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PUBLIC HEALTH ASSESSMENT

LOCKWOOD SOLVENT GROUNDWATER PLUME
(a/k/a LOCKWOOD SOLVENT GROUND WATER PLUME)
BILLINGS, YELLOWSTONE COUNTY, MONTANA


APPENDICES

APPENDIX A: FIGURES 1, 2 AND 3

Site Map
Figure 1. Site Map

Demographic Statistics
Figure 2. Demographic Statistics

Vicinity Map
Figure 3. Vicinity Map


APPENDIX B: TABLES 1 THROUGH 10

Table 1.

Contaminants of Concern in Private Wells at the Lockwood Solvents
Contaminant Range of Contaminants Detected (ppb) Guidance (ppb)
ATSDR Comparison Value (CV) EPA MCL EPA RAL
tetrachloroethene (PCE) ND -1900 10 (LTHA) 5 70
trichloroethene (TCE) ND - 150 none 5  
cis-1,2-dichloroethene ND - 590 70 (LTHA) 70  
vinyl chloride ND - 190 0.03 (CREG) 2  
carbon tetrachloride ND - 12 0.3 (CREG) 5  
1,1-dichloroethene ND - 3 0.06 (CREG) 7  
chloromethane ND - 7 3 (LTHA) none  
chloroethane ND - 16 none none  
1,1-dichloroethane ND - 9 none none  
chloroform ND - 59 6 (CREG) 80  
bromodichloromethane ND - 25 0.6 (CREG) 80  

Notes:

All contaminants in this table have concentrations which exceed ATSDR's comparison values. Shaded rows show chemicals with levels that exceeded EPA's maximum contaminant level (MCL) for drinking water.

ppb = parts per billion or parts VOC per billion parts of water.
ND = not detected
MCL = Maximum Contaminant Level
RAL = Removal Action Level

ATSDRs comparison values:
LTHA = Lifetime Health Advisory
CREG = Cancer Risk Evaluation Guide


Table 2.

Contaminants of Concern in Groundwater at the Lockwood Solvents Site
Contaminant Concentration Range (ppb) Guidance (ppb)
ATSDR Comparison Value EPA MCL
tetrachloroethene (PCE) ND - 4,279 10 (LTHA) 5
trichloroethene (TCE) ND - 3,770 none 5
cis-1,2-dichloroethene (DCE) ND - 15,200 70 (LTHA) 70
trans-1,2-dichloroethene ND - 100 200 (RMEG) 100
1,1-dichloroethane ND - 100 none none
vinyl chloride ND - 770 0.03 (CREG) 2
1,1-dichloroethene ND - 310 0.06 (CREG) 7
1,1,1-trichloroethane ND - 780 200 (LTHA) 200
carbon tetrachloride ND - 9 0.3 (CREG) 5
benzene ND - 6 0.6 (CREG) 5

Notes:

ppb = parts per billion or parts VOC per billion parts of water.
ND = not detected
MCL = Maximum Contaminant Level
RAL = Removal Action Level
ATSDRs comparison values: LTHA = Lifetime Health Advisory; CREG = Cancer Risk Evaluation Guide; RMEG = Reference Media Evaluation Guide


Table 3.

Contaminants of Concern in Residential Indoor Air Samples - Living Space Only (September 1999 through February 2002)
Contaminant Maximum Concentration (ppb) Comparison Value (ppb) Date Maximum Concentration Detected Maximum Concentration (µg/m3) Comparison Value (µg/m3) Source
tetrachloroethene (PCE) 19.8 40 Jan 2000 136.5 276 EMEG (chronic)
trichloroethene (TCE) 14.0 100 Jan 2000 76.5 546 EMEG (intermediate)
cis-1,2-dichloroethene (DCE) 4.7 9.2 June 2000 19.0 37 EPA RBC
vinyl chloride 0.62 0.04 June 2000 1.6 0.1 CREG
methylene chloride 40.9 0.85 Jan 2000 144.3 3 CREG
chloroform 0.40 0.008 Jan 2000 2.0 0.04 CREG
carbon tetrachloride 0.57 0.0109 April 2000 3.6 0.07 CREG
benzene 3.57 0.03 Jan 2000 11.6 0.1 CREG
bromodichloromethane 0.22 0.015 Jan 2000 1.5 0.1 EPA RBC
1,1-dichloroethene 0.03 0.005 June 2000 0.12 0.02 CREG
1,2-dichloroethane 0.1 0.010 October 2001 0.49 0.04 CREG

Shaded rows show chemicals with levels that exceeded the applicable comparison value.

Notes:

ND = not detected
ppb = parts per billion
µg/m3 = micrograms per cubic meter
ATSDRs comparison values: CREG = Cancer Risk Evaluation Guide; EMEG = Environmental Media Evaluation Guide
EPA RBC = EPA's Region III Risk-based concentration, 10/5/2000


Table 4.

Completed Exposure Pathways
Pathway Name Source Medium Exposure Point Exposure Route Receptor Population Time of Exposure Exposure Activities Primary Chemicals
Groundwater Contamination Unknown Groundwater
(private wells)
Water faucets Ingestion
Inhalation
Dermal
Residents, workers in identified area Past
Present
Future
Domestic use of well water (e.g., drinking, cooking, bathing etc.) tetrachloroethene (PCE)
trichloroethene (TCE)
cis-1,2-dichloroethene (DCE)
vinyl chloride
Indoor Air Subsurface vapor migration; volatilizat-aion Air Indoor air Inhalation Residents above plume; those who use well water Past
Present
Future
Showering, bathing, breathing contaminated indoor air tetrachloroethene (PCE)
trichloroethene (TCE)
cis-1,2-dichloroethene (DCE)
vinyl chloride


Table 5.

Potential Exposure Pathways
Pathway Name Source Medium Exposure Point Exposure Route Receptor Population Time of Exposure Exposure Activities Primary Chemicals
Surface Water/ Sediment Groundwater plume Surface water Coulson Ditch, A-J Gravel, Yellowstone River Ingestion
Inhalation
Dermal
Persons coming into contact with the ditch/river Past
Present
Future
Recreational use of ditch/river tetrachloroethene (PCE)
trichloroethene (TCE)
cis-1,2-dichloroethene (DCE)
vinyl chloride
Ground Water Unknown Groundwater (Private Wells) Water faucets Ingestion
Inhalation
Dermal
Persons with contaminated private wells not presently identified; wells outside Lomond Lane area Past
Present
Future
Domestic use of well water (drinking, cooking, bathing, etc.) tetrachloroethene (PCE)
trichloroethene (TCE)
cis-1,2-dichloroethene (DCE)
vinyl chloride
Soil Improper disposal of chemicals Soil Source area Inhalation
Dermal
Persons who dig into soil or contact contaminated soil Past
Present
Future
On-site remedial, sampling, or drilling activities tetrachloroethene (PCE)
trichloroethene (TCE)
cis-1,2-dichloroethene (DCE)
vinyl chloride
Biota Secondary receptors Plants, fish Residents' gardens, fish from Yellowstone River or A-J Gravel Ingestion Persons consuming contaminated plants or fish Past
Present
Future
Recreational gardening or catching fish intended for consumption tetrachloroethene (PCE)
trichloroethene (TCE)
cis-1,2-dichloroethene (DCE)
vinyl chloride


Table 6.

Maximum level of VOCs detected in private wells.
Contaminant Maximum level in private well ppb
tetrachloroethene (PCE) 1,900
trichloroethene (TCE) 150
cis-1,2-dichloroethene (DCE) 590
vinyl chloride 190
1,1-dichloroethene 3
1,1-dichloroethane 9
carbon tetrachloride 12
chloromethane 7
chloroethane 16
chloroform 59
bromodichloromethane 25


Table 7.

The maximum indoor air levels from homes in the Lockwood Solvents Site for air samples collected from 1999 and 2002. These maximum indoor air levels are compared to average background levels in indoor air for U.S. homes. Data are reported in µg/m3 and ppb.
Contaminant Maximum Level
Indoor Air Lockwood Homes
Average Background Level
Indoor Air U.S. Homes(3)
Maximum Level
Indoor Air Lockwood Homes
Average Background Level
Indoor Air U.S. Homes
µg/m3 µg/m3 ppb ppb
tetrachloroethene (PCE) 136 4.5 19 0.6
trichloroethene (TCE) 76 2.3 14 0.4
cis-1,2-dichloroethene 19   4.7  
vinyl chloride 1.6   0.6  
1,1-dichloroethene 0.1   0.03  
1,2-dichloroethane 0.1 0.1 0.02 0.02
methylene chloride 144.3   40  
chloroform 2 1.2 0.4  
carbon tetrachloride 3.6 1 0.6 0.15
benzene 11.6 9 3.6  
bromodichloromethane 1.5   0.2  


Table 8.

Maximum indoor air level detected in the most recent air samples collected in February 2002. These levels are compared to average background levels of indoor air in U.S. homes. Air levels are reported in µg/m3 and ppb.
Contaminant Maximum Level
Indoor Air Lockwood Homes February 2002
Average Background Levels
Indoor Air U.S. Homes
Maximum Level
Indoor Air Lockwood Homes February 2002
Average Background Levels
Indoor Air U.S. Homes
µg/m3 µg/m3 ppb ppb
tetrachloroethene (PCE) 39.5 4.5 5.7 0.6
trichloroethene (TCE) 5.9 2.3 1.1 0.4
cis-1,2-dichloroethene 6.3   1.6  
trans-1,2-dichlorethene 0.1   0.02  
vinyl chloride ND   ND  
1,1-dichloroethene 0.05   0.01  
1,2-dichloroethane 0.2 0.1 0.05 0.02
1,1-dichloroethane 0.1   0.02  
methylene chloride        
carbon tetrachloride 0.5 1 0.08 0.15
chloroethane 0.04   0.01  

* Denotes sample collected from crawl space.
** ND means not detected


Table 9.

Estimated total daily exposure in ppb compared to the available inhalation health guidelines (ATSDR's chronic and intermediate Minimal Risk Levels; and EPA's chronic Reference Concentrations). The total daily exposure was estimated by combining exposure from showering, from dermal intake, and from indoor air.
Contaminant Estimated Total Daily Exposure Intermediate/Chronic (ppb) Inhalation Guidelines (ppb)
Adults Children
Major contaminants of concern
tetrachloroethene (PCE) 99 78 40 cMRL
trichloroethene (TCE) 22 16 100 iMRL
cis-1,2-dichloroethene 42 35 none
vinyl chloride 19 17 30 iMRL
Minor contaminants of concern  
1,1-dichloroethene 0.2 0.2 20 iMRL
t-1,2-dichloroethene 0.04 0.02 200 iMRL
1,1-dichloroethane 0.8 0.6 none
methylene chloride 42 27 300 cMRL(4)
300 iMRL
chloroform 4 3 20 cMRL
50 iMRL
carbon tetrachloride 1 0.8 50 iMRL
benzene 4 2.4 4 iMRL
bromodichloromethane 1 1 none
chloromethane 1 0.8 50 cMRL
200 iMRL
chloroethane 2 1.4 10,000 cRfC
toluene 9 6 80 cMRL
ethylbenzene 2 1 1000 iMRL
1000 cRfC
xylene 2 1.2 100 cMRL
700 iMRL
styrene 0.5 0.4 60 cMRL
1,4-dichlorobenzene 0.1 0.1 100 cMRL
200 iMRL


Table 10.

Estimated bathroom air levels in ppb based on combining estimated bathroom air levels from showering with the estimated dermal exposure converted to an equivalent air concentration. These estimated bathroom air levels are used to evaluate acute (short-term) exposures.
Contaminant Estimated bathroom air level from shower ppb(5) Dermal intake converted to bathroom air level ppb(6) Estimated bathroom air level combining dermal and inhalation ppb(7)
Adults Children Adults Children Adults Children
tetrachloroethene 1,345 1,345 2,242 1,121 3,587 2,466
trichloroethene 132 132 220 110 352 242
cis-1,2-dichloroethene 715 175 1,192 596 1,907 1,311
vinyl chloride 351 351 585 292 935 643


APPENDIX C: DESCRIPTION OF TECHNICAL METHODS FOR ESTIMATING EXPOSURE TO VOCS

Acute Exposures

As mentioned previously, when residents bathe or shower in water contaminated with VOCs,chlorinated solvents such as tetrachloroethene (PCE), trichloroethene (TCE), dichloroethene(DCE), and vinyl chloride (VC) will enter the body in two ways. First, chlorinated solvents canpenetrate the skin during the time a resident is bathing or showering. Second, chlorinatedsolvents will evaporate from the water into indoor air where residents will be exposed when theybreathe the air.

Volatilization from showers

Scientists have studied how chemicals volatilize from shower water and have developedequations for estimating indoor air levels in the shower and bathroom (Andelman 1990, Jo et al.1990, Wester and Maibach 1986). Using the following equation, the maximum concentration of aVOC in the bathroom can be estimated for a 10-minute shower and for the 20-minute period inthe bathroom following a shower:

C air max = (k) (Fw) (Ts) (Cw) / Va

where

C air max = maximum concentration in air during the shower and after period in bathroom,
k = fraction of chemical that evaporates from water while showering (assumed to be 0.6),
Fw = flow rate of water through shower head in L/minute (assumed to be 8 liters/minute),
Ts = duration of shower in minutes (assumed to be 10 minutes),
Va = volume of shower and bathroom in liters, (assumed to be 10,000 liters, the approximate size of a small bathroom), and
Cw = concentration of VOC in water in mg/L (Andelman 1990).

The following example shows how units cancel to arrive at mg VOC per cubic meter of air.

C air max = (k) (Fw) (Ts) (Cw) / Va

C air max = (%) (L/min) (min) (mg VOC/L) / L

C air max = mg VOC / L air

C air max = mg/L air x 1000 L air/m3

C air max = mg/m3.

Using PCE at 1.9 mg/L (or 1,900 ppb) as an example, the following bathroom air concentrationis estimated:

C air max = (0.6) (8 L water/min)(10 min) (1.9 mg/L water) / 10,000 L air

C air max = 0.00912 mg/L air

C air max = 0.00912 mg/L air x 1000 L air/m3 = 9.12 mg/m3

C air max = 9.12 mg/m3 = 1.345 ppm or 1,345 ppb.

To determine the amount of VOC exposure from inhalation, adults are assumed to breathe 1 cubic meter of air each hour (EPA 1989).

Dermal intake converted to an air concentration

In addition to the exposure from breathing VOCs, people also absorb VOCs through their skinwhile showering and bathing. Using a skin permeability constant for VOCs, scientists havedeveloped an equation for estimating the amount of VOCs absorbed through the skin during ashower (Brown et al. 1984). The VOC exposure via skin can be estimated using the followingformula:

Skin dose =

(skin permeability constant) (duration of exposure)(total body surface area)(percent of body surface area exposed)(VOC concentration in water)(fraction remaining aftervolatilization)

The units are (L/cm2 x hr) (hr) (cm2) (%) (mg/L)(%), which cancel out to mg. The permeabilityconstant for chlorinated organics is assumed to be 0.001 L/cm-hr (Brown et al. 1984), and 40%of the VOCs are assumed to remain in the shower water after volatilization (Andelman 1985,McKone 1991) .

Because exposure to VOCs via the skin does not pass first through the liver, skin exposure islikely to be closer toxicologically to inhalation exposure than ingestion exposure. Like inhalationexposure, a VOC absorbed through the skin will be distributed throughout the body beforereaching the liver for detoxification. Therefore, to evaluate both inhalation exposure and skinexposure, it is necessary to convert the dose from skin absorption to an air concentration. Addingthe air concentration in the bathroom from taking a shower and the air concentration that isequivalent to the skin dose gives a total concentration in air that can be used to evaluate toxicityof a VOC from both routes of exposure.

The following example using PCE shows the estimated dose from skin absorption and how toconvert that estimated dose to an air concentration. First, it is necessary to estimate the skin dose,which was shown in the previous equation.

Skin dose = (0.001 L/cm2 x hr)(10/60hr)(20,000 cm2)(1)(1.9 mg/L)(0.4).

Skin dose = 2.53 mg PCE

Next, it is necessary to convert the skin dose of 2.53 mg to an air concentration.

Air concentration from skin exposure =

Skin dose / inhalation rate x shower duration =

2.53 / 1 m3/hr x 1 hr/60 minutes x 10 minutes = 15.2 mg/m3 or 2,242 ppb

Thus a concentration of 15.2 mg/m3 PCE in air will give a skin dose of 2.53 mg for a 10-minuteshower. The total exposure from volatilization and from skin absorption is 1,345 ppb plus 2,242ppb, which is 3,587 ppb PCE in air. Table 10 in Appendix B shows the individual exposure fromvolatilization and dermal absorption as well as the total exposure from combining both routes.

Chronic exposure

To evaluate chronic exposure, it is necessary also to include the additional VOC exposure thatoccurs during the remainder of the day indoors.

To estimate the total exposure of a specific VOC from bathing in contaminated water, thefollowing exposures must be considered:

Total exposure specific VOC = exposure shower inhalation + exposure bathroom inhalation + exposure shower skin

Thus, the equation to estimate each exposure pathway is as follows:

(Conc air max mg/m3) (1 m3/hr) (10/60 hr) +

(Conc air max mg/m3)(1m3/hr)(20/60 hr) +

(L/cm2 x hr)(hr)(cm2)(% surface area)(mg/L)(% remaining)

As an example, the total exposure for bathing in PCE-contaminated water containing 1.9 mg/LPCE is:

Total exposure PCE =

(9.12 mg/m3) (1 m3/hr) (10/60 hr) +

(9.12 mg/m3) ( 1 m3/hr) (20/60 hr) +

Total exposure PCE = 1.52 + 3.04 + 2.28 mg = 6.84 mg for a 10-minute shower and a 20-minutebathroom stay.

Using the maximum VOC detected, the exposure from summing all VOCs from bathing isestimated to be about 7 mg. This, however, is not the total exposure of VOCs for the day;residents are exposed to VOCs from breathing indoor air during the remainder of the day. Thisestimate can be made using the indoor air measurements that EPA and MDEQ collected. EPAand MDEQ collected air samples from two sampling dates (September 1999 and January 2000)before altering ventilation patterns in several homes to reduce indoor air levels of VOCs. Theresults from these two sample dates will be used to estimate VOC exposure.

While many of the VOCs detected in indoor air in Lockwood homes are at expected levels forindoor air, TCE and PCE appear to be somewhat elevated in a few homes. The maximum leveldetected in Lockwood indoor air is 76 ug/m3 (or 0.076 mg/m3 and 14 ppb) for TCE and 136ug/m3 (or 0.136 mg/m3 and 19 ppb) for PCE. The exposure for each VOC can be estimatedassuming a reasonable situation where someone stays at home most of the day. Typically, menbreath about 23 cubic meters of air each day and women breathe about 21 cubic meters of aireach day. Assuming that some time is spent away from the home each day, 20 m3/day is areasonable, average upper-end exposure situation. Thus the VOC exposure can be estimatedusing the following formula:

VOC exposure indoor air = (concentration of VOC indoors in ug/m3) (20 m3/day)(1mg/1000ug)

To estimate the total exposure to VOCs each day, it is necessary to sum the VOC exposure fromshowering, from skin contact, and from indoor air. The total amount of VOC exposure each dayat the few homes with the more highly contaminated well water is 28 mg, or 25 mg if methylenechloride is omitted. Methylene chloride is commonly found in air measurements at low levels. Itis generally believed to be present as a laboratory contaminant because it is often used inlaboratories that do analytical measurement. The amount detected in the Lockwood residentialsample, however, is unusually high (i.e., 144 ug/m3) and therefore might be real, and notnecessarily a laboratory contaminant. When summing the total VOC for just the chlorinatedchemicals (PCE, TCE, and DCE), the total exposure is about 22 mg each day.

The next step is to convert the total daily exposure (in mg/day) for each chemical (based onshower exposure, bathroom air exposure, dermal exposure, and indoor air exposure) into a dailydose based on mg/kg/day and a daily dose based on air concentration. These doses are used todetermine whether someone might experience harmful effects from exposure to VOCs viaseveral routes of exposure (i.e., inhalation and dermal combined).


APPENDIX D: HEALTH CONSULTATION: LOCKWOOD SOLVENTS, DECEMBER 9, 1999


HEALTH CONSULTATION

LOCKWOOD SOLVENTS
BILLINGS, YELLOWSTONE COUNTY, MONTANA
EPA FACILITY ID: MT0007623052

December 9, 1999

Prepared by:

Superfund Site Assessment Branch
Division of Health Assessment and Consultation
Agency for Toxic Substances and Disease Registry


TABLE OF CONTENTS

BACKGROUND AND STATEMENT OF ISSUES

DISCUSSION - SHOWERING

OUTDOOR WATER USE

VAPOR INTRUSION

OCCUPATIONAL EXPOSURE WATER COMPANY WORKERS

CHILD HEALTH INITIATIVE

CONCLUSIONS

RECOMMENDATIONS

PREPARERS OF REPORT

REFERENCES

APPENDIX A: HEALTH CONSULTATION, LOCKWOOD SOLVENTS SITE, DECEMBER 9, 1999



BACKGROUND AND STATEMENT OF ISSUES

The Montana Department of Environmental Quality (MDEQ) requested the Agency for ToxicSubstances and Disease Registry (ATSDR) review the results of well water samples collected atLockwood Solvent site in Billings, Montana. The purpose of the review was to determine (1) if chlorinated solvents in well water represent a public health concern for skin contact andbreathing during indoor (bathing) and outdoor water use, and (2) if contaminant levels in wellwater represent a public health concern from chlorinated solvent evaporation and migration intohomes via the soil gas pathway. Additionally, ATSDR was requested to determine if the levelsof groundwater contaminants present a health hazard to workers installing and repairing watermains.

The Lockwood Solvent site is located in the eastern portion of Billings, Montana. The site isbordered by Rosebud Lane to the south, Klenck Lane to the east and the Yellowstone River to thenorth and west.

The MDEQ collected well water samples from approximately 20 homes and 15 businessesduring 1998 and 1999. The samples were analyzed for volatile organic compounds (VOCs). Theresults of the water sampling were provided to ATSDR in a map prepared by MDEQ contractor(Pioneer Technical Services) dated February 17, 1999.

Results of the environmental sampling indicated that tetrachloroethene, TCE, vinyl chloride, andcis-1,2 dichloroethene are the four contaminants of concern. The maximum concentrations ofthese contaminants detected in groundwater are: tetrachloroethene (1.9 milligrams per liter(mg/L)), vinyl chloride (0.190 mg/L), TCE 0.150 (mg/L), and cis-1,2 dichloroethene (0.590mg/L). These contaminant levels were detected in a well at one home on Lomond Lane.

Residents of this home are provided an alternate source of water for drinking and bathing. Residents of eight additional homes in the Lockwood community are being provided bottleddrinking water.

The maximum concentrations of the contaminants of concern found at homes without alternatewater supplies for bathing are: tetrachloroethene ( 0.670 mg/L), vinyl chloride (0.160 mg/L),TCE (0.130 mg/L), and cis-dichloroethene (0.470 mg/L).


DISCUSSION - SHOWERING

When showering in chlorinated hydrocarbon-contaminated water, a resident may be exposedfrom (1) breathing the portion of the contaminant that is released into the air and (2) absorbingthe contaminant through the skin. A resident could inhale the vapor while showering and whilestanding in the bathroom immediately after showering.

Studies in humans have demonstrated that the dermal absorption dose of a chlorinated volatileorganic compound (chloroform) is comparable to the shower inhalation dose [1].

ATSDR made the following assumptions to estimate tetrachloroethene exposure to adults andchildren who are showering with tetrachloroethene-contaminated water:

(1) a resident would take a 10 minute shower once per day, and
(2) a resident spends an additional 15 minutes in the bathroom after showering.
(3) the rate of skin absorption of PCE is similar to rate for chloroform absorption

The maximum concentration of tetrachloroethene in the bathroom can be estimated by thefollowing mathematical formula [2]:

C sub a equals C sub w times k times F times t divided by V

where:

Ca = air concentration in milligrams per liter (mg/L)
Cw= tetrachloroethene concentration in tap water in milligrams per liter (0.67 mg/L)
k = volatile mass transfer coefficient in liter per minute (conservatively assumed to be .9)
F= flow rate in liters per minute (L/min) (assumed to be 8 liters per minute)
t = shower time in minutes (10 minute shower)
V = bathroom volume in liters (assumed to be 10,000 liters) (This is approximately the size of a small bathroom.)

If the concentration of tetrachloroethene in the shower water is 0.67 mg/liter, the maximumconcentration of tetrachloroethene in the bathroom air is estimated to be 4.8 milligrams per cubicmeter (mg/m3) or 0.71 parts per million (ppm) (6.78 mg/m3 = 1 ppm).

Assuming an adult breathes 1.0 cubic meter of air per hour and the water concentration is 0.67mg/liter, the estimated exposure during showering and subsequent bathroom use are as follows:

shower inhalation dose = (4.8 mg/m3) x (1.0 m3/hr) x (10/60 hr) = 0.8 mg

sink inhalation dose = (4.8 mg/m3) x (1.0 m3/hr) x (15/60 hr) = 1.2 mg

shower dermal dose = shower inhalation dose = 0.8 mg

total dose = showerinh + sinkinh + showerder = 2.8 mg/day

This model estimates a worst case air concentrations since it does not take into account dilutionfrom ventilation in the bathroom, and it assumes exposure at a maximum air concentrationthroughout duration of the bathroom use. The tetrachloroethene concentration will graduallyincrease to a maximum at the end of the shower then gradually decrease once the shower isturned off.

ATSDR has established an acute (short-term) inhalation Minimal Risk Level (MRL) of 0.2 ppmand a chronic (long-term) inhalation MRL of 0.04 ppm for tetrachloroethene. (ATSDR'smethods for reviewing environmental data are summarized in Appendix A.) The lowest observedadverse effect level (LOAEL) for acute inhalation exposure to tetrachloroethene is 50 ppm [3]. This is also the basis for the acute MRL. Humans exposed to 50 ppm for 4 hours were observedto have neurological effects (i.e. slight loss of visual contrast). This effect was not observed at10 ppm. At water concentration of 0.67 mg/liter, the predicted maximum air concentration of0.71 ppm during showering is approximately 70-fold less than the LOAEL.

The 0.04 ppm MRL (chronic) is based on increased reaction times by dry cleaning workersexposed to 15 ppm tetrachloroethene for ten years. This MRL includes an uncertainty factor of100. Exposure to tetrachloroethene at the 0.04 ppm (0.271 mg/m3)- MRL (chronic) is equivalentto a 6.5 mg per day dose for an adult breathing one cubic meter of air per hour for 24 hours. Theestimated total daily dose (inhalation and dermal) from shower-bathroom use (2.8 mg/day) isapproximately one third of the inhalation dose of exposure at the chronic MRL when the showerwater contains 0.67 mg/L.

The predicted maximum concentration of vinyl chloride during showering is 0.45 ppm, based ona groundwater concentration of 0.16 mg/L. ATSDR MRL for inhalation of vinyl chloride is 0.5ppm (acute) and 0.03 ppm (intermediate)[4]. The acute MRL is based on a no observed adverseeffect level (NOAEL) of 50 ppm. Laboratory animals were exposed to 50 ppm of vinyl chloridefor seven hours a day for a 10-day period without adverse effects to the adult animals or theirfetuses. The LOAEL for intermediate exposure to vinyl chloride is 10 ppm. Laboratory animalsexposed to 10 ppm of vinyl chloride for six months were observed to have increased liverweights. The MRL is based on this LOAEL and includes an uncertainty factor of 300. Thepredicted maximum air concentration is approximately 20-fold less than the LOAEL. ATSDRhas not established a chronic MRL for vinyl chloride for inhalation exposure. Vinyl chloride isrecognized as a cancer causing agent [4]. Studies have demonstrated that workers who havebreathed vinyl chloride over long periods (years) have an increased risk of developing livercancer. As a result, breathing low levels of vinyl chloride vapors over long periods may increasethe risk of developing liver cancer.

The predicted maximum concentration of TCE during showering is 0.174 ppm, based on agroundwater concentration of 0.13 mg/L of TCE. ATSDR has established an acute inhalationMRL of 2 ppm and intermediate inhalation MRL of 0.1 ppm for TCE [5]. The LOAEL for inhalation intermediate exposure to TCE is 50 ppm. Laboratory animals exposed to 50 ppm ofTCE for a six week period exhibited decreased wakefulness during exposure. The intermediateMRL is based on this study and includes an uncertainty factor of 300. The predicted maximumconcentration of TCE (0.174 ppm) is above the intermediate MRL (0.1 ppm). However, ATSDRdoes not anticipate adverse health effects to occur because of the short duration of exposure atthis level (less than one hour each day.) ATSDR has not established a chronic MRL for TCE forinhalation exposure.

The predicted air concentration during showering is 0.85 ppm based on a groundwaterconcentration of 0.47 milligrams per liter of cis-dichloroethene. ATSDR has not established anMRL for cis-dichloroethene because of a lack of data [6]. ATSDR has established anintermediate MRL for trans-dichloroethene of 0.2 ppm. This MRL is based on liver damage tolaboratory animals that were exposed to 200 ppm of trans-dichloroethene for a sixteen weekperiod and includes an uncertainty factor of 1,000.


OUTDOOR WATER USE

Breathing zone concentration of tetrachloroethene and other contaminants of concern duringoutdoor water use (e.g. sprinkler use) will be less than maximum concentrations predicted duringshowering because of dispersion, lower average outdoor temperature, and less atomization ofwater droplets. The amount of dermal exposure during outdoor use depends on the amount ofbody surface area in contact with the groundwater and duration of contact with the water. Dermal exposure from outdoor water use is likely to be similar to, or less, than dermal exposureresulting from a showering if contact time is 10 minutes per day or less.


VAPOR INTRUSION

ATSDR used the Johnson and Ettinger Model (tier-1) for Subsurface Vapor Intrusion to evaluatethe vapor intrusion pathway [7]. The screening model was run using the following inputs:maximum contaminant concentrations, depth below bottom of home (18 inches), depth belowgrade to water table (72 inches), average soil/groundwater temperature (48 F), and soil type(sand). Results of the initial modeling suggests that, based on worst case conditions, chlorinatedsolvent vapors could enter homes through crawl spaces and result in occupant exposure at lowlevels. Because this is an initial screening model, the results indicated the need for furtherinvestigation of this pathway.


OCCUPATIONAL EXPOSURE WATER COMPANY WORKERS

The American Conference of Governmental Industrial Hygienist's (ACGIH) Threshold LimitValue TLVs® for three of the contaminants of concern are the following: tetrachloroethene (25ppm); vinyl chloride (5 ppm), and TCE (50 ppm)[8]. ACGIH has not established a cis-dichloroethene. These exposure guidance values are based on an eight-hour time weightedaverage. Workplace concentrations of contaminants are unlikely to approach these valuesduring normal water company operations, based on the maximum concentrations detected ingroundwater. Workers may avoid dermal exposure to chlorinated solvent-contaminatedgroundwater by using the appropriate chemical resistant gloves (e.g., nitrile butyl rubber gloves).


CHILD HEALTH INITIATIVE

ATSDR's Child Health Initiative recognizes that the unique vulnerabilities of infants andchildren demand special emphasis in communities concerned about contamination of air andwater. Children are at greater risk than adults from certain kinds of exposures to hazardoussubstances released into their environment. Because children are smaller than adults, exposuremay result in higher dose per body weight. Also, children's developing body systems can sustaindamage if toxic exposures occur during critical growth stages. ATSDR has taken these factorsinto account in the development of this health consultation.


CONCLUSIONS

The predicted levels of chlorinated solvent vapors, including vinyl chloride, during showeringand bathroom use represent no apparent public health hazard to the Lockwood community,during short-term or intermediate term exposure (i.e., less than one year).

The low levels of chlorinated solvent vapors resulting from the use of contaminated well waterfor showering and bathing may present a public health hazard over long-term periods (severalyears) of exposure.

Results of the initial screening modeling suggest that low levels of chlorinated solvent vapor,including vinyl chloride, could possibly enter homes through home foundations by vaporintrusion. Breathing low levels of vinyl chloride vapor from vapor intrusion over long-termperiods would represent a public health hazard. However, additional sampling is necessary todetermine if this exposure pathway exists.

The anticipated levels of inhalation and dermal exposure resulting from outdoor use ofcontaminated well water by residents and workers of the Lockwood Water Users Association represent no apparent health hazard.


RECOMMENDATIONS

The recommendations listed below identify actions that ATSDR believes are prudent to reduceany potential health hazards that might be associated with long-term low level exposure tochlorinated solvents during showering and bathing.

The Environmental Protection Agency and the Montana Department of Environmental Qualityshould:

  1. develop and implement an alternate source of water supply for the Lockwood communityto prevent long-term exposure (e.g, longer than one year) to chlorinated solvents duringshowering and bathing.

  2. collect soil gas samples to investigate the vapor intrusion pathway into homes where thegroundwater contains greater than 0.005 mg/L of vinyl chloride. (Sampling shouldinclude active air samples for contaminants of concern.)

PREPARERS OF REPORT

Peter J. Kowalski, CIH
Environmental Health Scientist
Exposure Investigations and Consultations Branch
Division of Health Assessment and Consultation


Reviewed by

Susan Moore
Chief, Consultations Section
Exposure Investigations and Consultations Branch
Division of Health Assessment and Consultation

Greg Zarus
Atmospheric Scientist
Exposure Investigations and Consultations Branch
Division of Health Assessment and Consultation


REFERENCES

  1. Wan K. Jo, Clifford P. Weisel, and Paul J. Lioy; Routes of Chloroform Exposure and Body Burden from Showering with Chlorinated Tap Water; Risk Analysis.10(4) 575-580 (1990).

  2. Andelman, JB; Total Exposure to Volatile Organic Compounds in Potable Water. In Significance and Treatment of Volatile Organic Compounds in Water Supplies. LewisPublishers. Chelsea, MI. 485-504. (1990).

  3. Agency of Toxic Substances and Disease Registry. Toxicological Profile forTetrachloroethene. Atlanta: U.S. Department of Health and Human Services. PublicHealth Service. 1996.

  4. Agency of Toxic Substances and Disease Registry. Toxicological Profile for VinylChloride. Atlanta: U.S. Department of Health and Human Services. Public HealthService. 1997.

  5. Agency of Toxic Substances and Disease Registry. Toxicological Profile forTrichloroethylene. Atlanta: U.S. Department of Health and Human Services. PublicHealth Service. 1996.

  6. Agency of Toxic Substances and Disease Registry. Toxicological Profile for 1,2-Dichloroethene. Atlanta: U.S. Department of Health and Human Services. Public HealthService. 1996.

  7. User's Guide for the Johnson and Ettinger (1991) Model for Subsurface Vapor Intrusion into Buildings. Washington: U.S. Environmental Protection Agency.1997.

  8. 1998 TLVs® and BEIs®. Cincinnati: American Conference of Governmental Industrial Hygienists (ACGIH). 1998.

APPENDIX A: HEALTH CONSULTATION, LOCKWOOD SOLVENTS SITE, DECEMBER 9, 1999

ATSDR's approach to evaluating environmental data is to examine the pathways by which thepublic might be exposed. ATSDR looks for five elements of a completed exposure pathway.These elements are (1) a release of a chemical; (2) the mechanisms and media of transport (i.e.,how the chemical moves and whether it moves through air, soil, or water); (3) the point ofexposure (where actual or potential human contact with the chemical may occur); (4) the route ofexposure (such as eating, drinking, inhaling, etc.); and (5) the receptor population (details aboutthe people who may be exposed). If these elements are not present (or it is not reasonablypossible for all of the pathway elements to be complete), ATSDR notes that the pathway is notcompleted.

A completed exposure pathway is necessary for a health hazard to exist. The implications ofexposure are evaluated once a completed pathway has been established. The health effects frombreathing air contaminants depends on the type and amount of the contaminants, the duration ofexposure, and health of the exposure (receptor) population.

ATSDR uses media-specific comparison values (e.g., amount of chemical in air) to screen forfurther evaluation. ATSDR evaluated the type and amount of contaminants measured in the airsamples and compared them to ATSDR Minimal Risk Levels (MRLs) and American Conferenceof Governmental Industrial Hygienists (ACGIH) Threshold Limit Values (TLVs®).

MRLs are considered to be safe levels of exposure. They are developed using conservativeexposure assumptions and uncertainty factors and are generally much lower than exposureconcentrations noted to cause harmful health effects. MRLs are set below levels that, based oncurrent information, might cause adverse health effects in the people most sensitive to suchsubstance-induced effects. MRLs are established for acute (1-14 days), intermediate (15-364days), and chronic (365 days and longer) exposure durations, and for the oral and inhalationroutes of exposure. If the air contaminant levels are below the MRL, then the exposure isunlikely to be a public health concern. Due to conservative assumptions it should not beconcluded that a concentration greater than the comparison value will necessarily lead to harmfulhealth effects in healthy populations.

The ACGIH (ACGIH) Threshold Limits Values (TLVs®) represent the level of air contaminantsthat nearly all workers can be repeatedly exposed to without adverse health effects [3]. TLVs® are guidance values for occupational exposures that based on eight-hour time weighted averages.

Table of Contents



APPENDIX E: HEALTH CONSULTATION: LOCKWOOD SITE, MAY 3, 2000



HEALTH CONSULTATION

LOCKWOOD SITE
BILLINGS, YELLOWSTONE COUNTY, MONTANA
EPA FACILITY ID: MT0007623052

May 3, 2000

Prepared by:

Superfund Site Assessment Branch
Division of Health Assessment and Consultation
Agency for Toxic Substances and Disease Registry


TABLE OF CONTENTS

BACKGROUND AND STATEMENT OF ISSUES

DISCUSSION

TOXICOLOGICAL EVALUATION

CONCLUSIONS

RECOMMENDATION

REFERENCES

PREPARERS OF REPORT



BACKGROUND AND STATEMENT OF ISSUES

On March 29, 2000, the Agency for Toxic Substances and Disease Registry (ATSDR) received arequest from the U.S. Environmental Protection Agency (EPA) Region VIII to determine if thelevels of indoor air contaminants in two homes pose a health threat. These homes are located onLomond Lane in Lockwood, Montana above a groundwater plume contaminated primarily withtetrachloroethylene (PCE) and TCE (TCE). Several residents in the area are concerned aboutpossible exposures from vapors migrating into their homes and have requested that healthscreenings be conducted.

In December 1999, ATSDR issued a health consultation for this site evaluating several potentialhealth impacts from the groundwater contamination. One of the exposure pathways evaluatedwas the migration of VOCs into homes via soil gas. Based on the results of a screening model, ATSDR concluded that there was a possibility that vapors from the contaminated groundwatercould enter the foundations of homes, causing an indoor air health hazard. ATSDRrecommended that soil gas samples be collected from those homes under which groundwatercontained vinyl chloride at levels greater 0.005 milligrams per liter (mg/L).


DISCUSSION

On January 18, 2000, EPA collected indoor air samples from the crawl spaces and living spacesof the two homes having the highest PCE levels in the private wells. Four-hour samples werecollected onto carbon molecular sieve cartridges using a Gillian pump. EPA subsequently tooksteps to improve the indoor air quality in both homes by installing vents in the crawl spaces,placing air intakes in the attics, and replacing the duct work.

Based on ATSDR's previous evaluation of potential health impacts from indoor air contamination, the VOCs of concern for this site are tetrachloroethylene (PCE), TCE (TCE), vinyl chloride, and cis-1,2-dichloroethylene. In the first residence, PCE was found at 1500 ppb in the private groundwater well. Here, two indoor air samples were collected from the crawl space and one was collected from the dining room. The highest reported indoor air levels of PCE and TCE were 136.3 µg/m3 (or 20.1 parts per billion [ppb]) and 76.2 µg/m3 (or 14.2 ppb) respectively. Vinyl chloride was not detected. Cis-1,2-dichloroethylene was not included in the analysis. However, the highest level of trans-1,2-dichloroethylene was estimated at 1.5 µg/m3 (0.38 ppb) which is well below any level of health concern.

Other VOCs of concern were benzene, freon, methylene chloride, bromodichloroethane, andcarbon tetrachloride. In addition, the laboratory reported the presence of carbon dioxide andother matrix interferences in the samples. Since sorbent tube matrix samples cannot bereanalyzed, many of the contaminant levels had to be estimated.

In the second residence, where PCE was found at 990 ppb in the private well, one indoor air sample was collected in the crawl space and one was collected in the family room. The laboratory prepared the samples collected from this residence differently in order to prevent the matrix interference problems encountered with the samples from the first residence. The highest PCE and TCE levels found in the second residence were 34.9 µg/m3 (5.1 ppb) and 6.8 ug/m3 (1.3 ppb) respectively. Neither vinyl chloride nor trans-1,2-dichloroethylene were detected. Other VOCs of concern detected in the indoor air samples were chloroform, carbon tetrachloride, and benzene.


TOXICOLOGICAL EVALUATION

The highest reported PCE level (20.1 ppb) from these two homes was found in the living spaceand is lower than that which would be expected to cause any non-carcinogenic health effects. ATSDR's current comparison value of 40 ppb is based on increased reaction time in dry cleaningworkers exposed to an average of 15,000 ppb PCE for about 10 years and contains a safety factorof 100 [1]. A safety factor of 100 means that the comparison value is 100 times smaller than thelowest level shown to have any health effect. Therefore, even under the worst-case exposurefound in these air samples, no public health threat is likely.

Epidemiological studies of workers exposed to PCE have not provided clear evidence that PCEcauses cancer in exposed humans. The level of PCE detected in indoor air in these homes is wellbelow occupational exposure levels and would not be expected to pose a significant cancer risk.

The highest reported level of TCE (14.2 ppb) was also found in the living space. This level ismore than 1000 times lower than a level that has produced any adverse effect in animals, eithercancerous or non-cancerous [2]. Therefore, the levels of TCE found are not expected to pose anypublic health hazard to exposed adults and children.

Although methylene chloride was found at levels as high as 41.6 ppb, it is commonlyencountered as a laboratory contaminant and may not reflect the levels actually present in theindoor air. The remaining VOCs are not expected to cause adverse health effects.

It is important to note that many of the reported values were estimated because the levelsexceeded the laboratory's analytical instrument calibration range. Therefore, the actual levelsmay be somewhat higher than those reported. In March 2000, EPA conducted an additionalround of indoor air samples in the homes. The results of these analyses will be used to more accurately define the levels of indoor air contaminants in these homes.


CONCLUSIONS

  1. The reported levels of indoor air VOCs in the two homes on Lomond Lane are not likely to cause adverse health effects.

  2. The remediation undertaken by EPA to reroute air intakes in these homes is expected toreduce the VOC levels in the indoor air.

  3. Based on the available indoor air data, health screenings for adults and children are not warranted.

RECOMMENDATION

  1. Evaluate the results of additional air sampling when they become available to verify the validity of the above conclusions.

REFERENCES

  1. ATSDR. Agency for Toxic Substances and Disease Registry. Toxicological profile for Tetrachloroethylene. Atlanta: U.S. Department of Health and Human Services; September1997.

  2. ATSDR. Agency for Toxic Substances and Disease Registry. Toxicological profile for Trichloroethylene. Atlanta: U.S. Department of Health and Human Services; September1997.

PREPARERS OF REPORT

Gail E. Scogin
Environmental Health Scientist
Petitions Response Section
Exposure Investigations and Consultations Branch
Division of Health Assessment and Consultation


Reviewed by
:

Ken Orloff, Ph.D.
Toxicologist
Exposure Investigation Section
Exposure Investigations and Consultations Branch
Division of Health Assessment and Consultation

Maurice West, P.E.
Deputy Branch Chief
Exposure Investigations and Consultations Branch
Division of Health Assessment and Consultation

Table of Contents



3. The average background level is based on studies of indoor and outdoor air conducted by the EPA (Wallace 1987) . The average background level reported is the average of average background levels found at several locations around the United States.
4. cMRL = chronic MRL
iMRL = intermediate MRL
aMRL = acute MRL
5. The estimated VOC level in bathroom air is the same for adults and children because the amount of VOC evaporating into the air is not dependent upon who is taking a shower.
6. The estimated VOC level in bathroom air is different for adults and children because adults have a greater surface area for skin compared to children and therefore absorb more VOC during a shower. The increased intake of VOC via the skin is reflected as a higher concentration of VOC in bathroom air.
7. The estimated bathroom air level of VOC based on combined exposures from inhalation and dermal is less for children because their exposure via dermal intake is less.




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