Toluenesulphonamide

Endpoint summary

Description of key information

o/p-TSA is of low acute toxicity. Acute oral LD50 is 2400 mg/kgbw and dermal toxicity much lower.

Key value for chemical safety assessment

Acute toxicity: via oral route

Link to relevant study records

Reference

Endpoint:

acute toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Study period:

14 April 1986 - 06 May 1986

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Study performed under GLP and according to internationally accepted guidelines.

Qualifier:

according to guideline

Guideline:

OECD Guideline 401 (Acute Oral Toxicity)

GLP compliance:

yes

Test type:

standard acute method

Limit test:

no

Species:

rat

Strain:

Wistar

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Iffa-Credo, Brussels, Belgium
- Age at study initiation: no data, young.
- Weight at study initiation: The body weights of the males on day 0 ranged from 354 to 435 those of the females from 225 to 273 g.
- Fasting period before study: Feed was withheld overnight before dosing till approximately 4 hours after administration of the test substance.
- Housing: Four days prior to dosing the animals were individually housed in polycarbonate cages.
- Diet (e.g. ad libitum): ad libitum, standard laboratory animal diet (RMH-By pellet diameter 10 mm), which was obtained from Hope Farms, Woerden, The Netherlands.
- Water (e.g. ad libitum): ad libitum, tap-water
- Acclimation period: 7 days


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20-23
- Humidity (%): 40-80
- Air changes (per hr): no data
- Photoperiod (hrs dark / hrs light): 12/12


IN-LIFE DATES: 14 April 1986 - 06 May 1986

Route of administration:

oral: gavage

Vehicle:

corn oil

Details on oral exposure:

VEHICLE
- Concentration in vehicle: details not provided
- Amount of vehicle (if gavage): Fixed volume for all concentrations in ml/kg; does not exceed 10 ml/kg
- Justification for choice of vehicle: details not provided
- Lot/batch no. (if required): details not provided
- Purity: details not provided

MAXIMUM DOSE VOLUME APPLIED: does not exceed 10 ml/kg

DOSAGE PREPARATION (if unusual): no data

Doses:

1800, 2100, 2400 mg/kg bw day

No. of animals per sex per dose:

5

Control animals:

yes

Details on study design:

- Duration of observation period following administration: 14 days
- Frequency of observations and weighing: The animals are observed for a period of 14 days, i .e. every two hours on the day of administration of the test substance and once every day thereafter. Individual body weights of the animals are determined on the day of dosing, weekly thereafter and at death.
- Necropsy of survivors performed: yes
- Other examinations performed: none

Statistics:

The LD50 value, where possible a seperate value for males and females, is calculated from the observed mortality data, using any established statistical procedure, e.g. that of Litchfield and Wilcoxon (l949), Weil (1952) or Finney (1971).

Preliminary study:

Based on literature data on the LD50 values of the separate components of the test substance and the LD50 value of a related substance as provided
by the sponsor, three dose levels were selected: 1800, 2400 and 3200 mg/kg body weight. However, the highest dose presented a too viscose suspension that could not be adequately administered as one single dose. It was therefore decided to select one dose level in between 1800 and 2400 mg/kg, namely 2100 mg/kg.

Sex:

male/female

Dose descriptor:

LD50

Effect level:

ca. 2 400 mg/kg bw

Mortality:

Only in the high dose group 5 out of 10 animals died. There was no evident sex related effect. One female animal of the mid dose group had received only approximately 25% of its dose due to clogging of the test material in the dosing cannula. However this is not considered to have affected the outcome of this study, since no mortality was found in this treatment group. All deaths occurred within 3 days of dosing.

Clinical signs:

other: Major signs of toxicity were lethargy, unbalanced gait, dyspnea for the mid and low dose groups, and for the high dose group in addition to the afore mentioned symptoms, coma, bloody eye encrustation, absent or bloody stool and slimy salivation. All anima

Gross pathology:

Macroscopic examination of animals found dead generally revealed test substance related petechiae and/or haemorrhages of the stomach frequently combined with bloody intestinal content and marked haematuria. One male of the high dose group revealed an atrofic testis, which was not considered to be test substance related. Macroscopic examination of surviving animals at the end of the study showed no test substance related gross abnormalities.

Mortality:

Sex	Dose (mg/kg)	# deaths	Total # animals	Day 1	Day 2	Day 3	Day 4-15
	1800	0	5	0	0	0	0
M	2100	0	5	0	0	0	0
	2400	2	5	0	1	1	0
	1800	0	5	0	0	0	0
F	2100	0	5	0	0	0	0
	2400	3	5	2	1	0	0

Interpretation of results:

Category 5 based on GHS criteria

Remarks:

Migrated information

Conclusions:

The LD50 value for the sexes combined was estimated to be approximately 2400 mg/kg body weight.

Executive summary:

According to OECD401 and under GLP an acute oral toxicty study was performed with o/p-TSA. Three groups of Wistar rats, each comprising 5 males and 5 females, received a single oral dose of o/p-TSA at 1800, 2100 and 2400 mg/kg body weight, respectively. Only in the high dose group 5 out of 10 animals died. There was no evident sex related effect. All deaths occurred within 3 days of dosing. Major signs of toxicity were lethargy, ataxia and dyspnea for surviving animals, whereas for dead animals also coma was observed. For surviving animals these signs were reversible since as of day 4 no more abnormalities were observed during the 14-day observation period. Macroscopic examination of animal s found dead generally revealed test substance related petechiae and/or haemorrhages of the stomach frequently accompanied by bloody intestinal content and marked haematuria. Macroscopic examination of surviving animals at autopsy revealed no treatment related gross abnormalities. The LD50 value for the sexes combined was estimated to be approximately 2400 mg/kg body weight.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

LD50

Value:

2 400 mg/kg bw

Quality of whole database:

The results are in-line with other available information on both the substance itself as for its components p-TSA and o-TSA.

Acute toxicity: via inhalation route

Endpoint conclusion

Endpoint conclusion:

no study available

Acute toxicity: via dermal route

Link to relevant study records

Reference

Endpoint:

acute toxicity: dermal

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1957

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Limited reporting, none GLP, only one rabbit was dosed per dose level.

Reason / purpose for cross-reference:

reference to same study

Qualifier:

no guideline followed

Principles of method if other than guideline:

6 rabbits were dosed with increasing amounts of test substance applied on the skin and observed for evidence of toxicity

GLP compliance:

no

Test type:

other:

Limit test:

no

Species:

rabbit

Strain:

New Zealand White

Sex:

male/female

Details on test animals or test system and environmental conditions:

BW of rabbits between 1.6 and 2.3 kg

Type of coverage:

not specified

Vehicle:

corn oil

Details on dermal exposure:

A 25% suspension in corn oil was applied to the closely clipped, intact skin of New Zealand rabbits and observations made for evidence of toxicity. The treated areas were covered with plastic shields and a leather collar placed around the neck of each animal to prevent access to the sample.

Duration of exposure:

No data

Doses:

2.0, 3.5, 5.0, 6.0, 7.5 and 7.5 g/kg bw based on tests substance (Highest dose level of 7.5 g/kg was applied to both a male and a female animal)

No. of animals per sex per dose:

1. Only highes dose 2 (one male and one female)

Control animals:

not required

Details on study design:

Examinations included: observations on clinical signs and body weight changes during 5 days.

Sex:

male/female

Dose descriptor:

LD0

Effect level:

7 500 mg/kg bw

Based on:

test mat.

Mortality:

No mortality obsrved

Clinical signs:

other: No signs of systemic toxicity developed. Appetite and activity remained about normal. There was no evidence of paralysis such as developed when rabbits were fed the product orally.

Gross pathology:

Not performed

Animal	sex	BW in kg	Dose g/kg bw	BW change after 5 days	Results
1	Female	1.7	2.0	4.0%	survived
2	Male	2.1	3.5	6.0%	survived
3	Female	1.6	5.0	0.0%	survived
4	Female	1.9	6.0	5.0%	survived
5	Male	2.3	7.5	0.0%	survived
6	Female	2.0	7.5	3.0%	survived

The highest application of 7.5 g/kg bw was non lethal. No signs of systemic toxicity developed. Appetite and activity remained about normal. There was no evidence of paralysis such as developed when rabbits were fed the product orally.

The test article was not acutely toxic when applied to the skin of rabbits.

Interpretation of results:

not classified

Remarks:

Migrated information Criteria used for interpretation of results: EU

Conclusions:

No mortality or systemic toxicity was observed following dermal application of 7500 mg/kg bw of o/p-TSA when applied as a 25% suspension in corn oil.

Executive summary:

A 25% suspension in corn oil was applied to the closely clipped, intact skin of New Zealand rabbits and observations made for evidence of toxicity. The treated areas were covered with plastic shields and a leather collar placed around the neck of each animal to prevent access to the sample.

The following dose levels were applied on one animal each: 2.0, 3.5, 5.0, 6.0, 7.5 (male) and 7.5 (female) g/kg bw. Examinations included: observations on clinical signs and body weight changes during 5 days.

 

The highest application of 7.5 g/kg bw was non lethal. No signs of systemic toxicity developed. Appetite and activity remained about normal. There was no evidence of paralysis such as developed when rabbits were fed the product orally.

The test article was not acutely toxic when applied to the skin of rabbits.

 

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

discriminating dose

Value:

7 500 mg/kg bw

Quality of whole database:

Substance is of low acute oral toxicity, not requiring classification. Also no classification is required for skin or eye irritation. Information on absorption indicates that o/p-TSA is rapidly and completely absorbed by oral route, en only 20% by dermal route. Further acute testing by dermal route is therefore scientifically unjustified.

Additional information

Oral:

There are four studies available evaluating the acute oral toxicity of o/p-TSA:

 

The most reliable study (Notox, 1986) was performed in accordance to OECD 401 and in compliance with GLP. Three groups of Wistar rats, each comprising 5 males and 5 females, received a single oral dose of o/p-TSA at 1800, 2100 and 2400 mg/kg body weight, respectively. Only in the high dose group 5 out of 10 animals died. There was no evident sex related effect. All deaths occurred within 3 days of dosing. Major signs of toxicity were lethargy, ataxia and dyspnoea for surviving animals, whereas for dead animals also coma was observed. For surviving animals these signs were reversible since as of day 4 no more abnormalities were observed during the 14-day observation period. Macroscopic examination of animal s found dead generally revealed test substance related petechiae and/or haemorrhages of the stomach frequently accompanied by bloody intestinal content and marked haematuria. Macroscopic examination of surviving animals at autopsy revealed no treatment related gross abnormalities. The LD50 value for the sexes combined was estimated to be approximately 2400 mg/kg body weight.

 

There are three further studies evaluating the acute oral toxicity of o/p-TSA, but these are of lower validity based on limited reporting and pre-GLP performance:

- TNO, 1978      LD50 rat = 1790 mg/kg bw (95% c.i. 1.56 and 2.05 mg/kg).

- Younger Labs, 1957   LD50 rat = 3800 mg/kg bw (95% c.i. 3600 and 4050 mg/kg).

- Younger Labs, 1957   Minimum lethal dose rabbit 1250 to 1500 mg/kg bw.

 

Additionally, information available from p-TSA (LD50 rat = 2330 mg/kg bw) and o-TSA (LD50 rat = 2920 mg/kg) are well in-line.

 

Dermal:

Data is available from an old study (Younger Labs, 1974). The report is of low validity due to limited reporting, but it indicates that levels of 7500 mg/kg bw of the test substance do not result to mortality when exposed to the skin to two rabbits as a 25% suspension in corn oil. No ssigns of intoxication were reported. The LD50 therefore was concluded to exceed 7500 mg/kgbw.

 

Further support is available from information on dermal absorption: o/p-TSA is of low acute oral toxicity, not requiring classification. Also no classification is required for skin or eye irritation. Information on absorption indicates that o/p-TSA is rapidly and completely absorbed by oral route, but only 20% by dermal route. Further acute testing by dermal route is therefore scientifically unjustified.

 

Inhalation:

vp is 0.00004 Pa at 22°C, and the respirable fraction (≤ 4 µm) of the crystalline solid is < 1%. Additionally, the likelihood of exposures by aerosols from the use of the substance is also low (water solubility is low with 5.1 g/L at 20°C). Although no data is available via inhalation route, similar low toxicity can be expected.

Justification for selection of acute toxicity – oral endpoint
Most reliable study available.

Justification for selection of acute toxicity – inhalation endpoint
In accordance with column 2 of REACH Annex VIII, the test for acute inhalation toxicity (required in section 8.5) does not need to be conducted. Vp is low (0.00004 Pa at 22°C), and the crystalline solid is of low dustiness (the respirable fraction (≤ 4 µm) is <1%). In combination of low likelihood of exposures by aerosols from the use of the substance and the general low acute toxicity, testing of acute toxicity by inhalation is not necessary.

Justification for selection of acute toxicity – dermal endpoint
Only study available.

Justification for classification or non-classification

Available information indicates no toxicity by dermal route, and low oral toxicity with an LD50 of 2400 mg/kg resulting to a GHS classification for acute oral toxicity of Cat.5. In the EU however no classification is needed.

By inhalation route no data is available. Testing is however not indicated in view of the low likelihood of exposures. Similar low toxicity can be expected by all routes.

Consequently no classification for acute toxicity is required for EU CLP.

 

The acute oral studies show effects of neurodepression at near lethal doses. Due to low dermal absorption, and unlikely exposures via inhalation (very low vp, solid with no respirable fraction) and general low exposures, no narcotic effects will occur in humans. Classification for STOT-SE Cat.3 for narcotic effects is therefore not indicated.