Chlorosulphuric acid

Endpoint summary

Description of key information

Repeated dose toxicity: Oral

The no observed adverse effect level (NOAEL) for the test chemical is considered to be 625 mmol /kg.

Repeated dose toxicity: Inhalation

The no observed adverse effect concentration (NOAEC) is considered to be 5.52 mg/m3 when rodents were exposed to the test chemical.

Repeated dose toxicity: Dermal

This end point was considered for waiver considering that chlorosulphuric acid is an extremely strong acid with the pH less than 1. Thus, it shall always be handled with due precaution. The use of safety apparatus like hand gloves, goggles, etc is a common practice while handling concentrated acids in the industries. Thus, repeated exposure by the dermal route is highly unlikely due to which this end point was considered for waiver.

Key value for chemical safety assessment

Repeated dose toxicity: via oral route - systemic effects

Link to relevant study records

Reference

Endpoint:

sub-chronic toxicity: oral

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

data from handbook or collection of data

Remarks:

Experimental data from various test chemicals

Justification for type of information:

Data for the target chemical is summarized based on the data from various test chemicals

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across source

Qualifier:

according to guideline

Guideline:

other: Refer below principle

Principles of method if other than guideline:

WoE derived based on the experimental data from various test chemicals

GLP compliance:

not specified

Limit test:

no

Species:

rat

Strain:

Wistar

Sex:

male/female

Details on test animals or test system and environmental conditions:

1. TEST ANIMALS
- Source: No Data Available
- Age at study initiation: Approx. 1 year old
- Weight at study initiation: Approx. 350 grams
- Fasting period before study: No Data Available
- Housing: No Data Available
- Diet (e.g. ad libitum): Commercial rat diet ad libitum
- Water (e.g. ad libitum): Supplied daily ad libitum.
- Acclimation period: No Data Available.

ENVIRONMENTAL CONDITIONS
- Temperature (°C): No Data Available
- Humidity (%): No Data Available
- Air changes (per hr): No Data Available
- Photoperiod (hrs dark / hrs light): No Data Available

2. TEST ANIMALS
- Source: No Data Available
- Age at study initiation: No Data Available
- Weight at study initiation: Approx. 60 grams
- Fasting period before study: No Data Available
- Housing: The animals were housed in pairs in cages with wire mesh floors
- Diet (e.g. ad libitum): Commercial rat diet ad libitum
- Water (e.g. ad libitum): Supplied daily ad libitum.
- Acclimation period: No Data Available.

ENVIRONMENTAL CONDITIONS
- Temperature (°C): No Data Available
- Humidity (%): No Data Available
- Air changes (per hr): No Data Available
- Photoperiod (hrs dark / hrs light): No Data Available

Route of administration:

oral: feed

Vehicle:

other: Commercial Rat Diet

Details on oral exposure:

1. PREPARATION OF DOSING SOLUTIONS: The rats were offered the diet alone or supplemented with 312, 625, 937 or 1250 mmol/kg Dry matter. Batches of the diet were prepared using 125 ml of 2 5, 5-0, 7-5 or 10 0 mol /L solutions of HCl for the acid treatments respectively and 125 ml water for the control per kg basal diet. Each diet was offered ad libitum over a 9 week period to four male and four female rats in a randomized block design experiment.

DIET PREPARATION
- Rate of preparation of diet (frequency): No Data Available
- Mixing appropriate amounts with (Type of food): No Data Available
- Storage temperature of food: No Data Available.

VEHICLE
- Justification for use and choice of vehicle (if other than water): No Data Available
- Concentration in vehicle: 0, 312, 625, 937 or 1250 mmol/kg DM
- Amount of vehicle (if gavage): 0, 2.5, 5.0, 7.5 or 10.0 mol/L.
- Lot/batch no. (if required): No Data Available
- Purity: No Data Available

2. PREPARATION OF DOSING SOLUTIONS: The rats were given a commercial rat diet, either alone (control) or supplemented with HCl at 280, 420 or 560 mmol/kg dry matter (DM). Batches of the diet were prepared by pouring 140 ml of either 2, 3 or 4 mol.l-I solutions of HCl for the acid treatments respectively over a kg D.M. of the experimental diet and mixed thoroughly in a food mixer. The control diet was prepared by the addition of a similar amount of distilled water to the basal diet.

DIET PREPARATION
- Rate of preparation of diet (frequency): No Data Available
- Mixing appropriate amounts with (Type of food): No Data Available
- Storage temperature of food: No Data Available

VEHICLE
- Justification for use and choice of vehicle (if other than water): No Data Available
- Concentration in vehicle: 2, 3 or 4 mol/L
- Amount of vehicle (if gavage): No Data Available
- Lot/batch no. (if required): No Data Available
- Purity: No Data Available

Analytical verification of doses or concentrations:

not specified

Details on analytical verification of doses or concentrations:

No Data Available

Duration of treatment / exposure:

1. 7 weeks

Frequency of treatment:

Daily

Remarks:

0, 312, 625, 937 or 1250 mmol/Kg dry matter / 1

Remarks:

0, 280, 420 or 560 mmol/Kg dry matter / 2

No. of animals per sex per dose:

8 animals

Control animals:

yes, concurrent vehicle

Details on study design:

No Data Available

Positive control:

No Data Available

Observations and examinations performed and frequency:

1./2. CAGE SIDE OBSERVATIONS: No Data Available
- Time schedule: No Data Available
- Cage side observations checked in table [No.?] were included.

DETAILED CLINICAL OBSERVATIONS: No Data Available
- Time schedule: No Data Available

BODY WEIGHT: Yes
- Time schedule for examinations: No Data Available

FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study): Yes, residues were collected weekly and intake was calculated for weekly periods
- 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: Yes, intake was calculated for weekly periods

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 data

WATER CONSUMPTION AND COMPOUND INTAKE (if drinking water study): Yes
- Time schedule for examinations: Intake was calculated for weekly periods

OPHTHALMOSCOPIC EXAMINATION: No data
- Time schedule for examinations: No Data Available
- Dose groups that were examined: No Data Available

HAEMATOLOGY: Yes
- Time schedule for collection of blood: At the end of the experiment
- Anaesthetic used for blood collection: Yes, blood was collected by cardiac puncture using anesthesia.
- Animals fasted: No data available
- How many animals: No Data Available
- Parameters checked in table [No.?] were examined: No Data Available

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: At the end of the experiment
- Animals fasted: No Data Available
- How many animals: No Data Available
- Parameters checked in table [No.?] were examined. acid-base and mineral analysis

URINALYSIS: No data available
- Time schedule for collection of urine: No Data Available
- Metabolism cages used for collection of urine: No Data Available
- Animals fasted: No Data Available
- Parameters checked in table [No.?] were examined.

NEUROBEHAVIOURAL EXAMINATION: No data available
- Time schedule for examinations: No Data Available
- Dose groups that were examined: No Data Available
- Battery of functions tested: No Data Available
sensory activity / grip strength / motor activity / other: No Data Available

Sacrifice and pathology:

1./2. Sacrifice: Rats were sacrificed using exsanguination.

GROSS PATHOLOGY: Yes, After exsanguination, the rats were slaughtered and the right femur was removed from each animal, cleansed of adherent soft tissue and dried at 100 'C. It was subjected to fat extraction by petroleum ether in a Soxhlet apparatus, dried at 100 'C, weighed and the weight was recorded as fat free solids (FFS). The FFS were ashed at 560 'C and dissolved in 2 mol/L 1 nitric acid for subsequent analysis.

HISTOPATHOLOGY: Yes

Other examinations:

No Data Available

Statistics:

1. Where treatment effects were statistically significant the means were compared with each other using Duncan's multiple range test.

Clinical signs:

not specified

Mortality:

mortality observed, treatment-related

Description (incidence):

1. 100% mortality was observed at higher doses of 937 and 1250 mmol/kg. There was no mortality observed at 312 and 625 mmol/kg.

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

1. There was a significant reduction of the body weights of the animals in the higher dose groups of 937 and 1250 mmol/kg.
2. There was no treatment related significant effect on the weight gain of the animals at any dose groups.

Food consumption and compound intake (if feeding study):

effects observed, treatment-related

Description (incidence and severity):

1. There was a significant decrease in the food intake of 937 and 1250 mmol/kg.
2. No significant treatment related changes were observed in the food intake of the animals at any dose group.

Food efficiency:

not specified

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

effects observed, treatment-related

Description (incidence and severity):

1. The water intake was significantly increased by the test chemical supplementation except on the high level of supplementation, where the animals survived for a short period.
2. The water intake was found to be increased in all dose groups after the administration of the test chemical (P < 0001).

Ophthalmological findings:

not specified

Haematological findings:

effects observed, treatment-related

Description (incidence and severity):

1. Blood pH was significantly reduced by the test chemical supplementation. Plasma CO2 concentration was also reduced by the test chemical supplementation but the effect was not significant.
2. There was no significant effect of treatment on hematocrit levels or hemoglobin concentration in blood.

Clinical biochemistry findings:

not specified

Description (incidence and severity):

2. Supplementation with the test chemical in this experiment did not affect blood acid-base status as measured by blood pH, plasma CO2 and blood base excess. The treatment with the test chemical did not significantly affect the clinical chemistry parameters and mineral levels in the animals. Treatments did not significantly affect
(P > 005) femur length, FFS or the % ash in the bone or Ca, Mg, Na or K in the FFS

Urinalysis findings:

not specified

Behaviour (functional findings):

not specified

Immunological findings:

not specified

Organ weight findings including organ / body weight ratios:

not specified

Gross pathological findings:

not specified

Description (incidence and severity):

2. There were no gross pathological changes observed in the animals due to administration of the test chemical.

Neuropathological findings:

not specified

Histopathological findings: non-neoplastic:

not specified

Description (incidence and severity):

2. There were no observed changes in histopathological examination after the administration of the test chemical.

Histopathological findings: neoplastic:

not specified

Other effects:

not specified

Dose descriptor:

NOAEL

Remarks:

1

Effect level:

625 other: mmol /kg

Based on:

test mat.

Sex:

male/female

Basis for effect level:

body weight and weight gain

food consumption and compound intake

haematology

mortality

water consumption and compound intake

Dose descriptor:

LOAEL

Remarks:

1

Effect level:

937 other: mmol /kg

Based on:

test mat.

Sex:

male/female

Basis for effect level:

body weight and weight gain

food consumption and compound intake

haematology

mortality

water consumption and compound intake

Critical effects observed:

not specified

Conclusions:

The no observed adverse effect level (NOAEL) for the test chemical is considered to be 625 mmol /kg.

Executive summary:

Data available for the test chemicals was reviewed to determine the toxic nature of the test chemical upon repeated exposure. The studies are as mentioned below:

Repeated dose oral toxicity study was conducted to identify and evaluate effects of the test chemical on male and female Wistar rats for a period of 7 weeks. In this period, the rats were administered with the test chemical which was given through the oral feed route. The test chemical was mixed with the diet in concentrations of 2.5, 5.0, 7.5 or 10.0 mol/L and dose groups ofmmol /kg. The rats were given a commercial rat diet, either alone (control) or supplemented with the test chemical at 312, 625, 937 or 1250 mmol/ kg DM. The pH reached 1.82 after using higher dietary levels of the test chemical (i.e at 1250 mmol/kg). Batches of the diet were prepared by pouring 140 ml of either 2, 3 or 4 mol /l solutions of the test chemical for the acid treatments respectively over a kg D.M. of the experimental diet and mixed thoroughly in a food mixer. The control diet was prepared by the addition of a similar amount of distilled water to the basal diet. The rats were given access to the waterad libitum.The control animals were fed with animal diets mixed with distilled water. The rats were observed for body weight gain and feed consumption throughout the study.100% mortality was observed at higher doses of 937 and 1250 mmol/kg. There was no mortality observed at 312 and 625 mmol/kg. Also, there was a significant reduction of the body weights of the animals in the higher dose groups of 937 and 1250 mmol/kg. There was a significant decrease in the food intake of 937 and 1250 mmol/kg. The water intake was significantly increased by the test chemical supplementation except on the high level of supplementation, where the animals survived for a short period. After the administration of the test chemical for 7 weeks the animals were sacrificed by exsanguination and were slaughtered to isolate the femur bones of the animals. The blood was collected at the end of the experiment under the influence of anesthesia to evaluate blood acid status and CO2levels in the blood. Also, values of the minerals were determined. Blood pH was significantly reduced by the test chemical supplementation. Plasma CO2 concentration was also reduced by the test chemical supplementation but the effect was not significant. The supplementation of test chemical did not significantly cause any changes in the levels of calcium and phosphorus in the animals. Also, There were no gross pathological changes observed in the animals due to administration of the test chemical and There were no observed changes in histopathological examination after the administration of the test chemical. From all the observations, The no observed adverse effect level (NOAEL) and the low observed adverse effect level (LOAEL) for the test chemical after the administration for over 9 weeks to Wistar rats was found to be 625 mmol /kg and 937 mmol /kg respectively.  

A study was conducted to identify and evaluate effects of the test chemical on male and female Wistar rats for a period of 7 weeks. In this period, the rats were administered with the test chemical which was given through the oral feed route. The test chemical was mixed with the diet in concentrations of2, 3 or 4 mol/L and dose groups of 280, 420 or 560 mmol /kg.The rats were given a commercial rat diet, either alone (control) or supplemented with HCl at 280, 420 or 560 mmol /kg dry matter (DM). Batches of the diet were prepared by pouring 140 ml of either 2, 3 or 4 mol /l solutions of HCl for the acid treatments respectively over a kg D.M. of the experimental diet and mixed thoroughly in a food mixer. The control diet was prepared by the addition of a similar amount of distilled water to the basal diet. The rats were given access to the waterad libitum.The control animals were fed with animal diets mixed with distilled water. The rats were observed for body weight gain and feed consumption throughout the study. It was observed thatthere was no treatment related significant effect on the weight gain of the animals at any dose groups. Also, there was no significant change in the food intake of the animals throughout the test chemical. After the administration of the test chemical for 7 weeks the animals were sacrificed by exsanguination and were slaughtered to isolate the femur bones of the animals. The blood was collected at the end of the experiment under the influence of anesthesia to evaluate blood acid status, CO2 levels in the blood and hematocrit and hemoglobin values. Also, values of the minerals were determined. There were no significant changes in the hematocrit and hemoglobin values of the animals, the CO2 levels in the plasma were found to be normal and the blood pH was unchanged after the treatment of the test chemical. The mineral values of calcium, phosphorus, sodium and potassium were also found to be normal after 7 weeks of the treatment. Also, There were no gross pathological changes observed in the animals due to administration of the test chemical and There were no observed changes in histopathological examination after the administration of the test chemical. From all the observations, the No observed adverse effect level (NOAEL) for the test chemical after the administration for over 7 weeks is considered to be 560 mmol /kg when the test chemical was administered orally.

Based on the data available, the no observed adverse effect level (NOAEL) for the test chemical is considered to be 625 mmol /kg.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEL

22 788 mg/kg bw/day

Study duration:

subchronic

Species:

rat

Quality of whole database:

Data is from company source

Repeated dose toxicity: inhalation - systemic effects

Link to relevant study records

Reference

Endpoint:

short-term repeated dose toxicity: inhalation

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

data from handbook or collection of data

Remarks:

Experimental data from various test chemicals

Justification for type of information:

Data for the target chemical is summarized based on the from various test chemicals

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across source

Qualifier:

according to guideline

Guideline:

other: Refer below principle

Principles of method if other than guideline:

WoE derived based on the experimental data from various test chemicals

GLP compliance:

not specified

Species:

rat

Strain:

other: 1. Wistar, 2. Sprague Dawley

Remarks:

1. Alpk:APfSD strain, 2. Crl:CD(SD)Br

Sex:

female

Details on test animals or test system and environmental conditions:

1. TEST ANIMALS
- Source: Alderley Park, Macclesfield, Cheshire, UK
- Females (if applicable) nulliparous and non-pregnant: [yes/no]
- Age at study initiation: No data
- Weight at study initiation: No data
- Fasting period before study: No data
- Housing: Animals were housed in multiple rat racks at five per cage total initially
- Diet (e.g. ad libitum): Food ad libitum
- Water (e.g. ad libitum): Water ad libitum
- Acclimation period: 1-2 weeks

DETAILS OF FOOD AND WATER QUALITY: No data

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 ± 3 °C
- Humidity (%): 30–70%
- Air changes (per hr): at least 15 air changes per hou
- Photoperiod (hrs dark / hrs light): 12 h per day of fluorescent ligh

IN-LIFE DATES: From: To: No data

2. TEST ANIMALS
- Source: No data
- Age at study initiation: 6-7 weeks of age
- Weight at study initiation: No data
- Fasting period before study: No data
- Housing:
- Diet (e.g. ad libitum): No data
- Water (e.g. ad libitum): No data
- Acclimation period: No data

ENVIRONMENTAL CONDITIONS
- Temperature (°C): No data
- Humidity (%):No data
- Air changes (per hr): No data
- Photoperiod (hrs dark / hrs light): No data

IN-LIFE DATES: From: To: No data

Route of administration:

inhalation: aerosol

Type of inhalation exposure:

other: 1. nose only, 2. whole body

Vehicle:

air

Details on inhalation exposure:

1. GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: Resevoir chambers
- Method of holding animals in test chamber: No data
- Source and rate of air: Glass concentric jet atomizer
- Method of conditioning air: No data
- System of generating particulates/aerosols:
- Temperature, humidity, pressure in air chamber: Humidified dilution air was added, where appropriate, to maintain a humidity as close as possible to 50% inside the chambers.
- Air flow rate: Air flows were monitored and recorded frequently using variable area flowmeters and were altered as necessary to maintain the target concentrations and maintain a minimum of 12 air changes per hour
- Air change rate: No data
- Method of particle size determination: The aerodynamic particle size distribution of each test atmosphere was measured using a Marple Cascade Impactor (supplied by Schaeffer Instruments Ltd, Wantage, Oxon, UK) that aerodynamically separates airborne particles into predetermined size ranges. The amount of aerosol by weight in each size range was then used to calculate the mass median aerodynamic diameter (MMAD) and geometric standard deviation (GSD)
- Treatment of exhaust air: No data

TEST ATMOSPHERE
- Brief description of analytical method used: The particulate concentration of each test atmosphere, close to the animals’ breathing zone, was measured gravimetrically and analytically at least twice during each exposure. This was done by drawing each test atmosphere at a known flow rate, for a known time, through a 25-mm diameter polyvinyl chloride (PVC) GN-4 filter housed in a Delrin open-faced filter holder (both filters and holders were supplied by Gelman Sciences Ltd, Northampton, UK). The filter was weighed before and after the sample was taken and the gravimetric concentration was calculated by dividing the weight gain by the total volume of atmosphere sampled.

Analytical concentrations of sulphuric acid were determined by extracting the material collected on the filters and stages with water (1 × 5 ml wash) and isopropyl alcohol (IPA, 3 × 5 ml washes) and titrating the resulting solution with 0.005 M barium perchlorate, using Thorin as an indicator. A sharp colour change from yellow to salmon pink signified the end-point

- Samples taken from breathing zone: Yes

VEHICLE (if applicable)
- Justification for use and choice of vehicle: Air
- Composition of vehicle: No data
- Type and concentration of dispersant aid (if powder):
- Concentration of test material in vehicle: 0, 0.2, 1.0 or 5.0 mg/m3
- Lot/batch no. of vehicle (if required):
- Purity of vehicle: No data

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

1. The particulate concentration of each test atmosphere, close to the animals’ breathing zone, was measured gravimetrically and analytically at least twice during each exposure. This was done by drawing each test atmosphere at a known flow rate, for a known time, through a 25-mm diameter polyvinyl chloride (PVC) GN-4 filter housed in a Delrin open-faced filter holder (both filters and holders were supplied by Gelman Sciences Ltd, Northampton, UK). The filter was weighed before and after the sample was taken and the gravimetric concentration was calculated by dividing the weight gain by the total volume of atmosphere sampled.

Duration of treatment / exposure:

1. 28 days
2. 91 days

Frequency of treatment:

1. 5 days/week
2. 6 hours/day, 5 days/week

Remarks:

0, 0.2, 1.0 or 5.0 mg/m³ air / 1
Achieved concentrations: 0, 0.3, 1.38 and 5.52 mg/m3

Remarks:

0, 10, 20, 50 ppm (0, 15, 30, 75 mg/m3) / 2

No. of animals per sex per dose:

1. 10 females / group
2. 0 mg/m3: 10 males and 10 females
15 mg/m3: 10 males and 10 females
30 mg/m3: 10 males and 10 females
75 mg/m3: 10 males and 10 females

Control animals:

yes, concurrent vehicle

Details on study design:

1. - Dose selection rationale: No data
- Rationale for animal assignment (if not random): After an acclimatization period of 1–2 weeks, rats were assigned randomly to experimental groups by a method that takes into account the bodyweight of the animals
- Rationale for selecting satellite groups: No data
- Post-exposure recovery period in satellite groups: Yes, Recovery groups of five females were exposed to 0 or 5.0 mg m−3 for 28 days and retained without further treatment for either 4 or 8 weeks to monitor recovery
- Section schedule rationale (if not random): No data

2. - Dose selection rationale: No data
- Rationale for animal assignment (if not random): No data
- Rationale for selecting satellite groups: No data
- Post-exposure recovery period in satellite groups: Ten males and 10 females of each dose group were sacrificed on the following day of the fourth exposure and microscopically examined for the damage of respiratory tract.

Five males of each dose were sacrificed on the following day of the forth (five males) and the 90th (five males) exposure and the fixed cranial specimen were shipped to the sponsor.
- Section schedule rationale (if not random): No data

Positive control:

No data

Observations and examinations performed and frequency:

1. CAGE SIDE OBSERVATIONS: No data
- Time schedule: No data
- Cage side observations checked in table [No.?] were included. No data

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: Detailed clinical observations were recorded daily immediately prior to exposure

BODY WEIGHT: Yes
- Time schedule for examinations: The bodyweight of each rat was recorded before the first exposure, once a week thereafter and prior to termination

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

FOOD EFFICIENCY: No data
- 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 data

WATER CONSUMPTION AND COMPOUND INTAKE (if drinking water study): No data
- Time schedule for examinations: No data

OPHTHALMOSCOPIC EXAMINATION: No data
- Time schedule for examinations: No data
- Dose groups that were examined:

HAEMATOLOGY: No data
- Time schedule for collection of blood: No data
- Anaesthetic used for blood collection: No data
- Animals fasted: No data
- How many animals: No data
- Parameters checked in table [No.?] were examined. No data

CLINICAL CHEMISTRY: No data
- Time schedule for collection of blood: No data
- Animals fasted: No data
- How many animals: No data
- Parameters checked in table [No.?] were examined. No data

URINALYSIS: No data
- Time schedule for collection of urine: No data
- Metabolism cages used for collection of urine: No data
- Animals fasted: No data
- Parameters checked in table [No.?] were examined. No data

NEUROBEHAVIOURAL EXAMINATION: Yes / No / Not specified
- Time schedule for examinations: No data
- Dose groups that were examined: No data
- Battery of functions tested: sensory activity / grip strength / motor activity / other: No data

IMMUNOLOGY: No data
- Time schedule for examinations: No data
- How many animals: No data
- Dose groups that were examined: No data
- Parameters checked in table [No.?] were examined. No data

OTHER: Cell proliferation was investigated in animals terminated after 28 days of exposure. Two different techniques were used, depending on the region of the respiratory tract being examined. Bromodeoxyuridine (BrdU) labelling and subsequent immunolocalization of BrdU-containing nuclei were used for the assessment of cell proliferation in the lung. For this technique, five designated rats per group, per time point, were implanted subcutaneously with osmotic minipumps (Alzet 2ML1) for delivery of BrdU 7 days before termination (minipumps containing BrdU at a concentration of 15 mg ml−1).

For the nasal cavity and larynx, pulse labelling with tritiated thymidine followed by autoradiography was used. Five designated rats per group, per time point, were
injected intraperitoneally with tritiated thymidine at a dose level of 1 µCi g−1 bodyweight ∼1 h prior to scheduled termination.

At termination of both the main study and recovery groups, rats were killed by an overdose of halothane with subsequent exsanguination by cardiac puncture. All animals were subjected to a full examination or postmortem, involving an external observation and careful internal examination of all organs and structures. The
lung, trachea and small intestine were examined in situ and fixed in 10% neutral-buffered formol–saline or an appropriate fixative (the lung after inflation with 10%
neutral-buffered formol–saline).

After fixation, lung tissue was trimmed and processed to paraffin wax blocks and sections made and stained to reveal BrdU-positive nuclei. The heads from all designated animals were removed, excess skin and muscle was removed, the brain was excised and the nasal cavity was perfused with 10% formol–saline through the nasopharynx. The head was then immersed in formol–saline followed by decalcification with 20% formic acid. After processing, six standard sections were produced to include all the different epithelial cell types and accessory nasal structures. The sections taken represent sections 1, 6, 8, 15/17, 23 and 28. The six sections were exposed to nuclear emulsion (Ilford K2) for 8–10 weeks. Sections were developed and examined by light microscopy.

The larynx was removed from all animals, fixed in 10% neutral-buffered formalin for 24 h, trimmed and processed to paraffin wax blocks. Three standard sections
of larynx were prepared, these being taken at the level of the base of the epiglottis through the seromucinous glands (level 1), through the ventral pouch (level 2)
and through the cricoid cartilage (level 3), to include all different epithelial cell types of the larynx and underlying seromucinous glands (Bahnemann et al., 1995). Sections of larynx were exposed to nuclear emulsion (Ilford K2) for 8–10 weeks before being developed and examined by light microscopy.

2. CAGE SIDE OBSERVATIONS: Yes
- Time schedule: Twice daily
- Cage side observations checked in table [No.?] were included. Mortality and clinical signs

DETAILED CLINICAL OBSERVATIONS: No data
- Time schedule: No data

BODY WEIGHT: Yes
- Time schedule for examinations: Once a week

FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study):
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: Yes, once a week
- Compound intake calculated as time-weighted averages from the consumption and body weight gain data: No data

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 data

WATER CONSUMPTION AND COMPOUND INTAKE (if drinking water study): No data
- Time schedule for examinations: No data

OPHTHALMOSCOPIC EXAMINATION: No data
- Time schedule for examinations: No data
- Dose groups that were examined: No data

HAEMATOLOGY: Yes
- Time schedule for collection of blood: No data
- Anaesthetic used for blood collection: No data
- Animals fasted: No data
- How many animals: No data
- Parameters checked in table [No.?] were examined. erythrocyte count, hemoglobin, hematocrit, total and differential leukocyte counts, platelet and thrombocyte counts, mean corpuscular volume, mean corpuscular hemoglobin, and mean corpuscular hemoglobin concentration

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: No data
- Animals fasted: No data
- How many animals: No data
- Parameters checked in table [No.?] were examined. Glutamic pyruvic transaminase, urea nitrogen, total bilirubin, glucose, inorganic phosphorus, calcium, and alkaline phosphatase

URINALYSIS: Yes
- Time schedule for collection of urine: No data
- Metabolism cages used for collection of urine: No data
- Animals fasted: No data - Parameters checked in table [No.?] were examined. volume, appearance, occult blood, specific gravity, protein, pH, ketone, glucose

NEUROBEHAVIOURAL EXAMINATION: No data
- Time schedule for examinations: No data
- Dose groups that were examined: No data
- Battery of functions tested: sensory activity / grip strength / motor activity / other: No data

OTHER: No data

Sacrifice and pathology:

2. GROSS PATHOLOGY: Yes, Each animal was pathologically examined at necropsy and following organs were weighed [brain, heart, kidney, liver, and ovary/testis].

HISTOPATHOLOGY: Yes, the following tissues of the control and the highest dose group and [nasal turbinates, trachea, lung] of the low and the mid dose group were examined microscopically [nasal turbinates, trachea, lung, brain, heart, kidney, liver, testis, adrenal, duodenum, eyes and optic nerve, mesenteric lymph nodes, aorta, sternum bone, ear canal, bone marrow, colon, epididymis, jejunum, mandibular lymph nodes, oviducts, ovaries, prostate, skin, pituitary glands, spinal cord, sciatic nerve, peripheral nerve, salivary gland, spleen, thyroid glands, urinary bladder, uterus, thymus, fore and glandular stomach, pancreas, parathyroid, skeletal muscle, seminal vesicle, tongue, femur bone, cecum, esophagus, ileum, lacrimal gland, mammary glands, larynx].

Statistics:

1. All data (except cell proliferation data) were evaluated using analysis of variance and/or covariance for each specified parameter using the MIXED procedure of the
SAS Institute (1989) and were carried out separately for the main study and for recovery animals.

Cell proliferation data was analysed using ARTEMIS statistical methods (two-sided Student’s t-test).

2. Parametric data: ANOVA and Turkey’s (equal populations) or Scheffe’s (unequal populations) Test of multiple comparison

Non-Parametric data: Kruskal-Wallis ANOVA and test of multiple comparison

Discontinuous data: CHI-square or Fischer’s Exact Probability test

Clinical signs:

no effects observed

Description (incidence and severity):

1. No adverse clinical symptoms were seen due to the exposure apart from minor effects seen commonly due to the restraint used for nose only exposure, e.g. wet fur, snout stains.

Mortality:

not specified

Description (incidence):

2. One female of the highest dose group found dead on the 4th day of the treatment

Body weight and weight changes:

no effects observed

Description (incidence and severity):

1. There were no effects on bodyweight in any group at any time point
2. Slight and transient decrease in food consumption was observed in 10 ppm female, which was not considered to be dose related, and 50ppm male.

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:

not specified

Description (incidence and severity):

2. No biologically significant difference was observed in hematology.

Clinical biochemistry findings:

not specified

Description (incidence and severity):

2. No biologically significant difference was observed in hematology.

Urinalysis findings:

not specified

Description (incidence and severity):

2. No biologically significant difference was observed in urinalysis.

Behaviour (functional findings):

not specified

Immunological findings:

not specified

Organ weight findings including organ / body weight ratios:

no effects observed

Description (incidence and severity):

1. There were no effects on lung weight in any group at any time point

Gross pathological findings:

no effects observed

Description (incidence and severity):

1. There were no macroscopic abnormalities in any of the animals at the scheduled termination times.

Neuropathological findings:

not specified

Histopathological findings: non-neoplastic:

no effects observed

Description (incidence and severity):

1. There were no compound-related histopathological changes in the lung or nasal cavity after 28 days of exposure at any concentration. Significant histological changes were observed in the larynx.

2. Minimal to mild rhinitis was observed in the anterior portion of the nasal cavity at the histopathological observation above 20 ppm.

Histopathological findings: neoplastic:

effects observed, treatment-related

Description (incidence and severity):

1. Squamous metaplasia in the ventral epithelium at level 1 was evident and again was concentration-related in severity. Following exposure to 5.52 mg m−3 sulphuric acid, this effect was evident in some animals at level 2, lateral to the ventral pouch Parakeratosis was also seen in some animals at this level of the larynx. Following exposure to 0.30 mg m−3 sulphuric acid, some animals (6/10) showed minimal squamous metaplasia at level 1.

After 4 weeks of recovery, animals exposed to 5.52 mg m−3 test chemical showed evidence of squamous epithelial metaplasia at level 1 of the larynx. This lesion was less severe following 4 weeks of recovery than it was at the end of the 28-day exposure period, but there were no signs of further resolution after 8 weeks of recovery

Other effects:

no effects observed

Description (incidence and severity):

1. There were no exposure-related changes in labelling index in either the terminal bronchioles or central acinar alveoli of the lung or any of the levels of the nasal cavity at either time point examined: reduction in tritiated thymidine uptake in the olfactory epithelium at level 5 following exposure to 0.30 mg m−3 sulphuric acid for 28 days was the only statistically significant group mean difference from control values; the lack of dose response suggests that this was not biologically relevant.

Comparison of BrdU and tritiated thymidine labelling in the larynx showed that the magnitude of increase in labelling compared with controls was greater when
autoradiography of tritiated thymidine-labelled tissue was used.

Following exposure to 1.38 and 5.52 mg m−3, a treatment- and dose-related increase in cell proliferation was seen in the ventral epithelium at level 1 of the larynx after both 5 and 28 days of exposure, although the increases were larger at the earlier time point . No increases in cell proliferation were seen at level 2 or 3 after 5 or 28 days of exposure. No increases in cell proliferation were seen at any level in the larynx following both 5 and 28 days of exposure to 0.3 mg m−3 test chemical.

Dose descriptor:

NOAEC

Remarks:

1

Effect level:

5.52 mg/m³ air

Based on:

test mat.

Sex:

female

Basis for effect level:

other: No significant adverse effects were noted

Dose descriptor:

NOAEC

Remarks:

2

Effect level:

30 mg/m³ air

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: No significant adverse effects were noted

Critical effects observed:

not specified

Conclusions:

The no observed adverse effect concentration (NOAEC) is considered to be 5.52 mg/m3 when rodents were exposed to the test chemical.

Executive summary:

Data available for the test chemicals was reviewed to determine the toxic nature of the test chemical. The studies are as mentioned below:

Repeated dose inhalation toxicity study was performed to determine the toxic nature of the test chemical. Groups of 10 female animals were exposed for 6 h per day to target concentrations of 0, 0.2, 1.0 or 5.0 mg m−3 sulphuric acid for 5 days a week for 28 days. Recovery groups of five females were exposed to 0 or 5.0 mg/m3 for 28 days and retained without further treatment for either 4 or 8 weeks to monitor recovery. Prior to the start of the study, all rats were examined to ensure that they were physically normal and exhibited normal activity. During exposure they were observed frequently, and at the end of the daily exposure period each rat was examined. Detailed clinical observations were recorded daily immediately prior to exposure. During the recovery period the animals were checked daily and detailed observations were recorded weekly, recording any changes in clinical condition or behaviour. The bodyweight of each rat was recorded before the first exposure, once a week thereafter and prior to termination. Test atmospheres with target concentrations of 0.2, 1.0 and 5.0 mg m−3 analysed sulphuric acid were generated using a glass concentric jet atomizer to generate the atmospheres into two reservoir chambers (each fitted with a cyclone), one serving the exposure chambers for groups exposed to 0.2 and 1.0 mg m−3 and another serving exposure chambers for groups exposed to 5.0 mg m−3 . Clean, dry air (dried and filtered using equipment supplied by Atlas-Copco, Sweden) was passed through the atomizer to carry the atmosphere to each of the reservoir chambers and subsequently, after appropriate dilution, to the exposure chambers (internal volume = 36.8 l). Air flows were monitored and recorded frequently using variablearea flowmeters and were altered as necessary to maintain the target concentrations and maintain a minimum of 12 air changes per hour. Humidified dilution air was also added, where appropriate, to maintain a humidity as close as possible to 50% inside the chambers. There were no effects on bodyweight or lung weight in any group at any time point, and no adverse clinical symptoms were seen due to the exposure apart from minor effects seen commonly due to the restraint used for noseonly exposure, e.g. wet fur, snout stains. There were no macroscopic abnormalities in any of the animals at the scheduled termination times. Squamous metaplasia in the ventral epithelium at level 1 was evident and again was concentration-related in severity. Following exposure to 5.52 mg m−3 sulphuric acid, this effect was evident in some animals at level 2, lateral to the ventral pouch Parakeratosis was also seen in some animals at this level of the larynx. Following exposure to 0.30 mg m−3 sulphuric acid, some animals (6/10) showed minimal squamous metaplasia at level 1. After 4 weeks of recovery, animals exposed to 5.52 mg m−3 test chemical showed evidence of squamous epithelial metaplasia at level 1 of the larynx. This lesion was less severe following 4 weeks of recovery than it was at the end of the 28-day exposure period, but there were no signs of further resolution after 8 weeks of recovery. There were no exposure-related changes in labelling index in either the terminal bronchioles or central acinar alveoli of the lung or any of the levels of the nasal cavity at either time point examined: reduction in tritiated thymidine uptake in the olfactory epithelium at level 5 following exposure to 0.30 mg m−3 sulphuric acid for 28 days was the only statistically significant group mean difference from control values; the lack of dose response suggests that this was not biologically relevant. Comparison of BrdU and tritiated thymidine labelling in the larynx showed that the magnitude of increase in labelling compared with controls was greater when autoradiography of tritiated thymidine-labelled tissue was used. Following exposure to 1.38 and 5.52 mg m−3, a treatment- and dose-related increase in cell proliferation was seen in the ventral epithelium at level 1 of the larynx after both 5 and 28 days of exposure, although the increases were larger at the earlier time point . No increases in cell proliferation were seen at level 2 or 3 after 5 or 28 days of exposure. No increases in cell proliferation were seen at any level in the larynx following both 5 and 28 days of exposure to 0.3 mg m−3 test chemical. Exposure of rats for up to 28 days to 1.38 and 5.52 mg/m3 sulphuric acid aerosols resulted in no effect in the nasal passages or lungs and squamous metaplasia in a limited region of the larynx. Hence the no observed adverse effect concentration is considered to be 5.52 mg/m3.

Repeated dose inhalation toxicity study was performed to determine the toxic nature of the test chemical. The study was performed using male and female Crl:CD(SD)Br rats. The test chemical was studies at dose level of 0, 10, 20, 50 ppm (0, 15, 30, 75 mg/m3) for 91 days. The animals were exposed to the test chemical 6 hours/day, 5 days/week. Each animal was observed at least twice daily for incidence of mortality and clinical signs. Body weight and food consumption were individually measured once a week. Urine samples collected from 10 male and 10 female animals were analyzed. Blood samples collected from orbital sinus were measured for the parameters for hematology. Serum samples collected from abdominal aorta were measured for blood biochemistry. Each animal was pathologically examined at necropsy and histopathology was performed. One female of the highest dose group found dead on the 4th day of the treatment. Slight and transient decrease in food consumption was observed in 10 ppm female, which was not considered to be dose related, and 50ppm male. Minimal to mild rhinitis was observed in the anterior portion of the nasal cavity at the histopathological observation above 20 ppm. No biologically significant difference was observed in urinalysis, hematology and serum chemistry. Based on the observations made, the no observed effect concentration (NOAEC) for the test chemical is considered to be 30mg/m3 when male and female rats were exposed to the test chemical in a subchronic toxicity study.

Based on the observations made, the no observed adverse effect concentration (NOAEC) is considered to be 5.52 mg/m3 when rodents were exposed to the test chemical.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEC

5.52 mg/m³

Study duration:

subchronic

Species:

rat

Quality of whole database:

Data is from peer reviewed publication

Repeated dose toxicity: inhalation - local effects

Endpoint conclusion

Endpoint conclusion:

no study available

Repeated dose toxicity: dermal - systemic effects

Link to relevant study records

Reference

Endpoint:

repeated dose toxicity: dermal

Data waiving:

other justification

Justification for data waiving:

other:

Critical effects observed:

not specified

Endpoint conclusion

Endpoint conclusion:

no study available

Quality of whole database:

Waiver

Repeated dose toxicity: dermal - local effects

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

Repeated dose toxicity: Oral

Data available for the test chemicals was reviewed to determine the toxic nature of the test chemical upon repeated exposure. The studies are as mentioned below:

Repeated dose oral toxicity study was conducted to identify and evaluate effects of the test chemical on male and female Wistar rats for a period of 7 weeks. In this period, the rats were administered with the test chemical which was given through the oral feed route. The test chemical was mixed with the diet in concentrations of 2.5, 5.0, 7.5 or 10.0 mol/L and dose groups ofmmol /kg. The rats were given a commercial rat diet, either alone (control) or supplemented with the test chemical at 312, 625, 937 or 1250 mmol/ kg DM. The pH reached 1.82 after using higher dietary levels of the test chemical (i.e at 1250 mmol/kg). Batches of the diet were prepared by pouring 140 ml of either 2, 3 or 4 mol /l solutions of the test chemical for the acid treatments respectively over a kg D.M. of the experimental diet and mixed thoroughly in a food mixer. The control diet was prepared by the addition of a similar amount of distilled water to the basal diet. The rats were given access to the water ad libitum.The control animals were fed with animal diets mixed with distilled water. The rats were observed for body weight gain and feed consumption throughout the study.100% mortality was observed at higher doses of 937 and 1250 mmol/kg. There was no mortality observed at 312 and 625 mmol/kg. Also, there was a significant reduction of the body weights of the animals in the higher dose groups of 937 and 1250 mmol/kg. There was a significant decrease in the food intake of 937 and 1250 mmol/kg. The water intake was significantly increased by the test chemical supplementation except on the high level of supplementation, where the animals survived for a short period. After the administration of the test chemical for 7 weeks the animals were sacrificed by exsanguination and were slaughtered to isolate the femur bones of the animals. The blood was collected at the end of the experiment under the influence of anesthesia to evaluate blood acid status and CO2levels in the blood. Also, values of the minerals were determined. Blood pH was significantly reduced by the test chemical supplementation. Plasma CO2 concentration was also reduced by the test chemical supplementation but the effect was not significant. The supplementation of test chemical did not significantly cause any changes in the levels of calcium and phosphorus in the animals. Also, There were no gross pathological changes observed in the animals due to administration of the test chemical and There were no observed changes in histopathological examination after the administration of the test chemical. From all the observations, The no observed adverse effect level (NOAEL) and the low observed adverse effect level (LOAEL) for the test chemical after the administration for over 9 weeks to Wistar rats was found to be 625 mmol /kg and 937 mmol /kg respectively.  

A study was conducted to identify and evaluate effects of the test chemical on male and female Wistar rats for a period of 7 weeks. In this period, the rats were administered with the test chemical which was given through the oral feed route. The test chemical was mixed with the diet in concentrations of2, 3 or 4 mol/L and dose groups of 280, 420 or 560 mmol /kg.The rats were given a commercial rat diet, either alone (control) or supplemented with HCl at 280, 420 or 560 mmol /kg dry matter (DM). Batches of the diet were prepared by pouring 140 ml of either 2, 3 or 4 mol /l solutions of HCl for the acid treatments respectively over a kg D.M. of the experimental diet and mixed thoroughly in a food mixer. The control diet was prepared by the addition of a similar amount of distilled water to the basal diet. The rats were given access to the waterad libitum.The control animals were fed with animal diets mixed with distilled water. The rats were observed for body weight gain and feed consumption throughout the study. It was observed thatthere was no treatment related significant effect on the weight gain of the animals at any dose groups. Also, there was no significant change in the food intake of the animals throughout the test chemical. After the administration of the test chemical for 7 weeks the animals were sacrificed by exsanguination and were slaughtered to isolate the femur bones of the animals. The blood was collected at the end of the experiment under the influence of anesthesia to evaluate blood acid status, CO2 levels in the blood and hematocrit and hemoglobin values. Also, values of the minerals were determined. There were no significant changes in the hematocrit and hemoglobin values of the animals, the CO2 levels in the plasma were found to be normal and the blood pH was unchanged after the treatment of the test chemical. The mineral values of calcium, phosphorus, sodium and potassium were also found to be normal after 7 weeks of the treatment. Also, There were no gross pathological changes observed in the animals due to administration of the test chemical and There were no observed changes in histopathological examination after the administration of the test chemical. From all the observations, the No observed adverse effect level (NOAEL) for the test chemical after the administration for over 7 weeks is considered to be 560 mmol /kg when the test chemical was administered orally.

Based on the data available, the no observed adverse effect level (NOAEL) for the test chemical is considered to be 625 mmol /kg.

Repeated dose toxicity: Inhalation

Data available for the test chemicals was reviewed to determine the toxic nature of the test chemical. The studies are as mentioned below:

Repeated dose inhalation toxicity study was performed to determine the toxic nature of the test chemical. Groups of 10 female animals were exposed for 6 h per day to target concentrations of 0, 0.2, 1.0 or 5.0 mg m−3 sulphuric acid for 5 days a week for 28 days. Recovery groups of five females were exposed to 0 or 5.0 mg/m3 for 28 days and retained without further treatment for either 4 or 8 weeks to monitor recovery. Prior to the start of the study, all rats were examined to ensure that they were physically normal and exhibited normal activity. During exposure they were observed frequently, and at the end of the daily exposure period each rat was examined. Detailed clinical observations were recorded daily immediately prior to exposure. During the recovery period the animals were checked daily and detailed observations were recorded weekly, recording any changes in clinical condition or behaviour. The bodyweight of each rat was recorded before the first exposure, once a week thereafter and prior to termination. Test atmospheres with target concentrations of 0.2, 1.0 and 5.0 mg m−3 analysed sulphuric acid were generated using a glass concentric jet atomizer to generate the atmospheres into two reservoir chambers (each fitted with a cyclone), one serving the exposure chambers for groups exposed to 0.2 and 1.0 mg m−3 and another serving exposure chambers for groups exposed to 5.0 mg m−3 . Clean, dry air (dried and filtered using equipment supplied by Atlas-Copco, Sweden) was passed through the atomizer to carry the atmosphere to each of the reservoir chambers and subsequently, after appropriate dilution, to the exposure chambers (internal volume = 36.8 l). Air flows were monitored and recorded frequently using variablearea flowmeters and were altered as necessary to maintain the target concentrations and maintain a minimum of 12 air changes per hour. Humidified dilution air was also added, where appropriate, to maintain a humidity as close as possible to 50% inside the chambers. There were no effects on bodyweight or lung weight in any group at any time point, and no adverse clinical symptoms were seen due to the exposure apart from minor effects seen commonly due to the restraint used for noseonly exposure, e.g. wet fur, snout stains. There were no macroscopic abnormalities in any of the animals at the scheduled termination times. Squamous metaplasia in the ventral epithelium at level 1 was evident and again was concentration-related in severity. Following exposure to 5.52 mg m−3 sulphuric acid, this effect was evident in some animals at level 2, lateral to the ventral pouch Parakeratosis was also seen in some animals at this level of the larynx. Following exposure to 0.30 mg m−3 sulphuric acid, some animals (6/10) showed minimal squamous metaplasia at level 1. After 4 weeks of recovery, animals exposed to 5.52 mg m−3 test chemical showed evidence of squamous epithelial metaplasia at level 1 of the larynx. This lesion was less severe following 4 weeks of recovery than it was at the end of the 28-day exposure period, but there were no signs of further resolution after 8 weeks of recovery. There were no exposure-related changes in labelling index in either the terminal bronchioles or central acinar alveoli of the lung or any of the levels of the nasal cavity at either time point examined: reduction in tritiated thymidine uptake in the olfactory epithelium at level 5 following exposure to 0.30 mg m−3 sulphuric acid for 28 days was the only statistically significant group mean difference from control values; the lack of dose response suggests that this was not biologically relevant. Comparison of BrdU and tritiated thymidine labelling in the larynx showed that the magnitude of increase in labelling compared with controls was greater when autoradiography of tritiated thymidine-labelled tissue was used. Following exposure to 1.38 and 5.52 mg m−3, a treatment- and dose-related increase in cell proliferation was seen in the ventral epithelium at level 1 of the larynx after both 5 and 28 days of exposure, although the increases were larger at the earlier time point . No increases in cell proliferation were seen at level 2 or 3 after 5 or 28 days of exposure. No increases in cell proliferation were seen at any level in the larynx following both 5 and 28 days of exposure to 0.3 mg m−3 test chemical. Exposure of rats for up to 28 days to 1.38 and 5.52 mg/m3 sulphuric acid aerosols resulted in no effect in the nasal passages or lungs and squamous metaplasia in a limited region of the larynx. Hence the no observed adverse effect concentration is considered to be 5.52 mg/m3.

Repeated dose inhalation toxicity study was performed to determine the toxic nature of the test chemical. The study was performed using male and female Crl:CD(SD)Br rats. The test chemical was studies at dose level of 0, 10, 20, 50 ppm (0, 15, 30, 75 mg/m3) for 91 days. The animals were exposed to the test chemical 6 hours/day, 5 days/week. Each animal was observed at least twice daily for incidence of mortality and clinical signs. Body weight and food consumption were individually measured once a week. Urine samples collected from 10 male and 10 female animals were analyzed. Blood samples collected from orbital sinus were measured for the parameters for hematology. Serum samples collected from abdominal aorta were measured for blood biochemistry. Each animal was pathologically examined at necropsy and histopathology was performed. One female of the highest dose group found dead on the 4th day of the treatment. Slight and transient decrease in food consumption was observed in 10 ppm female, which was not considered to be dose related, and 50ppm male. Minimal to mild rhinitis was observed in the anterior portion of the nasal cavity at the histopathological observation above 20 ppm. No biologically significant difference was observed in urinalysis, hematology and serum chemistry. Based on the observations made, the no observed effect concentration (NOAEC) for the test chemical is considered to be 30mg/m3 when male and female rats were exposed to the test chemical in a subchronic toxicity study.

Based on the observations made, the no observed adverse effect concentration (NOAEC) is considered to be 5.52 mg/m3 when rodents were exposed to the test chemical.

Repeated dose toxcity: Dermal

This end point was considered for waiver considering that chlorosulphuric acid is an extremely strong acid with the pH less than 1. Thus, it shall always be handled with due precaution. The use of safety apparatus like hand gloves, goggles, etc is a common practice while handling concentrated acids in the industries. Thus, repeated exposure by the dermal route is highly unlikely due to which this end point was considered for waiver.

Based on the data available and applying the weight of evidence approach, the test chemical is not likley to be toxic upon repeated exposure by oral, dermal and inhalation route of exposure.

Justification for classification or non-classification

Based on the data available and applying the weight of evidence approach, the test chemical is not likley to be toxic upon repeated exposure by oral, dermal and inhalation route of exposure.