Registration Dossier

Administrative data

Description of key information

The LD50 values derived from the key studies were:
- LD50 (oral, rat) 305 mg/kg bw
- LC50 (inhalation, rat, 4 hour) > 5.88 mg/m³
- LD50 (dermal, rat) > 2000 mg/kg bw

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:
1987
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Guideline study conducted in accordance with GLP. However, no data on test substance purity were given.
Principles of method if other than guideline:
A study was performed to determine the acute oral median lethal dose (LD50) of the test material, administered as a solution in distilled water, in the Sprague-Dawley CFY strain rat. The method used followed that described in the OECO Guidelines forTesting of Chemicals (1981) No.
401 "Acute Oral Toxicity". Four groups, each of ten fasted animals (five males and five females), were given a single oral dose of test material preparation at dose levels of 250 to 2000 mg/kg bodyweight. Animals were observed for 14 days.
GLP compliance:
yes
Test type:
standard acute method
Limit test:
yes
Species:
rat
Strain:
Sprague-Dawley
Sex:
male/female
Details on test animals and environmental conditions:
Males, weight at study initiation: 100 - 144 g
Females, weight at study initiation: 97 - 148 g
All animals were about 5 to 8 weeks old.
Twenty-.four male and twenty-four female Sprague-Dawley CFY strain rats were supplied by Interfauna (UK) Limited, Wyton, Huntingdon, Cambridgeshire.
Acclimatisation period: five days.
The animals were housed in groups of up to five by sex in solid-floor polypropylene cages with sawdust bedding. With the exception of an overnight
fast immediately before dosing and for approximately two hours after dosing, free access to mains drinking water and food (Rat and Mouse Expanded Diet No. 1, Special Diet Services Limited, Witham, Essex, U.K.) was allowed throughout the study.
The animal room was maintained at a temperature of 19 - 23°C and relative humidity of 60 - 70%. The rate of air exchange was approximately 15
changes per hour and the lighting was controlled by a time switch to give 12 hours light and 12 hours darkness.
Route of administration:
oral: gavage
Vehicle:
water
Details on oral exposure:
Observation period: 14 days.
Doses:
Limit test: 2000 mg/kg bw
Range finding test: 100, 250, 500, and 1000 mg/kg bw
Main test: 250, 500, 1000, and 2000 mg/kg bw
Administered Volume: 10 ml/kg bw
No. of animals per sex per dose:
Limit test: 5 males + 5 females.
Range finding test: 1 male + 1 female.
Main test: 5 males + 5 females.
Control animals:
no
Details on study design:
The 2000 mg/kg bw was tested alone within a limit test, prior to the range finding test. The test substance was applied as single dose by gavage, using distilled water as vehicle; the administration volume was 10 ml/ kg bw. Following treatment, the animals were regularly examined for mortality and clinical signs of toxicity over an observation period of 14 days; body weights were recorded at test starting and during the observation period. All rats that died during the observation period as well as the surviving rats, which were sacrificed at the end of the observation period, were subjected to necropsy.
Statistics:
The LD50 and the 95% confidence limits were calculated by means of the method of Weil CS (Tables for convenient calculation of median-effective dose (LD50 or ED50) and instructions in their use. Biometrics 8: 249 - 263, 1952).
Sex:
male/female
Dose descriptor:
LD50
Effect level:
305 mg/kg bw
95% CL:
>= 167 - <= 556
Sex:
male
Dose descriptor:
LD50
Effect level:
273 mg/kg bw
95% CL:
>= 142 - <= 522
Sex:
female
Dose descriptor:
LD50
Effect level:
354 mg/kg bw
95% CL:
>= 127 - <= 981
Mortality:
Limit test: death occured
Range finding test: 1000 mg/kg bw: 2/2; 500 mg/kg bw: 1/2; 250 mg/kg bw: 0/2; 100 mg/kg bw: 0/2.
Main Test:
250 mg/kg: male: 1/5 dead after 1 hour; female: 1/5 dead after 1 hour and 1/5 dead after 2 hours.
500 mg/kg: male: 3/5 dead after 1 hour, 1/5 after 2 hours, and 1/5 after 1 day; female: 1/5 dead after 1 hour and 1/5 dead after 2 hours.
1000 mg/kg: male/female: 4/5 dead after 1 hour, 1/5 dead after 4 hours
2000 mg/kg: male: 3/5 dead after 1 hour, 2/5 after 4 hours; female: 2/5 dead after 1 hour and 3/5 dead after 4 hours.
see table 1 in section Remarks on results.
Clinical signs:
Common abnormalities noted in both decedents and surviving animals, one and four hours after dosing, were hunched posture, pilo-erection,
lethargy and decreased respiratory rate. Occasional of isolated signs of noisy respiration, ataxia, ptosis, pallor of the extremities and coma were also noted during this period. All surviving animais were normal two or three days after dosing except one female treated with 500 mg/kg which continued to show hunched posture and pilo-erection up to eleven days after treatment. This animal also showed uncontrolled
side to side and up and down head movement three to five days after dosing. This animal recovered and appeared normal twelve days after
dosing. One low dose male also showed signs of toxicity four to nine days after dosing but was normal on day ten (see details table 2).
Body weight:
A small number of surviving animals showed reduced bodyweight gain
over the first week; all surviving animals showed expected gains in
bodyweight over the second week.
Gross pathology:
Common abnormalities noted at necropsy of decedents were dark livers and kidneys, severe haemorrhage or ulceration of the gastric mucosa
and haemorrhage of the small and large intestines. Abnormally red lungs were noted at necropsy of decedents treated with dose levels of
500 mg/kg or greater. Dark spleens and sloughing of the non-glandular region of the stomach were also noted at necropsy of animals treated with 2000 mg/kg.

Table 1: Mortality of male and female animals in the main test of the study:

Dose level

Death

mg/kg

male

female

total

250

1/5

2/5

3/10

500

5/5

2/5

7/10

 1000  5/5 5/5  10/10   
 2000  5/5 5/5  10/10   

Table 2: Clinical signs and observations after dosing of animals with bronopol:

 Dose level (mg/kg)  Clinical observation Number showing effects during day of dosing (hour)          Number showing effects during day of observation                 
     1  4  1 8 -14 
 250 Hunched posture   8
   Pilo-erection  8
   Lethargy  8
   Decreased respiratory rate  8
   Noisy respiration  1
   Ataxia  1
   Pallor of the extremities  0
   Distended abdomen  0 1
   Comatose  1
   No abnormalities detected  0 6/7 
 500 Hunched posture   5
   Pilo-erection  5
   Lethargy  5
   Decreased respiratory rate  5
   Ataxia  2
   Ptosis  2
   Comatose  1
   Uncontrolled head movements  0
   No abnormalities detected  0 2/3 
 1000 Hunched posture   2  
   Pilo-erection  2  
   Lethargy  2  
   Decreased respiratory rate  2  
   Ataxia  2  
   Ptosis  2  
 2000 Hunched posture   3  1  
   Pilo-erection  3  1  
   Lethargy  3  1  
   Decreased respiratory rate  3  1  
   Ataxia  3 1  
   Pallor of the extremities  3 1  
   Ptosis  1 1  
   Comatose  2 1  
Endpoint conclusion
Endpoint conclusion:
adverse effect observed
Dose descriptor:
LD50
305 mg/kg bw
Quality of whole database:
The key study was selected.

Acute toxicity: via inhalation route

Link to relevant study records
Reference
Endpoint:
acute toxicity: inhalation
Type of information:
experimental study
Adequacy of study:
key study
Study period:
1986
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: No guideline was mentioned. It was not specified whether the study did follow GLP. The study was however well-documented and of scientific acceptability.
Principles of method if other than guideline:
No guideline given.
GLP compliance:
not specified
Remarks:
not specified
Species:
rat
Strain:
Sprague-Dawley
Sex:
male/female
Details on test animals and environmental conditions:
Animals source: Charles River (UK) Ltd., Margate
Weight range for both, males and females: 180 – 200 g
Age: about 6 to 8 weeks
The chamber temperature and the relative humidity for the control and the treated groups ranged between 15 and 19 °C and between 30 to 89%. The air flow rate was 15 litres/min. for the control group and between 13 to 18 litres/min. for the treated groups. The oxygen concentrations were within the range of 21 to 22 % for all groups.
Route of administration:
inhalation: aerosol
Type of inhalation exposure:
nose/head only
Vehicle:
other: filtered air
Duration of exposure:
4 h
Concentrations:
Analytical concentrations: 0, 0.038, 0.089, 0.588 mg/l
Nominal concentrations: 0, 1.80, 2.59, 23.23 mg/l
No. of animals per sex per dose:
5
Control animals:
yes
Details on study design:
The test was conducted with 3 test groups and one control group. Each test group (defined as group 2, 3 and 4) comprised 5 male and 5 female Sprague-Dawley rats. For test atmosphere preparation and in order to get an adequate preparation in terms of particle size and respirability, the test substance was milled by means of an ultracentrifugal mill prior to use. The test atmospheres were then prepared in a Perspex chamber (capacity: ca. 10 litres) by means of a Wright duct feed generator. The test substance was conducted continuously into the chamber with filtered air at flow rate of 13 - 18 litres/min; the air flow rate was monitored and recorded at 30 minute-intervals. The nominal test concentrations were 0, 1.80, 2.59, 23.23 mg/l; the corresponding measured concentrations were 0, 0.038, 0.089 and 0.588 mg/l. The animals were nose-head exposed to the test atmosphere for a period of 4 hours; the control animals received filtered air without test substance. The rats were observed hourly during the exposure and once a day over the observation period of 14 days for mortality and clinical signs of toxicity. Body weight was assessed prior test initiation, at the end of the 4 hour-exposure, once daily between day 1 and 7 of observation, on day 14 and prior sacrifice. Animals that died were subjected to gross pathological examination as well as histopathology. The surviving rats were sacrificed at the end of the observation period and were also subjected to gross pathology and histopathology. Particular attention was given to the nasal passages, the cranial cavity and the respiratory tract. Lungs, bronchi, trachea and nasal passages were examined; lungs, liver, kidney and skin samples from 2 animals were fixed in 10% neutral buffered formalin for the purpose of histopathological examination.
Sex:
male/female
Dose descriptor:
LC50
Effect level:
>= 0.588 mg/L air
Exp. duration:
4 h
Mortality:
Of the high dose group (0.588 mg/l) one male animal was found dead on the day following exposure; and 2 more animals (one male and one female) were killed for humane reasons because they suffered from inflammation of the eyes. The authors attribute the deaths of 3 animals at this level only to the local irritancy of bronopol. No deaths occurred in the control groups or at concentrations of 0.038 or 0.089 mg/l.
Clinical signs:
High dose group (0.588 mg/l): nasal discharge, red staining from the eyes, staining of the head and inflammation of the eyes was observed on the day of exposure in most animals, sometimes accompanied by swelling of the head, throat and/or forepaws. These signs were consistent with local irritation after direct contact with the test article. They generally had disappeared by the 3rd day. In some animals staining of the head reappeared at the end of the observation period. Marked stains persisted in one animal throughout the observation period and was accompanied by sores, fissuring and desquamation of the skin of the head during the second week. Remaining groups (0.038 or 0.089 mg/l): hunched posture or piloerection were seen in 6/10 animals in the intermediate dose group on the day of the treatment. No effects were seen in the 0.038 mg/l group. Various other incidental signs such as nasal secretion, red staining from the eyes, wetting of the fur and staining of the head were observed in control, low and intermediate dose groups either on the day of the treatment or the day after.These minor changes were attributed to the restraint procedure used for the animals.
Body weight:
Small body weight losses were observed for both control and treated animals. Almost all animals had returned to their pre-exposure body weight by day 4 of the observation period, and body weight gains were normal thereafter. The initial body weight losses were similar in treated and control groups and were attributed to the restraint procedure and not to the exposure to bronopol.
Gross pathology:
There were no treatment-related gross or histopathological findings in the kidneys, livers or lungs of the high dose level group animals. Local dermatitis and ulceration were seen in 2 high dose animals and were attributed to dermal exposure, but not to inhalation.
Other findings:
All the mean mass median diameters indicated that the test atmosphere was respirable. In fact, the reported mean values were 1.31, 1.99 and 6.66 µm respectively for the 0.038, the 0.089 and the 0.588 mg/L groups.

The NOEC was about 0.038 mg/L.

The ratio between measured and nominal test concentrations indicated a low efficiency in the generation of the test aerosol. However, the authors indicated that such a low efficiency is not unusual for aerosol generation from powder using the Wright dust feed generator and mainly is due to losses within the chamber.

Endpoint conclusion
Endpoint conclusion:
adverse effect observed
Dose descriptor:
discriminating conc.
588 mg/m³
Quality of whole database:
The key study was selected. Adverse effects are based on local irritation effects due to inhalation (aerosol).
LC50 (4 hr) > 588 mg/m³
NOEC (4 hr) > 38 mg/m³

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:
2000
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Guideline study conducted in accordance with GLP.
Qualifier:
according to
Guideline:
OECD Guideline 402 (Acute Dermal Toxicity)
GLP compliance:
yes
Test type:
fixed dose procedure
Limit test:
yes
Species:
rat
Strain:
Wistar
Sex:
male/female
Details on test animals and environmental conditions:
Young adult animals
(male animals approx. 8 - 16 weeks
female animals approx. 9 - 16 weeks)
Animal weights at start of Animals of comparable weight (200 g - 300 g ± 20% of the the study: mean weight)
Source: Charles River Laboratories, Sulzfeld, Germany
Type of coverage:
semiocclusive
Vehicle:
other: Tylose CB 30.000
Details on dermal exposure:
The test substance was prepared in 0.5% aqueous Tylose® and was applied to a skin area of about 50 cm2 (10% of body surface) under semi occlusive conditions for 24 hours.The test substance concentration in the vehicle was 80g/100 ml (w/v) and the application volume was 2.5 ml/kg
Duration of exposure:
24 hours
Doses:
2000 mg/kg bw
No. of animals per sex per dose:
5
Control animals:
no
Details on study design:
Five male and five female Wistar rats were treated with 2000 mg/kg bw test substance.The test substance was prepared in 0.5% aqueous Tylose® and was applied to a skin area of about 50 cm2 under semi-occlusive conditions for 24 hours.The test substance concentration in the vehicle was 80g/100 ml (w/v) and the application volume was 2.5 ml/kg. After 24 hours of exposure the treated skin was cleaned with water. The animals were checked for mortality twice each working day and once on Saturday, Sundays or holidays. They were observed for clinical symptoms of toxicity several times on the day of treatment and once daily thereafter. Body weights were recorded prior test start, weekly thereafter, and at the end of the observation period. The skin was examined 30 to 60 minutes following removal of the dressing, weekly thereafter, and at the end of the observation period. All rats that died and the surviving rats at the end of the study (18 days observation period) were subjected to necropsy and examined for gross pathology.Analytical determinations of the test substance preparation with respect to stability in the vehicle were performed prior to starting the toxicological study.
The assessment of skin findings was based on Draize JH (Appraisal of the safety of chemicals in food, drugs and cosmetics. The association of food and drug officials of the United States Austin, Texas, 1959).
Statistics:
Binomial test according to SNEDECOR GW (“Statistical methods”, 8th ed., Iowa State University Press/Ames, 1989).
Sex:
male/female
Dose descriptor:
LD50
Effect level:
> 2 000 mg/kg bw
Mortality:
No mortality occurred
Clinical signs:
The animals of both sexes displayed poor general state, dyspnoea and apathy as clinical symptoms; these symptoms lasted until day 1 of observation.Local effects at the application sites were seen in both, males and females and included white discoloration of the skin, erythema, edema, eczematoid skin change, scaling and crust formation.These effects lasted until the end of the observation period.
Body weight:
Body weights were inconspicuous.
Sex BW on Day 0 BW on Day 7 BW on Day 13
Males 246 g 247 g 263 g
Females 220 g 219 g 221 g
Gross pathology:
Excepted for incrustation and full thickness necrosis seen at the application site in 4/5 males and 5/5 females, pathological examination at necropsy revealed no further abnormalities.
Endpoint conclusion
Endpoint conclusion:
adverse effect observed
Dose descriptor:
discriminating dose
2 000 mg/kg bw
Quality of whole database:
The key study was selected. As LD50 value >2000 mg/kg was determined.

Additional information

Acute toxicity: oral
In a single dose study (Safepharm Laboratories Limited, 1987) the acute oral median lethal dose (LD50) of Bronopol was estimated by oral gavage in rat: Five male and five female Sprague-Dawley rats per test group were administered following doses of Bronopol: 250, 500, 1000 and 2000 mg/kg bw; the doses were selected on the basis of the results of a range-finding study conducted prior to the main test.
The 2000 mg/kg bw was tested alone within a limit test, prior to the range-finding test.The test substance was applied as single dose by gavage, using distilled water as vehicle; the administration volume was 10 mL/kg bw.

Following treatment, the animals were regularly examined for mortality and clinical signs of toxicity over an observation period of 14 days; body weights were recorded at test starting and during the observation period. All rats that died during the observation period as well as the surviving rats, which were sacrificed at the end of the observation period, were subjected to necropsy. The LD50 and the 95% confidence limits were calculated by means of the method of Weil (1952).

Mortality in the 250 and the 500 mg/kg bw group was 30 and 70%, respectively. At both highest tested doses of 1000 and 2000 mg/kg bw, mortality was 100%. Clinical symptoms indicative of toxicity were seen in all groups during the first hours following treatment and mainly included hunched posture, piloerection, lethargy and decrease in respiratory rate. Excepted for one male suffering from hunched posture, piloerection, lethargy and decreased respiratory rate from day 4 to day 9 of observation, all survivors of the 250 mg/kg bw group were free from symptoms from day 2 of observation. In the 500 mg/kg bw group, one surviving female displayed hunched posture and piloerection up to day 11 of observation; this animal furthermore showed uncontrolled head movements from day 3 to day 5. A small number of surviving animals showed reduced body weight gain over the first week; body weight gain over the second week of observation was as expected. Necropsy of the animals that died during the observation period revealed dark liver and kidneys, severe haemorrhage or ulceration of the gastric mucosa and haemorrhage of the small and large intestines. The dead animals of the 500, 1000 and 2000 mg/kg bw groups additionally showed abnormally red lungs, and those of the 2000 mg/kg be group had dark spleens and sloughing of the non-glandular stomach region.

Oral administration of Bronopol to male rats resulted in a LD50 value of 273 mg/kg bw and to female rats in a LD50 value of 374 mg/kg bw. Finally, a mean LD50 value of 305 mg/kg bw was proposed.

The study method used followed that described in the OECO Guidelines for Testing of Chemicals (1981) No. 401 "Acute Oral Toxicity". Thus, this study is classified as acceptable (key study).

Furthermore, in a study (Boots Pharmaceuticals, 1992/TX92163) groups of ten male and ten female Boots-Wistar rats were given single oral doses of Bronopol at 200, 280, 390, 550 or 770 mg/kg/bw, as a solution in distilled water. The rats were observed for a seven-day period. Most of the decedents and, at the end of the study, the survivors given 280 mg/kg/bw or more and subsequently killed, were dissected and examined macroscopically. No gross abnormalities were observed at necropsy of decendents or animals sacrificed at the end of the study. Oral administration of Bronopol to male rats resulted in a LD50 value of 307 mg/kg bw and to female rats in a LD50 value of 342 mg/kg bw. At the time the study was conducted (1972) GLP was not compulsory.

In an acute oral toxicity study groups of ten male Boots-Wistar rats were given single oral doses of Bronopol at 36, 54, 80, 120, 180, 270, 400 or 600 mg/kg bw, as a suspension in 0.4 % aqueous cellosize solution (Boots Company, 1988). The rats were observed for up to ten days after treatment. Decedents, and all rats given 80 mg/kg or more and killed at the end of the study, were dissected and examined post mortem. The oral administration of Bronopol to male rats resulted in a LD50 value of 254 mg/kg bw bw with a 95 % confidence interval of 177 to 431 mg/kg bw. At the time the study was conducted (1970) GLP was not compulsory. The study is classifed as acceptable (key study). This study is reported also in another study report (Boots Pharmaceuticals, 1992/TX92160) and represents an addendum of a further study (Sutton, 1970).

Based on a supporting study in mice (Shaw, 1972), after oral administration of Bronopol signs of toxicity appeared soon after dosing and were encountered at all doses (250, 300, 360, 430 or 520 mg/kg bw) in both males and female. The majority of mice died within 19 hours of dosing but there were some deaths up to 6 days later. At autopsy, ulceration of the stomach or duodenum, thickening of the intestinal wall, adhesions of the stomach to the liver and lesions on the liver surface were observed. The liver lesions appeared to be secondary reactions to the gastrointestinal damage. The oral LD50 to male mice was 374 mg/kg bw and to female mice 327 mg/kg bw.

Reference: Weil CS (1952) Tables for convenient calculation of median-effective dose (LD50 or ED50) and instructions in their use Biometrics 8: 249-265.

 

Acute toxicity: inhalation

Bronopol was tested for its acute inhalation toxicity in rats (Hazleton Laboratories Europe Ltd, 1986). The test was conducted with 3 test groups and one control group. Each test group comprised 5 male and 5 female Sprague-Dawley rats.

The test substance was milled before the test atmospheres were prepared. The test substance was conducted continuously into the chamber with filtered air at flow rate of 13–18 L/min; the air flow rate was monitored and recorded at 30 minute-intervals. The nominal test concentrations were 0, 1.80, 2.59, 23.23 mg/L; the corresponding measured concentrations were 0, 0.038, 0.089 and 0.588 mg/L.

The animals were nose-head exposed to the test atmosphere for a period of 4 hours; the control animals received filtered air without test substance. The rats were observed hourly during the exposure and once a day over the observation period of 14 days for mortality and clinical signs of toxicity. Body weight was assessed prior test initiation, at the end of the 4-hour-exposure, once daily between day 1 and 7 of observation, on day 14 and prior sacrifice. Animals that died were subjected to gross pathological examination as well as histopathology. The surviving rats were sacrificed at the end of the observation period and were also subjected to gross pathology and histopathology. Particular attention was given to the nasal passages, the cranial cavity and the respiratory tract. Lungs, bronchi, trachea and nasal passages were examined; lungs, liver, kidney and skin samples from 2 animals were fixed in 10% neutral buffered formalin for the purpose of histopathological examination.

The chamber temperature and the relative humidity for the control and the treated groups ranged between 15 to 19 °C and between 30 to 89 %. The air flow rate was 15 L/min for the control group and between 13 to 18 L/min for the treated groups. The oxygen concentrations were within the range of 21 to 22 % for all groups.

One male rat of the 0.588 mg/L group died whereas two further animals of the same test group (one male and one female) were sacrificed for humane reasons as they suffered from inflammation of the eyes. All animals of the remaining groups survived.Nearly all animals of the 0.588 mg/L group suffered from nasal discharge, red staining and inflammation of the eyes and staining of the head; sometimes accompanied by a swelling of the head, throat and/or the forepaws.These effects were consistent with local irritation of those areas, which came in direct contact with the test substance. These symptoms mainly were seen on the day of exposure and disappeared within 3 days; in some case, staining of the head reappeared at the end of the observation period. In one case (female of the 0.588 mg/L group) the marked staining persisted throughout the whole observation period and was accompanied by sores, fissuring and desquamation of the head skin during the second week of observation. In the 0.089 mg/L group, symptoms of toxicity included hunched posture and piloerection, which were seen in 6 of 10 animals. No symptoms were seen in the 0.038 mg/L group. Body weights showed no treatment-related effects.

Excepted for local dermatitis and ulceration of skin in two rats of the 0.588 mg/L group, which were attributed to direct dermal contact with the test substance rather than to its inhalation, no treatment-related effects were reported.

All the mean mass median aerodynamic diameters indicated that the test atmosphere was respirable. In fact, the reported mean values were 1.31, 1.99 and 6.66 µm, respectively for the 0.038, the 0.089 and the 0.588 mg/L groups.Conclusively, the LC50 was >0.588 mg/L and the NOEC was 0.038 mg/L.

In this acute inhalation toxicity study no guideline was mentioned; it was not specified whether the study followed GLP or not. Nevertheless, it is classified as acceptable (key study) because it is well-documented and of scientific acceptability.

 

Acute toxicity: dermal

In an acute dermal toxicity study (BASF AG, 2000), five male and five female Wistar rats were exposed to Bronopol. The test substance was applied as a suspension using 0.5% Tylose CB 30.000 in bidistilled aqua as vehicle and was used at a concentration of 80 g/100 mL vehicle. The administered volume was 2.5 mL/kg bw, corresponding to a dosage of 2000 mg/kg bw.

Animals were checked for mortality and were observed for clinical symptoms of toxicity. Body weights were recorded prior test start, weekly thereafter, and at the end of the observation period. The skin was examined 30 to 60 minutes following removal of the dressing, weekly thereafter, and at the end of the observation period. The assessment of skin findings was based on Draize JH (1959).

At the end of the observation period (about 14 days), the animals were sacrificed for the purpose of necropsy and were subjected to gross pathological examination.

No mortality occurred. Animals showed clinical symptoms of toxicity, which included poor general state, dyspnoea and apathy. These symptoms affected both, males and females, and lasted until day 1 of observation. Local effects at the application sites were seen in both, males and females and included white discoloration of the skin, erythema, oedema, eczematoid skin change, scaling and crust formation. These effects lasted until the end of the observation period. Body weights were inconspicuous. The skin of the application site showed incrustation and full thickness necrosis in 4/5 males and 5/5 females. No further abnormalities were seen.

No lethal effect was seen at the tested dose of 2000 mg/kg bw. Conclusively, the LD50 (males+females) was determined as >2000 mg/kg bw.

This GLP-conform study is classified as acceptable (key study), since it satisfies the guideline requirement for an acute dermal study according to OECD 402.

Reference: Draize JH (1959). Appraisal of the safety of chemicals in food, drugs and cosmetics. The association of food and drug officials of the United States Austin, Texas

Two supporting studies with methodological deficiencies are available for the test substance and arenamed for the sake of completeness.


Justification for selection of acute toxicity – oral endpoint
Key study: Reliable GLP-conform study according to GL OECD 401 (Safepharm Laboratories Limited, 1987).
Further key studies provide results within an acceptable range (Boots Pharmaceuticals, 1992; Boots Pharmaceuticals UK, 1992).

Justification for selection of acute toxicity – inhalation endpoint
Key study: No guideline was mentioned. It was not specified whether the study did follow GLP. The study was however well-documented and of scientific acceptability (Hazleton Laboratories Europe Ltd, 1986). Other studies show methodological deficiences (Huntingdon Research Centre, 1971) or tested product possessed only a small portion of the test substance (PSL, 1999).

Justification for selection of acute toxicity – dermal endpoint
Key study: Guideline study conducted in accordance with GLP (BASF AG, 2000).

Justification for classification or non-classification

Based on the results of the oral acute toxicity study, Bronopol is classified as Xn, R22 (harmful if swallowed) according to the criteria of Directive 67/548/EEC and as Cat. 4, H302 (harmful if swallowed) according to Regulation (EC) No 1272/2008 (self-classification).

Based on the results of the inhalation acute toxicity study, Bronopol is not subject for classification according to Regulation (EC) No 1272/2008.

Following the GHS criteria for specific target organ toxicity (single exposure) the test substance is classified as STOT SE 3 (respiratory irritant effects) according Regulation (EC) No 1272/2008.

 

Based on the results of the dermal acute toxicity study, Bronopol is not subject for classification according to the criteria of EU Directive 67/548/EEC and according to Regulation (EC) No 1272/2008.

 

In agreement with the key study-based self classification, Bronopol is currently classified as Xn, R22 (harmful if swallowed) according to the criteria of Directive 67/548/EEC and as Cat. 4, H302 (harmful if swallowed) according to Regulation (EC) No 1272/2008. Furthermore, it is currently classified as Xn, R21 (harmful in contact with skin) according to the criteria of EU Directive 67/548/EEC and as Cat. 4, H312 (harmful in contact with skin) according to Regulation (EC) No 1272/2008.