Human health risk assessment of explosives and heavy metals at a ...

Environ Geochem Health (2007) 29:259–269 DOI 10.1007/s10653-007-9101-5

ORIGINAL PAPER

Human health risk assessment of explosives and heavy metals at a military gunnery range Hyerim Ryu Æ Joon Kyoung Han Æ Jae Woong Jung Æ Bumhan Bae Æ Kyoungphile Nam

Published online: 17 May 2007
Springer Science+Business Media B.V. 2007

Abstract In this research, a risk assessment was undertaken in order to develop the remediation and management strategy of a contaminated gunnery site, where a nearby flood controlling reservoir is under construction. Six chemicals, including explosives and heavy metals, posing potential risk to environmental and human health, were targeted in this study. A sitespecific conceptual site model was constructed, based on effective, reasonable exposure pathways, to avoid any overestimation of the risk. Also, conservative default values were adapted to prevent underestimation of the risk when site-specific values were not available. The risks posed by the six contaminants were calculated using the API’s Decision Support System for Exposure and Risk Assessment, with several assumptions. In the crater-formed-area (Ac), the non-carcinogenic risks (i.e., HI values) of trinitro-toluene (TNT) and Cd were slightly larger than 1, but for RDX (Royal Demolition Explosives) was over 50. The total non-carcinogenic risk of the whole gunnery range was calculated to be 62.5, which was a

H. Ryu  J. K. Han  J. W. Jung  K. Nam (&) Department of Civil, Urban and Geosystem Engineering, Seoul National University, 151-744 Seoul, Republic of Korea e-mail: [email protected] B. Bae Department of Civil and Environmental Engineering, Kyungwon University, 461-701, Seongnam, Gyeonggi-do, Republic of Korea

significantly high value. The carcinogenicity of Cd was estimated to be about 10
3, while that for Pb was about 5 · 10
4, which greatly exceeded the generally acceptable carcinogenic risk level of 10
4–10
6. It was concluded from the risk assessment that there is an immediate need for remediation of both carcinogens and non-carcinogens before construction of the reservoir. However, for a more accurate risk assessment, further specific estimations of the changes in environmental conditions due to the construction of the reservoir will be required; and more over, the effects of the pollutants to the ecosystem will also need to be evaluated. Keywords Explosives  Heavy metals  Military gunnery range  Risk assessment

Introduction Risk refers to the realistic hazard of a chemical of interest in a specific environmental medium and, thus, can be considered as functions of exposure and availability to the acceptors (Alexander 1995). Because a risk assessment focuses on the quantitative evaluation of adverse effects to potential receptors, the outcome can provide effective and scientific evidence in the decision making step for environmental management. Therefore, performing a risk assessment on pollutants in contaminated territories has become an essential procedure for managing

123

260

hazardous substances and developing remediation strategies (Khan and Husain 2001; MacDonald 2000; McGraph et al. 2004). Similar to areas polluted by industrial activities, on maneuver sites, explosive compounds, including 2, 4, 6-trinitrotoluene (TNT), hexahydro-1, 3, 5-trinitro-1, 3, 5-triazine (Royal Demolition Explosive, RDX) and octahydro-1, 3, 5, 7-tetranitro, 1, 3, 5, 7-tetrazocine (High Melting Explosive, HMX), as well as heavy metals, are likely to contaminate soil and surface water, and can also leach into groundwater (Best et al. 1999). TNT is one of the most widely used explosive compounds. RDX is an explosive chemical, which has found widespread application in detonators, grenades and bombs as well as a variety of other military ordnance. HMX, a more powerful explosive than TNT, is used as a trigger mechanism for atomic weapons, a component in plastic explosives and in rocket fuels (ATSDR 1997; USEPA 1998). The importance of these explosive compounds as environmental contaminants is related to their wide use on military sites and potential adverse effects to human and other ecological receptors. Many researchers studying the acute and chronic toxicities of these compounds have reported their toxicity via the oral route to mammals, birds, amphibians and reptilians (Johnson and McAtee 2000; Salice and Holdsworth 2001; USACHPPM 2001). Despite the danger, no environmental regulations for these explosives as pollutants have been established in many countries, including Korea. This makes the risk assessment of explosives and related heavy metals in military gunnery ranges even more crucial. The aim of this research was to assess the risks posed at the target site by three explosive contaminants (i.e., TNT, RDX and HMX) and three heavy metals (i.e., Cd, Cu and Pb) in order to develop subsequent remediation practice and management strategy. The risk assessment was performed in conjunction with the environmental impact assessment for a reservoir construction nearby the gunnery range.

Site characterization The military gunnery range under consideration is located in Y-gun of Gyeonggi-do province, Korea, and has been operated by the Korean Army for over

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20 years. The total population at Y-gun is 17,974 while those in towns W and G, which are directly adjacent to the gunnery range, are 1,459 and 4,569, respectively. The main economical activities of the inhabitants in the area are farming, breeding cattle and deer, and fishing. Most of the inhabitants are supplied with tap water from the nearby water supply facility. However, it has been reported that some residents, including the workers at the reservoir construction site, are directly using and drinking surface water. Additionally, it is planned that a portion of the considered area to be submerged when the flood controlling reservoir construction is completed (KOWACO and MOCT 2005). In this research, the site was divided into four zones according to the type of usage and the concentration of existing pollutants (Fig. 1). Zones of A (40,487.5 m2) and B (3,700 m2) were the reported impact zones of the gunnery range. However, a particular region in zone A, where craters had formed at the earth surface due to severe bombing, was separately considered as zone Ac (6,014.5 m2). Zone C (50,403 m2) is not geographically included in the gunnery range, but from a survey was also found to be contaminated by leaching events, and, therefore, was considered to have significant influence on the risk calculation due to the planned submersion of this area when the reservoir construction was completed. The soil at the target site was surveyed and found to be composed mainly of silty clay, which was always slightly wet on the surface due to insufficient drainage. The temperature and precipitation data for this site was provided from the local observatory. Concentration data of various contaminants in the target area were obtained during an environmental impact assessment for the reservoir construction. According to these data, the concentrations of copper and lead were estimated to be higher than the environment standards (KOWACO and MOCT 2005). Cadmium, however, was detected at a relatively low level, but was also considered a potential hazard due to its high distribution coefficient to crops. So far, there has been no investigation on explosive chemicals, due to the absence of legal environmental regulations, despite their toxicity. Three heavy metals (Cd, Cu and Pb) and three explosives (TNT, RDX and HMX) were finally selected for the present risk assessment; an additional investigation was conducted to obtain

Environ Geochem Health (2007) 29:259–269

261

Fig. 1 Zoning of the study site

detailed information of their concentrations in surface soil, deep soil, groundwater and surface water at each zone. The number of sampling points for soil samples at Ac, A, B and C were 7, 29, 10 and 28, respectively; whereas, groundwater and surface water sampling was conducted at eight and six different points, respectively (Bae and Kim 2006). The average concentrations of the six contaminants in each zone are shown in Table 1. The environment standards for Cd, Cu and Pb in Korea are 1.5, 50 and 100 mg/kg soil, respectively, with the concentrations of Cu and Pb on the site being relatively high, especially for Cu in zone Ac, which exceeds the standards.

The physicochemical properties and toxicities of the six target compounds are presented in Table 2. The properties of the heavy metals were obtained from the Physical Properties Database (PHYSPROP) of Syracuse Research Corporation (Syracuse Research Corporation 2005) and those of the explosive compounds were from USACHPPM (Johnson and McAtee 2000; Salice and Holdsworth 2001; USACHPPM 2001). Both heavy metals and explosives were estimated to possibly leach into the groundwater and surface water due to their high water solubility. However, mass transfer into the air was considered less important due to their low vapor pressures and

Table 1 Concentrations of the target pollutants in soil, groundwater and surface water Environmental media


1

Soil (mg kg )

Groundwater (mg l
1)
1

Surface water (mg l ) 1

Heavy metals

Explosives

Cd

Cu

Pb

TNT

RDX

HMX

A

0.131

9.74

16.9

0.00340

0.722

0.295

Ac

0.220

83.0

13.9

0.0580

13.4

0.470

B C

0.0735 0.117

3.12 5.78

3.48 5.77

0.00306 ND1

0.265 0.00203

0.0743 0.0165

0.00157

0.00729

ND1

ND1

ND1

ND1

0.00950

1

1

1

ND1

1

ND

ND

ND

ND

ND: Not detected

123

123 0.0308@ 258C

mmHg atm m3 mol
1 – – cm

Vapor pressure

Henry’s law constant

Organic carbon distribution coefficient

Soil distribution coefficient

Dispersion coefficient in air4
1

6

5

4

3

2

1

ND1

ND1

0.03916

ND1 0.03916

0.00045

B2

ND1

The Institute for Environmental Research, Yonsei University 1995

RfD of copper and lead were derived from the level identified as safe for drinking water

Bae 2002

NA2

ND1 NA2

0.0005

C

6.71 · 10
6

0.064

300

14.33

ND1

4.57 · 10
7@ 208C

1.99 · 10
4@ 208C

130@ 208C

1.654

80.1

227.13

C7H5N3O6

0.0245@ 258C

3.02 · 10
9@ 258C

9,580@ 258C

11.3

327.5

207.20

Pb

Organic carbon distribution coefficient of lead was estimated with PcKoc presented by US EPA

NA: Not applicable

ND: No data

NA2

kg day mg
1

Inhalation slope factor

6.3

ND1 NA2

mg kg
1 day
1 ND1 kg day mg
1 NA2

Inhalation reference dose Oral slope factor

D 0.0375

B1

–

ND

1

ND1

mg kg
1 day
1 0.0005

ND

1

ND1

2.47

–

0.0245@ 258C

ND1

1083

63.55

Oral reference dose

cm s

2

37

–

112.40

Carcinogen Class (IRIS)

Dispersion coefficient in water

4.14 · 10
9@ 258C

mg l
1

Water solubility

s
1

123,000@ 258C

g cm
3

Density

2

4.24 · 10
9@ 258C

8.64

8C

4

421,000@ 258C

321

g mol

Cu

Melting point

Cd

Molecular weight


1

–

Molecular formula

TNT

Lead

Cadmium

Copper

Explosives

Heavy metals

Unit

Property

Table 2 Physicochemical properties and toxicities of the target pollutants

NA2

ND1 NA2

0.003

C

7.15 · 10
6

0.074

ND1

6.918

1.2 · 10
5

4.0 · 10
9@ 208C

38.4@ 20–258C

1.82

205–206

222.26

C3H6N6O6

RDX

NA2

ND1 NA2

0.05

D

6.02 · 10
6

0.063

ND1

3.4674

2.60 · 10
15@ 258C

3.33 · 10
14@ 208C

5–6.63@ 20–258

1.9

276–280

296.16

C4H8N8O8

HMX

262 Environ Geochem Health (2007) 29:259–269

Environ Geochem Health (2007) 29:259–269

Henry’s law constants compared to their water solubilities. All of the materials of interest, especially cadmium and lead which are known as possible carcinogen when contacted through ingestion or inhalation, are toxic to human.

Conceptual site model The conceptual site model (CSM) is a tool that evolves with the progression of site work as data gaps are filled. The development of the CSM should be viewed as a process throughout the whole duration of a project; from the initial characterization to the final response action, with recurring reviews until project closeout. It can help to focus on both general regulatory and more site-specific project objectives. An effective CSM needs facility, physical, release, land use and exposure and ecological profiles (USACE 2003). The risk assessment in this research focused on the inhabitants who will reside near the gunnery range after completion of the reservoir construction, but no information is currently available to specifically predict the demographics of the area. Thus, it was assumed that every risk receptors will inhabit the target site, and their farming and stockbreeding activities will also occur in the site, in order to avoid underestimation of the risks. A CSM was constructed to consider the sitespecific exposure pathways of the contaminants

263

(Fig. 2). For the worst-case-scenarios, all of the effective pathways, including minor and potential exposure pathways, were considered without any weighting factors. The general assumptions were as follows: firstly, heavy metals and explosives are released from the gunnery range to various environmental media. They then reach the receptors, either directly or indirectly, through the food chain or human action. Inhalation of surface soil indicates the inhalation of contaminated soil particles, which can be estimated using the Cowherd particulate emissions model. Exposure to contaminated surface water includes contact with both irrigation and domestic waters. Food chain pathways include ingestion of vegetables, crops, meats and fish.

Risk calculations The gunnery range has been in operation at this site for a sufficient duration (i.e., over 20 years), and therefore, the distribution of contaminants was assumed to have reached equilibrium. Thus, the measured data of the contaminant concentrations in each environmental medium were able to be directly used for risk calculations. In addition, chemical and biological degradation of the contaminants were assumed to be negligible. When conducting the risk assessment of the target site, only exposure pathways concluded to be

Fig. 2 Conceptual site model for the gunnery range

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Environ Geochem Health (2007) 29:259–269

Table 3 Parameters and values used for API’s DSS Properties

Unit

Zone Ac

Jury model

AT123D model

Box model

A

B

C

Effective porosity

–

0.25

0.25

0.25

0.3

Water content

(v/v)

0.19

0.223

0.231

0.3

Soil bulk density

g cm
3

1.8

1.8

1.8

1.8

Thickness of incorporation

m

0.3

0.3

0.3

0.3

Thickness of incorporation

m

0.001

0.001

0.001

0.001

Boundary layer thickness

cm

0.1

0.1

0.1

0.1

Unsaturated zone depth Fraction organic carbon

m –

5 0.034

20 0.058

20 0.082

0.001 0.054

Infiltration

cm year
1

30

30

30

30

Length

m

242.31 484.62

68.64

266.30

Width

m

51.92

68.64

266.30

173.08

Aquifer width and depth

–

infinite infinite

infinite infinite

Hydraulic conductivity

m year
1

12.906 12.906

12.906 12.906

Hydraulic gradient

m m
1

0.1

0.1

0.1

Longitudinal dispersivity

–

0.1

0.1

0.1

0.1

Transverse dispersivity

–

0.02

0.02

0.02

0.02

Vertical dispersivity

–

0.002

0.002

0.002

0.002

Average wind speed

m s
1

2.9

2.9

2.9

2.9

Source area

m2

6014.5 40487.5 3700

50403

Mixing height

m

2

2

2

2

Mixing width

m

77.55

201.22

60.83

224.51

30 4.3

30 4.3

30 4.3

– – –

Cowherd particulate emissions model Frequency of disturbance Fastest wind speed Erosion threshold wind speed

day month m s
1 m s
1


1

0.1

1

1

1

Fraction of area with vegetative cover –

0.99

0.99

0.99

–

PE index

100

100

100

–

–

Table 4 Main exposure parameters and factors Category

Unit

Submitted value

References

Average body weight of a Korean adult

Kg

65

Institute of Environmental Research, Yonsei University 2001

Daily air inhalation of Korean

m3/day

20

Institute of Environmental Research, Yonsei University 1995

Daily water ingestion of Korean

l/day

2

Institute of Environmental Research, Yonsei University 1995

Daily soil ingestion

kg/day

2.1 · 10
5

API 1999

Average body surface area of a Korean adult

cm2

15326

Institute of Environmental Research, Yonsei University 1995

Dermal contact coefficient

mg/cm2

1

API 1999

Skin permeability to inorganic substances

–

0.001

USEPA 2000a

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Environ Geochem Health (2007) 29:259–269

265

effective and reasonable were considered, to avoid any overestimation of the risk; however, at the same time, conservative default values for site-specific properties of each selected pathways were also adapted to prevent any underestimation. The carcinogenic and non-carcinogenic risks of the six contaminants were calculated using the API’s Decision Support System for Exposure and Risk Assessment (API 1999). Table 3 shows the site-specific properties used in contaminant transport models. Most of the coefficients concerned with human exposure routes were obtained from previous studies (Institute for Environmental Research, Yonsei University 1995, 2001), which are particularly suited to Koreans (Table 4). Skin permeability values of the contaminants were calculated using Dermwin, as presented in the USEPA (USEPA 2000a). (Table 4) The risks posed by the exposure of chemicals through the food chain were separately calculated by integrating data from previous studies (Bae 2002). As no ingestion data suited to Koreans were available, the U.S. standards were adopted in this study. Food ingestion was considered via four different pathways: by fruit & vegetables, by grains, by meat and by fish. The ingestion rates of each category of food to human were calculated by multiplying the existing concentration of the contaminants in the environmental media with the uptake coefficient of the food considered, Pathway-exposure factors (PEFs) and the Human Ingestion Factor. The PEF values and transfer coefficient of chemicals are listed in Tables 7 and 8, respectively. The oral risks were calculated by considering all four pathways for exposure to the six chemicals. However, for Cu and Pb, the valid pathway to humans was assumed to be only through the ingestion of fish due to lack of data of plant uptake from soils. The general numeric expressions for calculating the risk of non-carcinogenic and carcinogenic contaminants are as follows: Non
carcinogenicRisk ¼ HI ¼

n X

HQ

n X ½C  ½RC&EC I¼1

CarcinogenicRisk ¼

n X I¼1

The risk-calculating equation consists of three elements; the contaminant concentrations, the receptor and exposure characteristics, and the reference dose or slope factor. The RC and EC values vary with respect to the exposure situation and receptor activities, which includes factors, such as the exposure frequency, exposure duration, daily intake rate, daily inhalation rate, absorption factor, skin surface area, body weight of receptors and averaging time, and so on. The hazard index (HI) is a measure that refers to the non-carcinogenic risk, and is computed by summing the hazard quotient (HQ), which is the value of the daily intake divided by the reference dose of a particular pathway and chemical. The slope factor is an upper-bound estimate of a chemical’s probability of causing cancer over a 70-year lifetime, which is also referred to as the cancer potency factor. The reference dose is an estimated maximum level of daily exposure of a chemical to humans that can arise from any deleterious effects during life time. These values are identical for each substance, and can be obtained by laboratory tests or from references. The slope factors used in this study were obtained from the U.S. EPA’s Integrated Risk Information System (IRIS) database (USEPA 2005), which is widely regarded as a reliable source. However, the slope factors of lead, not available from the IRIS database, were adapted from the values estimated by the Institute of Environmental Research, Yonsei University (IERY), using a multistage model in the TOXRISK package (Institute for Environmental Research, Yonsei University 1995). Results and discussion

I¼1

¼

HI: Hazard index HQ: Hazard quotient C: Concentration of contaminants RC: Receptor characteristic EC: Exposure characteristic i: Individual exposure routes RfD: Reference dose SF: Slope factor

I

½RfD

½C  ½RC&ECI  ½SF

Based on the CSM (Fig. 2), the hazard quotient (HQ) of each pollutant was calculated for each exposure pathway and route in zones A, Ac, B and C to estimate the non-carcinogenic risk. The results are listed in Table 7, and a pollutant can be regarded safe or acceptable when the HQ is less than 1. The calculated results show that the values varied widely

123

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Environ Geochem Health (2007) 29:259–269

Table 5 Calculated hazard quotients and hazard indices of the target pollutants Soil Soil dust

A

Surface soil

Water

Vegetable Crop

Meat

Fish

Hazard Index

Drinking Shower

Inhalation Dermal contact

Ingestion Ingestion

Ingestion Ingestion Ingestion Ingestion Dermal contact

0.356

0.575

0.003

10
3

NA1

Cu

NA

1

0.013


3

10

NA

1

Pb

NA1

0.198

0.002

NA1

NA1

10
3

NE2

TNT

NA1

 10
3

10
3

0.047

0.034

10
3

0.012

10
3

1.669

1.198

0.021

0.024

10

NA1

0.964

10
3

NE2

NE2


3

2

2

Cd

RDX NA1


3


3

NA

1

Inhalation

10
3

NE2

NE2

NE2

NE2

0.934


3

2

2

2

NA1

0.013

NE2

NE2

NA1

0.200

NE2

NE2

NE2

NA1

0.081

10
3

NE2

NE2

NE2

NA1

2.879


3

2

2

2

1

0.150 4.257

NE2

NE2

1.216

2

NA1

0.109

10

NE

NE

NE

1

 10

 10

Cd

0.23

0.021

 10
3

Cu

NA

1

0.108

0.001

NA

Pb

NA1

0.163

0.002

NA1

NA1

10
3

NE2

NE2

NE2

NA1

0.165

TNT

NA1

0.006

10
3

0.803

0.577

0.002

NE2

NE2

NE2

NA1

1.388

2

2

2

1

HMX NA Total Ac

Food chain

RDX NA

1

HMX NA1

1

NA

1

10


3

NE

NE

NE

NE

NE

NE

NA

0.214

0.002

30.877

22.175

10

10
3

10
3

0.033

0.089

10
3

NE2

NE2

NE2

NA1

NE

NE

NE

NA

Total B

0.123 56.270

Cd

0.06

0.007

10
3

NA1

0.323

10
3

NE2

NE2

NE2

NE2

0.390

Cu

NA1

0.004

10
3

NA1

NA1

10
3

NE2

NE2

NE2

NA1

0.004

Pb

NA

1

0.041


3

10

NA

1

1


3

2

2

2

1

0.041

TNT

NA1

10
3

10
3

0.042

0.030

10
3

NE2

NE2

NE2

NA1

0.073

RDX NA1

0.004

10
3

0.611

0.439

10
3

NE2

NE2

NE2

NA1

1.055

HMX NA1

10
3

10
3

0.005

0.004

10
3

NE2

NE2

NE2

NA1

0.009

NA

10

NE

NE

NE

NA

Total C

53.269

1.572

Cd Cu

2

NE NA1

2

NE NE2

2

NE NE2

1

NA NA1

2

NE NA1

2

NE NE2

2

NE NE2

2

NE NE2

2

NE NE2

2

NE NA1

NR3 NR3

Pb

NA1

NE2

NE2

NA1

NA1

NE2

NE2

NE2

NE2

NA1

NR3

NA

1

NE

2

NE

2

NE

2

NE

2

NE

2

NE

2

NE

2

NE

2

NA

1

NR3

RDX NA

1

NE

2

NE

2

NE

2

NE

2

NE

2

NE

2

NE

2

NE

2

NA

1

NR3

NA1

NR3

TNT

HMX NA1

NE2

NE2

NE2

NE2

1

1

NE2

NE2

NE2

NE2

NR3

Total 2


3

GW Cd

–

–

–

NA

0.099

10

0.416

0.515

Cu

–

–

–

NA1

NA1

10
3

NE2

0.006

10
3

NA1

0.006

–

–

–

NA1

NA1

10
3

10
3

0.008

10
3

NA1

NA

10


3

NE

Total SW Cu

0.521

HI of the total gunnery range

62.628

1

NA: Not applicable (No reference dose or pathway-exposure factor)

2

NE: Applicable but non-effective exposure pathway

3

NR: No Risk (either for no available data or for non-effective pathways or both)

throughout the areas and with respect to pollutants. The hazard index, the summation of HQ values, indicates the total risk of the area. The HI value was largest in the area designated as Ac, due to very high

123

0.008

concentrations of Cu, Pb and RDX. Particularly, the non-carcinogenic risk of RDX has an extremely high value, 53.3. In contrast to the cases of Cu and Pb, where the RfD values for inhalation and human

3

2

1

NE

NA

1

2

Cd

NE2

NE2

Pb

NA

1

2.80 · 10

NA

1

1.12 · 10

NA

NE

2

2.39 · 10


5

8.16 · 10


5

1.22 · 10


4

3.11 · 10

1


6


5

1.36 · 10
5

NA

Cd

Pb

Cd

Pb

Cd

3.85 · 10
4

Pb


4

4.81 · 10

Cd


7


8

NA

1

NE2

NA

1

2.87 · 10

NA

1

1.15 · 10

NA

1

1.39 · 10
7

NA

1

NA

1

NE2

NA

NE

1

2

NA

NE

2

NA

1

NE2

NA

1

Ingestion

NR: No carcinogenic risk (or acceptable risk)

NE: Applicable, but a non-effective exposure pathway

NA: Not applicable (No reference dose or pathway-exposure factor)

GW

C

B

Ac

A

1

Ingestion

Dermal contact

Inhalation

1

Vegetables

Surface soil

Soil dust


4

Food chain

Soil

Table 6 Carcinogenic risks by cadmium and lead at the target site

1

NA

1

NE2

NA

NE

1

2

NA

NE

2

NA

1

NE2

NA

1

Ingestion

Crops


10


10

NA

1

NE2

NA

1

2.20 · 10

NA

1

8.80 · 10

NA

1

1.07 · 10
9

NA

1

Ingestion

Meats

1

NA

1

NE2

NA

NE

1

2

NA

NE

2

NA

1

NE2

NA

1

Ingestion

Fish

1

NA

1

NE2

NA

NE

1 2

NA

NE

2

NA

1

NE2

NA

1

Ingestion

Drinking

Water

1

NA

1

NE2

NA

NE

1 2

NA

NE

2

NA

1

NE2

NA

1

Dermal contact

Shower

2

2

2

2


4

5.62 · 10

NE2

NE

NE

NE

NE

NE

2

NE2

NE2

Inhalation

5.62 · 10
4

NR3

NR3

2.67 · 10
5

8.16 · 10
5

1.33 · 10
4

3.11 · 10
4

3.99 · 10
4

4.81 · 10
4

Carcinogenic risk

Environ Geochem Health (2007) 29:259–269 267

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Environ Geochem Health (2007) 29:259–269

Table 7 Formula for calculating pathway-exposure factors (PEFs) through ingestion Soil (kg/kg-day)

Drinking water (L/kg-day)

Water

Surface water (L/kg-day)

0.034

Fruit and vegetables

1.1 · 10
3 · Ksp

Grain Meat

7.9 · 10
4 · Ksp [0.012 + (0.038 · Ksp)] · Bt

0.14 · Bt 3.2 · 10
4 · BCF

Fish 1.5 · 10

Soil


6

Ksp: Soil/Plant distribution coefficient Bt: Meat/diet biotransfer factor in cattle BCF:Bioconcentration factor in fish

Table 8 Transfer coefficients of chemicals between different media Soil/plant distribution coefficient (Ksp)

Meat/diet biotransfer factor in cattle (Bt)

Bioconcentration factor in fish (BCF)

Cd

2.78

2.14E-08

3.162

Cu

0

6.76E-09

3.162

Pb HMX

0 3.2

1.35E-07 3.40E-08

3.162 0.5

RDX

6.3

1.90E-07

5

TNT

6.3

7.20E-05

10

toxicity factor through digesting farmed crops are not well known, the soil-plant distribution rate of RDX was relatively high, having a similar value, 6.3, to that of HMX. Therefore, for all the areas, with the exception of zone C, the extents of exposure via vegetables and crops were very high and the HI values for RDX were over 1. The non-carcinogenic risks of TNT and Cd had values slightly larger than 1 in zone Ac. For RDX, the calculated non-carcinogenic risk was over 50 in zone Ac, and greater than 1 in every zone, with the exception of zone C. However, in zone C, which is contaminated by chemicals leaching from the gunnery range and planned to be submerged after the completion of the reservoir construction, leaching of contaminants from the soil to surface or underground water was not included in the assumption; thus, the exposure pathways were considered invalid and the risk to be negligible. For HMX, Pb and Cu, the risks were under 1 in every area, so were assumed to possess no significant risks. The calculated non-carcinogenic risk of the total gunnery range was found to have a significantly high value, 62.6, implying an extremely

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hazardous situation. The resultant HI was simply the summation of HQ values. However, the possibility exists for interactions between different chemicals. Those interactions may alter the actual risk, leading to the requirement for a new approach to estimate the risk for chemical mixtures (USEPA 2000b). Therefore, further consideration of the interactions between chemicals may be needed to improve the accuracy of the current assessment. Of the six target chemicals, carcinogenicity values have only been reported for Cd and Pb. Cadmium is classified as a group B1 substance (probable carcinogen and have evidence for effect on human) by the US EPA and is reported to show carcinogenic effects when inhaled (USEPA 2005). Lead is classified as a group B2 substance, exhibiting a possibility of cancer when ingested or inhaled. These exposure routes were considered to be invalid for the carcinogenicity; therefore, were not included in the risk calculations. High levels of Cd and Pb were detected in every divided area of the target site, and Cd was also found in the groundwater. The carcinogenicities of Cd and Pb in the site were estimated to be about 10
3 and 5 · 10
4,

Environ Geochem Health (2007) 29:259–269

respectively (Tables 5 and 6), which greatly exceed the generally acceptable risk level of 10
4–10
6. The results from the risk assessment suggest that an immediate remediation practice for both carcinogens and non-carcinogens are required before the construction of the reservoir. However, for a more accurate risk assessment, further specific estimations will be required on condition shifts after the construction of the reservoir is completed. Moreover, the effects of the pollutants to the ecosystem will also need to be evaluated. Acknowledgements This research was sponsored by the KOSEF through the Advanced Environmental and Biotechnology Research Center (AEBRC) at POSTECH. An additional financial support was also made by the Basic Research Program of the Korea Science & Engineering Foundation (Grant No. R01-2006-000-10136-0). The authors would also like to thank the Research Institute of Engineering Science, Seoul National University, for their technical assistance.

References Alexander, M. (1995). How toxic are toxic chemicals in soil? Environmental Science and Technology, 29, 2713–2717. American Petroleum Institute (API). (1999). API’s Decision Support System for Exposure and Risk Assessment Version 2.0. Washington, DC: Health and Environmental Sciences Department Agency for Toxic Substances and Disease Registry (ATSDR). (1997). Toxicological Profile for HMX. Atlanta, GA: U.S. Department of Health and Human Services Bae, B. H. (2002). Research on prediction and remediation of water quality of Hantan river dam by accurate inspection of existing heavy metals and explosive chemicals in Darakdae gunnery range, KOWACO. Bae, B. H., & Kim, M. K. (2006). Distribution and transport of contaminants (heavy metals and explosives) in military gunnery range in Korea, Proceedings of 2006 Autumn Conference of Korean Society of Soil and Groundwater Environment (pp. 53–56). Daejeon, Korea: KAIST. Best, E., Sprecher, S., Larson, S., Fredrickson, H., & Bader, D. (1999). Environmental behavior of explosives in groundwater from the Milan Army Ammunition Plant in aquatic and wetland plant treatments. Removal, mass balances, and fate in groundwater of TNT and RDX. Chemosphere, 38, 3383–3396 Institute for Environmental Research, Yonsei University. (1995). Environmental Impact Assessment and Management: EIA and Management for Water Pollutants. Korea: Ministry of Environment Institute for Environmental Research, Yonsei University. (2001). Environmental Impact Assessment and Manage-

269 ment: Development of Integrated Risk Assessment and System for Environmental Pollutants. Korea: Ministry of Environment Johnson, M. S., & McAtee, M. J. (2000). Wildlife Toxicity Assessment for 2,4,6-Trinitrotoluene, U.S. Army Center for Health Promotion and Preventive Medicine (USACHPPM) Project Number 39-EJ-1138–00, Aberdeen Proving Ground, MD Khan, F. I., & Husain, T. (2001). Risk-based monitored natural attenuation – a case study. Journal of Hazardous Materials, B85, 243–272 Korea Water Resources Corporation (KOWACO), Ministry of Construction & Transportation of Korea (MOCT). (2005). Environmental Impact Assessment on Gunnam flood control reservoir construction site (draft), Ministry of Construction & Transportation of Korea (MOCT), Korea. MacDonald, J. A. (2000). Evaluating natural attenuation for groundwater cleanup. Environmental Science and Technology, 34, 346A–353 McGraph, D., Zhang, C. S., & Carton, O. (2004). Geostatistical analyses and hazard assessment on soil lead in Silvermines, area Ireland. Environmental Pollution, 127, 239–248 Salice, C.J., & Holdsworth, G. (2001). Wildlife Toxicity Assessment for 1,3,5-Trinitrohexahydro-1,3,5-Triazine (RDX), U.S. Army Center for Health Promotion and Preventive Medicine (USACHPPM), Project Number 39-EJ1138-01B, Aberdeen Proving Ground, MD. Syracuse Research Corporation (SRC).(2005). The Physical Properties Database (PHYSPROP) 2005 November updated, http://www.syrres.com/esc/physprop.htm US Army Corps of Engineers (USACE). (2003). Conceptual site models for ordnance and explosives and hazardous, toxic, and radioactive waste projects. US Army Center for Health Promotion and Preventive Medicine (USACHPPM). (2001). Wildlife Toxicity Assessment for HMX, Project Number 39-EJ-1138–01E, Aberdeen Proving Ground, MD. US Environmental Protection Agency (USEPA). (1998). Health advisory for octahydro-1,3,5,7-tetranitro, 1,3,5,7tetrazocine (HMX), PB90-273525, Prepared by the Office of Drinking Water, Washington, DC, for the U.S. Army Medical research and Development Command, Fort Detrick, Frederick, MD. US Environmental Protection Agency (USEPA). (2000a). Dermwin v1.43, Estimation Program Interface (EPI) Suite, Syracuse Research Corporation (SRC) and U.S. Environmental Protection Agency’s Office of Pollution Prevention and Toxics, Washington, DC. US Environmental Protection Agency (USEPA). (2000b). Supplementary Guidance for Conducting Health Risk Assessment of Chemical Mixtures. Washington DC: Risk Assessment Forum. US Environmental Protection Agency (USEPA). (2005). Integrated Risk Information System (IRIS) Database for Risk Assessment 2005 updated, U.S. Environmental Protection Agency’s Office of Research and Development, National Center for Environmental Assessment, Washington, DC.

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