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Evaluation of military activity impact on humans through a probabilistic ecological risk assessment. Example of a former missile base.

1. INTRODUCTION

Military activity is conducted in 'military areas' [1]. that are of significant value to environmentalists despite the widespread outcry about being badly Polluted. Such areas often occupy hundreds of thousands of hectares of land. After the 'cold war' and the inherent reduction of armies and weapons, these areas can be used as reserves, or used for agricultural or recreational purposes. It is clear that, as case may be, in order to decide their further use it is necessary to evaluate the degree of land contamination and the possible impact of pollutants on environmental objects to be used in the conduct of activities in such areas.

To make the right decision it is desirable to have particular criteria certain indicators of environmental condition that characterize both the danger to humans and for biota. The environmental risk--"probable damage to human life or health, environment, life or health of animals and plants considering the severity of the damage" [2] is a convenient criterion in this regard.

The method of ecological risk assessment of chemical pollutants' impact on humans and the biota is given by this article using an active military range as an example [3]. Deterministic assessment criteria, namely fixed parameters (e.g. assumed human body weight of 70 kg, the concentrations of chemicals in the soil the average of several etc.) are employed to evaluate risks.

The following cases are used depending on the importance of the problem, when deterministic data use:

* risk assessment based on the use of average reference values;

* risk assessment based on the largest values of reference variables that should be expected at a given location, usually 90th or 95th percentiles of value distribution.

Obviously, the latter case is used for conservative estimation when it is important to avoid underestimating the danger. In this case, if the level of acceptable risk is exceeded it is neccessary to apply measures to reduce it, and excessive conservatism may cause serious unjustified expenses. At the same time, using only averaged values of reference values while estimating the risk can lead to its underestimation for certain vulnerable categories of population or ecosystem components.

Probabilistic risk assessment uses probability distributions instead of point values of reference variables to calculate the risk, ultimately getting to a probabilistic distribution of risk values. In this case it is possible to derive the value of the probability of exceeding the risk level that is of interest, namely to quantify the uncertainty value, which is not possible while using determined values. Thus, probabilistic risk assessment provides unique and important additional information that is used for optimal risk management.

The aim of this paper is to show the importance and usefulness of applying the probabilistic risk assessment method for people living in a polluted environment by using a specific example.

2. RESEARCH SCOPE AND RESULTS

The scope of this article is supported by research [4] dealing with the condition of environment after termination missile base related activities.

The geographic area of concern for the article is the Zhytomyr Region (Ukraine) that housed the missiles complexes of the former Soviet Union (medium-range missiles 8K63, SS-4 <<Sandal>>, by NATO classification) between 1958 and 1989.

After the termination of the base its area was not exploited, and the locals living near the base had free access to its former area. The analysis of soil and water from open sources near the base, as well as the composition of water from underground springs, that local population use as drinking water, was conducted to determine the degree of contamination of the territory. The content of chemicals in objects under the study is given in Table 1.

2.1. Deterministic risk assessment

The evaluation of chemical compounds effect on human health and biota was initially conducted via deterministic risk assessment. The risk of chemical effects is determined by comparing the values of cancer risk CR and noncancer hazard index HI of acceptable values (Table 2).

The impact of pollutants on humans occurs with the use of contaminated water from underground sources and consumption of plants growing on contaminated soil as small surface water sources are used neither for agricultural, nor for recreational purposes. For the puposes of the analysis, let us consider the risk of carcinogenic and noncarcinogenic compounds on human health.

Carcinogenic risk is determined based on equation (1)

CR = [summation] [ICR.sub.i], (1)

where CR represents the value of full individual cancer risk caused by the action of carcinogens [N.sub.R];

ICR--the value of individual cancer risk caused by the action of the jth-carcinogen;

[N.sub.R]--total number of carcinogens.

ICR = ADD x SF, (2)

where ADD is the daily dose of harmful chemical consumed by the recipient;

SF--cancer slope factor for the substance, which characterizes the degree of increase in cancer risk along with the increasing of dose per unit.

Noncarcinogenic risk is determined by hazard index HI

HI = [summation over (j=1)] [HQ.sub.j], (3)

where HQ--hazard quotient of jth-substance;

N--total number of hazardous substances.

HQ = ADD/RfD, (4)

where RfD--reference dose, the value that characterizes the daily effect of the chemical during lifetime and probably does not put sensitive groups at health risk.

The average daily dose of ADD is determined from the equation (5),

ADD = ([C.sub.w] x C[W.sub.w] x E[F.sub.w] x E[D.sub.w]) + ([C.sub.f] x C[W.sub.f] x E[F.sub.f] x E[D.sub.f])/BW x AT, (5)

where C--concentration of the chemical;

CW--quantity of drinking water and food consumed by a person per day;

EF--frequency of action, the number of days per year;

ED--action duration, number of

years;

BW--average human body weight during exposure;

AT--averaging period of exposure in days.

Indexes <<w>> and <<f>> relate to drinking water and food, respectively.

Obviously, when calculating food consuming risk, we mean the additional risk caused by consuming products grown on the territory of the former missile base.

The territory of the former base is not used for agriculture, but locals pick up and consume wild berries and mushrooms.

The concentration of chemicals in food [C.sub.f] is determined from the equation (6)

[C.sub.f] = [C.sub.s] x U[F.sub.p], (6)

where C--concentration of the chemical in the soil;

U[F.sub.p]--factor of bioaccumulation of chemicals by plant from the soil.

U[F.sub.p] values which borrowed from [5] are presented in Table 3.

Risk calculations were carried out separately for adults and children. Initial data are presented in Table 3. Table 4 presents the results of calculations.

The above presented calculation shows that, from the toxicological point of view, underground water sources and plants grown in the soils of the former base, practically are not dangerous for people who consume them.

However, consumption of water from underground horizons has a significant carcinogenic hazard. The value of risk is within [10.sup.-3] - [10.sup.-4] and basically is unacceptable for the civilian population. It is clear that in a case like this it is advisable to conduct more complex probabilistic risk assessment since the environmental decisions, based on the results of deterministic evaluation, require additional expenditures on risk reduction.

2.2. Probabilistic risk assessment

While applying probabilistic risk assement, instead of point values of reference variables we use their probabilistic distributions, which are used as substitutions in the models for risk assessment. Thus, by employing the Monte Carlo method [7] we ultimately determine probability distribution of risk values. The Monte Carlo method suggests random selection of fixed values of the probability distributions of reference values and using them in models that form a decision. After a number of iterations you can build a distribution of desired value.

A probabilistic approach should include all components of the evaluation process. However, in practice only the component of exposure assessment is usually employed, at least in assessing the impact of pollutants on human health. In this respect, it is recommended to use values RfD and SF as point values till receiving additional data [6].

Thus, to determine risk probability values (equation (1) and (3)), it is necessary to determine the distribution of the average daily ADD dose of chemical substances that enter a human body with drinking water (receiving carcinogens from plants grown in contaminated soil will be neglected). This can be done by substituting probabilistic values of reference values in equation (5) and determining distribution of ADD by the Monte Carlo method. Except for the concentration of a [C.sub.w] chemical, other values are common" physiological parameters of human body and for that reason surrogate data defined in a different place can be used. For example, according to [6]

ADD = ([C.sub.w] x IRW)/1000, (6)

where ADD--normalized per mass unit daily dose of a chemical mg / (kg x day);

[C.sub.w]--concentration of the chemical in drinkwing water, mg / 1;

IRW--normalized per mass unit amount of drinking water, consumed by person per day, ml / (kg x day).

It is estimated [6], that IRW has the form of lognormal distribution with parameters depending on the age of the person consuming water. Hypothesizing that the data scatter on the concentration of harmful substances in water has normal distribution and is defined only by time variability, equation (6) can determine the distribution of ADD, and equation (1) can determine the distribution of CR. Initial data for the lognormal distribution IRW are given in Table 5, and normal distributions of [C.sub.w] are presented in Table 1 (for each w substance the values of the average concentration and its standard deviation are given).

[mu]--average value of the natural logarithm IRW; [sigma]--standard deviation of the natural logarithm IRW.

Risk assessment was conducted for children aged 1-6 and for adults aged 20-75.

Modeling was performed using spreadsheet Excel[R] with adding superstructure Crystal Ball[R]. Graphically the distribution of risks is reflected in Figure 1. The same figure demonstrates the risk values while using determined risk values for children and adults (straight lines).

From the figure it is clear that the use of deterministic exposure values gives rather too conservative risk assessment, especially for adults. More precise values are in smaller quantities. It is possible to state that for 90% of children, consuming water, risk value does not exceed 4,16 x [10.sup.-4], for 90% of adults 3,21 x [10.sup.-4].

3. CONCLUSION

Probabilistic risk analysis provides additional, more accurate information for decision making about the application of environmental protection measures. Often it enables to decrease expenses for conducting these measures.

REFERENCES

[1] KUSTROVA, M.: Nature Conservation Projects In Military Districts. / Journal of Defense Resourses Management. -2014, V.5, 1, P 105-112.

[2] Human and Ecological Risk Assessment: Theory and Practice// Dennis J. Paustenbach (Ed.).--New York, NY: Wiley, 2002.--1586 p.

[3] OREL, S., IVASCHENKO, O. Ecological safety management of forces through ecological risk assessment. / Science & Military.--2014, V.9, No.1, P. 42-46.

[4] NADTOCHIY P. et al. Problems of rehabilitation of the ground-landed resources of the Zhytomyr region, contaminated by military activity. // General ecology and agroecology. 2009. - N2.--P. 3-32. (in Ukrainian).

[5] EPA 530-D-99-001C. Screening Level Ecological Risk Assessment Protocol for Hazardous Waste Combustion Facilities. V.3. Washington, DC, 1999.--www.csu. edu/cerc/ researchreports/documents. usWasteCombustionFacilitiesVolume3. pdf.

[6] EPA/600/R-09/052F. Exposure factors handbook.--Washington, DC, 2011.--http:// www.epa.gov/ncea/efh.

[7] SOBOL I.M. Method MonteCarlo/ Moscow: Nauka, 1985.--80 pp. (in Russian).

Table 1. Qualitative characteristics of soil and water from surface
and underground water sources of former missile base (2007-2009)

Name of the                     The content of element, mg / kg
examined object
                                  Cu                     Ni

Soil                      56.7 [+ or -] 14.1     4.75 [+ or -] 1.18
Water from              0.0032 [+ or -] 0.0008   0.25 [+ or -] 0.06
  surface sources
Water from              0.0042 [+ or -] 0.001    0.093 [+ or -] 0.02
  underground sources

Name of the                     The content of element, mg / kg
examined object
                                 Pb                     Zn

Soil                     26.45 [+ or -] 6.6    280.3 [+ or -] 69.3
Water from              0.034 [+ or -] 0.008   0.026 [+ or -] 0.007
  surface sources
Water from                      0.00           0.024 [+ or -] 0.001
  underground sources

Name of the                   The content of element, mg / kg
examined object
                                Mn                    Fe

Soil                     12.8 [+ or -] 3.2    21.34 [+ or -] 5.3
Water from              0.13 [+ or -] 0.03    4.75 [+ or -] 1.20
  surface sources
Water from              0.089 [+ or -] 0.22   5.20 [+ or -] 1.3
  underground sources

Table 2. Classification of risk levels

Risk

Noncancerogenic       Cancerogenic CR       Risk level
HQ (HI)

<1.0                   < [10.sup.-6]        Minimum--desired (target)
                                            risk value during the
                                            conduct of health and
                                            environmental protection
                                            measures.

1.0-10.0          [10.sup.-4]-[10.sup.-6]   Medium--acceptable for
                                            conditions of military
                                            service. If effects the
                                            civilian population and
                                            requires a dynamic
                                            monitoring of the
                                            environment.

10.0-100.0        [10.sup.-3]-[10.sup.-4]   Significant--unacceptable
                                            for population; for
                                            military service
                                            conditions, dynamic
                                            control and in-depth
                                            study of the sources and
                                            consequences of possible
                                            harmful effects deciding
                                            on risk management
                                            measures is required.

>100.0                 > [10.sup.-3]        High--not acceptable for
                                            military service during
                                            peacetime and for the
                                            population. It is
                                            necessary to implement
                                            measures to eliminate or
                                            reduce the risk.

Table 3. Initial data for the determined coefficients of hazard and
carcinogenic risks assessment

Parameter                          Cu         Me       Zn

Cw, mg/l                         0.0042     0.089     0 024
C, mg/kg (dry mass)               56.7       425      26 45
UF                                0.4       0.123     0 123
RfD chron., mg / kg              0.019       0.14      03
SF, [(mg /(kg x day)).sup.-1]      --         --       --

                                           Children

C[W.sub.w], l/ day                            1
C[W.sub.f], mg /(kg x day)         Berries--35, mushrooms--2
E[F.sub.w] day                               350
EFW day                           Berries--90, mushrooms--150
ED, years                                 Children--6
BW, kg                                    Chi dren--15

AT, day                             Children--2190 (6 years),
                                 carcinogens--25550 (70 years)

Parameter                         Pb       Ni        Fe

Cw, mg/l                         030      0.093      5.2
C, mg/kg (dry mass)             280.3     12.8      21.34
UF                              0.045     0.032     0.123
RfD chron., mg / kg             0.0035    0.02       0.3
SF, [(mg /(kg x day)).sup.-1]    0347     0.91       --

                                         Adults

C[W.sub.w], l/ day                          2
C[W.sub.f], mg /(kg x day)        Berries--35, mushrooms--10
E[F.sub.w] day                             350
EFW day                          Berries--90, mushrooms--150
ED, years                                Adults--30
BW, kg                                   Adults--70

AT, day                          Children--10950 (30 years),
                                 carcinogens-25550 (70 years)

Note: The weight of food is given in dry mass per unit of human body
weight [6]

Table 4. Results of determined coefficients assessment of hazard and
carcinogenic risks from chemical contamination of soil and
underground water sources

Parameter           Cu         Mb         Zn         PE

Consumption of water from underground sources

HQ (children)      0.05       0.04       0.01       0.00
HQ (adults)       0 0061     0 0174     0 0022      0.00
ICR (children)      --         --         --        0 00
ICR (adults)        --         --         --        0 00

Consumption of plants grown on polluted soil

HQ (children)    1 70E-05   4.58E-06   1.38E-06   1.04E-06
HQ (adults)      1.2E-03    4.0E-05    6.22E-06   4.01E-04
ICR (children)      --         --         --      4.20E-09
ICR (adults)        --         --         --      2.83E-08

Parameter           Ni         Fe         [SIGMA]

Consumption of water from underground sources

HQ (children)      0.30       1.11       HI = 1.47
HQ (adults)       0.127      0.475       HI = 0.63
ICR (children)   4 64E-04              CR = 4.64E-04
ICR (adults)     9 94E-04      --      CR = 9.94E-04

Consumption of plants grown on polluted soil

HQ (children)    8.35E-07   2.11E-05    HI = 0.0013
HQ (adults)      5.6E-05    9.0E-05     HI = 0.0018
ICR (children)   6.51E-08      --      CR = 6.93E-08
ICR (adults)     4.39E-07      --      CR = 4.67E-07

Table no.5. The parameters for the lognormal
distributions of drinking water consumed by
person per day (IRW), ml / (kg x day) [6]

Age group,   [mu]   [sigma]   Lower limit   Upper limit
years

1-3          3.49    0.75        5.81         186.49
4-6          3.33    0.68        5.80         135.78
7-10         2.97    0.68        4.04          94.71
11-14        2.66    0.71        2.77          74.24
15-19        2.43    0.74        2.02          63.93
20-44        2.61    0.68        2.77          67.11
45-64        2.92    0.52        5.45          62.71
65-74        2.92    0.49        5.92          58.47
75+          2.88    0.50        5.61          56.84
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Author:Orel, Sergiy; Ivaschenko, Oleksiy
Publication:Journal of Defense Resources Management
Geographic Code:1USA
Date:Oct 1, 2015
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