1-chloro-2-nitrobenzene

Repeated dose toxicity: inhalation

Administrative data

Endpoint:

sub-chronic toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP-compliant study, performed according to a standard NTP protocol; no restrictions, fully adequate for assessment.

Data source

Reference

Reference 1

Reference Type:

study report

Title:

Unnamed

Year:

1993

Reference 2

Reference Type:

other: OECD SIDS

Title:

Unnamed

Year:

2001

Reference 3

Reference Type:

other: abstract

Title:

Unnamed

Year:

1991

Reference 4

Reference Type:

publication

Title:

Unnamed

Year:

1996

Materials and methods

Principles of method if other than guideline:

10 rats/sex/group, whole body exposure, clinical chemistry, hematology, body weight, organ weight, complete histopathology in all control rats and 18 ppm group and rats that died, gross lesions and selective organs of rats < 18-ppm-groups, additional 10 rats/sex/concentration: clinical pathology at day 1, day 4, day 23. Study included endpoints to assess effects on reproductive system.

GLP compliance:

yes

Limit test:

no

Test material

Reference

Name:

Unnamed

Type:

Constituent

Details on test material:

Purity 99%

Test animals

Species:

rat

Strain:

Fischer 344

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Simonsen Laboratories (Gilroy, CA)
- Age at initiation of treatment: 6 weeks
- Housing: individually
- Diet: pelleted NIH-07 Open Formula Diet (Zeigler Brothers Inc., Gardners, PA), ad libitum except during exposure
- Water: deionized, softened water (City ot Richland), ad libitum
- Acclimation period: 11 (males) or 12 (females) days

ENVIRONMENTAL CONDITIONS
- Temperature (°F): 75 ± 3
- Relative humidity (%): 55 ± 15
- Air changes: 12-18 times/hour
- Lighting: 12 hrs dark, 12 hrs (fluorescent) light

Administration / exposure

Route of administration:

inhalation: vapour

Type of inhalation exposure:

whole body

Vehicle:

air

Details on inhalation exposure:

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
Exposure apparatus:
Automated data acquisition and control system. All vapor transport lines and all airflows except the individual chamber dilution air inlet flows were heated and/or insulated to prevent crystallization of the test material. Bulk test material was melted by immersion of the storage container in a warm-water bath and then transferred into a flask which was immersed in a hot-oil bath and rotated. A stream of heated nitrogen was metered into the flask. The resulting vapor was forced into a condenser with temperature maintained by a water bath. Condensate was returned to the rotating flask.

Method of holding animals in test chamber: individual cages within the chambers.

Treatment of exhaust air: chambers were exhausted by a dampened downstream vacuum; exhaust was diluted with building air, passed through HEPA filters, and vented to the atmosphere.

TEST ATMOSPHERE
- Brief description of analytical method used: gas chromatography with electron capture detector
- Samples taken from multiple positions

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Mean concentrations in all chambers were between 98% and 101% of the target concentrations, with relative standard deviations ranging from 6% to 8%. At least 89% of all individual concentration measurements were within 10% of target concentrations. The uniformity of vapor concentration throughout each exposure chamber, measured prior to start and once during the study, was within specified limits (±5%.). Stability analyses GC with FID) showed no degradation of test material under experimental conditions.

Duration of treatment / exposure:

13 weeks.

Frequency of treatment:

6 hours plus T90 (20-25 minutes) per day, 5 days/week

Doses / concentrations

Doses / concentrations 1

Remarks:

Doses / Concentrations:
0, 1.1, 2.3, 4.5, 9 and 18 ppm
Basis:
nominal conc.

Doses / concentrations 2

Remarks:

Doses / Concentrations:
0, 7, 14.7, 28.8, 57.6, 115.2 mg/m3
Basis:
nominal conc.

No. of animals per sex per dose:

10 rats/sex/dose

Control animals:

yes, concurrent vehicle

Details on study design:

- Dose selection rationale: based on 2-week dose-range finding study with the same doses as used in the present study
- Rationale for selecting satellite groups: 10 rats/sex/concentration were subjected to clinical pathological examinations at days 1, 4 and 23.

Examinations

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS:
Animals were observed twice daily (observations were recorded weekly)

DETAILED CLINICAL OBSERVATIONS, NEUROBEHAVIOURAL EXAMINATION: No

BODY WEIGHT:
Animals were weighed at initiation of treatment, weekly thereafter, and at necropsy.

FOOD/WATER CONSUMPTION: No

OPHTHALMOSCOPIC EXAMINATION: No

HAEMATOLOGY AND CLINICAL CHEMISTRY:
- Time schedule for collection of blood: days 1 (methaemoglobin only), 4, 23 and at end of study.
- Anaesthetic used for blood collection: Yes (CO2:room air gas mixture).
- Sampling site and anticoagulant: retroorbital sinus, potassium EDTA (haematology) or none (serum for clinical chemistry).
- Animals fasted: No data.
- Haematology parameters: hematocrit, hemoglobin concentration, erythrocyte count, reticulocyte count, mean ceIl volume (MCV), mean cell hemoglobin (MCH), mean cell hemoglobin concentration (MCHC), platelet count, total and differential white blood cell count, methemoglobin.
- Clinical chemistry parameters: urea nitrogen, creatinine, total protein, albumin, globulin, alanine aminotransterase (ALT), alkaline phosphatase (AP), creatine kinase (CK), sorbitol dehydrogenase (SDH), bile acids.

URINALYSIS: No

Sacrifice and pathology:

GROSS PATHOLOGY: Yes

ORGAN WEIGHS: heart, right kidney, liver, lungs, spleen, right testis, thymus.

HISTOPATHOLOGY:
Complete histopathological examination on all animals of the control and highest exposure groups and all decedents.
Gross lesions and target organs (kidney, liver, nasal cavity, spleen) in all lower exposure groups.

Other examinations:

Additional reproductive toxicity endpoints:
Exposure levels examined: 0, 4.5, 9 and 18 ppm.
Parameters males: reproductive tissue weights, sperm analysis (morphology, motility, density).
Parameters females: vaginal cytology evaluations (estrous cycle length, percent of cycle spent in the various stages).

Results and discussion

Results of examinations

Details on results:

Mortality: no decedents.

Clinical signs: no clear signs of toxicity (no other information).

Body weight: no treatment-related changes.

Haematology:
- Increased methaemoglobin in both sexes, concentration-related (statistically significant in males: from 1.1 ppm at day 23; from 2.3 ppm at all time points with maximum of 1.14 g/dl at 18 ppm; statistically significant in females: from 1.1 ppm at week 13 and from 2.3 ppm at all time points with maximum of 1.04 g/dl at 18 ppm).
- Increased reticulocyte count, concentration-relalated (statistically significant in males: from 9 ppm at week 13; statistically significant in females: from 4.5 ppm at week 13, at 18 ppm also at days 4 and 23).
- Decreased haematocrit, haemoglobin and erythrocyte count, concentration-related ( statistically significant in males: 1.1 ppm(day 23), 4.4 ppm (week 13), 9 ppm (day 4, week 13),18 ppm (at all time points); statistically significant in females: at every dose group at week 13).
- Minor decreases in MCV, MCH and MCHC in males at 18 ppm (at day only) and females from 9 ppm (most time points).
- Increased nucleated erythrocytes in both sexes at 18 ppm at week 13; in males also at 18 ppm at day 4 and at 9 ppm at week 13.
- Decreased platelet count in both sexes from 9 ppm at day 4, concentration-related.
- Increased total white blood cells and lymphocytes in males from 1.1 ppm at week 13, weakly concentration-related.

Clinical chemistry:
- Increased total protein and albumin in both sexes from 9 ppm at day 23 and week 13.
- Increased SDH in both sexes from 9 ppm at most time points; in males SDH was also slightly increased at the lower exposure levels at day 4.
- Increased ALT at 18 ppm in males (day 4,day 23) and females (day 23); in males ALT was also slightly increased at 2.3, 4.5 and 9 ppm at day 4; at week 13, ALT was decreased at 9 ppm in males and at 9 and 18 ppm in females.
- Increased bile acids at day 4 from 2.3 ppm in males (concentration-related) and at 18 ppm in females.
- Decreased AP: in males from 4.5 ppm at week 13 (not concentration-related) and at 9 ppm at day 23; in females from 4.5 ppm (concentration-related) at day 23 and at 9 ppm at week 13.

Organ weights:
- Increased liver weight (absolute and relative) from 2.3 ppm in males and from 4.5 ppm in females, concentration-related.
- Increased spleen weight (absolute and relative) at 18 ppm in males and from 4.5 ppm in females, concentration related.
- Increased right kidney weight from 9 ppm in males (relative weight only) and at 18 ppm in females (absolute and relative weight).
- Decreased lung weight (absolute and relative) at 18 ppm in males.


Macroscopic examination: dark spleen at 18 ppm (2/10 males, 1/10 females).

Microscopic examination:
- Liver: cytoplasmic basophilia of centrilobular hepatocytes at 9 and 18 ppm in all males and most females (severity: minimal).
- Kidney: cytoplasmic pigment (presumably lipofuscin pigment) in proximal convoluted tubule cells at 18 ppm in all males and females, at 9 ppm in 4/10 males and 10/10 females, and at 4.5 ppm in 4/10 males. In addition, males showed a concentration-dependent increase in incidence (up to 10/10 at 18 ppm) and severity of tubule regeneration (from 1.1 ppm).
- Spleen: congestion (increased red blood cells with red pulp parenchyma) occurred in all groups, control included, but the severity was increased in males at 18 ppm and the incidence was increased in females at 9 and 18 ppm.
- Nasal cavity: increased incidence of hyperplasia/hypertrophy of the respiratory epithelium (restricted to the dorsal meatus and nasoturbinate of the most anterior nasal section) at all exposure levels in both sexes.

Reproductive toxicity endpoints:
- Males: decreases in left cauda epididymal weight, spermatid heads per testis and spermatid count at 18 ppm.
- Females: no treatment-related changes in vaginal cytology.

Effect levels

Dose descriptor:

LOAEC

Effect level:

7 mg/m³ air (nominal)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: see 'Remark'

Target system / organ toxicity

Critical effects observed:

not specified