14).For ingestion studies the lowest level tested and shown to be carcinogenic was 50 000 ng/kg bw/day given to mink, two times per week (15).Factory workers at the UDMH factory were exposed to 8-h average airborne DMN levels of about 11 600 ng/m3. If it is assumed that an average adult takes 16 breaths per minute, with a volume of 0.44 L each, then during the course of an 8-h work day, the adult will have in-
UNKNOWN
, * TIME IMIN 1
Figure 1. TEA-GC chromatogram following cryogenic trapping, extraction, and concentration taken on property of UDMH facility on November 19, 1975, between 1 5 0 and 2 5 0 p.m. DMN present at 36 000 ng/m3 level
Table 1. Air Data Collected on Site of UDMH Factory Date, 1975
Locatlon
Wind
11-19 11-19 11-19 11-19 11-19 11-19 11-19 11-19 11-21 11-21 11-24 11-24 11-24 11-24 11-24 10-15 10-15 10-15 10-15 11-24 11-24
NW of thermal destructor NW of thermal destructor NW of thermal destructor Next to ammonia plant Next to ammonia plant Next to ammonia plant Next to ammonia plant Next to ammonia plant 15 ft S of ammonia tanks 15 ft S of ammonia tanks S of SE corner of dimazine plant S of SE corner of dimazine plant S of SE corner of dimazine plant S of SE corner of dimazine plant S of SE corner of dimazine plant E parking lot E parking lot E parking lot E parking lot Thermal destructor stack V602 wet scrubber stack
E, 3 knots E, 3 knots N, 5 knots s, sw, 2 s, sw, 2 SW, 3 knots sw, w, 3 Calm N, 5 knots N, NW, 3 NE NE NE NE NE w , sw, 10 SW, 10 knots SW, 9 knots SW, 5 knots
582
Weather
Environmental Science & Technology
Temp,
O F
65 65 65 clear 61 60 59 60 52 57 51 rain
T h e , p.m.
NE
1:50-2:50 3:00-4:00 4:05-4:25 5:30-6:30 6:40-7:40 7:40-8:40 a:40-9:40 9:45-10:45 2: 15-3:15 3:20-4:20 11:40-12:40 1:oo-2:oo 2:55-3:55 7:oo-a:oo 7:00-8:00 12: 17-1:35 2:30-3:30 4: 15-5:45 6:00-7:00 4:25-5:00
NE
5:50-5:50
87 86' a5 80
DMN ng/mg
36 000 11 000 7 600 15 000 15 000 30 000 8 900 11 000 12 000 3 300 2 800 1900 4 500 5 500 5 600 13 000 15 000 11 000 a 700 12 000 14 000
h a l e d 3.3 m3o f a i r ( 4 ) .If it i s f u r t h e r assumed that t h e D M N was r e t a i n e d by t h e body, t h e n a f a c t o r y w o r k e r w o u l d h a v e a n i n t a k e of 39 000 ng o f D M N p e r 8-h day. R e s i d e n t i a l communities n e a r t h e f a c t o r y were exposed t o 2 4 - h average a i r b o r n e D M N levels of a b o u t 1070 ng/m3,c o r responding t o a n i n t a k e o f a b o u t 10 000 ng of D M N p e r day. Communities upwind and f a r removed f r o m t h e f a c t o r y were exposed t o a i r b o r n e D M N l e e k o f between a b o u t 30 a n d 100 ng/m3 for p a r t o f t h e day, corresponding t o a D M N i n t a k e o f a b o u t 300 ng p e r day. D i r e c t human exposure r e s u l t i n g from t h e D M N levels in t h e s o i l a n d in t h e estuary w o u l d n o t b e
expected t o b e significant. By comparison t h e expected t o t a l D M N i n t a k e f r o m e a t i n g f o u r slices o f cooked bacon w o u l d b e a b o u t 500 ng. T h e t o t a l D M N i n t a k e f r o m a p a c k of 20 cigarettes w o u l d b e a b o u t 1000 ng (16). W e conclude, t h e r e fore, t h a t t h e d a i l y D M N i n t a k e in c o m m u n i t i e s f a r removed f r o m t h e factory site was somewhat less t h a n t h e i n t a k e f r o m n o r m a l d i e t a r y routes. However, communities b o r d e r i n g t h e factory, a n d t h e f a c t o r y w o r k e r s themselves, h a d a D M N int a k e considerably in excess o f t h a t f r o m e a t i n g or smoking. T h e r i s k t o human h e a l t h o f d a i l y DMN i n t a k e s of t h e o r d e r o f 10 000-30 000 ng p e r d a y r e m a i n s t o b e assessed.
Table II. DMN in Community Air Within 800 Meters ( 1/2 mile) of UDMH Factory Tlme, p.m.
DMN ng/mA
NO, NO2, ppb
ND ND ND 1400 410 340
15, 15 a, 20 10, 15
70
11:lO-1:lO 1:30-3:30 3150-5130 4: 10-5: 10 8:30-9:30 3:45-4:45
61
5:00-6:00
1 800
57 57 49 47 56 56
8:20-9120 9:30-10:20 1115-2115 2: 15-3~15 7:00-9:00 11:oo-l:oo 1115-3~15
170 330 2 200 3 000 33 1800 1200
37, 25 50,25
56
3:45-5:45
130
37,50
Weather
Date, 1975
Location
Wlnd
N, NW, 9 knots NW, 10 knots NW, 9 knots
72 73 72
11-20 1 1-20 11-22 11-22 8-23 10-17 10-17
Patapsco Sewage Plant Patapsco Sewage Plant Patapsco Sewage Plant Northbridge Rd Northbridge Rd Conoco, corner Fairfield and Chesapeake Conoco, corner Fairfield and Chesapeake Minerac Corp. Minerac Corp. 200 yd, E in B Plot 200 yd, E in B Plot Chessie Coal Piers Chessie Coal Piers Chessie Coal Piers
SW, 6 knots Clear SW, 3 knots Clear-cloudy S, 4 knots S, 4 knots W, NW 7 knots W, NW 7 knots
10-17
Chessie Coal Piers
E, NE, 7 knots N, NE, 7 knots Rain E, 14 knots Rain
10-16 10-16 10-16 10-22 10-22 11-20 11-20
Temp,
'F
Table 111. DMN Levels in Community Air of Population Centers in Baltimore Date, 1975
11-22 11-22 11-22 12-14 12-14 12-14 12-14 12-14 12-13
Location
Corner Howard and Preston Corner Pratt and Commerce St. Corner Pratt and Commerce St. Corner N Baltimore and W Liberty on W Fairmount Ave. Corner Lombard and Calvert Ave. across News American Bldg Liberty and W Fayette St. South St. and Pratt St. South St. and Pratt St. Gov. Ritchie Highway, Brooklyn Park Plaza Shopping Center Rt. 2, Gov. Ritchie Highway Stahl and Ordnance Rd. Solly School, off Fort Smallwood Rd. Park, W Bay Ave. 4th and Edison St. Spruce and Fairhaven Ave.
Baltimore Baltimore Baltimore Baltimore
Baltimore Baltimore Baltimore
11-25 Northbridge and Cannery Rd. 11-25 Northbridge and Cannery Rd. 12-11 Cannery, 4th (playground) 12-11 12-11 12-11 12-11 12-15 12-15 12-15 12-15
Baltimore Baltimore Baltimore Baltimore Baltimore Baltimore Baltimore Baltimore
12-13 Spruce and Fairhaven Ave
Corner Cannery and 4th (playground) Corner Cannery and 4th (playground) Corner Cannery and 4th (playground) Corner Cannery and 4th (playsround) Corner Cannery and 4th (playiroundj 4th St. and Highland Ave., 4 Corners Rest. 4th St. and Highland Ave. 4th St. and Cannery (playground)
Variable, 2 knots W, SW, 7 knots W, SW, 7 knots W, SW, 7 knots
Temp, O F
Misc
Tlme
DMN ng/ma
41 47 47
Clear Clear Clear Foggy
6:42-755 a.m. 8:25-9:25 a.m. 9:25-10:25 a.m. 6:35-7:05 a.m.
26 88 110 49
41
Foggy
8:OO-9:00 a.m.
48
SE, 5-6 knots S, SW, 6 knots S, SW, 6 knots
42 42 42
Fog lifting Overcast Cloudy
9:OO-1O:OO a.m. 10:50-11:35 a.m. 11:OO-11:45 a.m.
22 28
E, NE NW
44 45 44 44 44 44
Cloudy Light rain Light rain Overcast Overcast Cloudy Cloudy
3:45-4:54 a.m. 5:55-7:13 a.m. 7:29-8:29 a.m. 8:53-9:42 a.m. 10:05-10:50 a.m. 11:02-12:35 p m . 2:OO-2:45 p.m.
110 36 31 23 21 16 125
Cloudy
3:OO-3:45 p.m.
116
Cloudy Overcast Clear, sunny Cloudy Cloudy Cloudy Cloudy Clear Clear 726 mm Hg
12:38-1:38 p.m. 5:OO-6:00 p.m. 10:45-11:45 a.m.
180 760 212
11:58-12:58 p.m. 1:45-2:45 p.m. 2:51-351 p.m. 4:OO-4:20 p.m. 7:37-8:37 a.m. 12:40-1:40 D.m. 2:32-4:32 p:m. - 655-7:30 p.m.
60 66 57 107 58 46 36 110
Baltimore
Arundel County Arundel County Arundel County Arundel County Arundel County Arundel County ArundeV Baltimore ArundeV Baltimore Baltimore Baltimore Baltimore
12-13 12-13 12-13 12-13 12-13 12-13
Weather Wlnd
city
N, NE, 10 knots
W, NW, light W, NW, light
E, light
sw sw
Cold
Volume 11, Number 6, June 1977
583
Table IV. Aquatic DMN Date. 1975
Description of sample site
11-21 11-24 10-10 10-10 10-10 10-10 10-17 10-17 10-21 11-21 11-21 11-21 11-21 11-20 11-20 11-20 11-20 11-20 11-20 11-22 Figure 2. Map of South Baltimore showing location of aquatic DMN
Acknowledgment The authors thank Edo Pellizzari of Research Triangle Institute for many valuable discussions; N. Belcher, J. Fronduto, F. Campagna, and C. Barrett for technical assistance; R. Stephany of R.I.V., Bilthoven, Netherlands, for GC-MS confirmation of the presence of DMN in a moist soil sample; Dan Fitzgerald of EPA, Region 3, Philadelphia, for providing many of the water samples taken from Stonehouse Cove; George Ferrarri of the Maryland Department of Health for valuable administrative assistance; and Neal Elphick, Joe Velonovski, Bill King, and Harry Kabernagle of FMC, not only for permission to collect samples on the FMC property, but also for providing every possible assistance at all hours of the day and night.
Literature Cited (1) Fine, D. H., Rounbehler, D. P., J. Chromatogr. 107,35 (1975). ( 2 ) Fine, D. H., Rounbehler, D. P., Belcher, N. M., in “Environmental N-Nitroso Compounds, Analysis and Formation”, E. A. Walker, P. Bogovski, and L. Criciute, Eds., p 401, International Agency for Research on Cancer (IARC) publ. no. 14, Lyon, France, 1976. (3) Fine, D. H., Rounbehler, D. P., Belcher, N. M., Epstein, S. S., “International Conference on Environmental Sensing and Assessment”, Catalogue #75-CH 1004-1 ICESA, pp 3&7, IEEE, New York, N.Y., 1976. (4) Fine, D. H., Rounbehler, D. P., Belcher, N. M., Epstein, S.S., Science, 192, 1328 (1976).
584
EnvironmentalScience & Technology
Tap water, Baltimore Commercial Wharf, Boston, ocean sample Off Pennington Ave., Baltimore Sewer sample, Baltimore Curtis Bay, near Chessie Piers Curtis Bay, near Chessie Piers Chessie Piers Chessie Piers Sewer sample, Buck River Stonehouse Cove, W of UDMH Facility Stonehouse Cove, W of UDMH Facility Stonehouse Cove, S of UDMH Facility Stonehouse Cove, S of UDMH Facility Stonehouse Cove, Buoy S “2”, Sur. Stonehouse Cove, Buoy S ”2”, 20’ Stonehouse Cove, Buoy S “4”, Sur. Stonehouse Cove, Buoy S “4”, 20’ Stonehouse Cove, Buoy N “6”, Sur. Stonehouse Cove, Buoy N “6”, 6’ Water drainage ditch, E of UDMH Facility 11-21 Mud Sample, S of UDMH Facility 11-21 Mud Puddle, of UDMH Facility
s
DMN, ng/L
N.D. (
