**3. Results and discussion**

#### **3.1. Proposal of legislative limit values**

#### *3.1.2. Prevention limit*

The prevention limits of the RE for two soil texture units are presented in **Table 1**. This separation includes light texture soils (loamy-sandy soils and gravel-sandy soils) and standard soils (all the other soil). The values show REs contents in the extract of Aqua regia (pseudototal contents). These values were derived from the background values of REs in Czech agricultural soils—the soil geochemical background plus the average diffuse anthropogenic load [4]. The prevention limits were derived from the soils developed on different soil substrates of the Czech Republic except of the soils developed on geochemically anomalous substrates. These causes including the substrates with increased REs contents of lithogenic or chalcogenic origin [27] must be under an individual evaluation.


2 Sandy soils, loamy-sandy soils, gravel-sandy soils.

**Table 1.** Proposed RE prevention limits in agricultural soils.

The POPs prevention limits are shown in **Table 2**. The differentiation of the soil texture units has no relevant reason for POPs and was not done. The POPs limit values are given in the form of total POPs contents in the soil. The background values of POPs in soil were derived from the average diffuse anthropogenic load (the dependency of POPs soil contents on nature background values is marginal). The real Czech background values [5] were adopted for legislative proposal.



contents in soil.

**Table 2.** Proposed POPs prevention limits in agricultural soils.

The exceeding of RE or POPs prevention limits signalises the increased anthropogenic soil load (over the background values). In the cases of prevention limits exceeding, the precaution measure is proposed: the use of sludge, dredged sediments, or biosolids on the field will be forbidden. This level of limit values has already been partially implemented in the Czech legislation, namely in the Decrees No. 382/2001 Coll. [28] and No. 257/2009 Coll. [29] for sewage sludge and dredged sediments [30] application on agricultural soils. The proposed prevention limits should be valid for all types of substances applied on the agricultural land generally.

The system of so-called background values is not absolutely unified and can be partially dif‐ ferent in individual EU countries. The Czech one is derived from German methodology where the background values are characterised as the concentration resulting from geologi‐ cal and pedological processes and including diffuse source inputs. This method is described in ISO 19258 (2005) [31] for RE and POPs and has international relevance. This methodology is used for the background value assessment in France and United Kingdom. Belgium, Lux‐ embourg, and Netherlands derive the REs and POPS background values only from clean reference areas without any anthropogenic inputs (concentrations found in soil unaffected by any human activity, respectively, soils possibly contaminated by line/point source are ex‐ ceeded). Nevertheless, the approaches can be different not only between the member coun‐ tries but between the regions of individual countries in some of them (LABO 1995 [32]) because of different geological and pedological processes and anthropogenic inputs influ‐ encing the values and the differences in legislation systems.

#### **3.2. Indication limits**

#### *3.2.1. Indication limit of food chain contamination and plant growth inhibition*

The indication limit values reflect the mobility of REs. The comparison of RE (pseudo) total contents and their mobile fraction analysed in the extract of 1 mol/L NH4NO3 are the princi‐ ple of indication limits. The limits of zootoxic REs (As, Cd, Pb, Tl, Hg) were proposed for the food chain protection purpose (**Table 3**). The mobility of REs dependency on soil properties complicates the limit values when indication values for Cd are most complicated because of Cd mobility dependency on soil texture and soil pH. The evaluation of REs pseudototal and mobile form must be done if the limit values are available. The exceeding of limit value of pseudototal or of mobile form means exceeding of indication limit. The proposal of this level of limit value was based on the testing of selected plant species (fodder plants, vegetables, and corns) in experimental and field conditions and general validity of proposed values was derived. The statistical probabilities of critical values exceeding in eatable or fodder plants can be resulted when RE indication limits in the soil are exceeded. The real exceeding of in‐ dication limit value in local field conditions must be confirmed by the testing on individual crop.


\*Total content by AMA technique.

The exceeding of limit value is valid in the case of any exceeding, a) Aqua regia extraction, b) 1mol/L NH4NO3 extraction when both analyses must be done if the limit values are available.

**Table 3.** Proposed indication limits of food chain contamination.

The indication limit values of plant growth inhibition (**Table 4**) were proposed for phytotoxic REs (Ni, Cu, and Zn) because the phytotoxicity can result into significant yield reduction. The limit values proposal was supported by the testing on plant species identical with previous indication limit value and the exceeding of indication limit values must be confirmed by the testing on individual crop in field conditions as well. In the cases of exceeding of both indication limit values the suitable remediation techniques for REs immobilisation (the liming, the application of inorganic or organic additives [33] are recommended).


The exceeding of limit value is valid in the case of any exceeding, a) Aqua regia extraction, b) 1 mol/L NH4NO3 extraction when both analyses must be done if the limit values are available.

**Table 4.** Proposed indication limits of plant growth inhibition.

#### *3.2.2. The indication limit values of human health protection*

The limit was proposed for zootoxic REs (**Table 5**) and selected POPs (**Table 6**). The model calculation of exposition scenario (method US EPA [16] was used as the principle for limit values assessment. The scenario calculates the effect of individual element/substance, the input into human bodies by inhalation, dermal, and oral inputs and the time period of exposition (estimated number of days per year). The calculated value is maximum tolerable value and the exceeding of this level of limit values could cause human health risk. The precaution defined in the legislation is based on the risk analysis of the site confirmed or excluded human health risk. The similar approach is applied in some EU countries, for example, limit value for human health protection is defined as decontamination limit for chlorinated substances in the soils of Germany (Federal Ministry of Justice and Consumer Protection of Germany).


1 Aqua regia extract—valid for all soil texture categories 2 Total content by AMA method

**Table 5.** Proposed RE indication limits of human health protection.


1 Σ PAHs—polycyclic aromatic hydrocarbons (anthracene, benzo(a)anthracene, benzo(b)fluoranthene, benzo(k)fluoranthene, benzo(a)pyrene, benzo(ghi)perylene, phenanthrene, fluoranthene, chrysene, indeno(1,2,3 cd)pyrene, naphthalene, pyrene).

2 Σ PCB congeners—28 + 52 + 101 + 118 + 138 + 153 + 180.

3 Σ DDT, DDE, DDD.

4 HCB and HCH (Σ α + β + γ)—analysed only by suspicion of their contents in soil. 5 International toxic equivalent value (I-TEQ PCDDs/Fs) (ng/kg)—analysed only by suspicion of increased PCDDs/Fs contents in soil.

**Table 6.** Proposed POPs indication limits of human health protection.

#### **3.3. The evaluation of health risks in floodplain soils in the Czech Republic**

The project proposed the methodology for evaluation of health risks in contaminated floodaffected soils useful in practical conditions [34]. The method of SSL was proposed for first screening evaluation. The method is based on the approaches of risk evaluation by US EPA [35] and EPA [36]. The methodology uses the exposition models of chemical inputs into human body. The predicted chronic daily doses are then compared with reference "effect-based" doses mathematically. The partial values of chemical substances concentrations and parameters of chosen exposition scenario (used in limit values assessment) for the main three exposition ways together are used in calculation:

Dust particles inhalation entering into air as secondary dust in the vicinity of evaluated lo‐ calities.


The SSL model was adopted for estimation of the human intake of soil contaminants and consequent risks. This method is based on the risk assessment procedure developed by US EPA. SSLs represent the risk-based soil concentrations derived for the individual chemicals of concern from equations combining exposure assumptions with toxicity criteria.

For each chemical, SSL is back-calculated from the target risk level, whereas an excess lifetime cancer risk (ELCR) is 1 × 10−6 for the soil exposure. Following equations are used to calculate SSL values for a residential population exposed to hazardous chemicals via all three exposure pathways. Default exposure parameters are provided whenever site-specific data are not available. The site specific exposure parameters were set out according to typical conditions of an intensive agriculture (arable land in alluvial areas). The detailed methodology is also described [37].

A. SSL based on non-carcinogenic risks

$$C = \frac{THQ \cdot BW\_c \cdot AT\_s}{EF\_r \cdot ED\_c \left[ \left( \frac{1}{R\text{f}D\_o} \cdot \frac{IRS\_c}{10^6 \text{mg} \text{ / kg}} \right) + \left( \frac{1}{R\text{f}D\_o} \cdot \frac{SA\_c \cdot AF\_c \cdot ABS}{10^6 \text{mg} \text{ / kg}} \right) + \left( \frac{1}{R\text{f}D\_i} \cdot \frac{IRA\_c}{VF\_s \text{or} PEF} \right) \right]} \tag{1}$$

where

**C** Contaminant concentration (SSL) (mg kg−1) Chemical-specific

**THQ** Target hazard quotient 1

**BWc** Body weight, child (kg) 15

**ATn** Averaging time, non-carcinogens (days) ED × 365

**EFr** Exposure frequency, resident (day yr−1) 250 (8 h/day)

**EDc** Exposure duration, child (years) 25

**IRSc** Soil ingestion rate, child (mg day−1) 100

**RfDo** Oral reference dose (mg kg−1 day−1) Chemical-specific

**SA** Dermal surface area, child (cm2 day−1) 3470

**AF** Soil adherence factor, child (mg cm−2) 0.12

**ABS** Skin absorption factor (unitless) Chemical-specific

**IRAc** Inhalation rate, child (m<sup>3</sup> day−1) 20

**RfDI** Inhalation reference dose (mg kg−1 day−1) Chemical-specific

**VFs** Volatilisation factor for soil (m<sup>3</sup> kg−1) Chemical-specific

**PEF** Particulate emission factor (m<sup>3</sup> kg−1) Chemical-specific

**B** SSL based on carcinogenic risks

$$C = \frac{TR \cdot AT\_c}{EF\_r \left[ \left( \frac{IFS\_{\text{adj}} \cdot CFF\_o}{10^6 \,\text{mg} \,/\,\text{kg}} \right) + \left( \frac{SFS\_{\text{adj}} \cdot ABS \cdot CFF\_o}{10^6 \,\text{mg} \,/\,\text{kg}} \right) + \left( \frac{InhF\_{\text{adj}} \cdot CFF\_i}{VF\_s \,orPEF} \right) \right]} \tag{2}$$

where

**C** Contaminant concentration (SSL) (mg kg−1) Chemical-specific

**TR** Target cancer risk 1E-06

**ATc** Averaging time, carcinogens (days) 25,550

**EFr** Exposure frequency, resident (day yr−1) 250 (8 h/day)

**IFSadj** Age-adjusted soil ingest. factor ([mg yr−1]/[kg day])−1 100

**CSFo** Oral cancer slope factor (mg kg−1 day−1) Chemical-specific

**SFSadj** Age-adjusted dermal factor ([mg yr−1]/[kg day−1]) 361

**ABS** Skin absorption factor (unitless) Chemical-specific

**InhFadj** Age-adjusted inhalation factor ([m3 yr−1]/[kg day−1]) 11

**CSFi** Inhalation cancer slope factor (mg kg day)−1 Chemical-specific

**VFs** Volatilisation factor for soil (m3 kg−1) Chemical-specific

**PEF** Particulate emission factor (m3 kg−1) Chemical-specific

In case of the exposure to multiple chemicals, total risk is calculated as an additive value according to following equation:

$$RISK\_{HUMAN} = \frac{\mathbf{c}\_1}{\mathbf{SSL}\_1} + \frac{\mathbf{c}\_2}{\mathbf{SSL}\_2} + \dots + \frac{\mathbf{c}\_l}{\mathbf{SSL}\_l} \tag{3}$$

Resulting ratio smaller than 1 indicates that the POP concentrations measured at the site are unlikely to result in an adverse health impact.

Following uncertainties must be taken into account in final result assessment:

