Chromium trinitrate

Endpoint summary

Key value for chemical safety assessment

Repeated dose toxicity: via oral route - systemic effects

Link to relevant study records

Reference

Endpoint:

sub-chronic toxicity: oral

Type of information:

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

Adequacy of study:

key study

Study period:

1997

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: one of soluble inorganic chorium (III) salts, CrCl3, as a similar structural analogue of chromic nitrate, can be used for read-across.

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 408 (Repeated Dose 90-Day Oral Toxicity Study in Rodents)

Deviations:

yes

Remarks:

20 weeks of exposure rather than only 13 weeks

GLP compliance:

not specified

Limit test:

no

Species:

rat

Strain:

Sprague-Dawley

Sex:

male

Details on test animals or test system and environmental conditions:

Four-week-old male Harlan Sprague-Dawley rats (eight per group)

Route of administration:

oral: feed

Vehicle:

not specified

Details on oral exposure:

CrCl3 was fed a diet supplemented with 0, 5, 25, 50, or 100 mg Cr/kg as chromium chloride for a period of 20 weeks.

Analytical verification of doses or concentrations:

not specified

Duration of treatment / exposure:

20 weeks

Frequency of treatment:

once daily

Remarks:

Doses / Concentrations:
0, 5, 25, 50, or 100 mg Cr/kg as chromium chloride, Daily Cr3+ intakes can be estimated to correspond to 0.35–7 mg/kg
Basis:
nominal in diet

No. of animals per sex per dose:

8

Control animals:

yes

Details on study design:

Four-week-old male Harlan Sprague-Dawley rats (eight per group) were fed a diet supplemented with 0, 5, 25, 50, or 100 mg Cr/kg as chromium chloride for a period of 20 weeks (Ander son et al., 1997). Daily Cr3+ intakes can be estimated to correspond to 0.35–7 mg/kg bw (estimated on the basis of default reference values given in Appendix VI of European Commission [2003]). If 200 g is used as a mean body weight, the highest dose corresponds to 7 mg chromium/kg bw.

Positive control:

N/A

Observations and examinations performed and frequency:

Effects on body weights, selected organ weights, and the histology of liver and kidneys were evaluated.

Sacrifice and pathology:

Histopathological examination was performed on four high-dose and four control rats. Haematology and biochemical analyses of blood (serum glucose, cholesterol, triglycerides, liver enzymes, blood urea nitrogen, total protein, and creatinine) were performed on animals at 11, 17, and 24 weeks of age.

Other examinations:

N/A

Statistics:

N/A

Clinical signs:

no effects observed

Mortality:

no mortality observed

Body weight and weight changes:

no effects observed

Food consumption and compound intake (if feeding study):

not specified

Food efficiency:

not specified

Water consumption and compound intake (if drinking water study):

not specified

Ophthalmological findings:

not specified

Haematological findings:

not specified

Clinical biochemistry findings:

effects observed, treatment-related

Description (incidence and severity):

Some sporadic, statistically significant changes were seen in some clinical chemistry parameters (lactate dehydrogenase, aspartate aminotransferase, serum creatinine levels).

Urinalysis findings:

not specified

Behaviour (functional findings):

not specified

Organ weight findings including organ / body weight ratios:

no effects observed

Gross pathological findings:

no effects observed

Histopathological findings: non-neoplastic:

no effects observed

Histopathological findings: neoplastic:

not specified

Details on results:

No changes in body or organ weights, no general signs of toxicity, and no changes in liver or kidney histopathology were seen.
Some sporadic, statistically significant changes were seen in some clinical chemistry parameters (lactate dehydrogenase, aspartate aminotransferase, serum creatinine levels), but because these changes did not show any dose or time dependency, they were not considered to be treatment related.

Dose descriptor:

NOAEL

Effect level:

> 7 mg/kg bw/day (actual dose received)

Based on:

element

Remarks:

chromium

Sex:

male

Basis for effect level:

other: see 'Remark'

Dose descriptor:

NOAEL

Effect level:

> 21.3 mg/kg bw/day (actual dose received)

Based on:

test mat.

Remarks:

chromium chloride

Sex:

male

Dose descriptor:

NOAEL

Effect level:

> 32 mg/kg bw/day (actual dose received)

Based on:

other: chromium trinitrate

Sex:

male

Basis for effect level:

other: results converted by molecular weight to reference substance intake

Critical effects observed:

not specified

Conclusions:

Based on these results, the highest dose level (7 mg chromium III/kg bw/day ) can be considered as a no-observed-adverse-effect level (NOAEL) for repeated dose toxicity (using 200 g as a mean body weight). Accordingly, this relates to a NOAEL of >32 mg/kg bw/d based on chromium trinitrate.

Executive summary:

This study was conducted to evaluate the toxicity of chromium chloride in rats exposed to 0, 5, 25, 50, or 100 mg Cr/kg chromium trichloride in the diet for 20 weeks (estimated to correspond to 0.35–7 mg/kg bw). No morphological changes of liver and renal damage were observed based on histopathological examination of kidneys and did not result in significant alterations in body weight gain at level of 15 mg chromium (III)/kg bw/day. However, in calculations, they used a rat body weight of only 100 g, which seems exceptionally low, because the normal weight of adult Sprague-Dawley rats is between 200 and 300 g. If 200 g is used as a mean body weight, the highest dose corresponds to 7 mg chromium/kg bw. Moreover no alterations in testers or epididymis weights were observed in rats at the highest dose.

Therefore, the no-observed-adverse-effects-level(NOAEL) of chromium trichloride is estimated to be 7 mg chromium (III)/kg bw/day. This value can be converted to a NOAEL of > 32 mg/kg bw/d based on molecular mass of chromium trinitrate.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEL

32 mg/kg bw/day

Study duration:

subchronic

Species:

rat

Repeated dose toxicity: inhalation - systemic effects

Link to relevant study records

Reference

Endpoint:

sub-chronic toxicity: inhalation

Type of information:

migrated information: read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Guideline-comparable study published in a peer-reviewed journal

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 413 (Subchronic Inhalation Toxicity: 90-Day Study)

GLP compliance:

not specified

Limit test:

no

Species:

rat

Strain:

other: CDF (Fischer 344)/Crl BR VAF/Plus

Sex:

male/female

Details on test animals or test system and environmental conditions:

Male and female rats approximately 5 weeks of age were housed in groups for three days and then individually housed in stainless steel, suspended wire-mesh cages and given free access to commercial laboratory feed and tap water during the non-exposure periods. Animal rooms were maintained on a 12-h light/dark cycle, temperature range was maintained at 21 +/- 2 degrees C, and the relative humidity range was 43 +/- 11%.

Route of administration:

inhalation: dust

Type of inhalation exposure:

nose only

Vehicle:

other: unchanged (no vehicle)

Remarks on MMAD:

MMAD / GSD: Mean particle size distribution in microns (GSD) for three test groups over 13 weeks was 4.2 (2.48), 4.2 (2.37), and 4.5 (2.50) for basic chromium sulphate for the low-, mid-, and high-exposure groups, respectively.

Details on inhalation exposure:

Rats were exposed in stainless steel and acrylic nose-only inhalation chambers operated with at least 12 chamber air changes per hour. Generation of basic chromium sulphate particles was accomplished using an auger dust feeder and an air micronizer.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Chamber samples were determined once per hour by standard gravimetric methods with periodic analysis for Cr(III) and Cr(VI).

Duration of treatment / exposure:

Main study: 13 weeks plus an additional 13-week recovery period for some animals.
Bronchoalveolar lavage parameters: 5 consecutive days

Frequency of treatment:

Main study: 6 hours per day/5 days per week for 65 exposures

Remarks:

Doses / Concentrations:
17, 54 or 168 mg/m3
Basis:
nominal conc.

Remarks:

Doses / Concentrations:
3, 10, or 30 mg/m3
Basis:
other: chromium (III) equivalents

No. of animals per sex per dose:

15 animals/sex/dose in the main study
5 animals/sex/dose for the bronchoalveolar lavage evaluation

Control animals:

yes

Details on study design:

Animals were randomly assigned to groups based on body weight. The desired exposure levels were selected to be multiples of the threshold limit value (TLV) for trivalent chromium and set at chromium equivalents of 3, 10, and 30 mg/m3.

Positive control:

No

Observations and examinations performed and frequency:

Animals were observed daily prior to and following each exposure for clinical signs of toxicity, and were observed twice daily for morbidity and mortality during the recovery period and on weekends. Individual body weights were recorded weekly during the exposure and recovery periods. All animals received an indirect ophthalmoscopic examination during the acclimation period and prior to terminal necropsy. Standard haematology, clinical biochemistry, and urinalysis determinations were conducted on animals (10/sex/group) at the end of exposures.

Sacrifice and pathology:

At necropsy the heart, lungs, liver, spleen, kidneys, brain, adrenal glands, thyroid/parathyroid glands, testes, and ovaries were weighed. Microscopic evaluation was conducted on all haematoxylin and eosin-stained tissues from the control and high-exposure level groups. The kidneys, liver, nasal tissue, trachea, lungs, larynx, mediastinal and mandibular lymph nodes, and gross lesions from all animals in the low- and mid-exposure level groups were also examined.

Other examinations:

Main study: Sperm motility, count and morphology
Bronchoalveolar lavage evaluation: Nucleated cell counts and cell differential counts were performed on pooled BALF. Chemical analyses for lactate dehydrogenase, total protein, beta-glucuronidase and glutathione reductase were performed.

Statistics:

One-way analysis of variance on body weights, clinical pathology laboratory tests, BALF data and organ weights. If the result was significant, Bartlett's test for homogeneity of variance was performed. If Bartlett's test was non-significant, Dunnett's t-test was used for pairwise comparisons. If Barlett's test was significant, the Welch t-test with Bonferroni correction was used for pairwise comparisons. The Kruskal-Wallis analysis of variance, followed where appropriate by Mann-Whitney test was used for those parameters where parametric analysis was inappropriate. The level for statistical significance was set at p

Clinical signs:

effects observed, treatment-related

Mortality:

mortality observed, treatment-related

Body weight and weight changes:

effects observed, treatment-related

Ophthalmological findings:

no effects observed

Haematological findings:

effects observed, treatment-related

Clinical biochemistry findings:

effects observed, treatment-related

Urinalysis findings:

no effects observed

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Gross pathological findings:

effects observed, treatment-related

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Details on results:

Main study

Six animals died on exposure day 1 as a direct result of the restraint tubes and they were replaced. One male from the basic chromium sulphate high-exposure (168 mg/m3) group died on exposure day 4 and was not replaced. Although the specific cause of death was not identified, this death was not considered related to exposure to basic chromium sulphate, since there were no significant signs of toxicity observed in any other animals from this group.

Clinical signs of toxicity were limited to sporadic labored breathing, noted during two of the weekly observations, in females exposed to the high concentration of basic chromium sulphate.

Statistically significant, exposure-related reduced mean body weights were observed in the males of the mid- and high-exposure groups and the females of the high-exposure group during the 13-week exposure period. At the recovery sacrifice, males from the same exposure groups continued to exhibit mean body weights that were significantly lower than the control group but body weight gains between treated and control groups were similar.

Most haematology, serum biochemistry, and urinalysis values were similar to the control group. Increased leukocytes associated with increased number of neutrophils, some statistically significant, were noted in mid-and high-exposure groups for males and females. Alkaline phosphatase was statistically elevated in high-exposure group females and serum cholesterol was statistically decreased in mid- and high- exposure group females.

At terminal sacrifice, males and females in all treatment groups demonstrated compound-related, statistically significant increases in mean absolute and relative lung/trachea weights. Statistically significant changes in absolute and/or relative weights of some other organs are listed below (See Table 1); changes in the weights of some organs are secondary to bodyweight effects and, with the exception of the lungs, effects occurred in the absence of microscopic correlates.

Gray lung discoloration was commonly observed in animals exposed to basic chromium sulphate at the mid- and high-exposure levels. The degree of discoloration increased with exposure level and was present both at the terminal and recovery sacrifices. Similar discoloration was observed in the mediastinal lymph nodes of animals exposed to basic chromium sulphate (recovery sacrifice only) while mediastinal lymph node enlargement was seen at all exposure levels. Tan focus/foci were observed in the lungs at the recovery sacrifice of a high percentage of males exposed to the high level of basic chromium sulphate.

Chronic inflammation was observed involving the alveoli of all exposure-level groups consisting of alveolar spaces filled with macrophages, neutrophils, lymphocytes, and cellular debris. Multifocal areas of granulomatous inflammation, characterized by infiltration of macrophages and multinucleated giant cells, was observed at all exposure levels and was closely associated with foreign material seen in the lung and presumed to the test article. These changes corresponded to the increased lung weights observed in all exposure groups. Green refractile foreign material was present in the larynx of animals in all treatment groups. Histiocytosis and lymphoid hyperplasia correlated with lymph node enlargement observed at necropsy. Changes in nasal tissues considered to be test article-related, were observed in males and females, and included acute inflammation, suppurative exudate, and mucoid exudate.

No apparent compound-related effects were noted for sperm motility or morphology for any concentration of basic chromium sulphate.

At recovery sacrifice, foreign material persisted in the lungs of some animals in all exposure groups, but with decreased incidence in most groups. Granulomatous inflammation of the lung decreased in incidence except in the males and females of the high-exposure group where the incidence was approximately equal to that of the terminal sacrifice animals of this group.

Bronchoalveolar lavage evaluation

Males and females at all exposure levels showed statistically reduced total nucleated cell counts. Segmented neutrophils increased while mononuclear cells decreased, although not to a statistically significant degree, at all concentration levels. Non-statistical increases in protein and lactic dehydrogenase were also observed. Increased amounts of cell debris and lysed cells were noted at all exposure levels.

Dose descriptor:

LOAEC

Effect level:

17 mg/m³ air (analytical)

Based on:

test mat.

Remarks:

chromium hydroxide sulphate

Sex:

male/female

Basis for effect level:

other: A NOAEC was not established in this study based on the pathological findings in the respiratory tract.

Dose descriptor:

LOAEC

Effect level:

3 mg/m³ air (analytical)

Based on:

element

Remarks:

Cr3+

Sex:

male/female

Basis for effect level:

other: A NOAEC was not established in this study based on the pathological findings in the respiratory tract.

Dose descriptor:

LOAEC

Effect level:

23.1 mg/m³ air (analytical)

Based on:

other: chromium trinitrate nonahydrate

Sex:

male/female

Basis for effect level:

other: A NOAEC was not established in this study based on the pathological findings in the respiratory tract.

Critical effects observed:

not specified

Selected organ weight changes at terminal and recovery sacrifices of rats exposed to basic chromium sulphate

		Control		17 mg/m^3	54 mg/m^3	168 mg/m^3
Males Lung/trachea
wt (g)		0.99 + 0.70(1.32 + 0.113)		1.26 + 0.071**(1.52 + 0.132)	1.51 + 0.088**(1.95 + 0.068**)	1.86 + 0.89**(2.67 + 0.144**)
wt/bw (% x 10)		4.42 + 0.187(3.89 + 0.214)		5.60 + 0.271**(4.66 + 0.373**)	7.15 + 0.252**(6.37 + 0.298**)	10.69 + 0.688**(8.77 + 0.274**)
Brain
wt (g)		1.79 + 0.087		1.82 + 0.055	1.76 + 0.061	1.71 + 0.069*
wt/bw (% x 10)		8.02 + 0.380		8.12 + 0.374	8.38 + 0.473	9.83 + 0.518**
Kidney
wt (g)		1.54 + 0.106		1.35 + 0.049**	1.62 + 0.085	1.64 + 0.082
wt/bw (% x 10)		7.62 + 0.300		7.28 + 0.207	7.30 + 0.283	7.78 + 0.350**
Liver
wt (g)		5.48 + 0.367		5.63 + 0.271	5.17 + 0.459	4.39 + 0.146**
wt/bw (% x 10)		2.45 + 0.070		2.50 + 0.050	2.45 + 0.091	2.53 + 0.120
Thyroid/parathyroid
wt (mg)		14 + 2.5		15 + 2.9	14 + 1.8	15 + 3.5
wt/bw (% x 10)		6.21 + 1.052		6.64 + 1.475	6.74 + 1.021	8.76 + 2.074*
Spleen
wt (g)		0.45 + 0.038		0.48 + 0.036	0.40 + 0.040*	0.32 + 0.035**
wt/bw (% x 10)		1.99 + 0.149		1.91 + 0.132	1.89 + 0.125	1.84 + 0.151
Testes
wt (g)		2.36 + 0.356		2.39 + 0.261	2.22 + 0.286	2.18 + 0.215
wt/bw (% x 10)		10.54 + 1.315		10.65 + 1.098	10.52 + 1.049	12.53 + 1.238**
Females Lung/trachea
wt (g)		0.81 + 0.081(0.93 + 0.079)		0.98 + 0.094**(1.08 + 0.120)	1.29 + 0.164**(1.59 + 0.120**)	1.66 + 0.084**(2.45 + 0.120**)
wt/bw (% x 10)		5.65 + 0.418(4.74 + 0.384)		6.99 + 0.619**(5.75 + 0.315*)	9.24 + 1.036**(8.02 + 0.750**)	12.89 + 1.134**(13.34 + 0.614**)
Thyroid/parathyroid
wt (mg)		12 + 1.9		11 + 1.3	12 + 1.8	14 + 2.1*
wt/bw (% x 10)		8.26 + 1.493		7.96 + 1.154	8.63 + 1.265	10.77 + 1.522**
Spleen
wt (g)		0.33 + 0.037		0.31 + 0.033	0.30 + 0.033	0.28 + 0.033**
wt/bw (% x 10)		2.32 + 0.268		2.19 + 0.212	2.17 + 0.162	2.19 + 0.273
Note: Organ weight changes, values given as mean + SD: bw = body weight. Non-bracketed values = terminal sacrifice, bracketed values = recovery sacrifice. * p < 0.05; ** p < 0.01

Conclusions:

No systemic toxicity was observed in rats following a 13-week nose-only inhalation study of basic chromium sulphate. Pathological findings were observed in the respiratory tract and are associated with the deposition of inhaled particulate material.

Executive summary:

The principal effects of basic chromium sulphate in a 13-week nose-only inhalation study were on the respiratory tract. Acidic, water-soluble basic chromium sulphate cleared more quickly than the insoluble chromium oxide administered to other groups of rats in the same study but produced more severe and widespread tissue reactions. Basic chromium sulphate produced effects in the mediastinal lymph node, lungs, laynx and nasal cavity. Pigment was still present in basic chromium sulphate-treated animals after the 13 -week recovery period, with partial recovery of the pathological lesions, and therefore, a NOAEC was not established in this study. A LOAEC of 17 mg/m3 was determined (equivalent to 3 mg/m3 Cr3 +), however it should be noted that the effects seen at this concentration were minimal in nature.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Repeated dose toxicity: inhalation - local effects

Link to relevant study records

Reference

Endpoint:

sub-chronic toxicity: inhalation

Type of information:

migrated information: read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Guideline-comparable study published in a peer-reviewed journal

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 413 (Subchronic Inhalation Toxicity: 90-Day Study)

GLP compliance:

not specified

Limit test:

no

Species:

rat

Strain:

other: CDF (Fischer 344)/Crl BR VAF/Plus

Sex:

male/female

Details on test animals or test system and environmental conditions:

Male and female rats approximately 5 weeks of age were housed in groups for three days and then individually housed in stainless steel, suspended wire-mesh cages and given free access to commercial laboratory feed and tap water during the non-exposure periods. Animal rooms were maintained on a 12-h light/dark cycle, temperature range was maintained at 21 +/- 2 degrees C, and the relative humidity range was 43 +/- 11%.

Route of administration:

inhalation: dust

Type of inhalation exposure:

nose only

Vehicle:

other: unchanged (no vehicle)

Remarks on MMAD:

MMAD / GSD: Mean particle size distribution in microns (GSD) for three test groups over 13 weeks was 4.2 (2.48), 4.2 (2.37), and 4.5 (2.50) for basic chromium sulphate for the low-, mid-, and high-exposure groups, respectively.

Details on inhalation exposure:

Rats were exposed in stainless steel and acrylic nose-only inhalation chambers operated with at least 12 chamber air changes per hour. Generation of basic chromium sulphate particles was accomplished using an auger dust feeder and an air micronizer.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Chamber samples were determined once per hour by standard gravimetric methods with periodic analysis for Cr(III) and Cr(VI).

Duration of treatment / exposure:

Main study: 13 weeks plus an additional 13-week recovery period for some animals.
Bronchoalveolar lavage parameters: 5 consecutive days

Frequency of treatment:

Main study: 6 hours per day/5 days per week for 65 exposures

Remarks:

Doses / Concentrations:
17, 54 or 168 mg/m3
Basis:
nominal conc.

Remarks:

Doses / Concentrations:
3, 10, or 30 mg/m3
Basis:
other: chromium (III) equivalents

No. of animals per sex per dose:

15 animals/sex/dose in the main study
5 animals/sex/dose for the bronchoalveolar lavage evaluation

Control animals:

yes

Details on study design:

Animals were randomly assigned to groups based on body weight. The desired exposure levels were selected to be multiples of the threshold limit value (TLV) for trivalent chromium and set at chromium equivalents of 3, 10, and 30 mg/m3.

Positive control:

No

Observations and examinations performed and frequency:

Animals were observed daily prior to and following each exposure for clinical signs of toxicity, and were observed twice daily for morbidity and mortality during the recovery period and on weekends. Individual body weights were recorded weekly during the exposure and recovery periods. All animals received an indirect ophthalmoscopic examination during the acclimation period and prior to terminal necropsy. Standard haematology, clinical biochemistry, and urinalysis determinations were conducted on animals (10/sex/group) at the end of exposures.

Sacrifice and pathology:

At necropsy the heart, lungs, liver, spleen, kidneys, brain, adrenal glands, thyroid/parathyroid glands, testes, and ovaries were weighed. Microscopic evaluation was conducted on all haematoxylin and eosin-stained tissues from the control and high-exposure level groups. The kidneys, liver, nasal tissue, trachea, lungs, larynx, mediastinal and mandibular lymph nodes, and gross lesions from all animals in the low- and mid-exposure level groups were also examined.

Other examinations:

Main study: Sperm motility, count and morphology
Bronchoalveolar lavage evaluation: Nucleated cell counts and cell differential counts were performed on pooled BALF. Chemical analyses for lactate dehydrogenase, total protein, beta-glucuronidase and glutathione reductase were performed.

Statistics:

One-way analysis of variance on body weights, clinical pathology laboratory tests, BALF data and organ weights. If the result was significant, Bartlett's test for homogeneity of variance was performed. If Bartlett's test was non-significant, Dunnett's t-test was used for pairwise comparisons. If Barlett's test was significant, the Welch t-test with Bonferroni correction was used for pairwise comparisons. The Kruskal-Wallis analysis of variance, followed where appropriate by Mann-Whitney test was used for those parameters where parametric analysis was inappropriate. The level for statistical significance was set at p

Clinical signs:

effects observed, treatment-related

Mortality:

mortality observed, treatment-related

Body weight and weight changes:

effects observed, treatment-related

Ophthalmological findings:

no effects observed

Haematological findings:

effects observed, treatment-related

Clinical biochemistry findings:

effects observed, treatment-related

Urinalysis findings:

no effects observed

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Gross pathological findings:

effects observed, treatment-related

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Details on results:

Main study

Six animals died on exposure day 1 as a direct result of the restraint tubes and they were replaced. One male from the basic chromium sulphate high-exposure (168 mg/m3) group died on exposure day 4 and was not replaced. Although the specific cause of death was not identified, this death was not considered related to exposure to basic chromium sulphate, since there were no significant signs of toxicity observed in any other animals from this group.

Clinical signs of toxicity were limited to sporadic labored breathing, noted during two of the weekly observations, in females exposed to the high concentration of basic chromium sulphate.

Statistically significant, exposure-related reduced mean body weights were observed in the males of the mid- and high-exposure groups and the females of the high-exposure group during the 13-week exposure period. At the recovery sacrifice, males from the same exposure groups continued to exhibit mean body weights that were significantly lower than the control group but body weight gains between treated and control groups were similar.

Most haematology, serum biochemistry, and urinalysis values were similar to the control group. Increased leukocytes associated with increased number of neutrophils, some statistically significant, were noted in mid-and high-exposure groups for males and females. Alkaline phosphatase was statistically elevated in high-exposure group females and serum cholesterol was statistically decreased in mid- and high- exposure group females.

At terminal sacrifice, males and females in all treatment groups demonstrated compound-related, statistically significant increases in mean absolute and relative lung/trachea weights. Statistically significant changes in absolute and/or relative weights of some other organs are listed below (See Table 1); changes in the weights of some organs are secondary to bodyweight effects and, with the exception of the lungs, effects occurred in the absence of microscopic correlates.

Gray lung discoloration was commonly observed in animals exposed to basic chromium sulphate at the mid- and high-exposure levels. The degree of discoloration increased with exposure level and was present both at the terminal and recovery sacrifices. Similar discoloration was observed in the mediastinal lymph nodes of animals exposed to basic chromium sulphate (recovery sacrifice only) while mediastinal lymph node enlargement was seen at all exposure levels. Tan focus/foci were observed in the lungs at the recovery sacrifice of a high percentage of males exposed to the high level of basic chromium sulphate.

Chronic inflammation was observed involving the alveoli of all exposure-level groups consisting of alveolar spaces filled with macrophages, neutrophils, lymphocytes, and cellular debris. Multifocal areas of granulomatous inflammation, characterized by infiltration of macrophages and multinucleated giant cells, was observed at all exposure levels and was closely associated with foreign material seen in the lung and presumed to the test article. These changes corresponded to the increased lung weights observed in all exposure groups. Green refractile foreign material was present in the larynx of animals in all treatment groups. Histiocytosis and lymphoid hyperplasia correlated with lymph node enlargement observed at necropsy. Changes in nasal tissues considered to be test article-related, were observed in males and females, and included acute inflammation, suppurative exudate, and mucoid exudate.

No apparent compound-related effects were noted for sperm motility or morphology for any concentration of basic chromium sulphate.

At recovery sacrifice, foreign material persisted in the lungs of some animals in all exposure groups, but with decreased incidence in most groups. Granulomatous inflammation of the lung decreased in incidence except in the males and females of the high-exposure group where the incidence was approximately equal to that of the terminal sacrifice animals of this group.

Bronchoalveolar lavage evaluation

Males and females at all exposure levels showed statistically reduced total nucleated cell counts. Segmented neutrophils increased while mononuclear cells decreased, although not to a statistically significant degree, at all concentration levels. Non-statistical increases in protein and lactic dehydrogenase were also observed. Increased amounts of cell debris and lysed cells were noted at all exposure levels.

Dose descriptor:

LOAEC

Effect level:

17 mg/m³ air (analytical)

Based on:

test mat.

Remarks:

chromium hydroxide sulphate

Sex:

male/female

Basis for effect level:

other: A NOAEC was not established in this study based on the pathological findings in the respiratory tract.

Dose descriptor:

LOAEC

Effect level:

3 mg/m³ air (analytical)

Based on:

element

Remarks:

Cr3+

Sex:

male/female

Basis for effect level:

other: A NOAEC was not established in this study based on the pathological findings in the respiratory tract.

Dose descriptor:

LOAEC

Effect level:

23.1 mg/m³ air (analytical)

Based on:

other: chromium trinitrate nonahydrate

Sex:

male/female

Basis for effect level:

other: A NOAEC was not established in this study based on the pathological findings in the respiratory tract.

Critical effects observed:

not specified

Selected organ weight changes at terminal and recovery sacrifices of rats exposed to basic chromium sulphate

		Control		17 mg/m^3	54 mg/m^3	168 mg/m^3
Males Lung/trachea
wt (g)		0.99 + 0.70(1.32 + 0.113)		1.26 + 0.071**(1.52 + 0.132)	1.51 + 0.088**(1.95 + 0.068**)	1.86 + 0.89**(2.67 + 0.144**)
wt/bw (% x 10)		4.42 + 0.187(3.89 + 0.214)		5.60 + 0.271**(4.66 + 0.373**)	7.15 + 0.252**(6.37 + 0.298**)	10.69 + 0.688**(8.77 + 0.274**)
Brain
wt (g)		1.79 + 0.087		1.82 + 0.055	1.76 + 0.061	1.71 + 0.069*
wt/bw (% x 10)		8.02 + 0.380		8.12 + 0.374	8.38 + 0.473	9.83 + 0.518**
Kidney
wt (g)		1.54 + 0.106		1.35 + 0.049**	1.62 + 0.085	1.64 + 0.082
wt/bw (% x 10)		7.62 + 0.300		7.28 + 0.207	7.30 + 0.283	7.78 + 0.350**
Liver
wt (g)		5.48 + 0.367		5.63 + 0.271	5.17 + 0.459	4.39 + 0.146**
wt/bw (% x 10)		2.45 + 0.070		2.50 + 0.050	2.45 + 0.091	2.53 + 0.120
Thyroid/parathyroid
wt (mg)		14 + 2.5		15 + 2.9	14 + 1.8	15 + 3.5
wt/bw (% x 10)		6.21 + 1.052		6.64 + 1.475	6.74 + 1.021	8.76 + 2.074*
Spleen
wt (g)		0.45 + 0.038		0.48 + 0.036	0.40 + 0.040*	0.32 + 0.035**
wt/bw (% x 10)		1.99 + 0.149		1.91 + 0.132	1.89 + 0.125	1.84 + 0.151
Testes
wt (g)		2.36 + 0.356		2.39 + 0.261	2.22 + 0.286	2.18 + 0.215
wt/bw (% x 10)		10.54 + 1.315		10.65 + 1.098	10.52 + 1.049	12.53 + 1.238**
Females Lung/trachea
wt (g)		0.81 + 0.081(0.93 + 0.079)		0.98 + 0.094**(1.08 + 0.120)	1.29 + 0.164**(1.59 + 0.120**)	1.66 + 0.084**(2.45 + 0.120**)
wt/bw (% x 10)		5.65 + 0.418(4.74 + 0.384)		6.99 + 0.619**(5.75 + 0.315*)	9.24 + 1.036**(8.02 + 0.750**)	12.89 + 1.134**(13.34 + 0.614**)
Thyroid/parathyroid
wt (mg)		12 + 1.9		11 + 1.3	12 + 1.8	14 + 2.1*
wt/bw (% x 10)		8.26 + 1.493		7.96 + 1.154	8.63 + 1.265	10.77 + 1.522**
Spleen
wt (g)		0.33 + 0.037		0.31 + 0.033	0.30 + 0.033	0.28 + 0.033**
wt/bw (% x 10)		2.32 + 0.268		2.19 + 0.212	2.17 + 0.162	2.19 + 0.273
Note: Organ weight changes, values given as mean + SD: bw = body weight. Non-bracketed values = terminal sacrifice, bracketed values = recovery sacrifice. * p < 0.05; ** p < 0.01

Conclusions:

No systemic toxicity was observed in rats following a 13-week nose-only inhalation study of basic chromium sulphate. Pathological findings were observed in the respiratory tract and are associated with the deposition of inhaled particulate material.

Executive summary:

The principal effects of basic chromium sulphate in a 13-week nose-only inhalation study were on the respiratory tract. Acidic, water-soluble basic chromium sulphate cleared more quickly than the insoluble chromium oxide administered to other groups of rats in the same study but produced more severe and widespread tissue reactions. Basic chromium sulphate produced effects in the mediastinal lymph node, lungs, laynx and nasal cavity. Pigment was still present in basic chromium sulphate-treated animals after the 13 -week recovery period, with partial recovery of the pathological lesions, and therefore, a NOAEC was not established in this study. A LOAEC of 17 mg/m3 was determined (equivalent to 3 mg/m3 Cr3 +), however it should be noted that the effects seen at this concentration were minimal in nature.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

LOAEC

23.1 mg/m³

Study duration:

subchronic

Species:

rat

Repeated dose toxicity: dermal - systemic effects

Endpoint conclusion

Endpoint conclusion:

no study available

Repeated dose toxicity: dermal - local effects

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

Oral Repeated dose toxicity

A study was conducted to evaluate the toxicity of chromium trichloride in rats exposed to 0, 5, 25, 50, or 100 mg Cr/kg bw in the diet for 20 weeks (estimated to correspond to 0.35–7 mg/kg bw). No morphological changes of liver and renal damage were observed based on histopathological examination of kidneys and did not result in significant alterations in body weight gain at level of 7 mg chromium/kg bw. Moreover no alterations in testes or epididymis weights were observed in rats at the highest dose.

Therefore, the no-observed-adverse-effects-level (NOAEL) of chromium trichloride is estimated to be 7 mg chromium (III)/kg bw/day. As both, chromium trichloride and chromium trinitrate are very soluble chromium(III) compounds and neither chloride nor nitrate are associated with repeated dose toxicity, a read-across from chromium trichloride to chromium trinitrate is justified and sufficient for hazard and risk assessment. The NOAEL value can be converted to a NOAEL of > 32 mg/kg bw/d based on molecular mass of chromium trinitrate.

Repeated dose inhalative toxicity

No systemic toxicity was observed in rats following a 13-week nose-only inhalation study of basic chromium sulphate, a surrogate substance to chromium trinitrate, also being a very soluble chromium(III) compound. Pathological findings were observed in the respiratory tract and are associated with the deposition of inhaled particulate material. The LOAEC, based on chromium trinitrate nonahydrate in this study was established at 23.1 mg/m3 air (3 mg/m3 Cr).

Similar physical inflammation reactions were observed in a 4 -6 week inhalative study with chromium trinitrate. In this subacute study also no systemic toxicity was observed but only a limited number of parameters were followed as the study focused on the investigation of lung tissue of rabbits by inhalative exposure. Thus, this study, although performed on the reference substance, is considered supportive and the subchronic study on the surrogate substance is used as key study for inhalative repeated dose toxicity.

Repeated dose dermal toxicity

No data is available on repeated dose dermal toxicity of chromium trinitrate or other chromium(III) compounds. As dermal absorption is very limited (see toxicokinetic assessment) such a study is not required as systemic toxicity is already assessed by the oral study above.

Justification for classification or non-classification

No classification for repeated dose toxicity is proposed for chromium trinitrate. The substance was found to be of low toxicity by the inhalation route (Derelanko et al, 1999); although a NOAEL was not identified, the findings seen in this study are primarily local and are not of sufficient severity to warrant classification. Low toxicity by the oral route was shown by the subchronic study with chromium(III) chloride (Anderson, 1997) where no systemic toxicity was seen. Data by dermal route are not available.

Thus, classification for repeated dose toxicity according to DSD (Directive 67/548/EEC) respectively specific target organ toxicity repeat exposure (STOT RE) according to CLP (Regulation EC No 1272/2008) is not proposed.