C for 2 to 3 weeks to maximize trihalomethane formation. Phase 3 had two parts. The samples identified as 3T were allowed to stand an additional 2 to 3 weeks. The samples identified as 3Q were quenched by addition of sodium thiosulfate. As expected, the highest trihalomethane values occurred in Phases 2 and 3T. Bromodichloromethane was detected in over 90% of the systems sampled. The median concentration under the various sample storage conditions ranged from 5.9 to 14 µ g/ L ( ppb), and the maximum concentration was 183 µ g/ L ( ppb). The mean concentrations of bromodichloromethane in Phases 1, 2, 3T, and 3Q were 18, 18, 17, and 9 µ g/ L ( ppb), respectively. Dibromochloromethane was detected in 73% of the systems sampled. The median concentration ranged from below the detection limit to 3 µ g/ L ( ppb), and the maximum value was 280 µ g/ L ( ppb). The mean concentrations of dibromochloromethane in Phases 1, 2, 3T, and 3Q were 8, 12, 11, and 6 µ g/ L ( ppb), respectively. The median bromoform concentration under all sampling conditions was below the detection limit of 0.3 µ g/ L ( ppb); the maximum value was 280 µ g/ L ( ppb). The mean concentrations of bromoform Phases 1, 2, 3T, and 3Q were 3, 4, 4, and 2 µ g/ L ( ppb), respectively. NOMS was conducted before the promulgation of the total trihalomethane regulation; therefore, these results may be higher than current levels.

The Community Water Supply Survey ( CWSS) was conducted by the EPA in 1978. The survey examined over 1,100 samples, representing over 450 water supply systems ( Brass et al., 1981). The samples were taken at the treatment plants and in the distribution systems. In the CWSS, 94% of the surface water supplies and 33% of the ground water supplies were positive for bromodichloromethane. For surface water supplies, the mean of the positives and the overall median were 12 and 6.8 µ g/ L ( ppb), respectively. The mean of the positives for ground water supplies was 5.8 µ g/ L ( ppb), and the overall median was below the minimum reporting limit of 0.5 µ g/ L ( ppb). For dibromochloromethane, 67% of the surface water supplies and 34% of the Draft  Do Not Cite or Quote February 20, 2003 IV  3 ground water supplies were positive. For surface water supplies, the mean of the positives and the overall median were 5.0 and 1.5 µ g/ L ( ppb), respectively. The mean of the positives for ground water supplies was 6.6 µ g/ L ( ppb), and the overall median was below the minimum reporting limit of 0.5 µ g/ L ( ppb). For bromoform, 13% of the surface water supplies and 26% of the ground water supplies were positive. The mean concentration of the positives in surface water supplies was 2.1 µ g/ L ( ppb), and the overall median was less than 1.0 µ g/ L ( ppb). The mean of the positives for ground water supplies was 11 µ g/ L ( ppb), and the overall median was below the minimum reporting limit of 0.5 µ g/ L ( ppb) ( Brass et al., 1981).

The Rural Water Survey ( RWS) was conducted between 1978 and 1980 by the EPA to evaluate the status of drinking water in rural America. Samples from over 2,000 households, representing more than 600 rural water supply systems, were examined. In the RWS, 76% of the surface water supplies and 13% of the ground water supplies were positive for bromodichloromethane 56% of the surface water supplies and 13% of the ground water supplies were positive for dibromochloromethane, and 18% of the surface water supplies and 12% of the ground water supplies were positive for bromoform. For the surface water supplies, the mean of the positives and the overall median concentrations were 17 µ g/ L ( ppb) and 11 µ g/ L ( ppb) for bromodichloromethane, 8.5 µ g/ L ( ppb) and 0.8 µ g/ L ( ppb) for dibromochloromethane, and 8.7 µ g/ L ( ppb) and < 0.5 µ g/ L ( ppb) for bromoform. For the ground water supplies, the mean of the positives was 7.7 µ g/ L ( ppb) for bromodichloromethane, 9.9 µ g/ L ( ppb) for dibromochloromethane and 12 µ g/ L ( ppb) for bromoform. The overall median for ground water supplies was below the minimum reporting limit of 0.5 µ g/ L ( ppb) for all three brominated trihalomethanes ( Brass, 1981).

The Ground Water Supply Survey ( GWSS) was conducted from December 1980 to December 1981 by the EPA to develop data on the occurrence of volatile organic chemicals in ground water supplies. Out of a total of 945 ground water systems that were sampled, 466 systems were chosen at random, and the remaining 479 systems were chosen on the basis of location near industrial, commercial, and waste disposal activities. Samples were collected at or near the entry to the distribution system, and trihalomethane formation was allowed to continue without quenching after sample collection. For bromodichloromethane, the median of the positives for the randomly chosen systems serving greater than 10,000 people was 1.4 µ g/ L ( ppb), and the occurrence rate was 36%. For the randomly chosen smaller systems, the median positive concentration was 1.6 µ g/ L ( ppb), and the occurrence rate was 54%. The nonrandomly chosen systems had a median positive concentration of 2.1 µ g/ L ( ppb) and an occurrence rate of 51%. For dibromochloromethane, the median positive concentration and the occurrence rate for the randomly chosen systems serving greater than 10,000 people were 2.1 µ g/ L ( ppb) and 31%, respectively; these values for the smaller systems were 2.9 µ g/ L ( ppb) and 52%. The nonrandomly chosen systems had a median positive concentration of 3.9 µ g/ L ( ppb) and an occurrence rate of 46%. For bromoform, the median positive concentration was 2.4 µ g/ L ( ppb) for the randomly chosen systems serving greater than 10,000 and 3.8 µ g/ L ( ppb) for the randomly chosen systems serving fewer than 10,000 people, with occurrence rates of 16% and 31%, respectively. The nonrandomly chosen systems had a median positive concentration of 4.2 µ g/ L ( ppb) and an occurrence rate of 31% ( Westrick et al., 1983). Draft  Do Not Cite or Quote February 20, 2003 IV  4 The National Screening Program for Organics in Drinking Water ( NSP), sponsored by the EPA, was conducted from June 1977 to March 1981 and sampled 169 systems nationwide. Samples were collected at the treatment facilities. For dibromochloromethane, the mean and median for 130 positives were 17.2 and 10 µ g/ L ( ppb), respectively. The maximum concentration found was 131 µ g/ L ( ppb) ( Boland, 1981).

The Technical Support Center ( TSC) of the Office of Ground Water and Drinking Water ( OGWDW) maintains a ground water contaminant database. For both bromodichloromethane and dibromochloromethane, the database contains 4,439 samples taken at the treatment facilities from nineteen states between 1984 and 1991. For bromodichloromethane, the mean concentration was 5.6 µ g/ L ( ppb), and the median was 3 µ g/ L ( ppb). For dibromochloromethane, the mean concentration was 3.0 µ g/ L ( ppb), and the median was 1.7 µ g/ L ( ppb). For bromoform, the database contains 1409 samples from 19 states taken at treatment facilities between 1984 and 1991. The mean and median concentrations were determined to be 2.5 µ g/ L ( ppb) and 1 µ g/ L ( ppb), respectively ( U. S. EPA, 1991).

Thirty five water utilities nationwide, 10 of which were located in California, were sampled for bromodichloromethane, dibromochloromethane, and bromoform in the clearwell effluent. Samples were taken for four quarters ( spring, summer, and fall in 1988 and winter in 1989). The median bromodichloromethane concentration for all four quarters was 6.6 µ g/ L ( ppb), with the medians of the individual quarters reported as 6.9, 10, 5.5 and 4.1 µ g/ L ( ppb), respectively, and with a maximum value of 82 µ g/ L ( ppb). For all four quarters, 75% of the measured concentrations were less than 14 µ g/ L ( ppb). The median dibromochloromethane concentration for all four quarters was 3.6 µ g/ L ( ppb), with the medians of the individual quarters reported as 2.6, 4.5, 3.8 and 2.7 µ g/ L ( ppb), respectively, and with a maximum value of 63 µ g/ L ( ppb). For all four quarters, 75% of the data were below 9.1 µ g/ L ( ppb). The median bromoform concentration for all four quarters was 0.57 µ g/ L ( ppb), with the medians of the individual quarters reported as 0.33, 0.57, 0.88, and 0.51 µ g/ L ( ppb), respectively, and with a maximum value of 72 µ g/ L ( ppb). For all four quarters, 75% of the bromoform concentrations were below 2.8 µ g/ L ( ppb) ( Krasner et al., 1989; U. S. EPA 1989a; 1989b).

The EPA's Technical Support Center compiled a database from its disinfection by products field studies. The studies included a chlorination by products survey, conducted from October 1987 to March 1989. In this survey, concentrations of bromodichloromethane, dibromochloromethane, and bromoform were determined in finished water from the treatment plant and in the distribution system. Systems using both surface water sources and ground water sources were analyzed.

Mean concentrations of bromodichloromethane, dibromochloromethane, and bromoform in finished water at the treatment plants were determined for surface water systems serving both greater than and less than 10,000 people. Forty two samples were taken from systems serving more than 10,000 people, and 20 samples were taken from systems serving fewer than 10,000 people. The mean concentration of bromodichloromethane was 12.7 µ g/ L ( ppb) in samples from systems serving more than 10,000 people ( 90th percentile, 25.0 µ g/ L ( ppb)) and 17.0 µ g/ L ( ppb) Draft  Do Not Cite or Quote February 20, 2003 IV  5 for samples from the smaller systems ( 90th percentile, 29.5 µ g/ L ( ppb)). The mean dibromochloromethane concentrations was 4.7 µ g/ L ( ppb) for samples from the larger systems ( 90th percentile, 13.8 µ g/ L ( ppb)) and 6.9 µ g/ L ( ppb) for samples from the smaller systems ( 90th percentile, 24.2 µ g/ L ( ppb)). The mean concentrations for bromoform were 0.7 µ g/ L ( ppb) ( 90th percentile, 1.5 µ g/ L ( ppb)) and 0.9 µ g/ L ( ppb) ( 90th percentile, 4.9 µ g/ L ( ppb)) in samples from the larger systems and samples from the smaller systems, respectively ( U. S. EPA, 1992a).

Mean bromodichloromethane, dibromochloromethane, and bromoform concentrations in distribution systems of these surface water systems also were analyzed. Thirty nine samples were taken from systems serving more than 10,000 people, and 11 samples were from systems serving fewer than 10,000 people. The mean bromodichloromethane concentrations in the larger systems and the smaller systems were 17.4 µ g/ L ( ppb) ( 90th percentile, 35.3 µ g/ L ( ppb)) and 24.8 µ g/ L ( ppb) ( 90th percentile, 51.0 µ g/ L ( ppb)), respectively. The mean dibromochloromethane concentrations were 6.3 µ g/ L ( ppb) ( 90th percentile, 17.3 µ g/ L ( ppb)) and 10.4 µ g/ L ( ppb) ( 90th percentile, 35.0 µ g/ L ( ppb)), respectively. Mean bromoform concentrations were 0.8 µ g/ L ( ppb) ( 90th percentile, 3.1 µ g/ L ( ppb)) and 1.4 µ g/ L ( ppb) ( 90th percentile, 5.1 µ g/ L ( ppb)), respectively ( U. S. EPA, 1992a).

Ground water systems serving less than 10,000 people were analyzed for bromodichloromethane, dibromochloromethane, and bromoform in seven finished water samples and in five distribution system samples. Mean bromodichloromethane concentrations in the finished water samples and in the distribution system samples were 1.1 µ g/ L ( ppb) ( 90th percentile, 2.6 µ g/ L ( ppb)) and 2.2 µ g/ L ( ppb) ( 90th percentile, 5.4 µ g/ L ( ppb)), respectively. Mean dibromochloromethane concentrations were 0.6 µ g/ L ( ppb) ( 90th percentile, 1.0 µ g/ L ( ppb)) and 1.8 µ g/ L ( ppb) ( 90th percentile, 3.6 µ g/ L ( ppb)), respectively. Mean bromoform concentrations were 0.6 µ g/ L ( ppb) ( 90th percentile, 2.6 µ g/ L ( ppb)) and 2.3 µ g/ L ( ppb) ( 90th percentile, 10 µ g/ L ( ppb)), respectively.

For ground water systems serving more than 10,000 people, dibromochloromethane and bromoform were not detected in single samples taken at the plant and from the distribution system, based on a detection limit of 0.2 µ g/ L ( ppb). Bromodichloromethane concentrations in the plant and distribution system samples were 0.2 and 0.4 µ g/ L ( ppb), respectively ( U. S. EPA, 1992a).

The U. S. Geological Survey conducted an assessment of volatile organic compounds in untreated ambient groundwater of the conterminous United States based on samples collected between 1985 and 1995 from 2948 wells. The sampled wells were located in rural and urban areas and included wells used for drinking and non drinking water purposes. A minimum reporting level of 0.2  g/ L ( ppb) was used for most of the compounds, including bromodichloromethane, dibromochloromethane, and bromoform. In samples from the 406 urban wells assessed, bromodichloromethane, dibromochloromethane, and bromoform were detected in 3.0%, 2.8%, and 2.8% of the wells examined, respectively. In samples from the 2542 rural wells examined, these compounds were detected in 0.8%, 0.6%, and 0.4% of the wells, respectively. The measured concentration of the compounds in well water were reported in summary graphics Draft  Do Not Cite or Quote February 20, 2003 IV  6 only. Thus, the values reported here are approximate based on visual inspection of the figures. The median concentrations measured in the positive samples from the urban wells was approximately 1.0  g/ L ( ppb) for all three compounds, while the maximum concentrations of bromodichloro methane, dibromochloromethane, and bromoform in the urban wells were approximately 11, 11, and 13  g/ L ( ppb), respectively. The median concentrations measured in the positive samples from the rural wells were approximately 0.4 to 0.5  g/ L ( ppb) for all three compounds, while the maximum concentrations of bromodichloromethane, dibromochloromethane, and bromoform in the rural wells were approximately 7, 10, and 18  g/ L ( ppb), respectively.

The most recent survey of the occurrence of brominated trihalomethanes in public water supplies ( PWSs) serving at least 100,000 persons resulted from the Information Collection Rule ( ICR) promulgated in May of 1996 for disinfectants and disinfection byproducts ( D/ DBPs). The rule covered both surface and ground water systems. Monitoring data were collected from about 300 water systems operating 501 plants over the18 month period between July 1997 and December 1998. At each plant, samples were collected monthly and analyzed for a variety of D/ DBPs on a monthly or quarterly basis. Bromodichloromethane, dibromochloromethane, and bromoform were among the analytes evaluated quarterly ( U. S. EPA, 2001a). Five samples were taken each quarter at each plant   one of the finished water and four of the water in the distribution system. Of the four samples from the distribution system, one represented a sample with the same residence time as a finished water sample held for a specific period of time, two represented approximate average water residence times in the system, and one sample was taken where water residence time in the system is the longest. For each plant and reporting period, EPA compiled several summary statistics. The Distribution System ( DS) Average value is the average of the four distribution system samples. The DS High Value is the highest concentration of the four distribution system samples collected by a plant in a given quarter. The DS High Value might be from any of the four samples and could vary from quarter to quarter depending on which sample yielded the highest concentrations in each quarter ( U. S. EPA, 2001a). Table IV 1 summarizes the results of all six of the quarterly reporting periods.

U. S. EPA set a minimum reporting level ( MRL) for bromodichloromethane, dibromochloromethane, and bromoform of 1.0  g/ L for the ICR. The MRL is a level below which systems were not required to report their monitoring results, even if there were detectable results. Values below the MRL were assigned a value of zero for the purpose of calculating averages; this assignment affects the calculation of mean values for finished water and DS high results and calculation of all DS average values.

Recent data for concentrations of brominated trihalomethanes are now available for 117 small surface water plants ( serving  10,000 people) from the National Rural Water Association Survey ( NWRA) ( U. S. EPA 2001b). Most, but not all, plants that participated in the survey took two samples at each of three sampling locations. One sample was taken between November, 1999, and March, 2000, and the other between July and November, 2000, for a total of 217 THM samples. The samples were taken at the finished water location, distribution system average Draft  Do Not Cite or Quote February 20, 2003 IV  7 residence time location, and maximum residence time location. These data are summarized in Table IV 2 below. Draft  Do Not Cite or Quote February 20, 2003 IV  8 Table IV 1. Brominated Trihalomethane Concentrations Measured in U. S. Public Drinking Water Systems Serving 100,000 or More Persons Source Data Type ( a) Number of Samples Median ( b) Mean ( b) 90th Percentile Range Bromodichloromethane (

g/ L)

Suface Water Finished 1856 6.6 8.2 17.5 < 1.0  49 DS Average 1656 8.6 10.2 20.3 0  65.8 DS High 1656 9.9 11.9 23.3 < 1.0  73 Ground Water Finished 604 < 1.0 7.9 6.80 < 1.0  27 DS Average 603 1.80 4.06 11.2 0  35.3 DS High 603 2.8 5.78 16.0 < 1.0  110 Dibromochloromethane (

g/ L)

Surface Water Finished 1853 1.9 4.03 12.0 < 1.0  55.1 DS Average 1655 2.40 4.72 13.2 0  67.3 DS High 1655 2.9 5.57 15.0 < 1.0  67.3 Ground Water Finished 604 < 1.0 1.38 4.10 < 1.0  33 DS Average 602 1.35 3.09 8.94 0  37.5 DS High 602 2.1 4.60 12.9 < 1.0  85 Bromoform (

g/ L)

Surface Water Finished 1853 < 1.0 0.998 2.88 < 1.0  34 DS Average 1653 0 1.18 3.10 0  34.3 DS High 1653 < 1.0 1.48 3.90 < 1.0  40 Ground Water Finished 602 < 1.0 0.838 2.20 < 1.0  21 DS Average 599 0.325 1.92 4.78 0  28.8 DS High 599 1.2 2.95 7.72 < 1.0  391 ( a) Finished = sample location after treatment, before entering the distribution system ( DS); DS Average = average of four sample locations in the DS; DS High = the highest concentration of the four distribution system samples collected by a plant in a given quarter. For purposes of calculations, all values below the minimum reporting level ( MRL) of 1.0

g/ L for all three compounds were assigned a value of zero. ( b) Median and mean of all samples including those below the MRL. Source: Disinfectants and Disinfection Byproducts ( D/ DBPs) ICR Data, U. S. EPA ( 2001a). Draft  Do Not Cite or Quote February 20, 2003 IV  9 Table IV 2 NRWA Brominated Trihalomethane Results for Small Surface Water Plants THM Sample Location Mean Median 90th Percentile Range Bromodichloromethane (

g/ L) Finished 11.2 6.5 26.6 0  84.4 DS Average 14.3 9.4 32.2 0  100.3 DS Max 15.9 10.2 34.2 0  121.1 Dibromochloromethane (

g/ L) Finished 5.0 1.1 13.4 0  83.1 DS Average 6.1 1.5 16.3 0  99.0 DS Max 6.7 1.9 17.1 0  91.6 Bromoform (

g/ L) Finished 4.0 0 1.2 0  333.4 DS Average 4.6 0 1.2 0  340.5 DS Max 4.5 0 1.3 0  349.7 Median and mean of all samples, including those below the detection limit. Source: National Rural Water Association Survey.

2. Other Studies Several less comprehensive surveys have analyzed drinking water for one or more of the brominated trihalomethanes. An overview of these studies is provided below.

The EPA Region V Organics Survey sampled finished water from 83 sites in a region that includes Illinois, Indiana, Michigan, Minnesota, Ohio, and Wisconsin. Bromoform was found at a median concentration of the positives of 1 µ g/ L ( ppb) and a maximum level of 7 µ g/ L ( ppb). A total of 14% of the locations sampled contained detectable levels of bromoform ( U. S. EPA, 1980). Kelley ( 1985) surveyed 18 drinking water plants in Iowa for trihalomethanes, and detected bromoform in five water supplies at concentrations ranging from 1.0 to 10 µ g/ L ( ppb).

The EPA's Five year Total Exposure Assessment Methodology ( TEAM) study measured the personal exposures of a probability based sample of residents in several U. S. cities to various organic chemicals in air and drinking water between 1981 and 1987. As part of the study, running tap water samples were collected from residences of nearly 850 study participants during the morning and the evening to test for brominated trihalomethane concentrations. The samples were quenched with sodium thiosulfate at the time of collection. Tables IV 3, IV 4, and IV 5 show bromodichloromethane, dibromochloromethane, and bromoform concentrations found in drinking water from the six cities surveyed. Samples of water were taken from each participating residence at the household taps and sodium thiosulfate added as a quenching agent. Draft  Do Not Cite or Quote February 20, 2003 IV  10 Table IV 3 Bromodichloromethane Concentrations in Drinking Water from the U. S. EPA TEAM Study ( µ g/ L)

Location Date Sampled Sample Size %

Measured Concentration µ g/ L ( ppb)

Mean Median Max Percentiles 25% 75% 90% 95%

Elizabeth/ Bayonne, New Jersey Fall 1981 340 99.7 13.6 13 23  15 16 18 Summer 1982 156 99.8 13.6 12 54  15 18 20 Winter 1983 49 100 5.4 5.8 16  7.1 8.3 8.3 Los Angeles, California Winter 1984 117 93 11 12 23 5.1 16 17 20 Summer 1984 52 96 20 24 38 7.7 31 33 37 Winter 1987 9 89 19 24 31

Summer 1987 7 100 26 27 36

Antioch/ Pittsburg, California Spring 1984 71 96 21 17 47 2.4 36 45 47 Devils Lake, North Dakota Fall 1982 24 73 0.21 0.18 1.0

Greensboro, North Dakota Fall 1982 24 93 7.1 7.8 11  9.2

Baltimore, Maryland Spring 1987 10 100 10 10 13

Adopted from Hartwell, ( 1987), Wallace et al. ( 1987), Wallace et al. ( 1988), and Wallace ( 1992) by U. S. EPA ( 1994b). Mean and median values of all samples, including those below the quantitation limit. Draft  Do Not Cite or Quote February 20, 2003 IV  11 Table IV 4 Dibromochloromethane Concentrations in Drinking Water from the U. S. EPA TEAM Study Location Date Sampled Sample Size %

Measured Concentration µ g/ L ( ppb)

Mean Median Max Percentile 25% 75% 90% 95%

Elizabeth/ Bayonne, New Jersey Fall 1981 340 99.7 2.4 2.4 8.4  2.7 3.2 3.4 Summer 1982 156 99.8 2.1 1.9 7.2  2.4 3.1 3.8 Winter 1983 49 93 1.4 1.6 3.0  1.8 2.0 2.1 Los Angeles, California Winter 1984 117 89 9.4 11 19 2.4 15 17 18 Summer 1984 52 85 28 32 55 15 42 43 48 Winter 1987 9 89 10 12 17

Summer 1987 7 100 24.7 18 70

Antioch/ Pittsburg, California Spring 1984 71 85 8 6.4 21 0.98 15 18 19 Devils Lake, North Dakota Fall 1982 24 18 0.09 0.06 0.45  0.06

Greensboro, North Dakota Fall 1982 24 93 1.2 1.2 1.9  1.5

Baltimore, Maryland Spring 1987 10 100 2.7 2.6 3.5

Adopted from Hartwell, ( 1987), Wallace et al. ( 1987), Wallace et al. ( 1988), and Wallace ( 1992) by U. S. EPA ( 1994b). Mean and median values of all samples, including those below the quantitation limit. Draft  Do Not Cite or Quote February 20, 2003 IV  12 Table IV 5 Bromoform Concentrations in Drinking Water from the U. S. EPA TEAM Study Location Date Sampled Sample Size %

Measured Concentration µ g/ L ( ppb)

Mean Median Max Percentile 25% 75% 90% 95%

Los Angeles, California Winter 1984 117 69 0.78 0.54 12 0.34 0.92 1.2 1.5 Summer 1984 52 90 8.08 3.0 78 2.0 5.9 13 53 Winter 1987 9 89 3.2 3.2 4.7

Summer 1987 7 100 25.5 9.6 113

Antioch/ Pittsburg, California Spring 1984 71 69 0.78 0.58 2.0 0.19 1.2 1.8 1.9 Adopted from Wallace ( 1992) by U. S. EPA ( 1994b). Mean and median values of all samples, including those below the quantitation limit. Bromoform was measured in fewer than 10% of samples from the other four cities in the TEAM study and are not presented here Furlong and D'itri ( 1986) reported that a survey of water treatment plants in Michigan detected bromodichloromethane in 35 of 40 plants at a median concentration of 2.7 µ g/ L ( ppb) and a maximum of 54.2 µ g/ L ( ppb); the mean of the positive samples was 7.4 µ g/ L ( ppb).

Dibromochloromethane was also detected in 30 plants at a median concentration of 2.2 µ g/ L ( ppb) and a maximum of 39.6 µ g/ L ( ppb); the mean of the positives was 5.1 µ g/ L ( ppb). Bromoform was detected at three of 40 plants sampled at concentrations of 0.9, 1.3, and 1.6 µ g/ L ( ppb).

Fair et al. ( 1988) analyzed drinking water from three community water supplies for chlorination by products. Bromodichloromethane concentrations ranged from 7.5 to 30 µ g/ L ( ppb) in finished water and from 9.9 to 36 µ g/ L ( ppb) in the distribution systems. Dibromochloromethane concentrations ranged from less than 0.5 to 19 µ g/ L ( ppb) in finished water at the plant and from less than 0.5 to 23 µ g/ L ( ppb) in the distribution systems. Bromoform concentrations ranged from less than 0.5 to 2.5 µ g/ L ( ppb) in finished water and from less than 0.5 to 3.1 µ g/ L ( ppb) in the distribution systems. Draft  Do Not Cite or Quote February 20, 2003 IV  13 Wallace et al. ( 1982) analyzed tap water for bromodichloromethane as part of a study to determine individual exposures to volatile organics during normal daily activities of students at the University of North Carolina, Chapel Hill. Bromodichloromethane was detected in 7 of 7 samples of tap water, at concentrations ranging from 15 to 20 µ g/ L ( ppb), with a mean of 17 µ g/ L ( ppb). The detection limit was 0.1 µ g/ L ( ppb).

Chang and Singer ( 1984) analyzed the bromoform concentration in drinking water samples prepared by the desalination of seawater. After pretreatment using either activated carbon or ultrafiltration, but prior to reverse osmosis treatment, bromoform concentrations were 13 ± 14 and 110 ± 59 µ g/ L ( ppb), respectively. After reverse osmosis was completed, the finished water product contained bromoform concentrations ranging from 2.0 to 51 µ g/ L ( ppb) ( mean, 20.17 µ g/ L ( ppb)) when activated carbon was used as a pretreatment and 127 µ g/ L ( ppb) when ultrafiltration was used. In the reverse osmosis treatment, three reverse osmosis membranes were evaluated. The cellulose triacetate filter resulted in concentrations of 51 µ g/ L ( ppb), while the polyether/ urea thin film spiral wound membrane and the polysulfone membrane filters which resulted in final concentrations of 5.0 µ g/ L ( ppb) and 2.25 µ g/ L ( ppb), respectively.

Bromodichloromethane, dibromochloromethane, and bromoform were detected in 9.5 to 12.8% of drinking water samples collected in 1987 in Nassau County, New York. The county draws its drinking water from underground aquifers. Bromodichloromethane and dibromochloromethane had similar concentration profiles, being detected in approximately 10% and 8.5% of the samples, respectively, at concentrations less than 4.9 ppb. The detection limit was 1 ppb for each chemical. Bromoform was detected in 8% of the samples at 2 to 4.9 ppb, in 2.5% of the samples at 5 to 9.9 ppb, and in less than 1% of the samples at 10 to 49.9 ppb. The detection limit was 2 ppb. None of the drinking water samples contained more than 50 ppb of any of the trihalomethanes, and less than 1% of the samples contained between 10 and 49.9 ppb of the brominated compounds ( Moon et al. 1990).

U. S. EPA conducted a study of contaminants in household water in nine residences as part of a larger study of health risks due to environmental contamination in the Lower Rio Grande Valley ( Berry et al., 1997). Samples of water used for drinking were taken once during a 3 day period in the spring and once during a 2 day period in the summer of 1993. Water used for drinking in the nine residences could be traced to one of three sources: the municipal water supply of Brownsville, Texas, vended water supplies ( municipal water that had undergone further treatment), and well water. Samples were collected using U. S. EPA protocols, including quality assurance samples and field blanks. The detection and minimum quantitation limits for each analyte were documented in other reports. Bromodichloromethane, dibromochloromethane, and bromoform were detected in the household water of seven of the nine residences during the spring and in five of the nine residences during the summer ( Berry et al., 1997). During the spring, the minimum, median, and maximum concentrations of bromodichloromethane for the seven positive samples were 3.2, 5.2, and 24.4

g/ L ( ppb), respectively. For dibromochloromethane, the values were 3.3, 5.1, and 17.3

g/ L ( ppb), respectively. For bromoform, the values were 1.0, 3.0, and 14.1

g/ L ( ppb), respectively. During the summer, the minimum, median, and maximum concentrations of bromodichloromethane in the five positive samples were 2.3, 7.7, and 34.3

g/ L Draft  Do Not Cite or Quote February 20, 2003 IV  14 ( ppb), respectively. For dibromochloromethane, the values were 1.8, 7.6, and 49.9

g/ L ( ppb), respectively, and for bromoform, the values were 1.6, 7.8, and 31.7

g/ L ( ppb), respectively.

Weisel et al. ( 1999) examined concentrations of trihalomethanes in the tap water of the homes of 49 women in New Jersey. The 49 residences were selected so that approximately half would represent the lower extreme of trihalomethane contamination and half the upper extreme of trihalomethane contamination identified in a previous study. Samples were stored unquenched on ice after collection and were analyzed within 24 hours. The three brominated trihalomethanes were detected in all 49 samples. The mean ( ± standard deviation) concentrations of bromodichloromethane, dibromochloromethane, and bromoform were 5.7 ± 8.6, 2.0 ± 2.1, and 0.73 ± 0.90

g/ L ( ppb), respectively. The median values for the three compounds were 2.6, 1.4, and 0.45

g/ L ( ppb), respectively. These values are not representative of New Jersey, because of the selection criteria for the residences. The ranges ( minimum to maximum) of concentrations measured for each compound were 0.06 to 48

g/ L ( ppb) for bromodichloromethane, 0.14 to 9.7

g/ L ( ppb) for dibromochloromethane, and 0.03 to 4.21

g/ L ( ppb) for bromoform.

3. Estimates of Tap Water Ingestion Exposure to Brominated Trihalomethanes a. Estimates Based on ICR Data for Disinfection Byproducts The data from EPA's ICR for disinfectants and disinfection byproducts ( U. S. EPA 2001a) offer several advantages over the other national studies for purposes of estimating national exposure levels of adults in the United States to brominated trihalomethanes via ingestion of drinking water. First, they are recent and reflect relatively current conditions. Second, data of very similar quality and quantity were collected systematically from a large number of plants ( 501) and systems ( approximately 300), including both surface and ground water systems. Third, the mean, median, and 90th percentile value were estimated on the basis of all samples taken, not just the sample detects. Thus, these descriptive statistics are representative of the exposures of the entire populations served by those systems, not just the populations served by systems with higher concentrations of these compounds. However, this study can not be considered representative of smaller public water supplies or water supplies from the most highly industrialized or contaminated areas.

Table IV 6 presents estimated drinking water exposures to brominated trihalomethanes of the adult populations served by large public water systems ( serving 100,000 or more persons) based on the ICR Occurrence Data ( U. S. EPA, 2001a). Exposure was calculated by multiplying the concentration of individual brominated trihalomethanes in drinking water by the average daily intake, assuming that each individual consumes two liters of water per day. The annual median, mean, and upper 90th percentile values are presented for both surface and ground water systems. Assuming that the DS High value actually represents the average exposure level of persons served by one plant distribution pipe with the longest water residence time, the DS High value might be used to estimate a high end exposure level. Thus, the 90th percentile of the DS High values are also presented in Table IV 6. Draft  Do Not Cite or Quote February 20, 2003 IV  15 Table IV 6 Estimated Drinking Water Exposures to Brominated Trihalomethanes in U. S. Public Drinking Water Systems Serving More than 100,000 Personsa Source Medianb Meanb 90th Percentileb DS High 90th Percentilec Bromodichloromethane (

g/ person/ day)

Surface Water 17 20 40 47 Ground Water 3.6 8.1 22 32 Dibromochloromethane (

g/ person/ day)

Surface Water 4.8 9.4 26 30 Ground Water 2.7 6.2 18 26 Bromoform (

g/ person/ day)

Surface Water 0 2.4 6.2 7.8 Ground Water 0.65 3.8 9.6 15 a Source: U. S. EPA ( 2001a). Assumes that each individual consumes 2 liters of water daily. Also assumes that concentrations at the drinking water tap are similar to concentrations in the distribution system ( DS) sampled at locations considered to be representative of average ( DS Average) and highest ( DS High) retention times ( see Table IV 1). b Based on concentrations from the DS Average values. c Based on the 90th percentile of the DS High values to represent a plausible high end exposure level.

For bromodichloromethane, the median, mean, and 90th percentile population exposures from surface water systems are estimated to be 17, 20, and 40 µ g/ person/ day, respectively. The same values for populations exposed to bromodichloromethane from ground water systems are lower   3.6, 8.1, and 22 µ g/ person/ day, respectively. For dibromochloromethane, the median, mean, and 90th percentile population exposures from surface water systems are estimated to be 4.8, 9.4, and 26 µ g/ person/ day, respectively. The corresponding values for populations exposed to dibromochloromethane from groundwater system are lower   2.7, 6.2, and 18 µ g/ person/ day, respectively. For bromoform, the median, mean, and 90th percentile population exposures from surface water systems are estimated to be near 0, 2.4, and 6.2 µ g/ person/ day, respectively. The same values for populations exposed to bromoform from ground water systems are higher   0.65, 3.8, and 9.6 µ g/ person/ day, respectively.

Average daily intake of dibromochloromethane was also evaluated for determination of the Relative Source Concentration. The details of this evaluation are presented in Appendix C. Intake for ingestion was calculated using mean intake rates of 1.2 or 0.6 L/ day for total and direct intake ( NRC, 1999), respectively. Direct intake includes consumption of water directly from the tap, but does not include intake of tap water used for preparation of heated items such tea, coffee, or soup. Based on the ICR distribution system average concentration of 4.72 µ g/ L for Draft  Do Not Cite or Quote February 20, 2003 IV  16 dibromochloromethane in surface water, the average daily total and direct and ingestion intakes would be 5.7 and 2.8 µ g/ day, respectively. Absorption of dibromochloromethane from tap water was estimated using methodology described in U. S. EPA ( 1992c), as modified by Vecchia and Bunge ( 2002). The average dermal uptake of dibromochloromethane was estimated to be 2 µ g per shower or bathing event. Intake via inhalation of dibromochloromethane volatilized during household activities ( e. g., showering, bathing, dishwashing, toilet flushing, etc.) was estimated using a three compartment model based on McKone ( 1987). This model estimated an average daily inhalation exposure of 7 µ g/ day for the volatilized compound. Parallel calculations were not performed for bromodichloromethane or bromoform, because these compounds are probable carcinogens. Therefore, in accordance with U. S. EPA policy, RSC analysis was not conducted.

b. Estimates of Ingestion Exposure Based on Other National Studies Exposure to bromodichloromethane, dibromochloromethane, and bromoform in drinking water from ground water supplies can be estimated from the median levels found in the GWSS. Based on the range of median levels ( 1.4   2.1 µ g/ L ( ppb)) and a consumption rate of two liters per day, the median exposure to bromodichloromethane may range from 2.8 to 4.2 µ g/ day. Similarly, median exposure to dibromochloromethane may range from 4.2 to 7.8 µ g/ day, and for bromoform, median exposure may range from 4.8 to 8.4 µ g/ day. Exposure to bromodichloromethane from surface water supplies can be estimated based on the range of median values observed under different conditions in NOMS, which mainly sampled surface water systems. Based on a range of 5.9   14 µ g/ L ( ppb), exposure to bromodichloromethane from surface water is estimated to be between 12 and 28 µ g/ day. Similarly, based on the range of medians reported for dibromochloromethane concentrations, the median exposure is estimated to be up to 6 µ g/ day. The median levels of bromoform in the surface water supplies have been found to be less than the EPA Drinking Water minimum reporting levels ( MRLs) of 0.5   1 µ g/ L ( ppb). An estimate of exposure based on the MRLs will be overly conservative because the actual concentration of bromoform is not detectable. Based on the range of MRLs, 0.5   1 µ g/ L ( ppb), the exposure to bromoform is estimated to range from 1 to 2 µ g/ day for surface water supplies.

Ingestion exposure to brominated trihalomethanes in drinking water can also be estimated from the concentrations found at the tap in the TEAM studies. Table IV 7 presents median, mean, 90th percentile, and 95th percentile estimates of daily intakes of bromodichloromethane, dibromochloromethane, and bromoform, based on an assumed drinking water ingestion rate of 2 liter per day. Table IV 7 provides estimates for those locations and seasons with a sample size of at least 50, with one exception. Devils Lake, ND, with a samples size of only 24, is added to represent an area with low concentrations. Thus, the influence of small sample size on distributional statistics should be minimized in Table IV 7. The median, mean, and 90th percentile values in Table IV 7 for the TEAM study can be compared with the corresponding values in Table IV 6 for the ICR Occurrence data.

Table IV 7 demonstrates that concentrations of brominated trihalomethanes are lower in winter than in summer, as would be expected on the basis of temperature. In this sample of Draft  Do Not Cite or Quote February 20, 2003 IV  17 Table IV 7. Estimated Distribution of Drinking Water Exposures to Brominated Trihalomethanes for Populations in U. S. EPA TEAM Study ( a)

Location Season Year Median ( b) Mean ( b) 90th Percentile ( b) 95th Percentile Bromodichloromethane (

g/ person/ day)

Elizabeth/ Bayone NJ summer 82 24 27 36 40 winter 83 12 11 17 17 Los Angeles, CA summer 84 48 40 66 74 winter 84 24 22 34 40 Antioch/ Pittsburg, CA spring 84 34 42 90 94 Devils Lake, ND fall 82 0.36 0.42 < 2.0 < 2.0 Dibromochloromethane (

g/ person/ day)

Elizabeth/ Bayone NJ summer 82 3.8 4.2 6.2 7.6 winter 83 3.2 2.8 4.0 4.2 Los Angeles, CA summer 84 64 56 86 96 winter 84 22 19 34 36 Antioch/ Pittsburg, CA spring 84 13 16 36 38 Devils Lake, ND fall 82 0.12 0.2 < 0.9 < 0.9 Bromoform (

g/ person/ day)

Los Angeles, CA summer 84 6.0 16.2 26 100 winter 84 1.1 1.6 2.4 3.0 Antioch/ Pittsburg, CA spring 84 1.2 1.6 3.6 3.8 ( a) Intakes estimated from data in Tables IV 3, IV 4, and IV 5 assuming a water ingestion rate of 2 liters per day. Selected locations and seasons with samples sizes over 50. Added Devils Lake, ND, to represent an area with low air concentrations. ( b) Median, mean, and upper percentiles estimated for entire population of city. Draft  Do Not Cite or Quote February 20, 2003 IV  18 geographic locations, estimates of the average of the population intakes of bromodichloromethane from drinking water range from 0.42 to 42

g/ person/ day. The upper 90th percentile estimates range from < 2.0 to 90

g/ person/ day. Estimates of the average population intake of dibromochloromethane from drinking water range from 0.2 to 56

g/ person/ day. The upper 90th percentile estimates range from < 0.9 to 86

g/ person/ day. Estimates of the average of the population intakes of bromoform, for those areas in which bromoform was measurable in a majority of the samples, range from 1.6 to 16.2

g/ person/ day. The upper 90th percentile estimates range from 2.4 to 26

g/ person/ day. Four of the six locations in the TEAM study, however, had a low frequency ( less than 10%) of detection of bromoform in measurable quantities.

c. Sources of Uncertainty in Estimates of Exposure from Drinking Water Sources of uncertainty in the estimates of ingestion exposure include use of different analytical methods, failure to report quantitation limits, using measures near the detection limit, failure to report how nondetects are handled when averaging values ( e. g., set to zero or one half the detection limit), and failure to report sample storage method and duration. In addition, many environmental factors influence the concentrations of these compounds in drinking water at the tap and in vended or bottled waters used for drinking. These factors include season and temperature, geographic location, source of water, residence time in distribution system, and others.

B. Exposure from Sources Other Than Drinking Water 1. Dietary Intake a. Measured Concentrations in Foods and Beverages Information on the levels of brominated trihalomethanes in foods and beverages is limited. Chlorine is used in food production for applications such as the disinfection of chicken in poultry plants and the superchlorination of water at soda and beer bottling plants ( Borum, 1991). Therefore, the possibility exists for contamination of foodstuffs by disinfection by products with resulting dietary exposure. The occurrence of bromodichloromethane in foods and beverages is the best characterized of the three compounds. Less information is available concerning the occurrence of dibromochloromethane or bromoform in foods and beverages in the United States. Some information is available from international studies, but may not be relevant to U. S. occurrence because of different water treatment and food processing practices. The available U. S. and international studies are summarized below.

Entz et al. ( 1982) analyzed food samples from Elizabeth, NJ, Chapel Hill, NC, and Washington, DC. for bromodichloromethane. A total of 39 different food items from each city were collected according to standards set for the FDA's Total Diet Market Basket Study. The Adult Market Basket, representing the diet of a teenage male, is divided into 12 food groups. Individual foods are prepared as generally consumed in the home and foods from each group are Draft  Do Not Cite or Quote February 20, 2003 IV  19 blended together in " the proper proportions" to form composites. In this study, foods were blended into four composites representing dairy products; meat, fish and poultry; oils, fats and shortening; and beverages. The estimated limit of quantitation for bromodichloromethane in each of these composites was 2.3, 4.5, 8.3, and 0.5 ng/ g, respectively. Five sets of each composite were tested for a total of 20 composites. Bromodichloromethane was detected in one dairy composite at 1.2 ppb and two beverage composites at 0.3 ppb and 0.6 ppb. Analysis of individual foods from the beverage and dairy composites found bromodichloromethane in three samples of cola soft drinks at concentrations of 2.3 ppb, 3.4 ppb, and 3.8 ppb and in one sample of butter at 7 ppb.

Uhler and Diachenko ( 1987) sampled 38 food and beverage products from 15 food processing plants in nine states. Plants were chosen on a " worst case" basis from areas where contaminated water would most likely be used in processing. In addition, processing plants were chosen for study only if they produced high fat content food that came in contact with water during processing or contained a high percentage of added water. Samples containing less than 1 ng/ g were considered nondetects. Bromodichloromethane was detected in 6 out of 37 tested food tested at the following levels: two samples of clear sodas at 1.2 and 2.3 ng/ g ( ppb) and one sample of dark cola at l. 2 ng/ g ( ppb) out of fifteen soft drinks, and three of six samples of ice cream at 0.6 to 2.3 ng/ g ( ppb). Bromodichloromethane was not found in any of the eight cheese samples analyzed.

U. S. EPA ( 1985) reported that bromodichloromethane was identified in bacon. No further information on sample size, detection limit, or study methodology was provided.

Abdel Rahman ( 1982) analyzed various soft drinks for bromodichloromethane and found average levels ranging from 0.2 to 6.6 µ g/ L ( ppb) for colas and from 0.1 to 0.2 µ g/ L ( ppb) for clear soft drinks ( Abdel Rahman, 1982). In Italy, Cocchioni et al. ( 1996) analyzed 61 samples of different commercially prepared beverages and 94 samples of mineral waters for volatile organohalogenated compounds. In the prepared beverages, they found maximum concentrations of bromodichloromethane, dibromochloromethane, and bromoform of 40.6, 13.9, and 10.7 µ g/ L ( ppb), respectively. The frequencies of detection of these three compounds in prepared beverages were 46% ( 28/ 61), 43% ( 26/ 61), and 11% ( 7/ 61), respectively, with detection limits for all three compounds of less than 1 µ g/ L ( ppb). In contrast, the maximum concentration of any of the halogenated organic compounds identified in mineral water, including chloroform, was 5.79 µ g/ L ( ppb).

McNeal et al. ( 1995) examined 27 different prepared beverages and mineral waters in the United States for bromodichloromethane, dibromochloromethane, and bromoform at detection limits of 0.1, 0.1, and 0.2 ng/ g ( ppb), respectively. Bromoform was not detected in any of the samples. Bromodichloromethane and dibromochloromethane were detected at 12 and 1 ng/ g ( ppb), respectively, in only one of seven types of mineral and sparkling waters examined. The positive sample was the only sparkling and flavored water of the group,. Bromodichloromethane was found in 1 of 5 flavored noncarbonated beverages examined, a fruit drink, at a concentration of 5 ng/ g ( ppb); dibromochloromethane was not detected in any of these five beverages. Draft  Do Not Cite or Quote February 20, 2003 IV  20 Bromodichloromethane was found in all 13 of the types of carbonated soft drinks examined, at concentrations ranging from 1 to 4 ng/ g ( ppb) for 12 of the drinks examined and at 12 ng/ g ( ppb) for the thirteenth. Dibromochloromethane was detected in only 4 of the 13 carbonated soft drinks examined at levels of 0.5 to 2 ng/ g ( ppb). None of the brominated trihalomethanes was detected in either of the two types of beer examined.

McNeal et al. ( 1995) also examined several types of prepared non beverage foods and water from canned vegetables in the United States for bromodichloromethane, dibromochloromethane, and bromoform. None of these compounds was detected in any of the samples. The foods examined included two types of canned tomato sauce, canned pizza sauce, canned vegetable juice, vegetable waters from two types of canned green beans and one type of sweet corn, duck sauces, beef extract, and Lite syrup product.

The U. S. Food and Drug Administration ( U. S. FDA, 2000) has analyzed for 18 volatile organic hydrocarbons ( VOCs), including bromodichloromethane and bromoform, in the Total Diet Study since 1995. Bromodichloromethane and bromoform were analyzed in a subset of 70 food items in 14 Market Baskets. During the period 1995 to 1999, bromodichloromethane was detected in one sample each of 11 non beverage food items ( sliced bologna, fried eggs, canned pork and beans, smooth peanut butter, homemade cornbread, raw orange, canned pineapple, boiled collards, red tomato, green pepper, and fast food hamburger) ( U. S. FDA, 2000). The detected concentrations ranged from 10 to 16 ppb, with the exception of fast food hamburger which contained 37 ppb. Bromodichloromethane was detected in one sample of bottled apple juice at a concentration of 33 ppb. The mean detected concentration of bromodichloromethane in three samples of tap water was 18 ppb. Dibromochloromethane was not included in the list of VOC analytes for the Total Diet Study. Bromoform was listed as an analyte, but no detections were reported in the data summary for 1991 to 1999. The detection limits for bromodichloromethane and bromoform were not reported.

Imaeda et al. ( 1994) examined bean curd commercially available in Japan for trihalomethanes. Neither bromoform nor dibromochloromethane were detected in any of the samples at a detection limit of 0.1 ppb. Bromodichloromethane was detected in 6 of 10 samples of bean curd at concentrations ranging from 1.2 to 5.2 ppb and in 1 of 10 samples of the water in the bean curd packages at 5.2 ppb.

Kroneld and Reunanen ( 1990) analyzed for brominated trihalomethanes in samples of pasteurized and unpasteurized cow's milk collected in Turku, Finland. The average concentration of bromodichloromethane measured in pasteurized milk was 0.008 µ g/ L ( ppb) ( range, undetectable to 0.03 µ g/ L ( ppb), detection limit not specified). Dibromochloromethane was detected in only one sample of pasteurized milk at 5 µ g/ L ( ppb). Traces of bromoform were detected but not quantified. Brominated trihalomethanes were not detected in unpasteurized milk. Their presence in pasteurized milk was considered to result from use of chlorinated water during processing.

b. Estimated Dietary Intake Draft  Do Not Cite or Quote February 20, 2003 IV  21 Estimates for dietary intake of brominated trihalomethanes by residents of the United States were not identified in the materials reviewed for this document. Furthermore, information on the levels in U. S. foods is too limited to independently calculate a reliable estimate. However, the available data suggest that the concentrations of brominated trihalomethanes in non beverage foods are likely low. The apparently low concentrations of brominated trihalomethanes in nonbeverage foods are consistent with the physical and chemical properties of these compounds. The levels of individual brominated trihalomethanes in beverages prepared in the United States appear to be less than or about equal to levels measured in disinfected surface water.

Toyoda et al. ( 1990) analyzed the dietary intake of bromodichloromethane, dibromochloromethane, and bromoform for 30 Japanese housewives in Nagoya and Yokohama, Japan. Duplicate portions of daily meals were collected for three consecutive days and sampled for all three brominated trihalomethanes. The types of food consumed were not reported. This omission prevents a meaningful comparison of the studied diet to that consumed by the U. S. population. The detection limits for bromodichloromethane, dibromochloromethane, and bromoform were reported to be 0.1, 0.2, and 0.5 ppb, respectively. The concentration of bromodichloromethane ranged from undetectable to 1.7 ppb ( average, 0.3 ± 0.3 ppb SD). The mean daily intake of bromodichloromethane was estimated to be 0.6 ± 0.5 µ g/ day. The concentration of dibromochloromethane ranged from undetectable to 0.6 ppb ( average, 0.1 ± 0.2 ppb), and the mean dietary intake was estimated to be 0.3 ± 0.3 µ g/ day. The concentration of bromoform ranged from undetectable to 8.1 ppb ( average, 0.5 ± 1.3 ppb). The mean dietary intake of bromoform was estimated to be 0.9 ± 1.3 µ g/ day.

Brominated trihalomethanes have been detected in a number of beverages. In conducting an exposure assessment, the potential exposures from drinking prepared beverages would not be added to the default assumption of an adult consuming 2 liters of drinking water per day. Instead, the prepared beverages would be considered part of the 2 liters of fluid intake per person per day.

2. Air Intake a. Concentrations in Outdoor Air Brominated trihalomethanes are usually found in outdoor air at low concentrations when all data, including nondetects, are considered. Brodzinsky and Singh ( 1983) reviewed, summarized, and critically evaluated existing data for brominated trihalomethane concentrations in ambient outdoor air for several urban/ suburban or source dominated locations across the United States ( Table IV 8). No concentration data were available for rural or remote areas. The authors reported mean, median, first and third quartile values, and minimum and maximum values by city. In addition, they reported the same measures when the data were grouped by type of location ( i. e., urban/ suburban or source dominated), and when all data were combined. Ambient air concentrations were reported for bromodichloromethane at Magnolia, AR, El Dorado, TX, Chapel Hill, NC, and Beaumont, TX. Bromodichloromethane was detected at mean concentrations of 0.76 ppt, 1.40 ppt, 120 ppt, and 180 ppt for those four cities, respectively, Draft  Do Not Cite or Quote February 20, 2003 IV  22 where ppt is expressed as parts per trillion by volume. Dibromochloromethane was detected in the air samples from Magnolia, AR, El Dorado, TX, Chapel Hill, NC, Beaumont TX, and Lake Charles, LA at mean concentrations of 0 ppt, 0.48 ppt, 14 ppt, 14 ppt, and 19 ppt, respectively. Bromoform was detected in air samples from Magnolia, AR, El Dorado, TX, and Lake Charles, LA, at concentrations of 1.5 ppt, 0.81 ppt, and 50 ppt, respectively. Air concentration data from these sites were combined for additional statistical analysis. The study authors indicated that a value of 0.0 was entered for samples below the detection limit. Mean ( ± standard deviation) outdoor air concentrations in urban/ suburban and source dominated locations, respectively, were 160 ± 29 ppt and 1.2 ± 0.4 ppt for bromodichloromethane; 15 ± 4 ppt and 0.28 ± 0.67 ppt for dibromochloromethane; and 50 ± 29 ppt and 1.1 ± 2.1 ppt for bromoform. Brodzinsky and Singh ( 1983) also calculated overall ( grand) means based on data from all sites. Grand mean values for bromodichloromethane, dibromochloromethane, and bromoform were 110 ppt ( n = 26, with one nondetect), 3.8 ppt ( n = 89, with 63 nondetects), and 3.6 ppt ( n = 78, with 60 nondetects), respectively. When expressed on a µ g/ m3 basis, the corresponding mean values for bromodichloromethane, dibromochloromethane, and bromoform are 0.74 µ g/ m3, 0.032 µ g/ m3, and 0.037 µ g/ m3. Draft  Do Not Cite or Quote February 20, 2003 IV  23 Table IV 8. Selected Concentration Data for Individual Brominated Trihalomethanes ( ppt) in Outdoor Air as Summarized in Brodzinsky and Singh ( 1983) a, b City n Nondetects Mean ( Std dev.) Median 3rd Quartile Maximum Reference Bromodichloromethane Individual Sites Beaumont, TX 11 0 180 ( 100) 180 180 180 Wallace ( 1981)

Chapel Hill, NC 6 0 120 ( 210) 120 120 120 Wallace ( 1981)

El Dorado, AR 7 1 1.4 ( 0.35) 1.6 1.6 1.6 Pellizzari and Bunch ( 1979)

Magnolia, AR 2 0 0.76 ( 0.0) 0.0 0.0 0.76 Pellizzari and Bunch ( 1979)

Totals Urban/ Suburban 17 0 160 ( 29) 180 180 180

Source Areas 9 1 1.2 ( 0.41) 1.6 1.6 1.6

Grand totals 26 1 110 ( 82) 120 180 180

Dibromochloromethane Individual Sites Beaumont, TX 11 0 14 ( 0.0) 14 14 14 Wallace ( 1981)

Chapel Hill, NC 6 0 14 ( 0.0) 14 14 14 Wallace ( 1981)

El Dorado, AR 40 35 0.48 ( 0.82) 0.0 0.82 2.5 Pellizzari et al. ( 1978)

Lake Charles, LA 4 0 19 ( 9.6) 21 27 27 Pellizzari ( 1979)

Magnolia, AR 28 28 0.0 ( 0.0) 0.0 0.0 0.0 Pellizzari et al. ( 1978) Table IV 8 ( cont.)

City n Nondetects Mean ( Std dev.) Median 3rd Quartile Maximum Reference Draft  Do Not Cite or Quote February 20, 2003 IV  24 Dibromochloromethane ( cont.)

Totals Urban/ Suburban 21 0 15 ( 4.2) 14 14 27

Source Areas 68 63 0.28 ( 0.67) 0.0 0.0 2.5

Grand Totals 89 63 3.8 ( 6.7) 0.0 2.5 27

Bromoform Individual Sites El Dorado, AR 46 35 0.81 ( 0.95) 0.43 1.3 2.7 Pellizzari et al. ( 1978)

Pellizzari and Bunch ( 1979)

Lake Charles, LA 4 0 50 ( 29) 62 68 71 Pellizzari ( 1979)

Magnolia, AR 28 25 1.5 ( 3.2) 0.0 0.29 8.3 Pellizzari et al. ( 1978)

Totals Urban/ Suburban 4 0 50 ( 29) 62 68 71

Source Areas 74 60 1.1 ( 2.1) 0.0 1.3 8.3

Grand Totals 78 60 3.6 ( 12) 0.0 1.5 71

a Includes only data considered to be of adequate, good, or excellent quality by the study authors.

b Concentrations are reported as parts per trillion by volume Draft  Do Not Cite or Quote February 20, 2003 IV  25 Shikiya et al. ( 1984) analyzed ambient air samples collected at four urban/ industrial locations in the California South Coast Air Basin from November 1982 to December 1983 for the presence of halogenated hydrocarbons. Data for bromodichloromethane, dibromochloromethane and bromoform were included in this analysis. The sampling locations were El Monte, downtown Los Angeles, Dominguez, and Riverside. The air samples were analyzed using gas chromatography with detection by electron capture. The quantitation limit, defined as a level 10 times greater than the noise level, was 10 ppt by volume for all three brominated trihalomethanes. The detection limit was defined as three times the noise level. Summary data for each compound included monthly means and composite means. The monthly means were calculated as the average of all data at a site that were above the quantitation limit for a single month; samples with concentrations below the limit of detection were not included in the calculations. The composite means were calculated as the average value of all data for each compound above the quantitation limit at each site. Most data in this report were presented graphically. A few additional details were presented in a short summary statement for each chemical. Thirty five percent of the samples had bromodichloromethane levels above the quantitation limit of 10 ppt ( 0.067 µ g/ m3). Peaks in the concentration of bromodichloromethane were observed at various sites in June and July, with downtown Los Angeles and Dominguez registering the highest monthly means of approximately 30 ppt ( 0.20 µ g/ m3). The highest reported concentration was 40 ppt ( 0.27 µ g/ m3). The highest composite mean of 100 ppt ( 0.67 µ g/ m3) for bromodichloromethane was observed at El Monte. In comparison, the remaining three locations had a composite mean of 20 ppt ( 0.08 µ g/ m3). For dibromochloromethane, only seventeen percent of the samples had levels above the quantitation limit of 10 ppt ( 0.085 µ g/ m3). The highest reported concentration, monthly mean, and mean composite for dibromochloromethane were 290 ppt ( 2.5 µ g/ m3), 280 ppt ( 2.4 µ g/ m3), and 50 ppt ( 0.43 µ g/ m3), respectively; all were recorded in downtown Los Angeles in June. Only two monthly means were above 160 ppt; the remainder of the monthly means were below 60 ppt. For bromoform, thirty one percent of the samples had concentrations above the quantitation limit of 10 ppt ( 0.10 µ g/ m3). Peaks in the concentration of bromoform were observed at various sites in May and June, with the downtown Los Angeles site registering the highest composite mean ( 40 ppt; 0.41 µ g/ m3) and the highest monthly mean ( 310 ppt; 3.2 µ g/ m3) in June 1983. Only two monthly means were greater than 160 ppt; the remainder of the monthly means were below 60 ppt.

Atlas and Schauffler ( 1991) collected replicate air samples at various locations on the Island of Hawaii during a month long field experiment to test an analytical method for determining halocarbons in ambient air. Dibromochloromethane was found at a mean level of 0.27 ppt, and bromoform was found at a mean concentration of 1.9 ppt. Information on sample size and detection limit were not provided in the secondary source that reported this study ( U. S. EPA 1994b).

Wallace et al. ( 1982) conducted a pilot study designed to field test personal air quality monitoring methods. Personal air samples were collected from students at two universities: Lamar University, Texas, located near a petrochemical manufacturing area, and the University of North Carolina ( UNC), located in a nonindustrialized area. The samples were analyzed for a number of volatile organic compounds, including brominated trihalomethanes. Draft  Do Not Cite or Quote February 20, 2003 IV  26 Bromodichloromethane was detected in 64% of personal air samples from 11 Lamar students, with a mean of 1.23 µ g/ m3 ( 0.18 ppb), a median of 1 µ g/ m3 ( 0.15 ppb), and a range of 0.12   3.72 µ g/ m3 ( 0.018   0.56 ppb). The limit of detection was 0.24 µ g/ m3 ( 0.036 ppb). At UNC, 17% of the samples from 6 students had detectable levels of bromodichloromethane. Concentrations ranged from 0.12   4.36 µ g/ m3 ( 0.017   0.65 ppb) ( mean, 0.83 µ g/ m3 ( 0.12 ppb); median, 0.12 µ g/ m3 ( 0.017 ppb)). Based on the above information, the average daily intake of bromodichloromethane from air using an inhalation rate of 20 m3/ day was estimated to be 25 µ g/ day for Lamar students and 17 µ g/ day for UNC students. Dibromochloromethane was not present above 0.12 µ g/ m3 ( 0.018 ppb) at either site.

b. Concentrations in Indoor Air Relatively few studies have reported the concentrations of trihalomethanes in the indoor air of homes. Kostiainen ( 1995) identified over 200 volatile organic compounds in indoor air of 26 houses identified by residents as causing symptoms such as headache, nausea, irritation of the eyes, drowsiness, and fatigue. Bromoform was detected at low ( unspecified) levels in 54 percent of the homes, and no mention was made of dibromochloromethane or bromodichloromethane.

Weisel et al. ( 1999) measured brominated trihalomethane concentrations in indoor air in New Jersey residences selected to examine low and high levels of drinking water contamination with trihalomethanes. Descriptive statistics for trihalomethane concentration in water were provided for the combined high and low concentration groups, but not for the individual categories. One valid 15 minute air sample was collected at each of 48 residences. The indoor air concentrations of bromodichloromethane averaged 0.38 ± 0.82 ( SD) µ g/ m3 ( 0.057 ± 0.12 ppb) and 0.75 ± 0.96 µ g/ m3 ( 0.11 ± 0.14 ppb) from the low and high water concentration groups, respectively. The detection frequencies were 12/ 25 and 16 / 23 in the low and high water concentration groups, respectively. The indoor air concentrations of dibromochloromethane averaged 0.44 ± 0.95 µ g/ m3 ( 0.052 ± 0.11 ppb) and 0.53 ± 0.84 µ g/ m3 ( 0.062 ± 0.09 ppb) from the low and high water concentration groups with detection frequencies of 5/ 25 and 7/ 23, respectively. For bromoform, the average concentrations from the low and high water concentration groups were 0.29 ± 0.93 µ g/ m3 ( 0.028 ± 0.089 ppb) and 0.35 ± 0.94 µ g/ m3 ( 0.034 ± 0.091 ppb), with detection frequencies of 8/ 25 and 4/ 23, respectively. It was not clear whether the averages were based on all measured samples or only those samples that were above the detection limit for each compound.

Kerger et al ( 2000) evaluated the transfer of bromodichloromethane and dibromochloromethane to indoor air in bathrooms during showering and bathing in homes supplied with chlorinated tap water. The test sites were three urban homes containing three bedrooms, a full bath, and approximately 1000 square feet of living space. The compounds were simultaneously measured in hot and cold tap water ( drawn from the kitchen sink) and in the shower/ bath enclosure and bathroom vanity area. Three shower protocols were examined: 6.8 min unventilated shower; 12 min unventilated shower and 6.8 min ventilated shower. Water flow rate and temperature were monitored but not controlled. Airborne vapor samples were captured by Summa canister and measured by gas chromatography using electron capture detection Draft  Do Not Cite or Quote February 20, 2003 IV  27 according to U. S. EPA method TO 14. Air samples were collected before, during and after the water use event, for a total of 16 showers and 7 baths. Data for several events were eliminated because of technical difficulties. For all shower protocols combined ( n = 12), the increase in average airborne concentration ( ± standard error), expressed as µ g/ m3, in shower enclosure or bathroom air per µ g/ L in water, was 1.8 ± 0.3 for bromodichloromethane and 0.5 ± 0.1 for dibromochloromethane. For baths ( n = 4), the average concentration increase during the bath was 0.59 ± 0.21 for bromodichloromethane and 0.15 ± 0.05 for dibromochloromethane. The relative contribution of each chemical was consistent with the relative concentration in water and its chemical and physical properties. The average exposures measured in this study were approximately 30% lower than results reported by other investigators using EPA analytical methods when data were normalized for water concentration, flow rate, shower volume, and duration. This difference may have resulted from differences in the air exchange rate between residential showers and laboratory test showers. These data are not adequate for characterizing levels of individual brominated trihalomethanes in the home because the measurements targeted a specific area of the residences and the sample size consisted of only three homes.

c. Estimates of Exposure from Air The data available for occurrence of brominated trihalomethanes in air do not permit calculation of a nationally aggregated intake estimate for the U. S. general population. To accurately estimate total daily inhalation exposures, factors including location and season, the fraction of time spent indoors compared with outdoors, potential exposures of individuals while showering or bathing, potential exposure from volatilization of brominated trihalomethanes during other household activities ( e. g., use of dishwashers, toilet flushing), exposures of individuals who spend large amounts of time at indoor pools, and potential for occupational exposures ( e. g., for laundromat or sewage treatment plant workers) require consideration. Although the existing data do not permit such a refined analysis, they may be used to roughly estimate intake from air. Based on the grand means calculated for multiple sampling locations by Brodzinsky and Singh ( 1983), exposure to bromodichloromethane, dibromochloromethane and bromoform resulting from inhalation of outdoor air can be roughly estimated assuming an inhalation rate of 20 m3/ day, 100% absorption, and exposure to outdoor air for a full 24 hours per day. Using the mean ambient air concentration of 110 ppt ( 0.74 µ g/ m3) by volume for all sites reported in Brodzinsky and Singh ( 1983), the daily intake of bromodichloromethane from outdoor air would be 21 µ g/ day. Assuming a mean air concentration of 3.8 ppt ( 0.032 µ g/ m3) for dibromochloromethane, daily intake would be 0.64 µ g/ day,. Assuming a mean air concentration of 3.6 ppt ( 0.037 µ g/ m3) by volume or bromoform, the daily intake would be 0.74 µ g/ day. Because these estimates are based on data from urban/ suburban and industrial sites only, they may represent high end exposures.

Adequate, nationally aggregated occurrence data are not available for calculating intake of brominated trihalomethanes from indoor air. The indoor air concentrations measured by Weisel et al. ( 1999) were not used for intake calculations because it could not be determined how the means for each compound were calculated ( i. e., whether all measurements were averaged or only those Draft  Do Not Cite or Quote February 20, 2003 IV  28 above the detection limit). In addition, the data were based on a single 15 minute air sample collected from each of 48 homes located in a single state.

While brominated trihalomethane concentrations might be expected to be higher in indoor air than in outdoor air due to confined space and additional indoor air sources ( e. g. volatilization from showering, baths, and other household activities), the available data do not allow such a comparison.

Based on data from personal air monitors, Wallace et al. ( 1982) estimated daily inhalation of bromodichloromethane to be 25 µ g/ day for 11 students attending a university located near a petrochemical manufacturing area and 17 µ g/ day for 6 students attending a university in a nonindustrialized area.. The personal air monitors registered bromodichloromethane from both indoor ( with the exception of showering and bathing) and outdoor exposures. Dibromochloromethane was not detected and no data were available for bromoform.

3. Concentrations and Exposures Associated with Swimming Pools and Hot Tubs Numerous studies have reported data for concentrations of brominated trihalomethanes and exposures associated with swimming pools and hot tubs. Exposure of swimmers or hot tub users to brominated trihalomethanes may result from dermal, ingestion, and inhalation exposure. When evaluating these data, it is important to note that additional disinfectants are routinely added to water contained in swimming pools and hot tubs; therefore, the levels of brominated trihalomethanes present may not be representative of those in tap water.

Armstrong and Golden ( 1986) measured bromodichloromethane, dibromochloromethane, and bromoform concentrations in the water and surrounding air of four indoor swimming pools, five outdoor swimming pools, and four hot tubs. Concentrations in air were measured two centimeters from the water surface. The bromodichloromethane concentrations of water in the outdoor pools ranged from 1 to 72 µ g/ L ( ppb) ( mean, 33 µ g/ L). Levels in the indoor pools ranged from 1 to 90 µ g/ L ( ppb) ( mean, 16 µ g/ L). The levels of bromodichloromethane in the hot tubs ranged from

0.1 to 105 µ g/ L ( ppb) ( mean, 17 µ g/ L). Means and ranges of the bromodichloromethane concentration two meters above the water surface for outdoor pools, indoor pools, and hot tubs, respectively, were: < 0.1 µ g/ m3 (< 0.015 ppb) ( range not reported), 1.7 µ g/ m3 ( 0.25 ppb) ( range < 0.1   10 µ g/ m3 ( 0.015   1.5 ppb)), and 1.4 µ g/ m3 ( 0.21 ppb) ( range < 0.1   10 µ g/ m3 ( 0.015   1.5 ppb)). The dibromochloromethane concentration of water in the outdoor pools ranged from < 0.1 to 8 µ g/ L ( ppb) ( mean, 4.2  g/ L ( ppb)). Levels in the indoor pools ranged from 0.3 to 30 µ g/ L ( ppb) ( mean, 9.5 µ g/ L ( ppb)). The level of dibromochloromethane in the hot tubs ranged from

0.1 to 48 µ g/ L ( ppb) ( mean, 14.4 µ g/ L ( ppb)). Means and ranges of the dibromochloromethane concentration two meters above the water surface for outdoor pools, indoor pools, and hot tubs, respectively, were: < 0.1 µ g/ m3 (< 0.01 ppb) ( range not reported), 0.9 µ g/ m3 ( 0.11 ppb) (< 0.1   5 µ g/ m3 ( 0.012   0.59 ppb)), and 0.7 µ g/ m3 ( 0.08 ppb) (< 0.1   5 µ g/ m3 ( 0.012   0.59 ppb)). The mean bromoform concentration in the outdoor pools was less than 0.1 µ g/ L ( ppb). Levels in the indoor pools ranged from less than 0.1 to 20 µ g/ L ( ppb) ( mean, 6 µ g/ L ( ppb)). The levels of bromoform in the hot tubs ranged from less than 0.1 to 62 µ g/ L Draft  Do Not Cite or Quote February 20, 2003 IV  29 ( ppb) ( mean, 13 µ g/ L ( ppb)). Means and ranges of the bromoform concentration two meters above the water surface for outdoor pools, indoor pools, and hot tubs, respectively, were: < 0.1 µ g/ m3 (< 9.7 ppt) ( range not reported), 9 µ g/ m3 ( 870 ppt) (< 0.1   14 µ g/ m3 ( 9.7   1360 ppt)), and 8 µ g/ m3 ( 770 ppt) (< 0.1   14 µ g/ m3 ( 9.7   1360 ppt)).

Cammann and Hübner ( 1995) compared concentrations of trihalomethanes in swimmers' and bath attendants' blood and urine before and after swimming or working in indoor swimming pools. Water and air concentrations were measure in different locations in the pool environment. The purpose was to determine whether blood levels of trihalomethanes would reflect inhalation exposure to trihalomethanes in the pool environment and whether those compounds also would appear in urine. Measured concentrations of bromodichloromethane, dibromochloromethane, and bromoform in samples of swimming pool waters collected at a depth of 10 to 20 cm were 0.69 to 5.64 µ g/ L ( ppb), 0.03 to 6.51 µ g/ L ( ppb), and 0.14 to 2.32 µ g/ L ( ppb) for the three compounds, respectively. Averages ( ± SD) of the 10 pool water measurements presented in Table 1 of the report were 2.12 ± 1.52 µ g/ L ( ppb), 1.11 ± 2.07 µ g/ L ( ppb), and 0.42 ± 0.73 µ g/ L ( ppb) for bromodichloromethane, dibromochloromethane, and bromoform, respectively. Average ( ± 1 SD) concentrations in the four air samples taken ( location of sampling not specified) were 15.4 ± 7.36 µ g/ m3 ( 2.30 ± 1.10 ppb), 1.94 ± 1.01 µ g/ m3 ( 0.228 ± 0.119 ppb), and below the quantitation limit ( QL) ( not specified, although probably 0.02 ppb) for bromodichloromethane, dibromochloromethane, and bromoform, respectively.

Measurements of bromodichloromethane in 8 bath attendants' blood before their shifts ranged from below QL for 12/ 18 measurements ( 67%) to 0.1 µ g/ L ( ppb) ( Camman and Hübner, 1995). After their shifts, the concentrations ranged from below QL in 7/ 18 measurements ( 39%) to 0.6  g/ L ( ppb). Similarly, measurements of bromodichloromethane in swimmers' blood was higher after than before swimming. Before swimming, blood concentrations of bromodichloromethane ranged from less than the QL in 10/ 20 ( 50%) swimmers to 0.2 µ g/ L ( ppb); while after swimming, blood concentrations were above the QL in all 20 swimmers, ranging from  0.02 to 0.4  g/ L ( ppb) in 19 of the swimmers. The twentieth swimmer had a blood concentration of  1.5  g/ L ( ppb). For all but two of the swimmers, blood concentrations of bromodichloromethane had dropped below the QL by the next day ( values for the other two swimmers were less than 0.1  g/ L ( ppb)). Dibromochloromethane and bromoform were not detected in the blood of either the bath attendants or swimmers. None of the brominated trihalomethanes were detected in the urine of the study subjects. Thus, only exposure to bromodichloromethane by inhalation ( bath attendants) or inhalation, dermal absorption, and ingestion ( swimmers) is reflected in increased blood levels of the compound. Blood levels of bromodichloromethane usually returned to pre exposure levels within 24 hours after the exposure .

Aggazzotti et al. ( 1998) evaluated concentrations of trihalomethanes in the blood and breath of five competitive swimmers regularly training in an indoor swimming pool in Italy. The group included three males and two females between the ages of 17 and 21 years. All were nonsmokers Concurrent sampling of blood, alveolar air, and environmental air occurred at five times for each of four sessions: ( a) at the University Department two hours before arriving at the pool, Draft  Do Not Cite or Quote February 20, 2003 IV  30 ( b) after one hour sitting near the edge of the pool, ( c), after one hour of swimming, ( d) back at the University one hour after swimming ended, and ( e) at the University 1.5 hr after swimming ended. While bromodichloromethane and dibromochloromethane were always found in water and environmental air samples at the pool immediately before and after the 1 hr swimming session, bromoform was rarely detected in the indoor pool air. None of the three brominated trihalomethanes were detected in the air at the University Department or in the alveolar air of the swimmers at the Department two hours before arriving at the pool. At the pool, prior to the swimming session, the means ( ± SD) of the four measured ambient air concentrations of bromodichloromethane, dibromochloromethane, and bromoform were10.5 ± 3.1 µ g/ m3 ( 1.6 ± 0.46 ppb; 4 detects), 5.2 ± 1.5 µ g/ m3 ( 0.61 ± 0.17 ppb; 4 detects), and 1 detect of 0.2 µ g/ m3 ( 0.02 ppb), respectively. At the pool, just after the 1 hr swimming session, the means ( ± SD) of the four measured ambient air concentrations of bromodichloromethane, dibromochloromethane, and bromoform were 20.0 ± 4.1 µ g/ m3 ( 2.99 ± 4.1 ppb; 4 detects), 11.4 ± 2.1 µ g/ m3 ( 1.34 ± 0.23 ppb; 4 detects), and 1 detect of 0.2 µ g/ m3 ( 0.02 ppb), respectively.

Concentrations of bromodichloromethane and dibromochloromethane in the alveolar air of the swimmers before and after the swimming session indicated inhalation uptake of both compounds ( Aggazzotti et al., 1998). At the pool, prior to the swimming session, the means ( ± SD) of the 20 measured alveolar air concentrations ( 5 swimmers assessed at each of 4 sessions) of bromodichloromethane and dibromochloromethane were 2.7 ± 1.2 µ g/ m3 ( 0.40 ± 0.18 ppb) and 0.8 ± 0.8 µ g/ m3 ( 0.09 ± 0.09 ppb), respectively. Bromoform was not detected in any of the 20 samples. At the pool, after the 1 hr swimming session, the means ( ± SD) of the alveolar air concentrations of bromodichloromethane and dibromochloromethane were 6.5 ± 1.3 µ g/ m3 ( 0.97 ± 0.19 ppb) and 1.4 ± 0.9 µ g/ m3 ( 0.16 ± 0.11 ppb), respectively. Bromoform was not detected in any of the 20 samples. Blood levels of bromodichloromethane and dibromochloromethane before and after swimming, on the other hand, were below detection limits in most samples, and hence showed no trends.

Aggazzotti et al. ( 1998) estimated uptake of the trihalomethanes of the resting and active swimmers using the following assumptions. At rest, the pulmonary ventilation rate of the women was 6 liters per minute ( L/ min) while that of men was 7.5 L/ min. During swimming, the ventilation rate of the women was 25 L/ min while that of the men 36 L/ min. The estimated uptake rates of bromodichloromethane for the five swimmers at rest ranged from 2.8 to 3.7  g per hour (  g/ h), with a mean value of 3.3 ± 0.41( SD)  g/ h for the three males and two females combined. The estimated uptake rates for the same individuals actively swimming were 20 to 30  g/ h, with a mean value of 26 ± 5.1  g/ h. The estimated uptake rates of dibromochloromethane for the five swimmers at rest ranged from 1.5 to 2.0  g/ h, with a mean value of 1.8 ± 0.23  g/ h. The estimated uptake rates during swimming increased to between 14 and 22  g/ h, with a mean value of 18 ± 3.6  g/ h. Occurrence of dermal uptake was acknowledged but not estimated.

Lindstrom et al. ( 1997) also assessed exposure of two competitive swimmers to bromodichloromethane during training sessions at an indoor pool. The indoor pool air concentrations of bromodichloromethane collected over 60 and 119 minute intervals were 2.76 and 3.02 µ g/ m3 ( 0.41 and 0.45 ppb), respectively. Breath samples were collected from the Draft  Do Not Cite or Quote February 20, 2003 IV  31 swimmers before, during, and for 3 hours after a training workout. Breath samples collected during the workout demonstrated a rapid uptake of bromodichloromethane to maximum alveolar concentrations of 5 to 6 µ g/ m3 ( 0.7 to 0.9 ppb), which are higher than the ambient air concentrations. The authors concluded that significant ( 80% of total exposure) dermal absorption of the related trihalomethane chloroform from water was occurring, but did not estimate the extent of dermal uptake for bromodichloromethane.

4. Soil Concentrations and Exposure Data on the concentration of brominated trihalomethanes in soil were not available in the materials reviewed for this document. Based on the measured Henry's Law constant and vapor pressure of the individual compounds, volatilization from both wet and dry soil surfaces should be relatively rapid ( U. S. EPA 1987). Therefore. exposure from soil ingestion is not considered to be a significant route for exposure to the brominated trihalomethanes.

C. Overall Exposure The RSC ( relative source contribution) is the percentage of total daily exposure that is attributable to tap water when all potential sources are considered ( e. g., air, food, soil, and water). Ideally, the RSC is determined quantitatively using nationwide, central tendency and/ or high end estimates of exposure from each relevant medium. In the absence of such data, a default RSC ranging from 20% to 80% may be used.

The RSC used in the current and previous drinking water regulations for dibromochloromethane is 80%. This value was established by use of a screening level approach to estimate and compare exposure to dibromochloromethane from various sources. Information considered for during this process is summarized in Appendix C. The use of the 80% value for the RSC for dibromochloromethane is supported by limited use of this chemical in industrial applications with potential for direct release to the environment. The use of the 80% value is further supported by apparently low concentrations in foods and soils and the potential for human exposure to dibromochloromethane in tap water via three exposure routes: 1) ingestion as drinking water; 2) inhalation of volatilized dibromochloromethane during use of tap water for household activities; and 3) by dermal exposure during showering, bathing, or other activities. The available data for concentrations of outdoor air and food, although limited, suggest that exposures via these routes are likely to be low when compared to water.

Parallel RSC calculations were not performed for bromodichloromethane and bromoform. The EPA has set the regulatory level for these chemicals in drinking water at zero because it has been determined that they are probable human carcinogens. Therefore, determination of an RSC is not relevant for these chemicals because it is the Agency's policy to perform RSC analysis only for noncarcinogens. Draft  Do Not Cite or Quote February 20, 2003 IV  32 D. Body Burden 1. Blood and Breath Levels Barkley et al. ( 1980) analyzed blood samples from nine residents of the old Love Canal area in 1978 for a variety of volatile organic compounds, including all three of the brominated trihalomethanes. Bromodichloromethane was detected in the blood of one individual; its concentration was 14 µ g/ L ( ppb). Dibromochloromethane and bromoform were not detected.

Antoine et al. ( 1986) analyzed the blood of 250 environmentally sensitive patients for 18 volatile organic compounds. Bromoform concentrations ranged from undetectable to 3.4 µ g/ L ( ppb), with a mean of 0.6 µ g/ L ( ppb).

Ashley et al. ( 1994) analyzed samples of whole blood of 600 or more people in the United States who participated in the Third National Health and Nutrition Examination Survey ( NHANES III) for 32 volatile organic compounds using analytical methods designed to measure extremely low concentrations. Bromodichloromethane, with a detection limit of 0.009 µ g/ L ( ppb) was detected only in 14% of 1072 samples. Dibromochloromethane, with a detection limit of 0.013 µ g/ L ( ppb), was detected in only 12% of 1035 samples. Using unprocessed commercial Vacutainer Tubes, Ashely et al. ( 1994) initially obtained measures of bromoform concentrations in blood similar to those reported by Antoine et al. ( 1986). However, using Vacutainer Tubes that had been processed to removed VOCs prior to use, Ashely et al. ( 1994) detected bromoform in less than 10% of samples analyzed at a detection limit of 0.027 µ g/ L ( ppb). Wallace ( 1997) obtained the summary statistics for bromodichloromethane and dibromochloromethane, which were not published in Ashely et al.' s ( 1994) paper. The mean ( ± SD) of the measured blood concentrations were 0.0077 ± 0.0178 and 0.00886 ± 0.00856 µ g/ L ( ppb), respectively. The median values were below the limit of detection. The upper 90th percentile values were 0.0122 and 0.0151 µ g/ L ( ppb), respectively.

Weisel et al. ( 1999) measured brominated trihalomethanes in the exhaled breath of female subjects after showering. The study authors recruited 49 women who had previously participated in a case control study on neural tube birth defects from locations throughout the state of New Jersey ( Klotz and Pyrch, 1999). The method used to select the subjects provided a wide range of brominated trihalomethane exposures within the home, in contrast to a distribution of exposures that might exist within a single water distribution system or within the general population. Exposure to brominated trihalomethanes was estimated by collection of duplicate cold tap water samples, collection of a 15 minute air sample, and responses to a 48 hour recall questionnaire on water use in the home. Post shower whole breath samples were collected by having the subject blow into a Tedlar ® sampling bag at the conclusion of a shower. Background breath samples were collected at a subsequent home visit by the investigators. Valid samples were obtained from 33 of the subjects. However, the time of post shower sample collection as reported by the subjects varied from immediately after the shower to 20 minutes later. As noted by the authors, the delay in sample collection is an important determinant in breath concentrations because trihalomethane breath concentration declines exponentially after exposure ceases. As a result, Draft  Do Not Cite or Quote February 20, 2003 IV  33 each subject was assigned to one of three groups: 1) breath sample collected within 5 minutes after completion of shower ( Group A; n = 13); 2) breath sample collected within 5 to 20 minutes after completion of shower ( Group B; n= 14); or 3) breath sample collected more than 20 minutes after showering ( Group C; n= 6). The breath concentrations on individual brominated trihalomethanes for each group were compared to measured water concentrations and estimates of exposure ( calculated as the product of the water concentration and reported duration of the shower; shower duration data and calculated exposure estimates were not reported).

The mean ( ± standard deviation) concentrations of bromodichloromethane, dibromochloromethane, and bromoform were 5.7 ± 8.6, 2.0 ± 2.1, and 0.73 ± 0.90  g/ L ( ppb), respectively. The median values for the three compounds were 2.6, 1.4, and 0.45  g/ L ( ppb), respectively. Bromodichloromethane showed significant correlations for breath and water concentration and breath and shower exposure for Groups A and B. Significant correlations for dibromochloromethane and bromoform were found for Group A participants. Analytical variability related to low concentrations of dibromochloromethane and bromoform ( near the detection limit) may have obscured trends in the data for Group B. source of in the houses and found significant correlations between the water concentration of each brominated trihalomethane and the concentration of that trihalomethane in expired air if the air samples were collected within 5 minutes of showering. Results of statistical analysis for Group C were not reported because the sample size was small and the authors considered the results questionable. The observed results were considered consistent with showering being a source of exposure to brominated trihalomethanes.

Backer et al. ( 2000) examined levels of brominated trihalomethanes in whole blood following three types of water use events by adult volunteers: showering for 10 minutes in tap water ( n= 11); bathing for 10 minutes in a tub filled with tap water ( n= 10); or consumption of one liter of tap water over a 10 minute period ( n= 10). Each participant provided a blood sample immediately before exposure, 10 minutes after exposure ended, and 30 minutes ( showering and bathing) or one hour ( ingestion) after exposure. Tap water and blood samples were analyzed by purge and trap/ gas chromatography/ mass spectrometry with detection capability in the parts per quadrillion range. Bromoform was not detected in either tap water or whole blood. Mean tap water concentrations of bromodichloromethane and dibromochloromethane were 6 µ g/ L and 1.1 µ g/ L, respectively. The highest levels of these compounds in whole blood occurred 10 minutes after exposure had ended. The second post exposure measurements showed that blood levels of both compounds had decreased, but were still above the pre exposure baseline levels in subjects who took showers or baths. Measurement data are shown in Table IV 9 below.

The study authors reported that similar relative findings were obtained for dibromochloromethane ( data shown graphically in the study report). These data indicate a dramatic difference between the whole blood levels resulting from ingestion and those resulting from bathing or showering ( including dermal, inhalation, and possibly ingestion exposure). Blood level increases observed for each compound after ingestion of one liter of water were less than 10% of those observed after bathing or showering for 10 minutes. The blood level increases observed for each compound 10 minutes after bathing or showering were significantly Draft  Do Not Cite or Quote February 20, 2003 IV  34 Table IV 9 Mean Bromodichloromethane Concentrations in Blood Following Three Types of Water Use Events Water Use Event Median Bromodichloromethane Concentration in Whole Blood ( pg/ mL)

Pre exposure 10 minutes post exposure 30 or 60 minutes postexposure 10 Minute Shower 3.3 19.4 10.3 ( 30 min)

10 Minute Bath 2.3 17.0 9.9 ( 30 min)

Ingestion of 1 L 2.6 3.8 2.8 ( 60 min)

increased ( p< 0.01) when compared to the post ingestion blood levels. Measurable levels of bromodichloromethane and dibromochloromethane in the pre exposure whole blood samples were attributed to recent prior exposure or to bioaccumulation after repeated exposure to tap water.

In addition to the differences observed in whole blood levels of bromodichloromethane and dibromochloromethane among exposure groups, the study authors observed that the blood concentration data for each chemical occurred in two clusters within each exposure group. The mean increases for the two clusters observed after bathing or showering were significantly different for bromodichloromethane. The same individuals who had greater increases of bromodichloromethane also experienced greater increases of dibromochloromethane and chloroform in the blood after bathing or showering. The underlying basis for the observed clustering is unknown, but was not related to gender. The study authors suggested that polymorphic expression of a metabolizing enzyme ( e. g. glutathione S transferase theta) or differences in fitness level ( resulting in inhalation of larger volumes of air) may have accounted for the observed pattern. However, they noted that differences in fitness level would more likely be expected to result in a continuous distribution.

Lynberg et al. ( 2001) conducted a field study in Corpus Christi, Texas, and Cobb County, Georgia, to evaluate exposure measures for disinfection by products, including brominated trihalomethanes. These areas were selected for study based on the following criteria: 1) relatively high trihalomethane concentrations relative to national averages; 2) high intrasystem differences that would result in a potential exposure gradient across the study population; 3) one water distribution system with predominately chlorinated species of trihalomethanes ( i. e., chloroform) and one water system with predominately brominated trihalomethanes; and 4) a water utility service population large enough to allow rapid selection of 25 mothers per geographic area who had given birth to healthy babies from June, 1998 through May, 1999. Exposure to individual trihalomethanes was assessed by collection of blood and water samples and by collection of information on water use patterns and tap water characteristics. Whole blood samples were collected before and after showering. Levels of individual trihalomethanes were determined for samples collected in the home of participants, in the distribution system, and at the water Draft  Do Not Cite or Quote February 20, 2003 IV  35 treatment plants. A modified version of the Total Exposure Model ( TEM) was used to estimate uptake of trihalomethanes into the bloodstream ( data for chloroform exposure were presented for one individual in Corpus Christi). The results of the study indicate that concentration of individual trihalomethanes varied by site and location within the water system ( Table IV 10). In Corpus Christi water samples, brominated trihalomethanes accounted for 71% of the total trihalomethane concentration by weight. In contrast, brominated trihalomethanes accounted for only 12% of the trihalomethanes in Cobb County water samples. Significant differences ( p = 0.0001) in the blood levels of dibromochloromethane and bromoform were observed between study locations ( Table IV 11). The differences between locations were evident both before and after showering. The study authors indicated that there was considerable variability in blood levels of trihalomethanes among participants from a single location. For example, pre shower chloroform blood levels in Cobb County ranged from 130 ppt to 1100 ppt. No data were presented for the brominated trihalomethanes. The variability was tentatively attributed to different patterns of household water use among participants. Significant increases ( p = 0.0001) in blood levels of all brominated trihalomethanes were observed after showering. The increases in dibromochloromethane and bromoform were significantly greater in Corpus Christi than in Cobb County. No TEM modeling data were presented for brominated trihalomethanes. However, TEM results presented for chloroform exposure for one study participant who consumed bottled water indicated that inhalation exposure in the household accounted for approximately 98% of the calculated 24 hour chloroform dose, with the remainder attributed to the dermal route. Overall, this study demonstrates that blood levels of brominated trihalomethanes vary significantly across populations, with water quality characteristics and water use activities being important variables.

Table IV 10 Median Tap Water Trihalomethane Levels ( ppb) in Cobb County and Corpus Christi Homes, Water Treatment Plants, and Distribution Systems Trihalomethane Cobb County Corpus Christi Home ( n= 25) Distribution System ( n= 20) Water Treatment Plant ( n= 7) Home ( n= 25) Distribution System ( n= 30) Water Treatment Plant ( n= 20)

Bromodichloromethane 13.5 12.5 9.5 12.2 8.3 9.5 Dibromochloromethane 1.7 2.4 1.4 13.5 12.6 14.3 Bromoform NDa ND ND 8.7 9.7 11.9 Chloroform 84.8 79 49.5 8.2 4.6 6.7 a ND, not detected ( detection limit < 1ppb) Draft  Do Not Cite or Quote February 20, 2003 IV  36 Table IV 11 Between Site Comparison of Median Blood Levels ( ppt) and Changes in Blood Levels ( ppt) after Showering Trihalomethane Before Shower After Shower Change in Blood Level after Showering Cobba Corpusb Cobb Corpus Cobb Corpus Bromodichloromethane 6.2 6.8 38 43 30 34 Dibromochloromethane 1.2 7.0 6.1 41 5.0 35 Bromoform 0.3 3.5 0.5 17 0.2 12 Chloroform 70 25 280 57 189 25 a Cobb County, Georgia b Corpus Christi, TX 2. Mother's Milk Pellizzari et al. ( 1982) analyzed the milk of eight nursing mothers for various compounds, including bromodichloromethane and dibromochloromethane. The samples were collected from 49 lactating women living in the vicinity of chemical manufacturing plants and/ or industrial user facilities in Bridgeville, PA, Bayonne, NJ, Jersey City, NJ, and Baton Rouge LA. Both compounds were identified in one of the eight samples. Actual concentrations and detection limits were not reported. Kroneld and Reunanen ( 1990) did not detect any of the brominated trihalomethanes in human milk in a study conducted in Turku, Finland.

E. Summary Brominated trihalomethanes are found in virtually all water treated for drinking; however, concentrations of individual forms vary widely depending on the type of water treatment, locale, time of year, sampling point in the distribution system, and source of the drinking water. Occurrence data for brominated trihalomethanes are available from 13 national surveys and 9 additional studies that are more restricted in scope. The procedures used for sampling processing and storage and calculation of summary statistics should be carefully considered when evaluating and comparing brominated trihalomethane occurrence data. Some methods restrict trihalomethane formation by refrigeration or the use of quenching agents, whereas others maximize trihalomethane formation by storage at room temperature. Approaches to data summarization vary by study in the treatment of data below the analytical detection level or minimum reporting level.

When all available national survey data are considered, bromodichloromethane concentrations in drinking water range from below the detection limit to 183 µ g/ L ( ppb), while dibromochloromethane and bromoform concentrations range from below the detection limit to 280 µ g/ L ( ppb). When data for the three brominated trihalomethanes are compared, the frequency of Draft  Do Not Cite or Quote February 20, 2003 IV  37 detection and measured concentrations of bromodichloromethane in drinking water supplies tend to be higher than those for dibromochloromethane. Bromoform is detected less frequently and at lower concentrations than the other two brominated trihalomethanes, except in some ground waters. Concentrations of all trihalomethanes in drinking water were generally lower when the raw water is obtained from ground water sources rather than surface water sources. The most recent national survey data are those collected by the U. S. EPA under the Information Collection Rule ( ICR). Monitoring data were collected over an 18 month period between July 1997 and December 1998 from approximately 300 water systems operating 501 plants and serving at least 100,000 people. Summary occurrence data stratified by raw water source ( groundwater or surface water) are available for finished water, the distribution system ( DS) average, and the DS high values. The mean, median, and 90th percentile values for surface water DS average concentrations in the ICR survey are 8.6, 70.2, and 20.3 µ g/ L, respectively, for bromodichloromethane ( range of individual values 0  65.8 µ g/ L); 2.4, 4.72, and 13.2 µ g/ L, respectively, for dibromochloromethane ( range 0  67.3); and 0. 1.18, and 3.10, respectively, for bromoform ( range 0  3.43).

Relatively few studies have analyzed non beverage foods for the occurrence of brominated trihalomethanes. In the few studies available, bromodichloromethane has been detected in nonbeverage foods ( i. e., in one sample of butter at 7 ppb, in three samples of ice cream at 0.6 to 2.3 ppb, in 6 of 10 samples of bean curd at 1.2 to 5.2 ppb, and in one sample of bacon ( probably below the minimal quantitation limit)). In addition, bromodichloromethane was detected in one sample each of eleven foods out of 70 tested in 14 Market Baskets for the FDA Total Diet Study. The detected concentrations ranged from 10 to 37 ppb for individual food items. Studies that analyzed non beverage foods for dibromochloromethane and bromoform detected neither compound in any of the samples. Brominated trihalomethanes have been detected in up to a third or one half of the types of prepared beverages examined in some studies, being detected most frequently in colas and other carbonated soft drinks. Bromodichloromethane has been found most frequently of the three compounds and bromoform the least frequently. Bromodichloromethane was detected in approximately half of the prepared beverages examined by McNeal et al. ( 1995) in the United States and in all of 13 soft drinks that they analyzed. With the exception of one of the 13 soft drinks examined by McNeal et al. ( 1995) with a concentration of 12 ppb, none of the at least 18 other measured concentrations of bromodichloromethane in soft drinks described above ( three from Entz et al. ( 1982), three from Uhler and Diachenko ( 1987), and the remaining 12 from McNeal et al. ( 1995)) exceeded a value of 4 ppb. Bromodichloromethane was detected in one sample of fruit juice at 5 ppb.

Exposure to brominated trihalomethanes via ingestion of drinking water was estimated using data obtained for disinfectants and disinfection byproducts under the Information Collection Rule ( ICR). ICR data offer several advantages over other national studies for purposes of estimating national exposure levels of adults in the United States to brominated trihalomethanes via ingestion of drinking water. First, they are recent and reflect relatively current conditions. Second, data of very similar quality and quantity were collected systematically from a large number of plants ( 501) and systems ( approximately 300), including both surface and ground water systems. Third, the mean, median, and 90th percentile value were estimated on the basis of Draft  Do Not Cite or Quote February 20, 2003 IV  38 all samples taken, not just the sample detects. Thus, these descriptive statistics are representative of the exposures of the entire populations served by those systems, not just the populations served by systems with higher concentrations of these compounds. However, this study can not be considered representative of smaller public water supplies or water supplies from the most highly industrialized or contaminated areas.

Exposure was calculated by multiplying the concentration of individual brominated trihalomethanes in drinking water by the average daily intake, assuming that each individual consumes two liters of water per day. The annual median, mean, and upper 90th percentile values are presented for both surface and ground water systems. Assuming that the DS High value actually represents the average exposure level of persons served by one plant distribution pipe with the longest water residence time, the DS High value might be used to estimate a high end exposure level.

For bromodichloromethane, the median, mean, and 90th percentile population exposures from surface water systems are estimated to be 17, 20, and 40 µ g/ person/ day, respectively. The same values for populations exposed to bromodichloromethane from ground water systems are lower   3.6, 8.1, and 22 µ g/ person/ day, respectively. For dibromochloromethane, the median, mean, and 90th percentile population exposures from surface water systems are estimated to be 4.8, 9.4, and 26 µ g/ person/ day, respectively. The corresponding values for populations exposed to dibromochloromethane from groundwater system are lower   2.7, 6.2, and 18 µ g/ person/ day, respectively. For bromoform, the median, mean, and 90th percentile population exposures from surface water systems are estimated to be near 0, 2.4, and 6.2 µ g/ person/ day, respectively. The same values for populations exposed to bromoform from ground water systems are higher   0.65, 3.8, and 9.6 µ g/ person/ day, respectively.

For purposes of comparison, estimates of ingestion exposure to bromodichloromethane, dibromochloromethane, and bromoform in drinking water were also estimated from data collected in other, older studies. Ingestion from ground water supplies was estimated from the median levels found in the Ground Water Supply Survey conducted by U. S. EPA in 1980 81. Based on the range of median levels ( 1.4   2.1 µ g/ L ( ppb)) and a consumption rate of two liters per day, the median ingestion exposure to bromodichloromethane may range from 2.8 to 4.2 µ g/ day. Similarly, median exposure to dibromochloromethane may range from 4.2 to 7.8 µ g/ day, and for bromoform, median exposure may range from 4.8 to 8.4 µ g/ day. Exposure to bromodichloromethane from surface water supplies can be estimated based on the range of median values observed under different conditions in the National Organics Monitoring Survey conducted by U. S. EPA in 1976 1977, which mainly sampled surface water systems. Based on a range of 5.9   14 µ g/ L ( ppb), exposure to bromodichloromethane from surface water is estimated to be between 12 and 28 µ g/ day. Similarly, based on the range of medians reported for dibromochloromethane concentrations, the median exposure is estimated to be up to 6 µ g/ day. The median levels of bromoform in the surface water supplies have been found to be less than the EPA Drinking Water minimum reporting levels ( MRLs) of 0.5   1 µ g/ L ( ppb). An estimate of exposure based on the MRLs will be overly conservative because the actual concentration of Draft  Do Not Cite or Quote February 20, 2003 IV  39 bromoform is not detectable. Based on the range of MRLs, 0.5   1 µ g/ L ( ppb), the exposure to bromoform is estimated to range from 1 to 2 µ g/ day for surface water supplies.

Ingestion exposure to brominated trihalomethanes in drinking water can also be estimated from the concentrations found at the tap in the U. S. EPA's Total Exposure Assessment Methodology ( TEAM) study. Estimates of the average of the population intakes for ingestion of bromodichloromethane from drinking water range from 0.42 to 42  g/ person/ day. The upper 90th percentile estimates range from < 2.0 to 90  g/ person/ day. Estimates of the average population intake of dibromochloromethane from drinking water range from 0.2 to 56  g/ person/ day. The upper 90th percentile estimates range from < 0.9 to 86  g/ person/ day. Estimates of the average of the population intakes of bromoform, for those areas in which bromoform was measurable in a majority of the samples, range from 1.6 to 16.2  g/ person/ day. The upper 90th percentile estimates range from 2.4 to 26  g/ person/ day. Four of the six locations in the TEAM study, however, had a low frequency ( less than 10%) of detection of bromoform in measurable quantities.

Sources of uncertainty in these estimates of ingestion exposure include use of different analytical methods, failure to report quantitation limits, using measures near the detection limit, failure to report how nondetects are handled when averaging values ( e. g., set to zero or one half the detection limit), and failure to report sample storage method and duration. In addition, many environmental factors influence the concentrations of these compounds in drinking water at the tap and in vended or bottled waters used for drinking. These factors include season and temperature, geographic location, source of water, residence time in distribution system, and others.

Average daily intake of dibromochloromethane via ingestion, dermal contact, and inhalation of compound volatilized during household use were also estimated for determination of the Relative Source Concentration ( RSC). Intake for ingestion was calculated using mean intake rates of 1.2 or 0.6 L/ day for total and direct intake ( NRC, 1999), respectively. Direct intake includes consumption of water directly from the tap, but does not include intake of tap water used for preparation of heated items such tea, coffee, or soup. Based on the ICR distribution system average concentration of 4.72 µ g/ L for dibromochloromethane in surface water, the average daily total and direct and ingestion intakes would be 5.7 and 2.8 µ g/ day, respectively. The average dermal uptake of dibromochloromethane was estimated to be 2 µ g per shower or bathing event. Average daily intake via inhalation of dibromochloromethane volatilized during to be 7 µ g/ day for the volatilized compound. Parallel calculations were not performed for bromodichloromethane or bromoform, because these compounds are probable carcinogens. Therefore, in accordance with U. S. EPA policy, RSC analysis was not conducted.

Some data on the occurrence of brominated trihalomethanes in foods and beverages are available from studies conducted in Italy, Japan, and Finland. These studies were also limited in scope to examination of relatively few food or beverage items. Bromodichloromethane, dibromochloromethane, and bromoform concentrations measured in foods and beverages in Italy, Japan and Finland ranged from undetectable to 40 ppb, undetectable to 13.9 ppb, and Draft  Do Not Cite or Quote February 20, 2003 IV  40 undetectable to 10.7 ppb, respectively. Because of possible differences in water disinfection or food processing practices, these data may not be representative of concentrations in foods and beverages produced in the U. S.

Concentrations in outdoor air were variable from site to site. When data from several urban/ suburban and source dominated sites in Texas, Louisiana, North Carolina and/ or Arkansas were combined, the resulting average outdoor air concentrations were 110 ppt ( 0.74 µ g/ m3) for bromodichloromethane, 3.8 ppt ( 0.032 µ g/ m3) for dibromochloromethane, and 3.6 ppt ( 0.037 µ g/ m3) for bromoform. A regional study conducted at several sites in southern California found bromodichloromethane, dibromochloromethane, and bromoform in 35%, 17%, and 31% of the samples, respectively. The maximum concentrations observed were 40 ppt ( 0.27 µ g/ m3) for bromodichloromethane; 290 ppt ( 2.5 µ g/ m3) for dibromochloromethane; 310 ppt ( 3.2 µ g/ m3) for bromoform. Bromodichloromethane was detected in 64% ( n= 11) and 17% ( n= 6) of personal air samples collected in Texas and North Carolina. The detected concentrations ranged from 0.12 to 4.36 µ g/ m3 ( 0.017 to 0.65 ppb). Dibromochloromethane was not detected.

Mean concentrations in indoor air ranged from 0.38 to 0.75 µ g/ m3 for bromodichloromethane 0.44 to 0.53 µ g/ m3 for dibromochloromethane, and 0.29 to 0.35 µ g/ m3 for bromoform, as determined from 15 minute samples collected in 48 New Jersey residences. In a separate study, levels of brominated trihalomethanes in indoor air were locally increased ( e. g., in shower/ bath enclosures and vanity areas) during showering and bathing events. The levels of individual brominated trihalomethanes in air were reported to be consistent with the levels in tap water.

The use of chlorine to disinfect swimming pools and hot tubs results in the formation of brominated trihalomethanes. Swimming pool and hot tub users are potentially exposed to brominated trihalomethanes via dermal contact, ingestion, and inhalation of compounds released to the overlying air. As a result, swimming pool and hot tub users may experience greater overall exposures to brominated trihalomethanes than the general population. One study indicated that bromodichloromethane, dibromochloromethane, and bromoform concentrations in swimming pool and hot tub water ranged from 1 to 105 µ g/ L ( ppb), from 0.1 to 48 µ g/ L ( ppb), and from less than 0.1 to 62 µ g/ L ( ppb), respectively. Concentrations of the same brominated trihalomethanes in the air two meters above the pool water ranged from less than 0.1 to 14 µ g/ m3 ( 0.015   2.09 ppb), from less than 0.1   10 µ g/ m3 ( 0.011   1.2 ppb), and from less than 0.1 to 5.0 µ g/ m3 ( 0.0097   0.48 ppb), respectively. Data from several studies confirm the uptake of brominated trihalomethanes from swimming pools and environs by dermal and/ or inhalation pathways.

No data for occurrence of brominated trihalomethanes in soil were available in the materials reviewed for this document. The chemical and physical properties of the brominated trihalomethanes indicate that they should volatilize readily from wet or dry soil surfaces. Therefore, ingestion of soil is not expected to be a significant route of exposure.

Exposure to brominated trihalomethanes via ingestion of drinking water was estimated using data obtained for disinfectants and disinfection byproducts under the Information Collection Rule ( ICR). ICR data offer several advantages over other national studies for purposes of Draft  Do Not Cite or Quote February 20, 2003 IV  41 estimating national exposure levels of adults in the United States to brominated trihalomethanes via ingestion of drinking water. First, they are recent and reflect relatively current conditions. Second, data of very similar quality and quantity were collected systematically from a large number of plants ( 501) and systems ( approximately 300), including both surface and ground water systems. Third, the mean, median, and 90th percentile value were estimated on the basis of all samples taken, not just the sample detects. Thus, these descriptive statistics are representative of the exposures of the entire populations served by those systems, not just the populations served by systems with higher concentrations of these compounds. However, this study can not be considered representative of smaller public water supplies or water supplies from the most highly industrialized or contaminated areas.

Exposure was calculated by multiplying the concentration of individual brominated trihalomethanes in drinking water by the average daily intake, assuming that each individual consumes two liters of water per day. The annual median, mean, and upper 90th percentile values are presented for both surface and ground water systems. Assuming that the DS High value actually represents the average exposure level of persons served by one plant distribution pipe with the longest water residence time, the DS High value might be used to estimate a high end exposure level.

For bromodichloromethane, the median, mean, and 90th percentile population exposures from surface water systems are estimated to be 17, 20, and 40 µ g/ person/ day, respectively. The same values for populations exposed to bromodichloromethane from ground water systems are lower   3.6, 8.1, and 22 µ g/ person/ day, respectively. For dibromochloromethane, the median, mean, and 90th percentile population exposures from surface water systems are estimated to be 4.8, 9.4, and 26 µ g/ person/ day, respectively. The corresponding values for populations exposed to dibromochloromethane from groundwater system are lower   2.7, 6.2, and 18 µ g/ person/ day, respectively. For bromoform, the median, mean, and 90th percentile population exposures from surface water systems are estimated to be near 0, 2.4, and 6.2 µ g/ person/ day, respectively. The same values for populations exposed to bromoform from ground water systems are higher   0.65, 3.8, and 9.6 µ g/ person/ day, respectively.

For purposes of comparison, estimates of ingestion exposure to bromodichloromethane, dibromochloromethane, and bromoform in drinking water were also estimated from data collected in other, older studies. Ingestion from ground water supplies was estimated from the median levels found in the Ground Water Supply Survey conducted by U. S. EPA in 1980 81. Based on the range of median levels ( 1.4   2.1 µ g/ L ( ppb)) and a consumption rate of two liters per day, the median ingestion exposure to bromodichloromethane may range from 2.8 to 4.2 µ g/ day. Similarly, median exposure to dibromochloromethane may range from 4.2 to 7.8 µ g/ day, and for bromoform, median exposure may range from 4.8 to 8.4 µ g/ day. Exposure to bromodichloromethane from surface water supplies can be estimated based on the range of median values observed under different conditions in the National Organics Monitoring Survey conducted by U. S. EPA in 1976 1977, which mainly sampled surface water systems. Based on a range of 5.9   14 µ g/ L ( ppb), exposure to bromodichloromethane from surface water is estimated to be between 12 and 28 µ g/ day. Similarly, based on the range of medians reported for Draft  Do Not Cite or Quote February 20, 2003 IV  42 dibromochloromethane concentrations, the median exposure is estimated to be up to 6 µ g/ day. The median levels of bromoform in the surface water supplies have been found to be less than the EPA Drinking Water minimum reporting levels ( MRLs) of 0.5   1 µ g/ L ( ppb). An estimate of exposure based on the MRLs will be overly conservative because the actual concentration of bromoform is not detectable. Based on the range of MRLs, 0.5   1 µ g/ L ( ppb), the exposure to bromoform is estimated to range from 1 to 2 µ g/ day for surface water supplies.

Ingestion exposure to brominated trihalomethanes in drinking water can also be estimated from the concentrations found at the tap in the U. S. EPA's Total Exposure Assessment Methodology ( TEAM) study. Estimates of the average of the population intakes for ingestion of bromodichloromethane from drinking water range from 0.42 to 42  g/ person/ day. The upper 90th percentile estimates range from < 2.0 to 90  g/ person/ day. Estimates of the average population intake of dibromochloromethane from drinking water range from 0.2 to 56  g/ person/ day. The upper 90th percentile estimates range from < 0.9 to 86  g/ person/ day. Estimates of the average of the population intakes of bromoform, for those areas in which bromoform was measurable in a majority of the samples, range from 1.6 to 16.2  g/ person/ day. The upper 90th percentile estimates range from 2.4 to 26  g/ person/ day. Four of the six locations in the TEAM study, however, had a low frequency ( less than 10%) of detection of bromoform in measurable quantities.

Sources of uncertainty in these estimates of ingestion exposure include use of different analytical methods, failure to report quantitation limits, using measures near the detection limit, failure to report how nondetects are handled when averaging values ( e. g., set to zero or one half the detection limit), and failure to report sample storage method and duration. In addition, many environmental factors influence the concentrations of these compounds in drinking water at the tap and in vended or bottled waters used for drinking. These factors include season and temperature, geographic location, source of water, residence time in distribution system, and others.

The RSC ( relative source contribution) is the percentage of total daily exposure that is attributable to tap water when all potential sources are considered ( e. g., air, food, soil, and water). Ideally, the RSC is determined quantitatively using nationwide, central tendency and/ or high end estimates of exposure from each relevant medium. In the absence of such data, a default RSC ranging from 20% to 80% may be used.

The RSC used in the current and previous drinking water regulations for dibromochloromethane is 80%. This value was established by use of a screening level approach to estimate and compare exposure to dibromochloromethane from various sources. Information considered for during this process is summarized in Appendix C. There are some uncertainties in the 80% RSC that are related to the availability of adequate concentration data for dibromochloromethane in media other than water. Parallel RSC calculations were not performed for bromodichloromethane and bromoform. The EPA has set the regulatory level for these chemicals in drinking water at zero because it has been determined that they are probable human Draft  Do Not Cite or Quote February 20, 2003 IV  43 carcinogens. Therefore, determination of an RSC is not relevant for these chemicals because it is the Agency's policy to perform RSC analysis only for noncarcinogens.

Brominated trihalomethanes have been detected in the blood and breast milk of humans. A national survey of volatile organic compounds in whole blood detected bromodichloromethane dibromochloromethane, and bromoform in 14%, 12%, and less than 10% of samples, respectively, when highly sensitive analytical methods were applied. Several studies have demonstrated that the level of individual brominated trihalomethanes in blood or breath increases shortly after exposure to these compounds in tap water during bathing and showering. Exposure during these events may occur by ingestion, dermal contact and/ or inhalation of the volatilized compound. In studies which examined households with differing concentrations of brominated trihalomethanes in tap water, the levels of individual brominated trihalomethanes in blood or exhaled breath paralleled the tap water concentration. The studies of showering and bathing indicate that water use patterns and water quality characteristics are important variables in determining the blood levels of brominated trihalomethanes. Dibromochloromethane was detected in one of eight samples of breast milk collected from women living in the vicinity of U. S. chemical manufacturing plants or user facilities. Draft  Do Not Cite or Quote February 20, 2003 V  1 V. HEALTH EFFECTS IN ANIMALS A. Acute Exposures This section presents data on the acute effects of brominated trihalomethanes. Acute lethality values for the brominated trihalomethanes are summarized in Table V 1. Additional acute toxicity data are summarized in Table V 2.

1. Bromodichloromethane Acute lethality of bromodichloromethane has been investigated in mice and rats. LD 50 values for male and female ICR Swiss mice were 450 and 900 mg/ kg, respectively ( Bowman et al., 1978). Chu et al. ( 1980) determined LD 50 values of 916 and 969 mg/ kg for male and female Sprague Dawley rats, respectively.

Bowman et al. ( 1978) administered bromodichloromethane in a single gavage dose in Emulphor ® : alcohol: saline ( 1: 1: 8) to ICR Swiss mice ( 10/ sex/ group). The administered doses ranged from 500 to 4,000 mg/ kg ( individual doses not reported). Sedation and anesthesia occurred at 500 mg/ kg. Males were more sensitive to the lethal effects of bromodichloromethane than females.

Table V 1 Summary of LD50 Values for Brominated Trihalomethanes Compound LD50 Values ( mg/ kg)

ICR Swiss Mouse a Sprague Dawley Rat b Male Female Male Female Bromodichloromethane 450 900 916 969 Dibromochloromethane 800 1200 1186 848 Bromoform 1400 1550 1388 1147 aBowman et al. ( 1978) bChu et al. ( 1980) Draft  Do Not Cite or Quote February 20, 2003 V  2 Table V 2 Summary of Acute Toxicity Studies for Brominated Trihalomethanes Reference Species Route Sex Number per dose group Duration Dose ( mg/ kg day) Results Bromodichloromethane Bowman et al. ( 1978) Mouse ICR Swiss Gavage ( aqueous) M, F 10 Single dose 500  4000 Anesthesia, sedation at 500 mg/ kg NTP ( 1987) Rat F344/ N Gavage ( corn oil) M, F 5 Single dose 150 300 600 1,250 2,500 Increased mortality at 600 mg/ kg day. Lethargy, labored breathing at 1250 mg/ kg day and above, 100% mortality at the two highest dose groups NTP ( 1987) Mouse B6C3F1 Gavage ( oil) M, F 5 Single dose 150 300 600 1,250 2,500 100% mortality at the two highest dose groups Lilly et al. ( 1994) Rat F344 Gavage ( corn oil) ( aqueous) M ? Single dose 0 200 ( LOAEL) 400 Renal tubule degeneration and necrosis; alteration in markers of renal function Lilly et al. ( 1996) Rat F344 Gavage ( corn oil or water) M 6 Single dose 0 200 ( LOAEL) 400 Renal tubule necrosis; alteration in markers of renal function Lilly et al. ( 1997) Rat F344 Gavage ( aqueous) M 5 Single dose 0 123 164 ( NOAEL) 246 ( LOAEL) 328 492 Decreased body weight; elevated liver and renal markers Keegan et al. ( 1998) Rat F344 Gavage ( aqueous) M 6 Single dose 0 21 31 41 ( NOAEL) 82 ( LOAEL) 123 164 246 Elevated renal markers; decreased liver weight and body weight Dibromochloromethane Bowman et al. ( 1978) Mouse ICR Swiss Gavage ( aqueous) M, F 10 Single dose 500  4000 Anesthesia, sedation Table V 2 ( cont.)

Reference Species Route Sex Number per dose group Duration Dose ( mg/ kg day) Results Draft  Do Not Cite or Quote February 20, 2003 V  3 NTP ( 1985) Rat F344/ N Gavage ( corn oil) M, F 5 Single dose 160 310 630 1250 2,500 Increased mortality at 630 mg/ kg and above, with 100% mortality in high dose group NTP ( 1985) Mouse B6C3F1 Gavage ( corn oil) M, F 5 Single dose 160 310 630 1250 2500 Increased mortality in females at 630 mg/ kg day and above and in males at 310 mg/ kg day and above; 100% mortality in males in two highest dose groups and females in two highest dose groups Müller et al. ( 1997) Rat Wistar Gavage ( olive oil) M 6 Single dose 0 83 167 333 667 Transient decrease in blood pressure and heart rate; decreased activity; effects on heart muscle contractility and changes in some cardiac parameters Bromoform Bowman et al. ( 1978) Mouse ICR Swiss Gavage ( aqueous) M, F 10 Single dose 500  4000 Ataxia, sedation, and anesthesia at 500 mg/ kg Chu et al. ( 1980) Rat SD* Gavage ( corn oil) M, F 10 Single dose 546 765 1071 1500 2100 Sedation, ataxia, liver and kidney congestion NTP ( 1989a) Rat F344/ N Gavage ( corn oil) M, F 5 Single dose 125 250 500 1,000 2000 No deaths at 500 and lower; 60% mortality at 1,000; 100% mortality at 2,000; shallow breathing in two highest dose groups NTP ( 1989a) Mouse B6C3F1 Gavage ( corn oil) M, F 5 Single dose 125 250 500 1,000 2000 10% mortality at 500 mg/ kg day * SD, Sprague Dawley Draft  Do Not Cite or Quote February 20, 2003 V  4 NTP ( 1987) administered single gavage doses of bromodichloromethane in corn oil to male and female F344/ N rats and B6C3F 1 mice ( 5/ sex/ dose) at 150, 300, 600, 1,250, or 2,500 mg/ kg. Animals were observed for 14 days, and a necropsy was performed on at least one male and one female in each dose group. All animals dosed with 1,250 or 2,500 mg/ kg died before the end of the study. At 600 mg/ kg, deaths occurred in two of five male rats, one of five female rats, five of five male mice, and two of five female mice. Clinical signs observed in rats at 1,250 or 2,500 mg/ kg included lethargy and labored breathing. Clinical signs observed in mice at or above 600 mg/ kg included lethargy, with the exception that this sign was not observed in highdose male mice. At necropsy, the liver from animals dosed with 1,250 or 2,500 mg/ kg appeared pale. No dose related effects were seen on body weight gain in animals that survived.