Chromium (III) hydroxide

Toxicity to soil microorganisms

Administrative data

Endpoint:

toxicity to soil microorganisms

Type of information:

other: experimental result from peer-reviewed assessment report

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

Information from a peer reviewed Assessment Report. Chromium(III) hydroxide is insoluble between pH 6.8 and 11 (see section 4.8). Under conditions < pH 6.8 hydrolysis takes place and at > pH11.5 hydroxocomplexes are formed. The main toxic principle of these solutions < pH6.8 and > pH11.5 is dissolved Cr(III). Therefore Chromium(III) choride is used as supporting substance.

Data source

Reference

Reference Type:

other: Peer reviewed assessment report

Title:

Unnamed

Year:

2005

Materials and methods

Test guideline

Qualifier:

according to guideline

Principles of method if other than guideline:

data from peer-reviewed assessment report

Test material

Test material information

Constituent 1

Reference substance name:

Chromium trichloride

EC Number:

233-038-3

EC Name:

Chromium trichloride

Cas Number:

10025-73-7

Constituent 2

Reference substance name:

Chromium(III) chloride

IUPAC Name:

Chromium(III) chloride

Results and discussion

Effect concentrations

Remarks on result:

other: See: Any other information on results incl. tables, data compitation from peer-reviewed EU Assesssment Report

Any other information on results incl. tables

Citation from EU RAR (2009): "Data on the toxicity of chromium (III) to soil processes have been taken from the review by Crommentuijn et al (1997). The values used in this risk assessment were selected from those presented in Table 4.4 of Appendix IV in the Crommentuijn review, applying the following criteria. Values for the NOEC or EC10 which were reported directly were used as NOEC values. Where an EC value for an effect between 10 and 20% was reported, a NOEC of half the EC value was taken. Effect levels greater than 20% were not used. Where results from different exposure periods were reported for the same study, the result from the longest available exposure matching the above criteria was taken. In one case, a NOEC and an EC10 value were presented for the same study and duration; in this case the geometric mean of the two values was used. The basic data are presented in Table VII.1. This includes the original values where the effect was between 10% and 20% (ie before division by two), and the values for different durations.

The selected values were used to determine a PNEC value for soil processes using the statistical extrapolation method. The log NOEC values were fitted to a normal distribution. The Kolmogorov-Smirnov test did not reject the hypothesis, that the log NOEC values came from a normal distribution. A plot of the observed and expected cumulative frequencies is included as Figure VII.1. The result of the statistical extrapolation calculation is a HC5-50% value of 5.9 mg/kg. For comparison, the HC5-95% value is 2.1 mg/kg.The data cover a range of processes: arylsulphatase, nitrification, N-mineralisation, phosphatase, respiration and urease. ..."

Some results were from Chromium(III)sulphate, but they are well in line with the effect concentrations of Chromium(III) chloride.

Applicant's summary and conclusion

Validity criteria fulfilled:

not applicable

Conclusions:

The results for soil processes using the statistical extrapolation method for the HC5-95% value and HC5-95% value is 5.9 mg/kg the is 2.1 mg/kg chromium(III) chloride. Some results were from Chromium(III)sulphate, but they are well in line with the effect concentrations of Chromium(III) chloride.

Executive summary:

Data on the toxicity of chromium (III), mostly Chromium(III) chloride, to soil processes (arylsulphatase, nitrification, N-mineralisation, phosphatase, respiration and urease) have been taken from the review by Crommentuijn et al (1997). The reported values for the NOEC or EC10 which were reported directly were used as NOEC values. For reported EC values for an effect between 10 and 20%, a NOEC of half the EC value was taken. Effect levels greater than 20% were not used. Where results from different exposure periods were reported for the same study, the result from the longest available exposure matching the above criteria was taken. In one case, a NOEC and an EC10 value were presented for the same study and duration; in this case the geometric mean of the two values was used.

Results:

HC5-50% = 5.9 mg/kg

HC5-95% = 2.1 mg/kg

Some results were from Chromium(III)sulphate, but they are well in line with the effect concentrations of Chromium(III) chloride.