1,2,3,4-tetrahydronaphthalene

Endpoint summary

Description of key information

Partly cited from SIAR to SIAM 19 (Berlin, 19-22 October 2004): In a 28 day toxicity study in rats with gavage application of up to 150 mg 1,2,3,4-tetrahydronaphthalene/kg bw/day, no mortalities occurred in any group. Squatting position and closed eyes were observed in all treated groups. There was a transient decrease in absolute body weights of all treated males. Results of hematology were indicative for a hemolytic anemia in males and females of the high dose group, which was still present, though to a lesser degree, at the end of the recovery period. As a secondary reaction to the anemia, the reticulocyte counts for high dose females were increased and the extramedullary hematopoesis in the spleen of both high dose genders was enhanced. Based on the adverse effects on blood and spleen (significant at 150 mg/kg bw/day but already beginning at 50 mg/kg bw/day), the NOAEL in this study was at 50 mg/kg bw /day (Hüls AG 1995). In 13-week inhalation studies on rats and mice (performed within the U.S. National Toxicology Program), no mortalities, no clinical abnormalities, and no gross pathological findings were observed at exposure concentrations up to and including 660 mg/m³ (NTP 2011). In mice, transitional epithelial eosinophilic granules were observed in the urinary bladder of all exposed groups (dose-related), the toxicological significance of this finding is however unclear. In female mice, a NOAEC of 41.2 mg/m³ was established based on uterus atrophy found at 82.4 mg/m³, and atrophy of the ovary at 330 mg/m³. The NOAEC for nasal lesions in rats was 82.4 mg/m³ in males and 41.2 mg/m3 in females, and 164.8 mg/m3 in mice (NTP 2011).

Key value for chemical safety assessment

Toxic effect type:

dose-dependent

Repeated dose toxicity: via oral route - systemic effects

Link to relevant study records

Reference

Endpoint:

short-term repeated dose toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1994-04-11 to 1994-05-24

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

EU Method B.7 (Repeated Dose (28 Days) Toxicity (Oral))

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 407 (Repeated Dose 28-Day Oral Toxicity Study in Rodents)

GLP compliance:

yes

Limit test:

no

Species:

rat

Strain:

Wistar

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ORGANISMS
- Source: Harlan Winkelmann, Borchen (Germany)
- Age: 6 - 8 weeks
- Weight at study initiation:    range of group mean weights, males: 190-200 g   range of group mean weights, females: 146-155 g
- Number of animals: total 30 males, 30 females

Route of administration:

oral: gavage

Vehicle:

corn oil

Details on oral exposure:

ADMINISTRATION / EXPOSURE 
- Vehicle: corn oil
- Total volume applied: 2 ml/kg bw

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Concentration (weight-%) in corn oil was determined by high-temperature GC

Duration of treatment / exposure:

28 days

Frequency of treatment:

daily

Dose / conc.:

0 mg/kg bw/day (nominal)

Remarks:

control group

Dose / conc.:

15 mg/kg bw/day (nominal)

Remarks:

low dose

Dose / conc.:

50 mg/kg bw/day (nominal)

Remarks:

mid dose

Dose / conc.:

150 mg/kg bw/day (nominal)

Remarks:

high dose

No. of animals per sex per dose:

5

Control animals:

yes, concurrent vehicle

Details on study design:

Post-exposure period: 14 days recovery (satellite groups only)
SATELLITE GROUPS AND REASONS THEY WERE ADDED: 
additional 150 mg/kg bw d  and control group for recovery study
DEVIATIONS FROM PROTOCOL: 
No fixation of tibia during necropsy

Positive control:

none

Observations and examinations performed and frequency:

CLINICAL OBSERVATIONS AND FREQUENCY: 
- Clinical signs: twice daily (weekends: once daily); detailed once a week
- Mortality: twice daily (weekends: once daily)
- Body weight: before first treatment, weekly thereafter until day of  necropsy
- Food consumption: weekly for each cage (5 rats/cage)
- Water consumption: daily for each cage
- Ophthalmoscopic examination: control and high dose groups during  acclimatization and prior to terminal bleeding
- Haematology: all animals twice for toxicokinetics during study plus  once (terminal) for serum chemical and haematological investigations:    
sodium, potassium, calcium, aspartate aminotransferase, alanine  aminotransferase, glucose, triglycerides, cholesterol, total bilirubin,  blood 
urea nitrogen, creatinine, total protein, albumin    red blood cell count, total white blood cell count, platelet count,  haemoglobin, haematocrit, 
erythrocyte indices (mean corpuscular volume,  mean corpuscular haemoglobin concentration), differential white blood  cell count, reticulocyte 
count
- Urinalysis: end of study; non-satellite groups additionally on days 3  (males) and 4 (females)   volume, specific gravity, pH, colour,    
semiquantitative: protein, glucose, ketone, urobilinogen, blood  ingredients   urine sediment analysis: leucocytes, erythrocytes, bacteria, epithelial  
cells (squamous), oxalate crystals, triple phosphate crystals, urate  crystals
ORGANS EXAMINED AT NECROPSY (MACROSCOPIC AND MICROSCOPIC): 
- Macroscopic:    weights of adrenals, kidneys, liver, spleen, testes   adrenals, aorta (thoracic), anus, brain, caecum, coagulation gland,  colon, 
concha (tattooed), duodenum, epididymides, eyes, exorbital  lacrimal glands, gross lesions, heart, ileum, jaw (upper), jejunum,  kidneys, larynx, 
liver, lungs, lymph nodes (skin, cervical & mesenteric), mammary  gland, muscle (skeletal), ovaries, oesophagus, pancreas, pituitary,  prostate, 
rectum, salivary glands, sciatic nerve, seminal vesicles, skin,  spinal cord (cervical), spleen, stomach, testes, thymus, thyroid /  parathyroid, tongue, 
trachea, urinary bladder, uterus, vagina   bone marrow smears
- Microscopic: eyes, kidney, liver, lung, lymph nodes, oesophagus,  Peyer's patches, spleen, uterus
OTHER EXAMINATIONS: toxicokinetics: see separate report and entry

Sacrifice and pathology:

- Gross pathology: 
No macroscopic lesions considered to be related to  treatment were observed. There were rare cases of ophthalmia / ulceration  of the cornea due
 to blood sampling and one subcutaneous purulent  alteration due to application failure. 
- Histopathology: Findings consisted of spontaneous lesions in males and  females of all groups such as hydrometriosis of the uterus, calcification  
of Peyer's patches, hyaline casts in the kidney and multifocal  lymphocytes in the lung. Acute and chronic lesions of the eyes due to  bloodletting 
were observed occasionally. In the oesophagus subacute or  chronic traumatization due to application failure was observed in some  animals. There  were also pigmentation in the lymph nodes cervicales  caused by tattooing ears.   
Kidneys: No lesions except hyaline casts, also in controls; no lesions  in recovery group   
Liver: Extramedullary haematopoiesis in animals of all groups,  considered normal; no lesions in recovery group   
Spleen: Treatment related slight increase of haematopoiesis in 4/5 high  dose males and 2/5 high dose females
- Other: Several clinical signs in one intermediate dose female could be  attributed at necropsy to an application failure.

Statistics:

STATISTICAL METHODS: 
- Kruskal Wallis non parametric analysis of variance, in case of  significance followed by Wilcoxon, Mann, and Whitney U tests: body  weights, body 
weight changes, organ weights, differential blood count,  urine analysis data 
- one way analysis of variance (ANOVA) incorporating Bartlett's test for homogeneity of variance and if indicated followed by  Kruskal Wallis or 
Scheffe Test: haematological data (except differential  blood count) and serum clinical chemistry data
- Median (geometric mean), minimum, maximum: differential blood count

Clinical signs:

effects observed, treatment-related

Description (incidence and severity):

no mortalities; Piloerection, alopecia, and transient squatting position were observed in control and dose groups. High dose animals additionally revealed reduced activity at the start of the study

Mortality:

no mortality observed

Description (incidence):

no mortalities; Piloerection, alopecia, and transient squatting position were observed in control and dose groups. High dose animals additionally revealed reduced activity at the start of the study

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

Significantly decreased absolute bodyweight was observed in high dose males throughout the study. No statistically significant differentes concerning weight and weight gain were observed during recovery. However, high dose males showed a clear weight gain

Food consumption and compound intake (if feeding study):

no effects observed

Food efficiency:

effects observed, treatment-related

Description (incidence and severity):

Food conversion rate was clearly increased in male high dose group

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

no effects observed

Ophthalmological findings:

no effects observed

Haematological findings:

effects observed, treatment-related

Description (incidence and severity):

High dose males revealed a statistically significant decrease in red blond cell count (RBC). RBC in high dose females was equally reduced, though not significant. After recovery, RBC was still decreased in high dose males.

Clinical biochemistry findings:

effects observed, treatment-related

Description (incidence and severity):

significant increase was observed in serum sodium concentration in high dose animals of either sex.

Urinalysis findings:

effects observed, treatment-related

Description (incidence and severity):

Urine of all dose groups revealed a change in colour to yellow-brown, darker than urine colour of controls. A statistically significant increase in oxalates in high dose males wasobserved.

Behaviour (functional findings):

no effects observed

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Description (incidence and severity):

High dose males revealed a statistically significant increase in relative weight of spieen. After the two week recovery period, a significant increase of absolute spieen weight was still observed in high dose males

Gross pathological findings:

no effects observed

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Description (incidence and severity):

Substance-related slight increase of haematopoiesis in the spieen was observed in 4 out of 5 male animals of the high dose group

Details on results:

TOXIC RESPONSE/EFFECTS BY DOSE LEVEL: 
- Mortality: No mortalities in either dose group
- Clinical signs:    
Control group: slight alopecia for a maximum of 4 (males) and 19  (females) consecutive days; piloerection slight in females and 
moderate  in males   
Low dose: Alopecia in one female; piloerection slight to moderate in females (maximum 10 consecutive days) and throughout the study in males;  
squatting position and closed eyes in either sex (maximum 5 consecutive days)   
Intermediate dose: Piloerection slight to mode rate in all animals  throughout the study; alopecia in one female; squatting position for several 
times in all animals; closed eyes in 7 animals (on maximum 3 consecutive days); slightly abnormal gait and lop-sided head in one male   
High dose: Slight to moderate piloerection (maximum 14 consecutive days  in females / throughout the study in males); Squatting  position in all 
females (on maximum 5 consecutive days) at begin of study, repeatedly and transient in all males throughout the study; closed eyes for 1 (first) day 
in females and for up to 5 days in all males; reduced activity in all  males on days 1 and 2; lethargy in  two animals (1 day); tonic convulsions on day 2 and absence of auditory startle reflex in one male   
Recovery groups: Complete absence of piloerection in all animals within  several days after end of treatment
- Body weight gain: No statistically significant differences in either  dose group of either sex. Absolute body weights only affected significantly in 
all treated males (decrease) on days 7 and 21 and in high dose males additionally on day 28  (11.3 % below control). A gain in this latter group was
the only significant observation in body weights  during recovery.
- Food/water consumption: Food conversion rate was clearly increased in  high dose males. Low and high dose females showed a  less pronounced  
increase. Food conversion of high dose males decreased during recovery.  No overt intergroup differences in water  consumption were observed. 
- Ophthalmoscopic examination: Cornea damages in several animals due to  repeated blood sampling; no signs of test substance 
related effects in  either dose group
- Clinical chemistry:    
Sodium: statistically significant increases in all high dose animals  and in low dose males, close to historical control data 
maximum in control males, still statistically increased after recovery in high dose  males   
Total bilirubin: Experimental difficulties (lipaemia, values close to  detection limit) were met. No clear differences could be observed in treated 
versus control groups.   
Calcium and creatinine: Increased only in females of intermediate dose  group   
Glucose: The range of historical control data was slightly exceeded in  seven dosed animals (one low, two intermediate, four high dose animals  
including two recovery)    
Other parameters: No clear pattern of change   
Recovery group: For cholesterol, total bilirubin, and alkaline  phosphatase small, yet significant differences were observed for both sexes
- Haematology:    
Red blood cell count: decreased significantly in males and  insignificantly in females of high dose group, improvement with males during recovery 
still left a significant decrease    
Reticulocytes: significantly increased in high dose females   
Eosinophiles: significant increase in high dose females   
Recovery group: significant increase in haemoglobin and consequently in  MCV and MCH of dosed females   
Other: Deviations in two individual intermediate dose animals could in  one case be explained by application failure
- Urinalysis:    
Colour: change to yellow-brown, darker colour in treated animals, not  dose dependent   
Urine sediment analysis: dose-dependent increase in oxalates,  statistically significant in high dose males with individual values beyond the range of the historical control data also for three  intermediate dose males. Recovery left oxalates of two individuals beyond  the range of the historical 
control data. High presence of oxalates in  urine was also observed in one or two individuals each of all female control and high dose groups 
including both recovery groups.  
Triplephosphates were significantly increased and erythrocytes  significantly decreased in high dose males.   
Urine volume: significantly increased in high dose females   
Urine pH: significantly decreased in high dose females (6.80, control  8.20) and one intermediate dose female. Unusual presence of glucose in  
urine and high presence of ketone was also observed in the high dose  female with the lowest pH of urine.
- Organ weights: Relative kidney weights were insignificantly increased in high dose  animals.   Relative spleen weights were increased statistically 
significantly in high dose males and insignificantly, not dose related in intermediate and  high dose females. Absolute spleen weights were 
decreased in low dose  females.  In the high dose male recovery group, absolute weight of spleen and  relative weight of adrenals were increased.

Key result

Dose descriptor:

NOAEL

Effect level:

50 mg/kg bw/day (nominal)

Sex:

male/female

Basis for effect level:

clinical signs

Key result

Dose descriptor:

LOAEL

Effect level:

150 mg/kg bw/day (nominal)

Sex:

male/female

Basis for effect level:

clinical signs

organ weights and organ / body weight ratios

Critical effects observed:

not specified

Conclusions:

Upon 28-day oral gavage administration a NOAEL of 50 mg/kg bw/d was observed in Wistar rats.

Executive summary:

Tetrahydronaphthalene (THN) was administered by gavage to three groups of five male and five female Wistar rats, Hsdf Win:WU strain. Administration was performed for 4 weeks, at dose levels of 15, 50 and 150 mg/kg/day. A control group of five males and five females was dosed with the vehicle (corn oil) alone. A control and a high dose recovery group each consisting of five males and five females, respectively, were observed for a period of 14 days after the end of the dosing period. Clinical signs, bodyweight, food and water consumption were monitored during the study. Blood chemistry and haematology as well as a urine analysis were evaluated for all animals at the end of the study. Ophthalmological examinations were performed on animals of the control and high dose groups prior to the start and at the end of the study.

Oral administration of the test material tetrahydronaphthalene to rats for a period of 28 days at a maximum dose leveI of 150 mg/kg/day resulted in treatment-related effects such as reduced bodyweight, increased relative spleen weight, increased haematopoiesis in spleen, reduced red blood cell count and an increase of reticulocytes suggesting an adverse effect an circulating erythrocytes. These adverse effects are regarded as transient and were reversible when the administration of the test substance was stopped. Minor and equivocal changes were observed in some clinical chemistry and urine analysis parameters. No such effects except for the equivocal changes in clinical chemistry and urine analysis were demonstrated in animals treated with 50 mg/kg/day, and no changes at all were observed at a dose level of 15 mg/kg/day. Therefore, the "No Observed Adverse Effect Level" (NOAEL) was considered to be 50 mg/kg/day for both sexes.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

NOAEL

50 mg/kg bw/day

Study duration:

subacute

Species:

rat

Quality of whole database:

RL 1 (reliable without restriction)

Organ:

blood

spleen

Repeated dose toxicity: inhalation - systemic effects

Link to relevant study records

Reference

Reference 1

Endpoint:

sub-chronic toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

1996-08-19 to 1996-11-21

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Comparable to guideline study with acceptable restrictions

Principles of method if other than guideline:

NTP Test Protocol, see Test Conditions

GLP compliance:

yes

Limit test:

no

Species:

mouse

Strain:

B6C3F1

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ORGANISMS
- Source: Taconic, Germantown (New York, USA)
- Age: approximately 6 weeks at first exposure
- Number of animals: 10 per dose and sex
Feed was available ad libitum except during exposure and urine collectionperiods;
water was available ad libitum.
Mice were housed individually

Route of administration:

inhalation

Type of inhalation exposure:

whole body

Vehicle:

air

Remarks on MMAD:

MMAD / GSD: no data

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

The Tetrahydronaphthalene concentrations in the exposure chambers were monitored by an online gas chromatograph. Samples were drawn from each exposure chamber approximately every 24 minutes during each 6‑hour exposure period.
Chamber concentration uniformity was maintained throughout the studies.

Duration of treatment / exposure:

14 weeks

Frequency of treatment:

6 h/day, 5 days/week; additionally: last sunday before terminal sacrifice

Dose / conc.:

0 mg/m³ air

Remarks:

0 ppm

Dose / conc.:

41.2 mg/m³ air

Remarks:

7.5 ppm

Dose / conc.:

82.4 mg/m³ air

Remarks:

15 ppm

Dose / conc.:

165 mg/m³ air

Remarks:

30 ppm

Dose / conc.:

330 mg/m³ air

Remarks:

60 ppm

Dose / conc.:

660 mg/m³ air

Remarks:

120 ppm

No. of animals per sex per dose:

10

Control animals:

yes, concurrent vehicle

Details on study design:

Post-exposure period: sacrifice on day after last exposure
SATELLITE GROUPS AND REASONS THEY WERE ADDED:
As part of the disease  control program, five male and five female mice were submitted for a  pre-exposure health examination. Sera were collected 
from five mice of  each sex from extra animals 20 days after arrival and from the control  group at the end of the study. Sera were tested for viral and mycoplasmal  antibodies.

Observations and examinations performed and frequency:

CLINICAL OBSERVATIONS AND FREQUENCY: 
- Clinical signs: twice daily including weekends
- Mortality: twice daily including weekends
- Body weight: weekly
- "Observations": weekly
- Hematology: All animals were bled at terminal necropsy. Hematologic  evaluations included: red blood cell count, volume of packed cells & spun  
hematocrit, hemoglobin, mean corpuscular volume, mean corpuscular  hemoglobin, mean corpuscular hemoglobin concentration, white blood cell   count, differential count (absolute), absolute reticulocyte count,  platelet count & morphologic assessment, erythrocyte morphologic  assessment.
OTHER EXAMINATIONS: 
- Micronuclei in erythrocytes: Two blood smears were taken from all core  study animals at necropsy. One of these slides was subject to 
micronuclei  determination.
- Sperm morphology & vaginal cytology (SMVCE): Vaginal cytology was  evaluated for 12 days during the last 2 weeks of the study on all  remaining 
females in the 0-, 30-, 60-, and 120-ppm groups. Epididymal  sperm concentration, spermatid heads/testis, and left caudal, epididymal  & 
testicular weights were evaluated in surviving males from the same  groups.

Sacrifice and pathology:

ORGANS EXAMINED AT NECROPSY (MACROSCOPIC AND MICROSCOPIC): 
- Macroscopic: Complete necropsy; weights of liver, thymus, right kidney,  right testis, heart, lungs.
- Microscopic: Complete histopathology on all 0- and 120-ppm mice  included the following tissues: adrenal glands, brain, clitoral glands,  
esophagus, femur (including bone marrow & joint surfaces), gallbladder,  gross lesions, tissue masses, regional lymph nodes, heart, aorta, large  
intestine (cecum, colon, rectum), small intestine (duodenum, jejunum,  ileum), kidneys (left only for males), larynx, liver, lungs & mainstem  
bronchi, lymph nodes (mandibular, mesenteric, bronchial, mediastinal),  mammary glands & adjacent skin, nasal cavity & nasal turbinates (three  
sections), ovaries, pancreas, parathyroid glands, pituitary glands,  preputial glands, prostate, salivary glands, spleen, stomach (forestomach  & 
glandular), testes, epididymis, seminal vesicles, thymus, thyroid  glands, trachea, urinary bladder, uterus.   Target tissues identified at 120 ppm 
were examined at lower  concentrations to no-effect level or lowest exposure concentration. 
Gross  lesions were examined in all groups.

Other examinations:

At the end of the studies, sperm samples were collected from core study male animals in the 0, 30, 60, and 120 ppm groups for sperm motility evaluations. The following parameters were evaluated: spermatid heads per testis and per gram testis, spermatid counts, and epididymal spermatozoal motility and concentration. The left cauda, left epididymis, and left testis were weighed. Vaginal samples were collected for up to 12 consecutive days prior to the end of the studies from core study females exposed to 0, 30, 60, or 120 ppm for vaginal cytology evaluations. The percentage of time spent in the various estrous cycle stages and estrous cycle length were evaluated.

Statistics:

STATISTICAL METHODS: A modified Dunnett's t-test (Xybion Path / Tox  System; Cedar Knolls, New Jersey) was used to compare the treated groups  
to the control group with respect to body and organ weights, and  organ:body weight ratios. Corresponding statistics for hematology, and  clinical 
chemistry were calculated using the Statistical Analysis System  (SAS Institute; Berkeley, California).

Clinical signs:

no effects observed

Mortality:

no mortality observed

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

reduced body weight gain at the highest dose level

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:

effects observed, treatment-related

Description (incidence and severity):

Total erythrocytes and packed cell volumes were decreased, accompanied by increased mean corpuscular hemoglobin, mean corpuscular volume, and mean corpuscular hemoglobin concentration measurements and reticulocyte concentrations in both sexes from 30 ppm on (females more sensitive). Effects indicative for anemia.

Clinical biochemistry findings:

no effects observed

Urinalysis findings:

effects observed, treatment-related

Description (incidence and severity):

Dark-colored urine at 30 ppm (7/10 each for males and females) and higher (all animals), effect obseved in the first weeks of treatment, not adverse

Behaviour (functional findings):

not specified

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Description (incidence and severity):

The relative and absolute kidney weight was reduced in mice in the 60 and 120 ppm group. Relative liver weights were increased in males (120 ppm) and females (30 and greater), which may be an adaptive effect as no toxicologically adverse histopathological effects occured in the liver.

Gross pathological findings:

no effects observed

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Description (incidence and severity):

Atrophy of the uterus and ovaries in females; Metaplasia and hyaline droplets in the nose

Histopathological findings: neoplastic:

no effects observed

Details on results:

TOXIC RESPONSE/EFFECTS BY DOSE LEVEL: 
- Mortality and time to death: no mortalities in any group
- Clinical signs: no gross observations in any group
- Body weight gain: lower by 8.9 % (males, significant) and 7.0 %  (females, insignificant), respectively, in highest dose groups
- Haematology: Total erythrocytes and packed cell volumes were decreased,  accompanied by increased mean corpuscular hemoglobin, mean 
corpuscular  volume, and mean corpuscular hemoglobin concentration measurements and  reticulocyte concentrations in both sexes at 60 or 
120 ppm. Platelet  concentrations were increased in these same groups.
- Urinalysis:    Dark-colored urine at 30 ppm (7/10 each for males and females) and  higher (all animals)
- Organ weights:    
Kidney: relative and absolute weights reduced in males and females in 60, and 120 ppm groups   
Liver: relative liver weights increased for males (120 ppm) and females (60 and 120 ppm), may be an adaptive effect
Heart: relative (120 ppm) and absolute (60 and 120 ppm) decrease in  males
- Gross pathology: no gross observations in any group
- Histopathology:   No lesions were observed in the liver, kidney, heart, or testes that  correlated with any of the weight changes observed. Atrophy of olfactory epithelium correlated very well with observations  in the previous 14-day study.    
Ovary and uterus atrophy was observed in high dose females (60 and 120 ppm). 
Transitional epithelial eosinophilic granules were observed in the  urinary bladder of all animals exposed (dose-related), the significance  of this finding is unclear.

Key result

Dose descriptor:

NOAEC

Effect level:

165 mg/m³ air

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: uterus atrophy at higher dose levels

Key result

Dose descriptor:

LOAEC

Effect level:

330 mg/m³ air

Based on:

test mat.

Sex:

male/female

Basis for effect level:

body weight and weight gain

haematology

histopathology: non-neoplastic

organ weights and organ / body weight ratios

Critical effects observed:

not specified

Conclusions:

The NOAEC was 30 ppm = 165 mg/m3 and the LOAEC: 60 ppm = 330 mg/m3 in males and females.

Executive summary:

Groups of 10 male and 10 female mice were exposed to tetrahydronaphthalene at concentrations of 0, 7.5, 15, 30, 60, or 120 ppm, 6 hours plus T90 (12 minutes) per day, 5 days per week for 14 weeks. All mice survived to the end of the study. Mean body weights of 60 and 120 ppm males were significantly less than those of the chamber controls. Dark stained urine was observed in the catch pans of mice exposed to 30, 60, or 120 ppm during the first month of the study.

A minimal decrease in the erythron in both sexes that resulted in a hematopoietic response was observed. The relative liver weights of 120 ppm males and 30 ppm or greater females were significantly greater than those of the chamber controls. This was considered to be an adaptive response as no further histopathological adverse liver effects could be observed. Incidences of olfactory epithelium metaplasia in 60 and 120 ppm males and females, respiratory epithelium hyaline droplet accumulation in 120 ppm males and 60 and 120 ppm females, cytoplasmic eosinophilic granules within the transitional epithelium lining the urinary bladder in all exposed groups of males and females, and ovarian atrophy and uterine atrophy in 60 and 120 ppm females were significantly increased. The NOAEC was 30 ppm = 165 mg/m³ in males and females.

Reference 2

Endpoint:

sub-chronic toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1996-08-19 to 1996-11-19

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Comparable to guideline study with acceptable restrictions

Principles of method if other than guideline:

Method: other: NTP Test Protocol, see Test Conditions

GLP compliance:

yes

Limit test:

no

Species:

rat

Strain:

Fischer 344

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ORGANISMS
- Source: Taconic, Germantown (New York, USA)
- Age: approximately 6 weeks at first exposure
- Number of animals: Total of 25 males and 20 females per dose = 5 male  renal toxicity rats + 10 male and 10 female core study rats
 + 10 male and  10 female clinical pathology rats
Feed was available ad libitum except during exposure and urine collectionperiods;
water was available ad libitum.
Rats and mice were housed individually.

Route of administration:

inhalation

Type of inhalation exposure:

whole body

Vehicle:

air

Details on inhalation exposure:

ADMINISTRATION / EXPOSURE 
- Type of exposure: whole-body inhalation

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

The tetralin concentrations in the exposure chambers were monitored by an online gas chromatograph. Samples were drawn from each exposure chamber approximately every 24 minutes during each 6‑hour exposure period.
Chamber concentration uniformity was maintained throughout the studies.

Duration of treatment / exposure:

14 weeks

Frequency of treatment:

6 h/day, 5 days/week; additionally: last sunday before terminal sacrifice

Dose / conc.:

0 ppm

Remarks:

control

Dose / conc.:

7.5 ppm

Remarks:

41.2 mg/m3

Dose / conc.:

15 ppm

Remarks:

82.4 mg/m3

Dose / conc.:

30 ppm

Remarks:

165 mg/m3

Dose / conc.:

60 ppm

Remarks:

330 mg/m3

Dose / conc.:

120 ppm

Remarks:

660 mg/m3

No. of animals per sex per dose:

10

Control animals:

yes, concurrent vehicle

Details on study design:

Post-exposure period: sacrifice on day after last exposure

Observations and examinations performed and frequency:

CLINICAL OBSERVATIONS AND FREQUENCY: 
- Clinical signs: twice daily including weekends
- Mortality: twice daily including weekends
- Body weight: weekly (core study rats)
- "Observations": weekly
- Hematology: Sampling from 10 animals per dose and sex on days 3 and 23  (after exposures, clinical pathology rats) and at terminal sacrifice  
(core study rats). Evaluations included: red blood cell count, volume of  packed cells and spun hematocrit, hemoglobin, mean corpuscular volume,   mean corpuscular hemoglobin, mean corpuscular hemoglobin concentration,  white blood cell count, differential count (absolute), absolute  
reticulocyte count, platelet count, Morphological assessment.
- Biochemistry: Blood urea nitrogen, sorbitol dehydrogenase, alanine  aminotransferase, total protein, albumin, alkaline phosphatase, total  bile acids,  creatine kinase, creatinine.
- Urinalysis: 16-hour collection during week 12 on all surviving core  study animals, with access to water but not food. Measurements included:  
volume, specific gravity, appearance (visual inspection), microscopic  examination of sediment from centrifuged sample, glucose, protein,  
N-acetyl-beta-glucosaminidase, creatinine (to be used to normalize other  values), alkaline phosphatase, aspartate aminotransferase, lactate  
dehydrogenase, gamma glutamyl transaminase

OTHER EXAMINATIONS: 
- Assessment of kidneys after 2 weeks (5 renal toxicity rats), at 6 weeks  (5 male clinical pathology rats), and at terminal  sacrifice (5 male core  study  rats): Histopathology and evaluation of cell proliferation  (positive control: cross section of small intestine) in left kidney,  measurement of 
a2u-globulin in right kidney
-  Sperm morphology & vaginal cytology (SMVCE): Vaginal cytology was  evaluated for 12 days during the last 2 weeks of the study in all  remaining 
females in the 0-, 30-, 60-, and 120-ppm groups. Epididymal  sperm concentration, spermatid heads/testis, and left caudal, epididymal  & 
testicular weights were evaluated in surviving males from the same  groups.

Sacrifice and pathology:

ORGANS EXAMINED AT NECROPSY (MACROSCOPIC AND MICROSCOPIC): 
- Macroscopic: Complete necropsy; weights of liver, thymus, right kidney,  right testis, heart, lungs.
- Microscopic: Complete histopathology on all 0- and 120-ppm-rats  included the following tissues: adrenal glands, brain, clitoral glands,  
esophagus, femur (including bone marrow & joint surfaces), gross lesions,  tissue masses, regional lymph nodes, heart, aorta, large intestine  
(cecum, colon, rectum), small intestine (duodenum, jejunum, ileum),  kidneys (left only for males), larynx, liver, lungs, mainstem bronchi,  lymph 
nodes (mandibular, mesenteric, bronchial, mediastinal), mammary  glands & adjacent skin, nasal cavity & nasal turbinates (three sections),  ovaries,  pancreas, parathyroid glands, pituitary glands, preputial  glands, prostate, salivary glands, spleen, stomach (forestomach &  glandular), testes / 
epididymis / seminal vesicles, thymus, thyroid  glands, trachea, urinary bladder, uterus.   
Target tissues identified at 120 ppm were examined at lower  concentrations to no-effect level or lowest exposure concentrations.  
Gross lesions were examined in all groups.

Other examinations:

At the end of the studies, sperm samples were collected from core study male animals in the 0, 30, 60, and 120 ppm groups for sperm motility evaluations. The following parameters were evaluated: spermatid heads per testis and per gram testis, spermatid counts, and epididymal spermatozoal motility and concentration. The left cauda, left epididymis, and left testis were weighed. Vaginal samples were collected for up to 12 consecutive days prior to the end of the studies from core study females exposed to 0, 30, 60, or 120 ppm for vaginal cytology evaluations. The percentage of time spent in the various estrous cycle stages and estrous cycle length were evaluated.

Statistics:

STATISTICAL METHODS: A modified Dunnett's t-test (Xybion Path / Tox  System; Cedar Knolls, New Jersey) was used to compare the treated groups  
to the control group with respect to body and organ weights, and  organ:body weight ratios. Corresponding statistics for hematology, and  clinical 
chemistry were calculated using the Statistical Analysis System  (SAS Institute; Berkeley, California).

Clinical signs:

no effects observed

Mortality:

no mortality observed

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

reduced body weight at 120 ppm males

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:

effects observed, treatment-related

Description (incidence and severity):

modest regenerative anemia was observed in both sexes,  primarily in groups exposed to 60 and 120 ppm

Clinical biochemistry findings:

effects observed, treatment-related

Description (incidence and severity):

Serum alanine aminotransferase decreased at 60 and 120 ppm (both sexes)

Urinalysis findings:

effects observed, treatment-related

Description (incidence and severity):

dark stained urine

Behaviour (functional findings):

not specified

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Gross pathological findings:

no effects observed

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Description (incidence and severity):

Olfactory necrosis and regeneration,

Histopathological findings: neoplastic:

no effects observed

Details on results:

TOXIC RESPONSE/EFFECTS BY DOSE LEVEL: 
- Mortality and time to death: no mortalities in any group
- Clinical signs: no clinical abnormalities in any group
- Body weight gain: lower by 6.1 % (males) and 5.7 % (females),  respectively, in highest dose groups
- Clinical chemistry: Minimal nephropathy was observed in males in the  higher exposure groups. Clinical chemistry data were consistent with  
nephropathy. serum alanine aminotransferase decreased at 60 and 120 ppm (both sexes)
- Haematology: A modest regenerative anemia was observed in both sexes,  primarily in groups exposed to 60 and 120 ppm.
- Urinalysis:    Dark-stained urine at 30, 60, and 120 ppm.    Urine aspartate aminotransferase values significantly higher in males  (ca. 2.5) and 
females (ca. 17 times control values) at the 120 ppm level.   Urine lactic dehydrogenase (LDH):creatinine ratio significantly, but  modestly 
increased  in the two highest dose levels, LDH activity increased  in 120 ppm females group.
- Organ weights:    
Kidney: Increased right kidney:body weight ratio in males (15, 60, and  120 ppm) and females (15 ppm and higher); mean absolute  right kidney  
weight slightly increased in all treated groups;   
Liver:body weight ratios increased in males ( 120 ppm) and  females (60 and 120 ppm); mean absolute liver weight slightly increased  
in all groups exposed;
- Gross pathology: no gross observations in any dose group
- Histopathology:   Olfactory necrosis and regeneration at 30 ppm, confirming the irritation potential of 1,2,3,4-tetrahydronaphthalene. 
The NOAEC for nasal lesions  was 15 ppm in males and in females.    
Hyaline droplet accumulation in kidneys of males increased slightly  with increased exposure; a NOAEC was not clear.   
Minimal nephropathy in males in the higher exposure groups
- Other: Concentrations of a2u-globulin generally increased with exposure  concentration and time on study in all groups of male F344/N rats

Key result

Dose descriptor:

NOAEC

Effect level:

82.4 mg/m³ air

Based on:

test mat.

Sex:

male

Basis for effect level:

histopathology: non-neoplastic

Remarks on result:

other: corresponds to 15 ppm

Key result

Dose descriptor:

LOAEC

Effect level:

165 mg/m³ air (nominal)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

histopathology: non-neoplastic

Remarks on result:

other: corresponds to 30 ppm

Critical effects observed:

not specified

Incidences of selected nonneoplastic lesions in F344/N rats in the 3-month inhalation study of tetrahydronaphthalene

	Control	7.5 ppm	15 ppm	30 ppm	60 ppm	120 ppm
Kidney Male Accumulation Hyaline droplet
week 2	2^a/5^b(1.0)^c	2/5 (1.0)	3/5 (1.0)	4/5 (1.8)	5/5 (1.8)	5/5 (1.6))
week 6	5/5 (1.4)	5/5 (1.2)	5/5 (1.6)	5/5 (2.0)	5/5 (2.4)	5/5 (2.4)
week 14	10/10 (1.0)	10/10 (1.1)	10/10 (2.0)	10/10 (2.0)	10/10 (2.0)	10/10 (2.0)
Nose Olfactory Epithelium necrosis
Male	0/10	0/0	0/10	4*/10 (1.8)	10**/10(2.0)	10**/10(2.0)
Female	0/10	0/10	1/10(1.0)	6**/10(1.2)	10**/10(1.6)	10**/10(2.0)

^*Significantly different (P<0.05) from the chamber control group by the Fisher exact test

^**Significantly different (P<0.01) from the chamber control group by the Fisher exact test

^aNumber of animals with lesions

^bnumber of animals examined

^cAverage severity of grade of lesions in affected animals -1= minimal, 2=mild, 3=moderate, 4 =marked

Organ Weights and Organ-Weight-to-Body-Weight Ratios for F344/N Rats in the 3-Month Inhalationstudy with tetrahydronaphthalene^a

	Control	7.5 ppm	15 ppm	30 ppm	60 ppm	120 ppm
Male Necropsy body wt	294 ± 8	301 ± 7	299 ± 6	301 ± 8	289 ± 8	276 ± 5
Heart           Absolute	0.82 ± 0.03	0.84 ± 0.03	0.83 ± 0.01	0.84 ± 0.02	0.84 ± 0.03	0.77 ± 0.02
Relative	2.791 ± 0.034	2.776 ± 0.037	2.775 ± 0.025	2.795 ± 0.052	2.891 ± 0.041	2.800 ± 0.027
R. Kidney        Absolute	0.86 ± 0.03	0.93 ± 0.03	0.94 ± 0.02	0.92 ± 0.03	0.92 ± 0.03	0.90 ± 0.02
Relative	2.930 ± 0.037	3.082 ± 0.070*	3.143 ± 0.043*	3.051 ± 0.032*	3.181 ± 0.044**	3.270 ± 0.032**
Liver         Absolute	8.48 ± 0.31	8.88 ± 0.25	9.59 ± 0.31*	9.00 ± 0.32	8.61 ± 0.34	8.65 ± 0.25
Relative	28.80 ± 0.56	29.53 ± 0.36	31.99 ± 0.62**	29.86 ± 0.44	29.76 ± 0.49	31.26 ± 0.52**
Female  Necropsy body wt	183± 4	190 ± 4	184 ± 3	180 ± 4	178 ± 4	173 ± 3
R. Kidney Absolute	0.60 ± 0.01	0.63 ± 0.02	0.64 ± 0.01	0.64 ± 0.01	0.64 ± 0.02*	0.66 ± 0.01**
Relative	3.275 ± 0.044	3.314 ± 0.060	3.492 ± 0.041**	3.543 ± 0.059**	3.622 ± 0.056**	3.827 ± 0.048**

^*Significantly different (P<0.05) from the chamber control group by William’s or Dunnett’s test

^**Significantly different (P<0.01) from the chamber control

a Organ weights (absolute weights) and body weights are given in grams; organ-weight-to-body-weight ratios (relative weights) are given as

mg organ weight/g body weight (mean ± standard error).

 

Conclusions:

A NOAEC for local effects of 15 ppm (82.4 mg/m³) was observed based on increased incidences of olfactory epithelium necrosis and of olfactory epithelium regeneration in 60 and 120 ppm rats.

Executive summary:

Groups of 10 male and 10 female rats were exposed to tetrahydronaphthalene at concentrations of 0, 7.5, 15, 30, 60, or 120 ppm, 6 hours plus T90 (12 minutes) per day, 5 days per week for 14 weeks. The same exposure concentrations were given to additional groups of 10 male and 10 female clinical pathology study rats for up to 6 weeks and five male renal toxicity rats for 2 weeks.

All rats survived to the end of the study. Mean body weights of 120 ppm male rats were significantly less than those of the chamber controls. During the first 4 weeks of exposure, dark-stained urine was observed in the catch pans of rats exposed to 30, 60, or 120 ppm. Tetrahydronaphthalene induced a minimal decrease in the erythron in both sexes that resulted in a hematopoietic response.

Increased urine aspartate aminotransferase and urine lactate dehydrogenase activities (males and females) and glucose/creatinine ratio (males), suggestive of renal injury were observed. The absolute kidney weights of 60 and 120 ppm females and the relative kidney weights of males and females exposed to 15 ppm or greater were significantly greater than those of the chamber controls. Concentrations of [alpha]2u‑globulin in the kidney of exposed male rats were generally greater than those of the chamber controls at all time points and greater at 6 and 14 weeks than at 2 weeks. A LOAEC of 7.5 ppm (41.2 mg/m³) was observed based on hyaline droplet formation. This was not considered relevant for humans because of the species specific mechanism of toxicity. There were significantly increased incidences of olfactory epithelium necrosis and of olfactory epithelium regeneration in rats exposed to 30 ppm (165 mg/m³) and higher.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

NOAEC

41.2 mg/m³

Study duration:

subchronic

Species:

rat

Quality of whole database:

RL 1 (reliable without restriction)

Repeated dose toxicity: inhalation - local effects

Link to relevant study records

Reference

Endpoint:

sub-chronic toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1996-08-19 to 1996-11-19

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Comparable to guideline study with acceptable restrictions

Principles of method if other than guideline:

Method: other: NTP Test Protocol, see Test Conditions

GLP compliance:

yes

Limit test:

no

Species:

rat

Strain:

Fischer 344

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ORGANISMS
- Source: Taconic, Germantown (New York, USA)
- Age: approximately 6 weeks at first exposure
- Number of animals: Total of 25 males and 20 females per dose = 5 male  renal toxicity rats + 10 male and 10 female core study rats
 + 10 male and  10 female clinical pathology rats
Feed was available ad libitum except during exposure and urine collectionperiods;
water was available ad libitum.
Rats and mice were housed individually.

Route of administration:

inhalation

Type of inhalation exposure:

whole body

Vehicle:

air

Details on inhalation exposure:

ADMINISTRATION / EXPOSURE 
- Type of exposure: whole-body inhalation

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

The tetralin concentrations in the exposure chambers were monitored by an online gas chromatograph. Samples were drawn from each exposure chamber approximately every 24 minutes during each 6‑hour exposure period.
Chamber concentration uniformity was maintained throughout the studies.

Duration of treatment / exposure:

14 weeks

Frequency of treatment:

6 h/day, 5 days/week; additionally: last sunday before terminal sacrifice

Dose / conc.:

0 ppm

Remarks:

control

Dose / conc.:

7.5 ppm

Remarks:

41.2 mg/m3

Dose / conc.:

15 ppm

Remarks:

82.4 mg/m3

Dose / conc.:

30 ppm

Remarks:

165 mg/m3

Dose / conc.:

60 ppm

Remarks:

330 mg/m3

Dose / conc.:

120 ppm

Remarks:

660 mg/m3

No. of animals per sex per dose:

10

Control animals:

yes, concurrent vehicle

Details on study design:

Post-exposure period: sacrifice on day after last exposure

Observations and examinations performed and frequency:

CLINICAL OBSERVATIONS AND FREQUENCY: 
- Clinical signs: twice daily including weekends
- Mortality: twice daily including weekends
- Body weight: weekly (core study rats)
- "Observations": weekly
- Hematology: Sampling from 10 animals per dose and sex on days 3 and 23  (after exposures, clinical pathology rats) and at terminal sacrifice  
(core study rats). Evaluations included: red blood cell count, volume of  packed cells and spun hematocrit, hemoglobin, mean corpuscular volume,   mean corpuscular hemoglobin, mean corpuscular hemoglobin concentration,  white blood cell count, differential count (absolute), absolute  
reticulocyte count, platelet count, Morphological assessment.
- Biochemistry: Blood urea nitrogen, sorbitol dehydrogenase, alanine  aminotransferase, total protein, albumin, alkaline phosphatase, total  bile acids,  creatine kinase, creatinine.
- Urinalysis: 16-hour collection during week 12 on all surviving core  study animals, with access to water but not food. Measurements included:  
volume, specific gravity, appearance (visual inspection), microscopic  examination of sediment from centrifuged sample, glucose, protein,  
N-acetyl-beta-glucosaminidase, creatinine (to be used to normalize other  values), alkaline phosphatase, aspartate aminotransferase, lactate  
dehydrogenase, gamma glutamyl transaminase

OTHER EXAMINATIONS: 
- Assessment of kidneys after 2 weeks (5 renal toxicity rats), at 6 weeks  (5 male clinical pathology rats), and at terminal  sacrifice (5 male core  study  rats): Histopathology and evaluation of cell proliferation  (positive control: cross section of small intestine) in left kidney,  measurement of 
a2u-globulin in right kidney
-  Sperm morphology & vaginal cytology (SMVCE): Vaginal cytology was  evaluated for 12 days during the last 2 weeks of the study in all  remaining 
females in the 0-, 30-, 60-, and 120-ppm groups. Epididymal  sperm concentration, spermatid heads/testis, and left caudal, epididymal  & 
testicular weights were evaluated in surviving males from the same  groups.

Sacrifice and pathology:

ORGANS EXAMINED AT NECROPSY (MACROSCOPIC AND MICROSCOPIC): 
- Macroscopic: Complete necropsy; weights of liver, thymus, right kidney,  right testis, heart, lungs.
- Microscopic: Complete histopathology on all 0- and 120-ppm-rats  included the following tissues: adrenal glands, brain, clitoral glands,  
esophagus, femur (including bone marrow & joint surfaces), gross lesions,  tissue masses, regional lymph nodes, heart, aorta, large intestine  
(cecum, colon, rectum), small intestine (duodenum, jejunum, ileum),  kidneys (left only for males), larynx, liver, lungs, mainstem bronchi,  lymph 
nodes (mandibular, mesenteric, bronchial, mediastinal), mammary  glands & adjacent skin, nasal cavity & nasal turbinates (three sections),  ovaries,  pancreas, parathyroid glands, pituitary glands, preputial  glands, prostate, salivary glands, spleen, stomach (forestomach &  glandular), testes / 
epididymis / seminal vesicles, thymus, thyroid  glands, trachea, urinary bladder, uterus.   
Target tissues identified at 120 ppm were examined at lower  concentrations to no-effect level or lowest exposure concentrations.  
Gross lesions were examined in all groups.

Other examinations:

At the end of the studies, sperm samples were collected from core study male animals in the 0, 30, 60, and 120 ppm groups for sperm motility evaluations. The following parameters were evaluated: spermatid heads per testis and per gram testis, spermatid counts, and epididymal spermatozoal motility and concentration. The left cauda, left epididymis, and left testis were weighed. Vaginal samples were collected for up to 12 consecutive days prior to the end of the studies from core study females exposed to 0, 30, 60, or 120 ppm for vaginal cytology evaluations. The percentage of time spent in the various estrous cycle stages and estrous cycle length were evaluated.

Statistics:

STATISTICAL METHODS: A modified Dunnett's t-test (Xybion Path / Tox  System; Cedar Knolls, New Jersey) was used to compare the treated groups  
to the control group with respect to body and organ weights, and  organ:body weight ratios. Corresponding statistics for hematology, and  clinical 
chemistry were calculated using the Statistical Analysis System  (SAS Institute; Berkeley, California).

Clinical signs:

no effects observed

Mortality:

no mortality observed

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

reduced body weight at 120 ppm males

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:

effects observed, treatment-related

Description (incidence and severity):

modest regenerative anemia was observed in both sexes,  primarily in groups exposed to 60 and 120 ppm

Clinical biochemistry findings:

effects observed, treatment-related

Description (incidence and severity):

Serum alanine aminotransferase decreased at 60 and 120 ppm (both sexes)

Urinalysis findings:

effects observed, treatment-related

Description (incidence and severity):

dark stained urine

Behaviour (functional findings):

not specified

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Gross pathological findings:

no effects observed

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Description (incidence and severity):

Olfactory necrosis and regeneration,

Histopathological findings: neoplastic:

no effects observed

Details on results:

TOXIC RESPONSE/EFFECTS BY DOSE LEVEL: 
- Mortality and time to death: no mortalities in any group
- Clinical signs: no clinical abnormalities in any group
- Body weight gain: lower by 6.1 % (males) and 5.7 % (females),  respectively, in highest dose groups
- Clinical chemistry: Minimal nephropathy was observed in males in the  higher exposure groups. Clinical chemistry data were consistent with  
nephropathy. serum alanine aminotransferase decreased at 60 and 120 ppm (both sexes)
- Haematology: A modest regenerative anemia was observed in both sexes,  primarily in groups exposed to 60 and 120 ppm.
- Urinalysis:    Dark-stained urine at 30, 60, and 120 ppm.    Urine aspartate aminotransferase values significantly higher in males  (ca. 2.5) and 
females (ca. 17 times control values) at the 120 ppm level.   Urine lactic dehydrogenase (LDH):creatinine ratio significantly, but  modestly 
increased  in the two highest dose levels, LDH activity increased  in 120 ppm females group.
- Organ weights:    
Kidney: Increased right kidney:body weight ratio in males (15, 60, and  120 ppm) and females (15 ppm and higher); mean absolute  right kidney  
weight slightly increased in all treated groups;   
Liver:body weight ratios increased in males ( 120 ppm) and  females (60 and 120 ppm); mean absolute liver weight slightly increased  
in all groups exposed;
- Gross pathology: no gross observations in any dose group
- Histopathology:   Olfactory necrosis and regeneration at 30 ppm, confirming the irritation potential of 1,2,3,4-tetrahydronaphthalene. 
The NOAEC for nasal lesions  was 15 ppm in males and in females.    
Hyaline droplet accumulation in kidneys of males increased slightly  with increased exposure; a NOAEC was not clear.   
Minimal nephropathy in males in the higher exposure groups
- Other: Concentrations of a2u-globulin generally increased with exposure  concentration and time on study in all groups of male F344/N rats

Key result

Dose descriptor:

NOAEC

Effect level:

82.4 mg/m³ air

Based on:

test mat.

Sex:

male

Basis for effect level:

histopathology: non-neoplastic

Remarks on result:

other: corresponds to 15 ppm

Key result

Dose descriptor:

LOAEC

Effect level:

165 mg/m³ air (nominal)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

histopathology: non-neoplastic

Remarks on result:

other: corresponds to 30 ppm

Critical effects observed:

not specified

Incidences of selected nonneoplastic lesions in F344/N rats in the 3-month inhalation study of tetrahydronaphthalene

	Control	7.5 ppm	15 ppm	30 ppm	60 ppm	120 ppm
Kidney Male Accumulation Hyaline droplet
week 2	2^a/5^b(1.0)^c	2/5 (1.0)	3/5 (1.0)	4/5 (1.8)	5/5 (1.8)	5/5 (1.6))
week 6	5/5 (1.4)	5/5 (1.2)	5/5 (1.6)	5/5 (2.0)	5/5 (2.4)	5/5 (2.4)
week 14	10/10 (1.0)	10/10 (1.1)	10/10 (2.0)	10/10 (2.0)	10/10 (2.0)	10/10 (2.0)
Nose Olfactory Epithelium necrosis
Male	0/10	0/0	0/10	4*/10 (1.8)	10**/10(2.0)	10**/10(2.0)
Female	0/10	0/10	1/10(1.0)	6**/10(1.2)	10**/10(1.6)	10**/10(2.0)

^*Significantly different (P<0.05) from the chamber control group by the Fisher exact test

^**Significantly different (P<0.01) from the chamber control group by the Fisher exact test

^aNumber of animals with lesions

^bnumber of animals examined

^cAverage severity of grade of lesions in affected animals -1= minimal, 2=mild, 3=moderate, 4 =marked

Organ Weights and Organ-Weight-to-Body-Weight Ratios for F344/N Rats in the 3-Month Inhalationstudy with tetrahydronaphthalene^a

	Control	7.5 ppm	15 ppm	30 ppm	60 ppm	120 ppm
Male Necropsy body wt	294 ± 8	301 ± 7	299 ± 6	301 ± 8	289 ± 8	276 ± 5
Heart           Absolute	0.82 ± 0.03	0.84 ± 0.03	0.83 ± 0.01	0.84 ± 0.02	0.84 ± 0.03	0.77 ± 0.02
Relative	2.791 ± 0.034	2.776 ± 0.037	2.775 ± 0.025	2.795 ± 0.052	2.891 ± 0.041	2.800 ± 0.027
R. Kidney        Absolute	0.86 ± 0.03	0.93 ± 0.03	0.94 ± 0.02	0.92 ± 0.03	0.92 ± 0.03	0.90 ± 0.02
Relative	2.930 ± 0.037	3.082 ± 0.070*	3.143 ± 0.043*	3.051 ± 0.032*	3.181 ± 0.044**	3.270 ± 0.032**
Liver         Absolute	8.48 ± 0.31	8.88 ± 0.25	9.59 ± 0.31*	9.00 ± 0.32	8.61 ± 0.34	8.65 ± 0.25
Relative	28.80 ± 0.56	29.53 ± 0.36	31.99 ± 0.62**	29.86 ± 0.44	29.76 ± 0.49	31.26 ± 0.52**
Female  Necropsy body wt	183± 4	190 ± 4	184 ± 3	180 ± 4	178 ± 4	173 ± 3
R. Kidney Absolute	0.60 ± 0.01	0.63 ± 0.02	0.64 ± 0.01	0.64 ± 0.01	0.64 ± 0.02*	0.66 ± 0.01**
Relative	3.275 ± 0.044	3.314 ± 0.060	3.492 ± 0.041**	3.543 ± 0.059**	3.622 ± 0.056**	3.827 ± 0.048**

^*Significantly different (P<0.05) from the chamber control group by William’s or Dunnett’s test

^**Significantly different (P<0.01) from the chamber control

a Organ weights (absolute weights) and body weights are given in grams; organ-weight-to-body-weight ratios (relative weights) are given as

mg organ weight/g body weight (mean ± standard error).

 

Conclusions:

A NOAEC for local effects of 15 ppm (82.4 mg/m³) was observed based on increased incidences of olfactory epithelium necrosis and of olfactory epithelium regeneration in 60 and 120 ppm rats.

Executive summary:

Groups of 10 male and 10 female rats were exposed to tetrahydronaphthalene at concentrations of 0, 7.5, 15, 30, 60, or 120 ppm, 6 hours plus T90 (12 minutes) per day, 5 days per week for 14 weeks. The same exposure concentrations were given to additional groups of 10 male and 10 female clinical pathology study rats for up to 6 weeks and five male renal toxicity rats for 2 weeks.

All rats survived to the end of the study. Mean body weights of 120 ppm male rats were significantly less than those of the chamber controls. During the first 4 weeks of exposure, dark-stained urine was observed in the catch pans of rats exposed to 30, 60, or 120 ppm. Tetrahydronaphthalene induced a minimal decrease in the erythron in both sexes that resulted in a hematopoietic response.

Increased urine aspartate aminotransferase and urine lactate dehydrogenase activities (males and females) and glucose/creatinine ratio (males), suggestive of renal injury were observed. The absolute kidney weights of 60 and 120 ppm females and the relative kidney weights of males and females exposed to 15 ppm or greater were significantly greater than those of the chamber controls. Concentrations of [alpha]2u‑globulin in the kidney of exposed male rats were generally greater than those of the chamber controls at all time points and greater at 6 and 14 weeks than at 2 weeks. A LOAEC of 7.5 ppm (41.2 mg/m³) was observed based on hyaline droplet formation. This was not considered relevant for humans because of the species specific mechanism of toxicity. There were significantly increased incidences of olfactory epithelium necrosis and of olfactory epithelium regeneration in rats exposed to 30 ppm (165 mg/m³) and higher.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

NOAEC

41.2 mg/m³

Study duration:

subchronic

Species:

rat

Quality of whole database:

RL 1 (reliable without restriction)

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

Partly cited from SIAR to SIAM 19 (Berlin, 19-22 October 2004):

Inhalation

In a subchronic inhalation study, 25 male and 20 female Fischer 344 rats per dose level were exposed (whole body) to nominal 1,2,3,4-tetrahydronaphthalene concentrations of 7.5; 15; 30; 60; 120 ppm = 41.2; 82.4; 165; 330; 660 mg/m3 = exposure levels 1; 2; 3; 4; 5 for 13 weeks on 6 h/day, 5 days/week (NTP, 1997 b). Rats were subdivided into groups of 5 male renal toxicity rats + 10 male and 10 female core study rats + 10 male and 10 female clinical pathology rats. Blood was sampled from 10 animals per dose and sex on days 3 and 23 (after exposures, clinical pathology rats) and at terminal sacrifice (core study rats). Urine was sampled for 16 hours during week 12 on all surviving core study animals. At terminal sacrifice, which was done the day after the last exposure, weights of liver, thymus, right kidney, right testis, heart and lungs were determined, and complete necropsy was performed. In histopathology, target tissues identified at 120 ppm were examined at lower concentrations to no-effect level or lowest exposure concentrations. Gross lesions were examined in all groups. Clinical observations were performed in all animals throughout the in-life study period. Kidneys were assessed after 2 weeks (5 renal toxicity rats), at 6 weeks (5 male clinical pathology rats), and at terminal sacrifice (5 male core study rats): Histopathology and evaluation of cell proliferation were done in the left kidneys, measurement of α2u-globulin in the right kidneys. In order to determine whether 1,2,3,4-tetrahydronaphthalene may be a reproductive toxicant, vaginal cytology was evaluated for 12 days during the last 2 weeks of the study in all remaining females in the 0-, 30-, 60-, and 120-ppm groups (0, 165, 330, and 660 mg/m3). Epididymal sperm concentration, spermatid heads/testis, and left caudal, epididymal and testicular weights were evaluated in surviving males from the same groups.

No mortalities and no clinical abnormalities were observed in any group. Body weight gain was lower by 6.1 % (males) and 5.7 % (females), respectively, in the highest dose groups. Clinical chemistry of males of the higher exposure groups was consistent with nephropathy. Hematology revealed a modest regenerative anemia in both sexes, primarily at exposure levels 4 and 5. In urinalysis, dark-stained urine was observed at exposure levels 3-5. Urine aspartate aminotransferase values were significantly higher in males (ca. 2.5) and females (ca. 17 times control values) at the highest exposure level. The urine lactic dehydrogenase (LDH):creatinine ratio was significantly, but modestly increased in the two highest dose levels, and LDH activity was increased in high dose females. There was an increased right kidney : body weight ratio in all groups of exposure levels > 2 except level 3 males; the mean absolute right kidney weight was slightly increased in all treated groups. The liver : body weight ratios were increased in males (levels 2 and 5) and females (levels 4 and 5), and the mean absolute liver weight was slightly increased in all groups exposed. Gross pathology revealed no gross observations in any dose group. Findings in histopathology were olfactory necrosis and regeneration, confirming the irritation potential of 1,2,3,4-tetrahydronaphthalene. The NOAEL for nasal lesions was 15 ppm (82.4 mg/m3) in males and in females. Hyaline droplet accumulation in kidneys of males increased slightly with increased exposure; since effects were observed even at the lowest exposure concentration, a NOAEL could not be determined. Minimal nephropathy was found in males in the higher exposure groups. Concentrations of α2u-globulin generally increased with exposure concentration and time on study. It is noted that α2u-globulin related nephropathy is species- and gender specific and is not considered to be of relevance to humans. Therefore, the α2u-globulin related nephropathy was not used for deciding on the NOAEL.

A similar subchronic inhalation study was performed by NTP (1997 a) in B6C3F1 mice, which were exposed whole-body in groups of 10 per dose and sex to nominal 1,2,3,4- tetrahydronaphthalene concentrations of 7.5; 15; 30; 60; 120 ppm = 41.2; 82.4; 165; 330; 660 mg/m3 = levels 1; 2; 3; 4; 5 for 13 weeks on 6 h/day, 5 days/week. All animals were bled only at terminal necropsy. Beside complete necropsy, weights of liver, thymus, right kidney, right testis, heart, and lungs were determined. In histopathology, target tissues identified at 120 ppm (660 mg/m3) were examined at lower concentrations to no-effect level or lowest exposure concentrations. Gross lesions were examined in all groups. Clinical observations were performed in all animals throughout the in-life study period. Two blood smears were taken from all core study animals at necropsy. One of these slides was subject to micronuclei determination. In order to determine whether 1,2,3,4-tetrahydronaphthalene may be a reproductive toxicant, vaginal cytology was evaluated for 12 days during the last 2 weeks of the study on all females in the 0-, 30-, 60-, and 120-ppm groups (0, 165, 330, and 660 mg/m3). Epididymal sperm concentration, spermatid heads/testis, and left caudal, epididymal & testicular weights were evaluated in all males from the same groups. No mortalities and no clinical abnormalities were observed in any group. Body weight gain was lower by 8.9 % (males, significant) and 7.0 % (females, insignificant), respectively, in the highest dose groups. In hematology, total erythrocytes and packed cell volumes were decreased, accompanied by increased mean corpuscular hemoglobin, mean corpuscular volume, and mean corpuscular hemoglobin concentration measurements and reticulocyte concentrations in both sexes at levels 4 and 5. Platelet concentrations were increased in these same groups. Dark-colored urine was observed at level 3 (7/10 each for males and females) and higher (all animals). Relative and absolute weights of right kidneys were reduced in males of levels 2, 4, and 5. Relative liver weights were increased for males (level 5) and females (levels 4 and 5), which may be primarily attributed to lower body weight gain in these groups. The relative (level 5) and absolute (levels 4 and 5) heart weights were decreased in males. Gross pathology revealed no gross observations in any group. In histopathology, no lesions were observed in the liver, kidney, heart, or testes that correlated with any of the weight changes observed. Atrophy of the olfactory epithelium correlated very well with observations in the previous 14-day study. Ovary and uterus atrophy was observed in high dose females. Incidences at minimal doses of observation were 2/10 (15 ppm = 82.4 mg/m3, uterus) and 4/10 (60 ppm = 330 mg/m3, ovary). Transitional epithelial eosinophilic granules were observed in the urinary bladder of all animals exposed (dose-related), the significance of this finding is unclear. Ignoring transitional epithelial eosinophilic granules of the urinary bladder, the NOAEL was 7.5 ppm = 41.2 mg/m3 (LOAEL: 15 ppm = 82.4 mg/m3; uterus atrophy) in females and 15 ppm (82.4 mg/m3) in males (LOAEL: 30 ppm = 165 mg/m3; dark-colored urine) (NTP, 1997 a). Higher test concentrations were used by Cardani (1942), who exposed three guinea pigs (2 males, 1 female) to a single test concentration for 8 hours/day until all animals were dead, i.e. for 22 days. A saturated atmosphere was generated by 3 wash bottles with pure test substance in sequence. The exposure concentration of 1,480 mg/m3 air was calculated as consumption of test substance divided by volume of air. Animals died on days 17 (male) and 22 (remaining animals). Clinical signs were piloerection, restlessness, apathy, immobility, and trembling. Body weights decreased by 21; 16; and 15 %, respectively. Food consumption was reduced. Hematology revealed slight anemia and leucopenia, and urinalysis showed oliguria, albuminuria, hematuria, increased formation of urine cylinders and dark staining of urine. In histopathology, toxic centrilobular atrophy of the livers, signed by hyperemia, cloudy swelling and fatty degeneration were observed. Kidneys of all animals showed necrotic nephrosis. Lungs showed localized broncho-pneumonia.

Dermal

The reliability of the only dermal repeated dose study with 1,2,3,4-tetrahydronaphthalene published cannot be assessed due to lacking information on doses. The study was performed by Cardani (1942), who treated two guinea pigs of differing sex for 16 days twice daily at an interval of several hours with a cotton swab soaked with 1,2,3,4-tetrahydronaphthalene. The application area had been shaved and treated with barium sulfide for removal of hair. Animals died on days 11 (female) and 16 (male). Clinical signs were piloerection, restlessness, apathy, immobility, and trembling. Body weights decreased by 12 % (male) and 8 % (female), respectively. Food consumption was reduced. Hematology revealed slight anemia and leucopenia, and in urinalysis oliguria, albuminuria, hematuria, increased formation of urine cylinders and dark staining of urine were found. At gross pathology, the skin application area showed squamous and crusted eczema. Histopathology findings were toxic centrilobular atrophy of the livers, signed by hyperemia, cloudy swelling and fatty degeneration. Kidneys of both animals showed necrotic nephrosis. Lungs showed localized broncho-pneumonia. Oral

The subacute toxicity of 1,2,3,4-tetrahydronaphthalene with gavage application in rats was tested by Hüls AG (1995 a) in accordance with Directive 84/449/EEC, B.7 (1992). The study was combined with toxicokinetic investigations. Six groups each comprising five Wistar rats per sex were assigned to the following dose levels: vehicle control (2 groups); 15; 50; 150 mg/kg bw/day; 150 mg/kg bw/day reversal group. 2 ml/kg bw of the vehicle corn oil including the appropriate doses of 1,2,3,4-tetrahydronaphthalene were applied by gavage for 28 consecutive days. No mortalities occurred in any group. Piloerection and alopecia were observed in all groups including controls, the former symptom fading away within a few days of recovery. Squatting position and closed eyes were observed in all treated groups, and reduced activity in high dose males. There was a transient decrease in absolute body weights of all treated males, which was still significant (-11.3 %) in the high dose group on day 28 and compensated during the recovery period. It corresponded to an increased food conversion rate, which decreased during the recovery period, in high dose males. A less pronounced increase in food conversion rate was observed in low and high dose females.

No signs of test substance related effects were detected in ophthalmoscopic examination. Clinical chemistry showed some significant changes, but a dose-response relationship only has to be discussed for sodium, which was significantly increased in all high dose animals and in low dose males but also high (close to historical control maximum) in the control males. Results of hematology included a significant decrease of the red blood cell count in males (insignificant in females of high dose group); improvement with males during recovery still left a significant decrease. Reticulocytes and eosinophiles were significantly increased in high dose females. The recovery group showed a significant increase in hemoglobin and consequently in MCV and MCH of dosed females. The urine volume was significantly increased in high dose females. The colour of the urine showed a change to yellow-brown and dark, which was not dose dependent. Urine sediment analysis gave a dose-dependent increase in oxalates, which was statistically significant in high dose males with individual values beyond the range of the historical control data also for three intermediate dose males. Recovery left oxalates of two individuals beyond the range of the historical control data. High presence of oxalates in urine was also observed in one or two individuals each of all female control and high dose groups including both recovery groups. Triplephosphates were significantly increased and erythrocytes significantly decreased in high dose males. The urine pH was significantly decreased in high dose females (6.80, control 8.20) and one intermediate dose female. Unusual presence of glucose in urine and high presence of ketone was also observed in the high dose female with the lowest pH of urine. Changes in organ weights were scarce and focussed on the spleen, the relative weight of which was increased statistically significantly in high dose males and insignificantly, not dose related in intermediate and high dose females. Absolute spleen weights were decreased in low dose females. In the high dose male recovery group, absolute weight of spleen and relative weight of adrenals were increased. Gross pathology revealed no macroscopic lesions considered to be related to treatment. Findings of histopathology consisted of spontaneous lesions in males and females of all groups such as hydrometriosis of the uterus, calcification of Peyer's patches, hyaline casts in the kidney and multifocal lymphocytes in the lung. The NOAEL is 50 mg/kg bw/day, and the LOAEL is 150 mg/kg bw/day (Hüls AG, 1995).

The cataract formation reported by Basile (1939) for rabbits after oral application of 1,2,3,4- tetrahydronaphthalene for 30 - 40 days at doses of 0.2 - 1 ml/day supports the assumption that this substance has an adverse effect on eyes. Cataract formation was further studied by Fitzhugh and Buschke (1949) in rats. They found no cataract formation with 1,2,3,4-tetrahydronaphthalene itself but with 1,2,3,4-tetrahydro-2-naphthol, which is a metabolite of 1,2,3,4-tetrahydronaphthalene. It was suggested that the difference in the effects of 1,2,3,4-tetrahydronaphthalene on the eye of the rat and the rabbit might be due to metabolic differences, the cataractogenic metabolite 1,2,3,4-tetrahydro- 2-naphthol being predominant in the rabbit and the non-cataractogenic 1,2,3,4-tetrahydro-1- naphthol being predominant in the rat (Basile, 1939). However, the ratio 1,2,3,4-tetrahydro-2- naphthol / 1,2,3,4-tetrahydro-1-naphthol is about 1:2 in rabbits (Elliott and Hanam, 1968) and about 1:4 in rats (Servé, 1989). This means that differences in metabolism cannot account completely for the differences between these species. Anyway, the absence of cataract observations in more recent animal studies indicates that the potential for cataract formation of 1,2,3,4-tetrahydronaphthalene is low.

Cited from SIAR to SIAM 19 (Berlin, 19-22 October 2004):

In 13-week inhalation studies on rats and mice (performed within the U.S. National Toxicology Program and currently available only as abstracts plus key tables), no mortalities, no clinical abnormalities, and no gross pathological findings were observed at exposure concentrations up to and including 660 mg/ m³. In mice, transitional epithelial eosinophilic granules were observed in the urinary bladder of all exposed groups (dose-related), the toxicological significance of this finding is however unclear. In female mice, uterus atrophy was found at 82.4 mg/ m³, and atrophy of the ovary at 330 mg/ m³. In rats, a NOAEL could also not be established due to increased liver weight down to the lowest tested concentration (41.2 mg/m³). The NOAEL for nasal lesions in rats was 82.4 mg/ m³in males and 41.2 mg/ m³in females, and 164.8 mg/ m³in mice.

In a 28 day toxicity study in rats with gavage application of up to 150 mg 1,2,3,4-tetrahydro­naphthalene/ kg bw/day, no mortalities occurred in any group. Squatting position and closed eyes were observed in all treated groups. There was a transient decrease in absolute body weights of all treated males. Results of hematology were indicative of a hemolytic anemia in males and females of the high dose group, which was still present, though to a lesser degree, at the end of the recovery period. As a secondary reaction to the anemia, the reticulocyte counts for high dose females were increased and the extramedullary hematopoesis in the spleen of both high dose genders was enhanced. Based on the adverse effects on blood and spleen (significant at 150 mg/kg bw/day but already beginning at 50 mg/kg bw/day), the NOAEL in this study was at 15 mg/kg bw /day.

Repeated dose toxicity: via oral route - systemic effects (target organ) cardiovascular / hematological: spleen

Repeated dose toxicity: inhalation - systemic effects (target organ) respiratory: nose

Justification for classification or non-classification

In the available repeated dose toxicity studies with oral and inhalation routes of exposure, some adverse effects occured, however, based on the data, classification for specific target organ toxicity is not required according to CLP regulation 1272/2008.