Potassium chromate

Long-term toxicity to fish

Administrative data

Endpoint:

long-term toxicity to fish, other

Remarks:

Several chronic fish studies summarised in EU RAR

Type of information:

migrated information: read-across based on grouping of substances (category approach)

Adequacy of study:

key study

Study period:

1976 to 1983

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

The EU RAR summarises the results of a number of fish chronic studies which, individually, have limitations regarding study design and reliabilty. However the results of these studies when taken as a whole, provide an adequate assessment of chronic toxicity to fish. The data are considered to fulfil the criteria laid down in Annex XI to Regulation 1907/2006: adequate for classification and labelling, adequate coverage of key parameters (reproduction and growth, in addition to other parameters), exposure duration comparable or longer that Article 13(3) methods, adequate documentation provided: EU RAR, of which parts have been copied to this endpoint record. Reliability for endpoint also increased based on test results from several species.

Data source

Reference

Reference Type:

review article or handbook

Title:

European Union Risk Assessment Report: chromium trioxide, sodium chromate, sodium dichromate, ammonium dichromate and potassium dichromate

Author:

European Chemicals Bureau

Year:

2005

Bibliographic source:

3rd. Priority List; Volume 53

Materials and methods

Test guideline

Qualifier:

no guideline followed

Principles of method if other than guideline:

Several studies reported, collectively, providing a weight-of-evidence to address the endpoint of chronic toxicity.

GLP compliance:

no

Test material

Test material information

Constituent 1

Reference substance name:

Chromium trioxide

EC Number:

215-607-8

EC Name:

Chromium trioxide

Cas Number:

1333-82-0

IUPAC Name:

1333-82-0

Constituent 2

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:

sodium dichromate

Constituent 3

Reference substance name:

Sodium dichromate

EC Number:

234-190-3

EC Name:

Sodium dichromate

Cas Number:

10588-01-9

Molecular formula:

Cr2Na2O7

IUPAC Name:

sodium dichromate

Details on test material:

For some fish species, toxicity data are available for more than one of the chromium (VI) compounds included in this assessment. The available information indicates that, when expressed on a total chromium concentration, there are no significant differences between the toxicity of sodium chromate, sodium dichromate and potassium dichromate (allowing for differences in water properties). This is as would be expected if the equilibria between the chromate and dichromate anions are established in the test medium. Little information is available for ammonium dichromate and chromic acid, but it would be expected that their toxicity would be similar to that of the other chromates/dichromates, when expressed on a total
chromium concentration basis.

Sampling and analysis

Analytical monitoring:

yes

Details on sampling:

Various sampling procedures based on multiple studies

Test solutions

Vehicle:

no

Details on test solutions:

Various media prepared based on multiple studies

Test organisms

Test organisms (species):

other: Range of species used

Study design

Test type:

other: Range of test designs used

Water media type:

freshwater

Limit test:

no

Remarks on exposure duration:

Range used from several studies

Post exposure observation period:

None reported

Test conditions

Hardness:

Range used from several studies

Test temperature:

Range used from several studies

pH:

Range used from several studies

Dissolved oxygen:

Range used from several studies

Salinity:

Not applicable

Nominal and measured concentrations:

Range used from several studies

Details on test conditions:

Range used from several studies

Reference substance (positive control):

not specified

Results and discussion

Effect concentrations

Remarks on result:

other: See "Any other information on results incl. tables" below.

Details on results:

Putte et al. (1981b) observed increased sensitivity in younger fish, with LC50 values of 7.6 mg/l at 4 months rising to 45 mg/l at 9 months.
As well as effects on survival, growth and reproduction, chromium (VI) (mainly as potassium dichromate) has been shown to cause a variety of sublethal haemotological, pathological, physiological and behavioural effects. These effects are detailed below.

In experiments with the freshwater fish Channa punctatus, 10 mM and 1.0 mM of chromium (VI) (as potassium dichromate, equivalent to 520 and 52 mg Cr/l) significantly decreased the rate of absorption of xylose (a sugar) by the intestine over 1 hour, whereas 0.01 mM and 0.001 mM (equivalent to 0.52 and 0.052 mg Cr/l) significantly increased the rate of absorption of xylose over the same period (Sastry and Sunita, 1983a).

In another series of experiments with Channa punctatus, fish were exposed to sublethal concentrations of chromium (VI) (as potassium dichromate) of 2.6 mg Cr/l for 15 and 30 days at a pH of 7.4. At the end of the experiment, the fish were dissected and various organs were analysed. At both exposure levels, fish were found to be hyperglycemic and hyperlactemic (elevated blood glucose levels and a decrease in liver glycogen content was seen). An elevation of the activity of enzymes involved in glycolysis and the Kreb¿s cycle was also seen in muscles and liver, indicating that the metabolic rate of the exposed fish was higher than that of controls (Sastry and Tyagi, 1982; Sastry and Sunita, 1982 and 1984). Similar results were found in a 120 day exposure to the same concentration (Sastry and Sunita, 1983b).

An experiment was carried out with the freshwater fish Tilapia sparrmanii in order to determine the effect of chromium on blood coagulation at acidic (pH 5), physiological (pH 7.4) and alkaline (pH 9) pHs. Fish were exposed to 0.098 mg/l of potassium dichromate (i.e. 0.034 mg Cr (VI)/l) over 96 hours. Fish exposed to chromium contracted thrombocytopenia (a blood disease caused by a shortage of thrombocytes present in blood) with an increase in water pH (Van Pittius et al., 1992).

Gill and Pant (-1978) found that acute (12 and 24 hours) and chronic exposure (30 and 60 days) of the freshwater fish Barbus conchonius to potassium dichromate (chromium concentration 41.2 mg Cr (VI)/l for acute exposures, 0.687 and 1.03 mg Cr (VI)/l for chronic exposures) in hard water (395 mg/l as CaCO3, pH 7.1), resulted in anomalies in peripheral blood and tissues of fish. Pathological changes were also observed in gills, kidneys and liver of chromium-exposed fish.

A study was carried out to assess the avoidance behaviour of rainbow trout (Oncorhynchus mykiss) pre-exposed to sublethal levels of chromium (VI) (as potassium dichromate). Fish were pre-exposed to chromium (VI) concentrations ranging from 0.01 to 3.0 mg Cr (VI)/l. An avoidance threshold of 0.028 mg Cr (VI)/l was determined for fish not pre-exposed to chromium (VI), while avoidance thresholds for pre-exposed fish increased linearly with the level of preexposure. A level of 0.8 mg Cr (VI)/l was proposed as a critical pre-exposure level for short term recovery of normal chemoreceptive capacity (Anestis and Neufeld, 1986).

Vaile and Calamari (1984) studied the immune response in rainbow trout (Oncorhynchus mykiss) exposed to chromium (VI) (as potassium dichromate) over a 4-month exposure period. Fish were exposed to 0.05 (¿safe¿ concentration) and 0.200 (¿effect¿ concentration) mg Cr (VI)/l. The kinetics of antibody production against human red blood cells were monitored. Chromium (VI) was ineffective at reducing the humoral immune response, that is, there was no evidence of sublethal effects of the metal on the immune system of fish at the levels tested.

Bogé et al. (1988) investigated effects of chromium (VI) as potassium dichromate on enzymatic activities and transport processes of intestinal brush border membrane (alkaline phosphatase and maltase activities, glycine adsorption) of rainbow trout (Oncorhynchus mykiss). The experiments
were carried out by perfusion for 30 minutes of solutions containing either 141 or 14 mg Cr (VI)/l. The higher concentration was lethal to trout over 24 hours exposure. Chromium (VI) exposure lead to a severe decrease of alkaline phosphatase activity growing more severe with increasing chromium (VI) concentration and with time. An approximate 50% inhibition of activity was observed after 30 min with the 141 mg Cr (VI)/l exposure and after 90 min with 14 mg Cr (VI)/l exposure. Enzyme activity remained low after removal of chromium, indicating no recovery of initial activity. No effect of chromium on maltase activity was observed. Chromium (VI), this time as sodium dichromate, was an inhibitor of glycine absorption in trout at high concentrations: 90% inhibition at 14.1 g Cr (VI)/l whereas concentrations of 1.4 g Cr (VI)/l caused no effect.

Temmink et al. (1983) investigated the mechanism of toxicity of chromium (VI) as sodium chromate in fingerling rainbow trout (Oncorhynchus mykiss). Fingerling trout were exposed to 3.2 mg Cr (VI)/l at pH 6.5 for up to 11 days to induce hyperplasia of the gill epithelium. Hyperplasia disappeared in gills of those fish that survived exposure and recovered in control conditions for 0.5 to 4 weeks. The toxic effect of chromium (VI) was thought to occur by a three step process with the first step being degeneration and eventual death of the epithelial cells - the plasma membrane being the primary target for oxidative action of chromium (VI) (Temmink et al., 1983).

Singh and Sivalingam (1982) investigated the effects of heavy metals, including chromium (VI) (as potassium dichromate), on the activity of the liver enzyme catalase of Sarotherodon mossambicus. High concentrations of chromium (VI) caused inhibition of catalase activity. Catalase activity was inhibited by 21% and 37% at concentrations of 30 mg Cr (VI)/l and 40 mg Cr (VI)/l, respectively.

Brown trout (Salmo trutta, 1 year old), and mirror carp (Cyprinus carpio, 3+ years old) were exposed to low-levels of potassium dichromate, 1.01 mg Cr (VI)/l over 266 days (38 weeks). The humoral antibody response to MS2 bacteriophage was followed using a 50% viral neutralisation assay method. Immuno-suppression was observed in both fish species. Total suppression of the immune response was observed in the carp exposed to chromium (VI) and these fish also showed symptoms of acute toxicosis (moribund within 11 weeks). Other sublethal effects seen in the study included a significant loss in weight in exposed fish compared with controls. (O¿Neill, 1981).

Jana and Sahana (1988) reported no change in the levels of free amino acids in muscle or protein in kidney or testis of fish (Clarias batrachus) exposed to sodium chromate (5 mg Cr (VI)/l for 14 days at pH 8.5. A small decrease in the dry weight of certain organs (muscle, liver, kidney, stomach, intestine, testis and ovary) was noted in exposed fish when compared with controls.

Kranz and Gercken (1987) investigated whether sublethal concentrations of potassium dichromate (0.175 and 0.7 mg Cr (VI)/l) induce changes in the occurrence of splenic melano-macrophage centres (MMC) in juvenile plaice (Pleuronectes platessa) after 27 days exposure. Macrophages are cells of the immune system which, amongst others, remove foreign particles and effete or damaged cells from an organism. Chromium accumulated to a level of 0.4 mg/kg at both exposure concentrations. Exposure to both levels of chromium (VI) caused a continuous increase in the frequency of splenic MMC in plaice, although the average size of the MMC decreased, therefore the total area did not increase (Kranz and Gercken, 1987).

Any other information on results incl. tables

The results of the chronic fish toxicity studies evaluated in the EU RAR are summarised below:

Species	Life stage	Endpoint	Value	Reference
Catastomus commersoni	Egg/fry	30-day NOEC (g) 60-day NOEC (g)	0.923a 0.29a	Sauter et al. (1976) Sauter et al. (1976)
Esox lucius	Egg/fry	20-day NOEC (s)	0.538a	Sauter et al. (1976)
Ictalurus punctatus	Egg/fry	30-day NOEC (g) 30-60-day NOEC (g)	0.15a 0.305a	Sauter et al. (1976) Sauter et al. (1976)
Oncorhynchus mykiss	Egg/fry Alevin-juvenile	60-day NOEC (g) 60-day NOEC (s) 8-m NOEC (g) 8-m NOEC (m)	0.051a 0.384a 0.1a 0.2a	Sauter et al. (1976) Sauter et al. (1976) Benoit (1976) Benoit (1976)
Oryzias latipes	Embryo/ larval	40-day NOEC (m) 40-day NOEC (g)	3.5 35	Sloof and Canton (1983) Sloof and Canton (1983)
Pimephales promelas	Larval 4-week egg/larvae larvae	7-day NOEC (g) 7-day NOEC (s) 412-day NOEC (s) 9-w LOEC (g) 412-day NOEC (g) NOEC (r) 60-day NOEC (s) 60-day NOEC (g) 30-day NOEC (g) 30-day NOEC (m)	1.1 4.2 1 0.018* 3.95 >3.95 1 1 0.05a >3.06a	De Graeve et al. (1991) De Graeve et al. (1991) Pickering (1980) Pickering (1980) Pickering (1980) Pickering (1980) Pickering (1980) Pickering (1980) Broderius and Smith Jr. (1979) Broderius and Smith Jr. (1979)
Poecilia reticulata	3-4 week	28-day NOEC (m) 28-day NOEC (g)	3.5 3.5	Sloof and Canton (1983) Sloof and Canton (1983)
Salvelinus fontinalis	Embryo/ juvenile	8-m NOEC (g) 8-m NOEC (m)	0.01a 0.2a	Benoit (1976) Benoit (1976)
Salvelinus namaycush	Egg/fry	60-day NOEC (g) 60-day NOEC (s)	0.105a 0.82a	Sauter et al. (1976) Sauter et al. (1976)

Notes: all results are from tests with potassium dichromate except:

a - sodium dichromate.

All concentrations as Cr. (s) - survival; (m) - mortality; (g) - growth; (r) ¿ reproduction.

* - the authors viewed this result as a temporary effect and did not consider it significant in deriving a maximum allowable concentration. The value has not been included in the derivation of a mean NOEC for growth in the RAR.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

Based on a review of existing fish data from the EU RAR, an acceptable assessment of chronic toxicity was achieved.

Executive summary:

From the EU RAR the effects of chromium (VI) have been reported on fish of different ages and on survival, growth and reproduction. Chromium (VI) (mainly as potassium dichromate) has been shown to cause a variety of sublethal haemotological, pathological,physiological and behavioural effects on fish.