Registration Dossier

Administrative data

Endpoint:
short-term repeated dose toxicity: inhalation
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Study period:
1980
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Study well documented meeting generally accepted scientific principles, acceptable for assessment.
Cross-referenceopen allclose all
Reason / purpose:
reference to same study
Reason / purpose:
reference to other study

Data source

Reference
Reference Type:
publication
Title:
Early effects of inhaled Ca-DTPA on the rat lung
Author:
Smith VH, Dagle GE, Gelman RA, Ragan HA
Year:
1980
Bibliographic source:
Toxicol Lett 7, 9-16

Materials and methods

Test guideline
Qualifier:
no guideline followed
Principles of method if other than guideline:
Inhalation exposure of rats to Ca-DTPA, 2-4 h/day, 12 times
GLP compliance:
not specified
Limit test:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Type:
Constituent
Test material form:
solid - liquid: suspension
Details on test material:
- Name of test material: Calcium trisodium salt of DTPA

Test animals

Species:
rat
Strain:
Wistar
Sex:
female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Hiltop Laboratories
- Weight at study initiation: Approximately 320 gm
- Fasting period before study: None
- Housing: 5/cage
- Diet ( ad libitum): Except during exposure
- Water ( ad libitum):Except during exposure
- Acclimation period:Not specified


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20-24 °C
- Humidity (%): 40-60 %
- Photoperiod: (12 hrs dark / 12 hrs light):

Administration / exposure

Route of administration:
inhalation: aerosol
Type of inhalation exposure:
whole body
Vehicle:
air
Remarks on MMAD:
MMAD / GSD: See the attachment Table 1
Details on inhalation exposure:
GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: 60-liter polymethylmethacrylate exposure chamber
- Method of holding animals in test chamber: individual stainless steel mesh cages
- Source and rate of air: not specified
- Method of conditioning air: not specified
- System of generating particulates/aerosols: The aerosols were generated by a nebulizer operated by air at 373 kPa pressure, mproducing chamber concentrations of upto 2 mg Ca-DTPA/L
- Temperature, humidity, pressure in air chamber: not specified
- Air flow rate: not specified
- Air change rate: not specified
- Method of particle size determination: Data for estimating the aerosol size was obtained with a Mercer cascade impactor. Subsequent calculations of MMAD and associated statistics were made by a computer code
- Treatment of exhaust air: not specified

TEST ATMOSPHERE
- Brief description of analytical method used: Aerosol concentrations of Ca-DTPA were continuously sampled by a water bubbler trap operated at a slightly negative pressure relative to the chamber. All air and aerosol flows were set with aid of pressure or vaccum gauges and flowmeters and checked at each exposure with a calibrated wet test meter. DTPA analyses of the cascade impactor stages and the bubbler solutions were made by titration with Zr(IV) using xylenol orange indicator for the DTAP moiety or by AAS for the Ca moiety.
- Samples taken from breathing zone: not specified

Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
DTPA analyses of the cascade impactor stages and the bubbler solutions were made by titration with Zr(IV) using xylenol orange indicator for the DTAP moiety or by AAS for the Ca moiety.
Duration of treatment / exposure:
12 daily exposures, necropsy 21 (10 rats/group) or 42 days (remaining 10 rats/group) after last exposure
Frequency of treatment:
2 or 4 h/day for 12 days
Doses / concentrationsopen allclose all
Remarks:
Doses / Concentrations:
10 % (2 hrs); 0.42 +/- 0.04 mg/L
Basis:
analytical conc.
Remarks:
Doses / Concentrations:
20 % (2 hrs); 0.88 +/- 0.07 mg/L
Basis:
analytical conc.
Remarks:
Doses / Concentrations:
40 % (2 hrs); 1.30 +/- 0.14 mg/L
Basis:
analytical conc.
Remarks:
Doses / Concentrations:
40 % (4 hrs); 1.18 +/- 0.08 mg/L
Basis:
nominal conc.
No. of animals per sex per dose:
20 rats
Control animals:
yes
Details on study design:
See the attachment Table 1
Positive control:
Not applicable

Examinations

Observations and examinations performed and frequency:
CAGE SIDE OBSERVATIONS: Yes
DETAILED CLINICAL OBSERVATIONS: No
BODY WEIGHT: Yes
FOOD CONSUMPTION: No
FOOD EFFICIENCY: No
WATER CONSUMPTION: No
OPHTHALMOSCOPIC EXAMINATION: No
HAEMATOLOGY: Yes
- Time schedule for collection of blood: Prior to death at 42 days
- Anesthetic used for blood collection: Yes, ether
- Parameters checked: number of white and red cells, HB, MCV, MCH, MCHC differential leukocyte count, reticulocytes, platelets
CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: Prior to death at 42 days
- Parameters checked: blood urea nitrogen, serum alkaline phosphatase, serum glutamic oxaloacetic transaminase, glucose and serum proteins
URINALYSIS: No
NEUROBEHAVIOURAL EXAMINATION: No

Sacrifice and pathology:
GROSS PATHOLOGY: Yes, including lung weight
HISTOPATHOLOGY: Yes
Other examinations:
None
Statistics:
See the attachment

Results and discussion

Results of examinations

Clinical signs:
effects observed, treatment-related
Mortality:
mortality observed, treatment-related
Body weight and weight changes:
no effects observed
Food consumption and compound intake (if feeding study):
not examined
Food efficiency:
not examined
Water consumption and compound intake (if drinking water study):
not examined
Ophthalmological findings:
not examined
Haematological findings:
no effects observed
Clinical biochemistry findings:
no effects observed
Urinalysis findings:
not examined
Behaviour (functional findings):
not examined
Organ weight findings including organ / body weight ratios:
no effects observed
Gross pathological findings:
no effects observed
Histopathological findings: non-neoplastic:
effects observed, treatment-related
Histopathological findings: neoplastic:
not examined
Details on results:
One rat exposed to 40% Ca-DTPA died within 48 h after last exposure.
Body weights and lung weights showed no significant differences among the various groups of rats. Hematological parameters and serum chemistry measurements were within normal limits in all animals measured.
Histopathological findings in the lungs of the animals are summarized inTable 2. Pulmonary histiocytosis, a sign of inflammation, was observed in
higher incidence in treated rats than in control rats. After 21 days recovery 39% of the treated animals and 10% of the controls exhibited histiocytosis, (Chi-square = 7.7, P < 0.01), and after 42 days recovery the incidences were 16% and 0%, respectively, (Chi-square = 5.3, P < 0.03). This lesion seemed somewhat more severe in rats exposed to the highest Ca-DTPA doses; however, the lesions were always focal in subpleural perivascular or peribronchiolar regions of the lung parenchyma and included only a small portion of the total lung volume. The histiocytosis appeared to be reversible, since there was a greater incidence in rats killed 21 days following treatment than in those killed at 42 days. In the treated groups reversibility of the histiocytosis was statistically significant (Chi-square = 6.5, P < 0.01), but was less clearly so in the control animals (Chi-square = 3.2, P < 0.08).
There was no difference in the incidence of emphysema at either 21 or 42 days between control and Ca-DTPA-treated groups, nor was there a significant correlation of the occurrence of emphysema and histiocytosis in the same rats.

Effect levels

Dose descriptor:
NOAEL
Effect level:
0.42 mg/L air (analytical)
Based on:
test mat.
Sex:
female
Basis for effect level:
other: The incidence and severity of pulmonary histiocytosis observed in rats exposed to 0.42 mg/L were similar to those observed in the chamber and 0.9% NaCl aerosol control group

Target system / organ toxicity

Critical effects observed:
not specified

Any other information on results incl. tables

The estimated amount of Ca-DTPA deposited in the lung and the Ca-DTPA aerosol size parameters are shown in Table I. The Ca-DTPA and NaCI doses were calculated from the measured aerosol concentrations, a minute volume of 0.191/min (estimated for a 320-g rat from data in refs. 14, 15) and retention by the lung of 30% of the inhaled aerosol. The latter value is in the 20-30% retention range quoted by VoIf [16] and is in agreement with the deposition fraction for 1.4 to 2.5-gm MMAD particles in the human lung [17] . In rats 100% of DTPA reaching the deep lung, 15% of that on the nasopharyngeal surfaces, and 30% of that on the trachea is absorbed [5] , as is about 5% of the DTPA swallowed. [18] . Similar values have been reported for the dog [19] . Consequently, one would expect a greater absorbed dose of DTPA than that represented by the lung deposit alone. In eight preliminary experiments in¬volving 4 rats per exposure DTPA measured in urine collected over 24-48 h [20,21], representing > 95% of the absorbed dose [18] , averaged 43% (sx = 7.6%) of the calculated inhaled DTPA. This compares favorably to our as¬sumed 30% deposition in the lung. The inhalation treatment of humans with Ca-DTPA usually involves a 15 to 30-min exposure to aerosols produced from 1 g of Ca-DTPA in the nebulizer solution [1-3,22] with doses estimated at 10 -30% of the aerosol (< 5 mg/kg for a 70 -kg man). Thus, the doses for rats in Table I are roughly 2-9 times those typically encountered by man.

Applicant's summary and conclusion

Conclusions:
It was concluded that multiple inhalation exposures to Ca-DTPA at lung depositions that are 2-9 times the usual human deposition, induced only a mild, focal and reversible pulmonary histiocytosis in the rat. At a level of 0.42 mg/L (420 mg/m3), the incidence and severity of the histiocytosis was comparable to that in the chamber- and aerosol control group; this level, therefore, was considered a NOAEC.
Executive summary:

Inhalation of calcium trisodium diethylenetriaminepentaacetate (Ca-DTPA) increases the removal of plutonium and other transuranics from the body.

Data are required to determine possible biological effects from inhaled DTPA. Female rats were given a single or 12 daily, 2-4-h, inhalation exposures to aerosols of 10, 20 and 40% Ca-DTPA and the lungs were examined at 21 and 42 days following the last exposure. No pulmonary pathology was found from the single inhalation treatment with Ca-DTPA while only a slight, peripheral, histiocytosis was observed in the lungs of multiple-treated rats. There was no significant effect of DTPA treatments on body weight, lung weight, hematology or serum chemistry values.