Slags, ferrochromium-manufg.

Other distribution data

Administrative data

Endpoint:

other distribution data

Type of information:

calculation (if not (Q)SAR)

Remarks:

Migrated phrase: estimated by calculation

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Well documented study. Not a guideline study.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2005

Report date:

2005

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

other: EPA 1996 MMSOILS 4.0

Principles of method if other than guideline:

The flow of metals was calculated in the risk assessment using quantitative modeling methods. The MMSOILS 4.0 software (EPA 1996) was used for the calculations. The software includes various submodels. The model takes into consideration, among other things, diffusion, transport with water (advection), and dispersion. Dispersion occurs when polluted water and clean groundwater get mixed near the edges of the polluted areas, mainly as the result of discontinuation in the flow. The dispersion factor is hard to define. Basically, it must be done on the basis of data from literature. In this study, the used dispersion factors were the typical values in the MMSOILS manual. Dispersion did not play a major role in this study, because the soil layer insatiated with water was rather thin in the examples and the transport distance to the groundwater control point was short. The key source data and formulas of the MMSOILS model are described in Rossi's report (attached in section 13. Assessment reports).

GLP compliance:

no

Type of study:

other: Calculation of metal transport from soil to ground water

Test material

Test material information

Constituent 1

Reference substance name:

Slags, ferrochromium-manufg.

EC Number:

273-727-6

EC Name:

Slags, ferrochromium-manufg.

Cas Number:

69012-27-7

IUPAC Name:

silicon(4+) dialuminium(3+) dichromium(3+) pentamagnesium(2+) undecaoxidandiide silicate

Results and discussion

Any other information on results incl. tables

Trivalent chromium does not dissolve readily from FeCr-slag. It is absorbed strongly into soil and moves there very slowly. According to the example calculations, trivalent chromium does not travel from road structures in moraine and sand soil to a well 10 m away even in thousands of years.

In gravel soil the calculated concentration in a well 10 m away is at highest 1,4 x 10 ^-17 microg/l in 10 000 years.

Hexavalent chromium is quite mobile in soil. The concentration of hexavalent chromium in ground water is very small, because the concentration of hexavalent chromium in FeCr-slag is very small. The reduction of hexavalent chromium has a significant impact on the groundwater chromium content, especially in moraine and sand soil where water and chromium move more slowly. Groundwater flows quickly in areas with gravel soil, diluting the metals which may reach groundwater from the structures. Paving the structure with material with poor water permeability decreased the metal content clearly more than structures with good water permeability did.

Table 1 below shows the calculated Cr6+ content in groundwater near road structures in which FeCr-slag products were used.

Table 1. Maximum hexavalent chromium content based on modeling, of structures containing FeCr-slag products at the groundwater control point 10m from the road side.

Soil type	Maximum content of Cr μg/l
	Paved		Unpaved
	Is not reduced	Is reduced	Is not reduced	Is reduced
- Gravel	7x10^-13	6x10^-2	2x10^-3	0.4
- Moraine	4x10^-11	5x10^-1	3x10^-2	3.0
- Sand	1x10^-11	1,6	0.1	9

The worst case scenario is unpaved structure and no reduction happening. In that case, the highest concentration of hexavalent chromium in nearby well is reached in 40 - 100 years. Concentration is still negligible compared to maximum acceptable concentration for drinking water (50 microg/l).

Table 2 shows the calculated Molybdenum content in groundwater near road structures in which FeCr-slag products were used.

Table 2.Maximum Molybdenum content based on modeling, of structures containing FeCr-slag products at the groundwater control point 10m from the road side (calculation period of 4000 years).

Soil type	Maximum content of Mo μg/l
	Paved	Unpaved
-Gravel	0.02	0.1
- Moraine	0.2	0.9
- Sand	0.4	2.4

Table 3 compares the maximum concentration levels of substances in FeCr-slag products gathered from the example calculations to the maximum acceptable concentrations for drinking water. The example calculations for FeCr-slag products show that chromium or molybdenum content in groundwater cannot rise above the maximum acceptable concentration for drinking water even if no reduction occurs for chromium.

Table 3. Maximum chromium and molybdenum content based on example calculations on FeCr-slag product structures compared to quality standards for drinking water (The Ministry of Social Affairs and Health 2000, Finland)

Substance	Calculated maximum content microg/l	Quality standard for drinking water microg/l	Calculated maximum content / quality standard
Cr^6+	9	50	0.18
Mo	2.4	70	0.03

Applicant's summary and conclusion

Conclusions:

Metals in FeCr-slag products are highly insoluble and they don’t cause pollution to groundwater or form any significant risk to human, animals or plants. Based on the calculations concentration of Cr or Mo does not exceed any threshold limit set to quality of drinking water.