2-Thiophenecarboxylic acid, 5-chloro-

Endpoint summary

Description of key information

Study conducted according to OECD test guideline 407, Wistar rats 5/sex/dose; 5-Chlorthiophen-2-carbonsäure in  2% Chremophor EL® administered by gavage at dose levels of 0 (control), 50, 170 and 500 mg/kg bw/day for 28 consecutive days; result: NOAEL: 50 mg/kg bw/d

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:

2007-02-26 to 2007-07-30

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

27 July 1995

GLP compliance:

yes

Limit test:

no

Species:

rat

Strain:

Wistar

Remarks:

Hsd Cpb:VVU

Details on species / strain selection:

The study was conducted on rats, a species recommended in guidelines for subacute toxicity studies.

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Harlan Winkelmamr GmbH, Borchen, Germany
- Females (if applicable) nulliparous and non-pregnant: yes
- Age at study initiation: 5 weeks
- Weight at study initiation: Males: 169 (153 - 184) g
Females: 140 (116 - 158) g
- Housing: At their arrival the animals were placed together, separated by sex, in some Makrolon® cages Type III and transported into the animal room where they were put individually into Makrolon® cages Type Ila up to tattooing. From tattooing to necropsy animals were kept in groups with 2 or 3 animals in Makrolon® cages Type IV. For enviromnental enrichment wooden blocks supplied by Tapvei OY, 73 620, Kortteinen, Finland, were provided to each cage and renewed as necessary.
- Diet (e.g. ad libitum): The diet consisted of a fixed-forrnula standard diet (supplied by Provimi Kliba SA, CH-4303 Kaiseraugst, Switzerland). Diet (Provimi Kliba SA 15 W10 (3883.0. 15 pellet)) was provided in racks integrated in cage-lids for ad libitum consumption except during the 16h urine sampling period.
- Water (e.g. ad libitum): tap water, water was supplied in polycarbonate bottles with a capacity of approximately 300 ml for ad libitum consumption (2 bottles per cage).
- Acclimation period: 8 days

DETAILS OF FOOD AND WATER QUALITY: The nutritive composition and contaminant content ofthe standard diet were routinely checked and analyzed. The tap water complied with the actual German Drinking Water Ordinance ("Trinkwasser-Verordnung” ofDecember 5, 1990; Federal Law Gazette No. 66 edited December 12, 1990, page 2612 and supplemented on May 21, 2001, Federal Law Gazette No. 24, issued on May 28, 2001, page 959 ff). The results of food and water analyses were stored. The available data provided no indication of any effect on the study objective.

ENVIRONMENTAL CONDITIONS
- Temperature (°C):22+/-2
- Humidity (%): 55+/-5
- Air changes (per hr):10
- Photoperiod (hrs dark / hrs light): 12/12

IN-LIFE DATES:
Study Initiation Date: February 23, 2007
Experimental Starting Date: February 27, 2007
(=First Day of Treatment)
End of In-Life-Phase: March 29, 2007
Total Duration of Study: 31 days
Duration of Treatment: 29/30 days
Necropsy: March 28, 2007 (males)
March 29, 2007 (females)
0 Experimental Completion Date: May 24, 2007

Route of administration:

oral: gavage

Vehicle:

other: 2% aqueous Cremophor EL®

Details on oral exposure:

PREPARATION OF DOSING SOLUTIONS: The test item was formulated with 2% aqueous Cremophor EL® as suspension at the appropriate concentrations at room temperature and maximally used over the stability period of 8 days. The test substance was administered as a suspension.


VEHICLE
- Justification for use and choice of vehicle (if other than water): 2% aqueous Cremophor EL®
- Concentration in vehicle: 5, 17, 50 mg/mL
- Amount of vehicle (if gavage): 10 mL/kg bw

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Investigation on homogeneity and stability of the test item was done prior to the study. The correct concentrations and homogeneity in the formulations given to the rats were determined twice by analytical examination during the study.
For analytical investigations, samples from the test item formulations covering the test item concentration range used in the study were taken. These samples were diluted with methanol into the working range and subsequently quantified by a spectrometric method (UV-VIS). The detection wave length is 274 nm. Standard solutions of the authentic test item were used for calibration. Standard solutions of the authentic test item were used for calibration. Linearity, Precision, Specificity, Robustness and Accuracy of the analytical method were evaluated apart from this GLP-study and fulfil the predefined acceptance criteria. Additionally system suitability tests in terms of specificity, precision and linearity indicated, that qualified analytical procedures were followed during the study.
Analysis of blank samples (0 mg/mL) revealed no measurable traces of test item.
The analytical data reveal that the homogeneity of the formulations is given. The content checks assure that during the study appropriate and equal mixture procedures were followed. Formulations are homogenous and stable for at least 8 days at room temperature.

Duration of treatment / exposure:

28 days

Frequency of treatment:

daily

Dose / conc.:

500 mg/kg bw (total dose)

Dose / conc.:

170 mg/kg bw (total dose)

Dose / conc.:

50 mg/kg bw (total dose)

Dose / conc.:

0 mg/kg bw (total dose)

No. of animals per sex per dose:

5

Control animals:

yes, concurrent vehicle

Details on study design:

- Dose selection rationale: Dose levels have been selected based on the results obtained in a previous 2-week rat gavage study with 5-Chlorthiophen-2-carbonsäure with 0, 50, 150, 300 and 500 mg/kg b.w. and additionally on the results of single animals treated with 300, 500, 750 and 1000 mg/kg for few days. Results of the 2-week study: Clinical observations, mortality and food intake did not give any evidence for treatment-related effects up to 500 mg/kg. Body weight was inconspicuous in males up to 300 mg/kg and in all female groups. Males at 500 mg/kg showed a slightly delayed body weight gain. Water consumption was increased in males at 150 mg/kg and above and in females at 300 mg/kg and above (up to 46 and 40%). Relative liver weights were higher in both sexes at least at 300 mg/kg and above compared to controls. Relative spleen and kidney weights were slightly higher in females at 500 mg/kg whereas relative prostate weight appeared slightly lower at this dose compared to controls. At necropsy thickened stomach and elongated intestine were observed in both sexes at 300 mg/kg and above. Correspondingly to the increased liver weight, liver appeared enlarged in 300 and/or 500 mg/kg rats; in one high dose rat areas were noted for epididymides. Previous to the 2-week study single animals (1 male and 1 female each) were treated with 300, 500, 750 and 1000 mg/kg for a few days. Rats at 1000 and 750 mg/kg died or had to be killed in moribund condition on day 2 or 3. The 500 mg/kg male had to be killed on day 6 of treatment; no clinical findings were seen in the 500 mg/kg female and the 300 mg/kg rats for a period ofup to 7 days of treatment.
Therefore, the proposed dose levels for the 4-weeks study were 0-50-170-500 mg/kg b.w. of 5-Chlorthiophen-2-carbonsäure.

- Fasting period before blood sampling for clinical biochemistry: non-fasted

- Section schedule rationale (if not random): All animals scheduled for terminal necropsy and all rats to be sacrificed moribund were killed by exsanguination under deep diethyl ether anesthesia and necropsied. Their organs and tissues were subjected to thorough gross pathological examination. The organs and tissues fixed and the methods of fixation are described in the Pathology Report. Animals that died spontaneously were necropsied at the earliest opportunity. From these animals the organs and tissues were handled as described above.
- Dose range finding studies: see above under "rationale for dose-selection"

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: twice daily, once daily on weekends and public holidays


DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: weekly

BODY WEIGHT: Yes
- Time schedule for examinations: daily

FOOD CONSUMPTION AND COMPOUND INTAKE: weekly
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: Yes
- Compound intake calculated as time-weighted averages from the consumption and body weight gain data: No

FOOD EFFICIENCY:
- Body weight gain in kg/food consumption in kg per unit time X 100 calculated as time-weighted averages from the consumption and body weight gain data: No

WATER CONSUMPTION AND COMPOUND INTAKE: Yes
- Time schedule for examinations: weekly

OPHTHALMOSCOPIC EXAMINATION: No

HAEMATOLOGY: Yes
- Time schedule for collection of blood: on day 29
- Anaesthetic used for blood collection: No
- Animals fasted: No
- How many animals: all

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: on day 29
- Animals fasted: No
- How many animals: all

PLASMA/SERUM HORMONES/LIPIDS: No

URINALYSIS: Yes
- Time schedule for collection of urine: on day 28 for 16 h
- Metabolism cages used for collection of urine: Not specified
- Animals fasted: No

NEUROBEHAVIOURAL EXAMINATION: Yes
- Time schedule for examinations: Open Field Observation (OFO): once before start and once weekly thereafter; Functional Observational Battery: day 23/24; Motor Activity: day 24/25
- Dose groups that were examined: all
- Battery of functions tested: - home cage pbse_rvation: posture, piloerection, gait abnormalities, involuntary motor
movements, vocalization, others
- observations during handlirgg; ease of removing, reaction to being handled, muscle tone, palpebral closure, lacrimation, nasal discharge, salivation, stains, body temperature, pupil size, pupil response
- open field observations: piloerection, respiratory abnormalities, posture, involuntary motor movements, stereotypy, bizarre behavior, gait abnormalities, vocalization, arousal, rearing, defecation, urination, others
- the following manipulative tests were additionally performed:
approach response, touch response, auditory response, tail pinch response, righting reflex, grip strength and landing foot splays.

IMMUNOLOGY: No

Sacrifice and pathology:

GROSS PATHOLOGY: Yes (see table)

HISTOPATHOLOGY: Yes (see table)

Optional endpoint(s):

Optional endpoints: No

Statistics:

see under "Any other information on materials and methods incl. tables"

Clinical signs:

effects observed, treatment-related

Description (incidence and severity):

Daily observations and detailed weekly examinations revealed salivation in one
male at 500 mg/kg (animal no. 19) from day 23 to day 29 and breathing sounds in another male at 500 mg/kg (animal no. 20) on day 16. No clinical signs were seen in treated males up to 170 mg/kg and in all treated females.

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

The mean body weights of treated males and females did not differ toxicologically relevantly from controls up to 170 mg/kg in males and up to 500 mg/kg in females. Males and females at 500 mg/kg showed a slight body weight reduction after the first treatment with the test substance The body weight development was general
slightly reduced in males at this group At the end of treatment, the difference to control was 11%; however, before the start of treatment, the difference to control was already 6%. A transient body weight reduction from day 27 to 28 could be observed in all groups caused by fasting during urine sampling period

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

effects observed, treatment-related

Description (incidence and severity):

Water intake per animal and per kg body weight was markedly increased in both sexes at 500 mg/kg (per animal 27% in males and 35% in females, per kg body weight 41% in both sexes). No toxicologically relevant changes in water intake was deterniind in both sexes up to 170 mg/kg.

Haematological findings:

effects observed, non-treatment-related

Description (incidence and severity):

Hematological investigation revealed decreased count of erythrocytes (ERY), decreased hemoglobin concentration (HB) as well as decreased hematocrit (HCT) value in both sexes at 500 mg/kg. The count of reticulocytes (RETI) was slightly increased in both sexes at 500 mg/kg (RETI not statistically significantly in females). The mean corpuscular erythrocyte volume (MCV) was statistically significantly increased in males at 500 mg/kg. The MCHC mean in males at 170 mg/kg, which was statistically significantly different from control values, is considered to be of no toxicological relevance, since the difference from control was negligibly low and it did not show a correlation with the dose administered. The count of leucocytes (LEUCO) was increased in females at 500 mg/kg and the counts of neutrophils (NEUTRO) and monocytes (MONO) were increased in both sexes at this dose (mostly p>0.05; increase of LEUCO and MONO was slight). The count of eosinophils (EOS) was slightly decreased in males at 170 mg/kg and above and in females at 500 mg/kg (females: p>0.05).

Description (incidence and severity):

Determination ofplasma enzyme activities revealed increased activities of aspartate aminotransferase (ASAT) in both sexes at 500 mg/kg (p>0 05 % in females) Activity of alanine aminotransferase(ALAT) was slightly but statistically significantly higher in both sexes at 500 mg/kg compared to controls, however, the differences to controls were small and all individual values were within the 2s range of historical data. Determination of substrates in blood samples showed slightly decreased total protein concentration (PROT) in males (p≤ 0.01) as well as increased urea and slightly increased creatinine (CREA) concentrations in females at 500 mg/kg. Glucose concentrations in females at 50 and 170 mg/kg, which were statistically significantly different from control values, are considered to be ofno toxicological relevance since the differences from control were negligibly low and they did not show a correlation with the dose administered.

Urinalysis findings:

effects observed, non-treatment-related

Description (incidence and severity):

Urinalysis showed slightly reduced pH values in 500 mg/kg males (p≤0.05).
The semi-quantitatively determined blood, bilirubin, glucose, urobilinogen were unremarkable in all groups; the concentrations of ketone bodies were slightly increased in both sexes at 170 mg/kg and above. The sediments showed no abnormalities in treated male or female animals compared to respective controls.

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Description (incidence and severity):

Absolute and relative thymus weights were reduced in both sexes at 500 mg/kg (absolute: 32% in males, 25% in females; relative: 26% in both sexes). Relative liver (15% in males, 38% in females) and kidney (12% in males, 28% in females) weights were increased in both sexes at 500 mg/kg (in females also absolute liver (37%) and kidney (29%) weights were increased; all changes: at least p≤0.05).
Absolute brain and testis weights were slightly reduced in males at 500 mg/kg (brain 11%, testis 14%). Absolute (p>0.05) and relative heart weights were slightly increased in females at 500 mg/kg (14-15%). The determination of the weights ofthe other organs gave no evidence for treatment-related effects.

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Description (incidence and severity):

Histopathology revealed minimal to moderate neuronal degeneration with reactive gliosis in the hippocampus (CA1-3), the gyrus dentatus and in the retrosplenial and piriform cortex in 1/5 males and 4/5 females at 500 mg/kg. Slight sciatic nerve fiber degeneration and subsequent moderate thigh muscle atrophy were found in the female no. 39 at 500 mg/kg, which was also affected by thymic atrophy. In the liver, increased glycogen storage ofperiportal hepatocytes was diagnosed in males at 170 mg/kg and above (incidence: 0-0-4-5) and in females at 500 mg/kg (incidence: 0-0-0-5). Decreased hepatocellular fat storage was found in both sexes at 500 mg/kg.
In the spleen, hemopoiesis was slightly increased in females at 500 mg/kg. Corresponding to the observed gross findings, squamous cell hyperplasia and hyper-/dyskeratosis up to a moderate severity level were detected at the limiting ridge of the forestomach to the glandular stomach in both genders at 500 mg/kg and in one male at 170 mg/kg. These findings were accompagnied by basophilia ofthe adjacent glandular epithelium ofthe gastric fundus. Sperm granulomas in 2 males at 500 mg/kg were assessed as occasional findings that are usually found as well in control animals. All other findings not being mentioned in detail are regarded to be individual or strain-, gender-, age-related or handling-derived alterations, which are well documented in publications about laboratory animals and/or are equally distributed among control and treated animals.

Key result

Dose descriptor:

NOAEL

Effect level:

50 mg/kg bw (total dose)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

behaviour (functional findings)

body weight and weight gain

clinical biochemistry

gross pathology

haematology

histopathology: non-neoplastic

organ weights and organ / body weight ratios

Critical effects observed:

yes

Lowest effective dose / conc.:

50 mg/kg bw/day (actual dose received)

System:

musculoskeletal system

Organ:

other: sciatic nerve degeneration

Treatment related:

yes

Dose response relationship:

no

Relevant for humans:

not specified

Critical effects observed:

yes

Lowest effective dose / conc.:

50 mg/kg bw/day (actual dose received)

System:

nervous system

Organ:

brain

Treatment related:

yes

Dose response relationship:

no

Relevant for humans:

not specified

Critical effects observed:

yes

Lowest effective dose / conc.:

50 mg/kg bw/day (actual dose received)

System:

gastrointestinal tract

Organ:

stomach

Treatment related:

yes

Dose response relationship:

no

Relevant for humans:

not specified

Conclusions:

Under the conditions described the no-observed-adverse-effect level (NOAEL) for the administration of 5-Chlorthiophen-2-carbonsäure orally by gavage was 50 mg/kg b.w. in male and in female rats.
The NOAEL is based on adverse neurological behaviour observed in the 500 mg/kg group but also in 1 female of the 170 mg/kg group, all other significant findings occurred in the 500 mg/kg dose group only, BW was not affected at all. Based on these results and in absence of any histopathological findings in 50 & 170 mg/kg groups classification for STOT-RE is not warranted.

Executive summary:

In a subacute toxicity study according to OECD guideline 407 (1995) 5-Chlorthiophen-2-carbonsäure (100% a.i.) was administered to Wistar rats 5/sex/dose 2% Chremophor EL® by gavage at dose levels of 0 (control), 50, 170 and 500 mg/kg bw/day for 28 consecutive days.

No mortality occurred. The Clinical sign observed was salivation in one male for several days and breathing sounds in another male on a single day at 500 mg/kg. No other changes were observed at the weekly detailed clinical observations. Neurotoxicity assessment revealed the following effects: A slightly reduced mean count of rearings in 500 mg/kg males (14.4 -- 10.8 — 11.2 — 6.8); a trend could also be seen in females at this dose (18.6 - 19.0 — 20.2 — 15.2). Correspondingly, MA tests revealed slightly and partly dose-dependently reduced vertical activity in both sexes at 170 and 500 mg/kg. Absolute brain weight was slightly reduced in males at 500 mg/kg (11%). Histopathology revealed minimal to moderate neuronal degeneration with reactive gliosis in the hippocampus, the gyrus dentatus and in the retrosplenial and piriform cortex in 1/5 males and 4/5 females at 500 mg/kg. Slight sciatic nerve fiber degeneration and subsequent moderate thigh muscle atrophy were found in one 500 mg/kg female. In summary, clinical and morphological findings are indicative of a neurotoxicological potential of 5-Chlorthiophen-2-carbonsäure starting at 170 mg/kg.

Body weight was slightly reduced in both sexes at 500 mg/kg after the first treatment with the test substance; the body weight development was generally slightly lower in males at this dose than in controls. At the end of treatment, the difference to control was 11%; however, before the start of treatment, the difference to control was already 6%.

Water intake was markedly increased in both sexes at 500 mg/kg (41% per kg body weight). Serum electrolytes were inconspicuous. Urinalysis showed slightly reduced pH values in 500 mg/kg males and slightly increased ketone body concentrations in both sexes at 170 mg/kg and above (ketone body see also below). Sediments showed no abnormalities in any group. Absolute (females) and relative (both sexes) kidney weights were increased at 500 mg/kg (12% in males, 28-29% in females); histopathology did not reveal any test substance-induced changes. The increase in water intake is interpreted as a consequence of the local irritative effect of 5-Chlorthiophen-carbonsäure on the mucosa of the G1 tract and is not considered an expression of damage to the kidneys as histopathological changes of the kidneys as well as changes in urine and blood parameters indicative of kidney damage are absent.

Hematological investigation revealed decreases in HCT, ERY count and HB concentration in both sexes at 500 mg/kg and the count of RETI was slightly increased in both sexes and the MCV value in malesat this dose. In the spleen, hemopoiesis was slightly increased in females at 500 mg/kg. The count of LEUCO (slight degree) was increased in females and the counts of NEUTRO and MONO (slight degree) were increased in both sexes at 500 mg/kg. The count of EOS was slightly decreased in males at 170 mg/kg and above and in females at 500 mg/kg.

Absolute and relative thymus weights were reduced in both sexes at 500 mg/kg (about 25-32%); in one 500 mg/kg female thymic atrophy was diagnosed.

Clinical laboratory tests revealed increased activity of ASAT and slightly increased activity ofALAT in both sexes at 500 mg/kg (ASAT in females: p>0.05), which is concluded to be adverse. Determination of substrates in blood samples showed slightly decreased total PROT concentration in males and slightly increased CREA and urea concentrations in females at 500 mg/kg. Absolute liver weight in females and relative liver weights in both sexes were increased at 500 mg/kg (15% in males, about 38% in females). Increased glycogen storage of periportal hepatocytes was diagnosed in males at 170 mg/kg and above (incidence: 0-0-4-5) and in females at 500 mg/kg (incidence: 0-0-0-5). Decreased hepatocellular fat storage was found in both sexes at 500 mg/kg. Changes in glycogen and fat storages in the liver as well as in urine ketone body concentrations (see above) may be indicative for metabolic alterations induced by the test substance.

During necropsy dilations of the stomach as well as white areas at the limiting ridge of the forestomach to the glandular stomach were found in both sexes at 500 mg/kg. Correspondingly, squamous cell hyperplasia and hyper-/dyskeratosis up to a moderate severity level were detected in the described area in both sexes at 500 mg/kg and in one male at 170 mg/kg. These findings were accompanied by basophilia of the adjacent glandular epithelium of the gastric fundus and are concluded as adverse.

Absolute, but not relative testes weight was slightly reduced in males at 500 mg/kg (14%). Sperm granulomas in 2 males at 500 mg/kg were assessed as occasional findings that are usually found as well in control animals. Due to the only slight difference to control animals and in the absence of corresponding morphological changes the reduction in testes weight is considered toxicologically not relevant.

Relative heart weight was slightly increased in females at 500 mg/kg (14%); without histopathological correlate, no toxicological relevance is assumed.

 

 

Under the conditions described the no-observed-adverse-effect level (NOAEL) for the administration of 5-Chlorthiophen-2-carbonsäure orally by gavage was 50 mg/kg b.w. in male and in female rats.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

NOAEL

Study duration:

subacute

Experimental exposure time per week (hours/week):

168

Species:

rat

Quality of whole database:

Study conducted according to OECD test guideline 407, reliability is considered high

System:

gastrointestinal tract

Organ:

stomach

Repeated dose toxicity: inhalation - systemic effects

Endpoint conclusion

Endpoint conclusion:

no study available

Repeated dose toxicity: inhalation - local effects

Endpoint conclusion

Endpoint conclusion:

no study available

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

In a subacute toxicity study according to OECD guideline 407 (1995) 5-Chlorthiophen-2-carbonsäure (100% a.i.) was administered to Wistar rats 5/sex/dose 2% Chremophor EL® by gavage at dose levels of 0 (control), 50, 170 and 500 mg/kg bw/day for 28 consecutive days.

No mortality occurred. The Clinical sign observed was salivation in one male for several days and breathing sounds in another male on a single day at 500 mg/kg. No other changes were observed at the weekly detailed clinical observations. Neurotoxicity assessment revealed the following effects: A slightly reduced mean count of rearings in 500 mg/kg males (14.4 -- 10.8 — 11.2 — 6.8); a trend could also be seen in females at this dose (18.6 - 19.0 — 20.2 — 15.2). Correspondingly, MA tests revealed slightly and partly dose-dependently reduced vertical activity in both sexes at 170 and 500 mg/kg. Absolute brain weight was slightly reduced in males at 500 mg/kg (11%). Histopathology revealed minimal to moderate neuronal degeneration with reactive gliosis in the hippocampus, the gyrus dentatus and in the retrosplenial and piriform cortex in 1/5 males and 4/5 females at 500 mg/kg. Slight sciatic nerve fiber degeneration and subsequent moderate thigh muscle atrophy were found in one 500 mg/kg female. In summary, clinical and morphological findings are indicative of a neurotoxicological potential of 5-Chlorthiophen-2-carbonsäure starting at 170 mg/kg.

Body weight was slightly reduced in both sexes at 500 mg/kg after the first treatment with the test substance; the body weight development was generally slightly lower in males at this dose than in controls. At the end of treatment, the difference to control was 11%; however, before the start of treatment, the difference to control was already 6%.

Water intake was markedly increased in both sexes at 500 mg/kg (41% per kg body weight). Serum electrolytes were inconspicuous. Urinalysis showed slightly reduced pH values in 500 mg/kg males and slightly increased ketone body concentrations in both sexes at 170 mg/kg and above (ketone body see also below). Sediments showed no abnormalities in any group. Absolute (females) and relative (both sexes) kidney weights were increased at 500 mg/kg (12% in males, 28-29% in females); histopathology did not reveal any test substance-induced changes. The increase in water intake is interpreted as a consequence of the local irritative effect of 5-Chlorthiophen-carbonsäure on the mucosa of the G1 tract and is not considered an expression of damage to the kidneys as histopathological changes of the kidneys as well as changes in urine and blood parameters indicative of kidney damage are absent.

Hematological investigation revealed decreases in HCT, ERY count and HB concentration in both sexes at 500 mg/kg and the count of RETI was slightly increased in both sexes and the MCV value in malesat this dose. In the spleen, hemopoiesis was slightly increased in females at 500 mg/kg. The count of LEUCO (slight degree) was increased in females and the counts of NEUTRO and MONO (slight degree) were increased in both sexes at 500 mg/kg. The count of EOS was slightly decreased in males at 170 mg/kg and above and in females at 500 mg/kg.

Absolute and relative thymus weights were reduced in both sexes at 500 mg/kg (about 25-32%); in one 500 mg/kg female thymic atrophy was diagnosed.

Clinical laboratory tests revealed increased activity of ASAT and slightly increased activity ofALAT in both sexes at 500 mg/kg (ASAT in females: p>0.05), which is concluded to be adverse. Determination of substrates in blood samples showed slightly decreased total PROT concentration in males and slightly increased CREA and urea concentrations in females at 500 mg/kg. Absolute liver weight in females and relative liver weights in both sexes were increased at 500 mg/kg (15% in males, about 38% in females). Increased glycogen storage of periportal hepatocytes was diagnosed in males at 170 mg/kg and above (incidence: 0-0-4-5) and in females at 500 mg/kg (incidence: 0-0-0-5). Decreased hepatocellular fat storage was found in both sexes at 500 mg/kg. Changes in glycogen and fat storages in the liver as well as in urine ketone body concentrations (see above) may be indicative for metabolic alterations induced by the test substance.

During necropsy dilations of the stomach as well as white areas at the limiting ridge of the forestomach to the glandular stomach were found in both sexes at 500 mg/kg. Correspondingly, squamous cell hyperplasia and hyper-/dyskeratosis up to a moderate severity level were detected in the described area in both sexes at 500 mg/kg and in one male at 170 mg/kg. These findings were accompanied by basophilia of the adjacent glandular epithelium of the gastric fundus and are concluded as adverse.

Absolute, but not relative testes weight was slightly reduced in males at 500 mg/kg (14%). Sperm granulomas in 2 males at 500 mg/kg were assessed as occasional findings that are usually found as well in control animals. Due to the only slight difference to control animals and in the absence of corresponding morphological changes the reduction in testes weight is considered toxicologically not relevant.

Relative heart weight was slightly increased in females at 500 mg/kg (14%); without histopathological correlate, no toxicological relevance is assumed.

 

 

 

Justification for classification or non-classification

Under the conditions described the no-observed-adverse-effect level (NOAEL) for the administration of 5-Chlorthiophen-2-carbonsäure orally by gavage was 50 mg/kg b.w. in male and in female rats.

The NOAEL is based on adverse neurological behaviour observed in the 500 mg/kg group but also in 1 female of the 170 mg/kg group, all other significant findings occurred in the 500 mg/kg dose group only, BW was not affected at all.

Base on these results and in absence of any histopathological findings in the 50 & 170 mg/kg groups classification for STOT-RE according to Regulation (EU) 1272/2008 (CLP) is not warranted.