Chromium hydroxide nitrate (Cr(OH)(NO3)2)

Bioaccumulation: aquatic / sediment

Administrative data

Endpoint:

bioaccumulation in aquatic species: fish

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

28 day exposure

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Justification for type of information:

Published research covering Chromium VI salts.
It shoud be noted that although the exposure was to Cr VI, other references are made to research showing bioavailability to Cr VI being greater than Cr III. Therefore, this is considered to be a good surrogate to demonstrate the low rates of accumulation in fish under laboratory conditions.

Data source

Reference

Reference Type:

publication

Title:

Unnamed

Year:

2016

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 305 (Bioconcentration: Flow-through Fish Test)

Version / remarks:

Although test conducted 2015, this guideline best reflects the methods used.

GLP compliance:

not specified

Remarks:

Research study

Test material

Test material information

Constituent 1

Reference substance name:

Potassium dichromate

EC Number:

231-906-6

EC Name:

Potassium dichromate

Cas Number:

7778-50-9

Molecular formula:

Cr2H2O7.2K

IUPAC Name:

Potassium dichromate

Specific details on test material used for the study:

Analytical grade

Radiolabelling:

no

Sampling and analysis

Details on sampling:

These were filtered and stored at -20°C prior to analysis the chromium concentration in water by ICP methods

Test solutions

Vehicle:

no

Details on preparation of test solutions, spiked fish food or sediment:

Stock solution was delivered to five test aquariums via automatic pipettes.

Test organisms

Test organisms (species):

other: Oreochromis aureus

Details on test organisms:

Wild caught juvenile

Study design

Route of exposure:

aqueous

Justification for method:

aqueous exposure method used for following reason: Research performed at limit of toxicity

Test type:

flow-through

Water / sediment media type:

natural water: freshwater

Total exposure / uptake duration:

d

Test conditions

Hardness:

ca 130 mg/l CaCO3

Test temperature:

Species ideally maintained 25 C

pH:

Ca 7.5

Dissolved oxygen:

Aerated throughout to maintain saturation

Nominal and measured concentrations:

Cr VI+ as 10, 15, 20, 25 and 30 ug/L
The highest concentration demonstrated a toxicity limit with reduced survival (ca 50%)

Reference substance (positive control):

no

Results and discussion

Lipid content

Remarks on result:

not measured/tested

Bioaccumulation factor

Bioaccumulation factor 1

Conc. / dose:

10 µg/L

Temp.:

ca. 25 °C

pH:

7.5

Type:

BCF

Value:

ca. 125 dimensionless

Basis:

edible fraction

Calculation basis:

other: Direct analysis

Bioaccumulation factor 2

Conc. / dose:

15 µg/L

Temp.:

ca. 25 °C

pH:

7.5

Type:

BCF

Value:

ca. 160 dimensionless

Basis:

edible fraction

Time of plateau:

28 d

Calculation basis:

other: Direct analysis

Bioaccumulation factor 3

Conc. / dose:

20 µg/L

Temp.:

ca. 25 °C

pH:

7.5

Type:

BCF

Value:

ca. 450 dimensionless

Basis:

edible fraction

Time of plateau:

28 d

Calculation basis:

other: Direct analysis

Bioaccumulation factor 4

Conc. / dose:

25 µg/L

Temp.:

ca. 25 °C

pH:

7.5

Type:

BCF

Value:

ca. 430 dimensionless

Basis:

edible fraction

Time of plateau:

28 d

Calculation basis:

other: direct analysis

Depuration

Remarks on result:

not measured/tested

Rate constants

Remarks on result:

not measured/tested

Metabolites:

Not identified

Any other information on results incl. tables

The study relied on measuring tissues taken at 7, 14, 21 and 28 days.

The mesurements in the table below are extracted direcrtly from the publication and show a reduced rate of accumulation at the end of the 28 day exposure. The top concentration resulted in ca 50% mortality.

Chromium Conc. (Cr^6+mg /L) in water	Maximum level Chromium indifferentTissuesin exposure days (d)
	7^thday			14^thday			21^thday			28^thday
	G	S	M	G	S	M	G	S	M	G	S	M
Control(0)	0.001	0.002	0.001	0.004	0.003	0.002	0.004	0.003	0.002	0.007	0.006	0.005
10	1.15	0.91	0. 4	3.20	1.38	0.75	4.20	2.25	0.95	3.06	2.72	1.25
15	3.71	1.6	0.9	6.50	2.85	1.45	6.54	3.25	1.75	7.95	4.91	2.43
20	4.77	2.1	1.2	9.35	4.45	2.20	33.45	18.20	8.64	37.41	19.1	9.03
25	9.85	4.2	2.5	15.95	9.10	4.31	37.85	18.75	9.55	40.61	22.5	10.81
30	11.25	6.4	3.29	23.75	13.25	6.45	41.56	22.10	10.31	44.83	25.3	12.25
G= gill, S= skin and M=muscle

Applicant's summary and conclusion

Validity criteria fulfilled:

not applicable

Conclusions:

Although concentration of the metal were higher in the fish at the end of exposure, the results suggest that a plateau was being reached after about 28 days with toxicity at the highest treatment level. It is considered that Cr III will accumulate at a lower level in view of lower bioavailability.

Other research has been conducted on organisms other than fish a review of Chromium by the UK Marine Conservation body (SAC) reports similar BCF and concludes:

Hunt and Hedgecott (1992) reported some information on the bioaccumulation of Cr IV. Laboratory experiments on annelids, crustaceans and molluscs have resulted in bioconcentration factors (BCFs) in the range 158 to 596 for annelids and 383 to 620 (based on dry weights) for molluscs and crustaceans in the laboratory. Much lower BCFs have been calculated in the field: 0.46 to 15 for annelids and <1 for molluscs and crustaceans. These BCFs indicate that chromium is not expected to bioaccumulate under field conditions.