Chromium trinitrate

Repeated dose toxicity: inhalation

Administrative data

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

Data source

Reference

Reference Type:

publication

Title:

Thirteen-week subchronic rat inhalation toxicity study with a recovery phase of trivalent chromium compounds, chromic oxide, and basic chromium sulfate.

Author:

Derelanko MJ, Rinehart WE, Hilaski RJ, Thompson RB, Loser E

Year:

1999

Bibliographic source:

Toxicological Sciences 25: 278-288

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

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

GLP compliance:

not specified

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

Chromium hydroxide sulphate

EC Number:

235-595-8

EC Name:

Chromium hydroxide sulphate

Cas Number:

12336-95-7

Constituent 2

Reference substance name:

Basic chromium sulphate

IUPAC Name:

Basic chromium sulphate

Test material form:

solid: particulate/powder

Remarks:

migrated information: powder

Details on test material:

No further details

Test animals

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%.

Administration / exposure

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

Doses / concentrations

Doses / concentrations 1

Remarks:

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

Doses / concentrations 2

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

Examinations

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

Results and discussion

Results of examinations

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.

Effect levels

1

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.

2

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.

3

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.

Target system / organ toxicity

Critical effects observed:

not specified

Any other information on results incl. tables

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

Applicant's summary and conclusion

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.