N-butyltin trichloride

Endpoint summary

Description of key information

Acute Oral Toxicity

The oral LD50 for the test material in rats is reported as 2.2 g/kg bw, confidence limits (1.9-2.7 g/kg bw). However, the volumes of dosage administration were large (up to 4 mL/100 g). Hence, LD50 should be reported as >2 g/kg bw (>2000 mg/kg bw).

Acute Inhalation and dermal toxicity studies

The test material is corrosive and therefore exposure of animals via inhalation or the dermal route to the high concentrations as required for an acute inhalation or dermal study is expected to cause severe pain and distress. For animal welfare reasons, no studies are required.

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:

Not stated

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Remarks:

Restrictions: The dose volumes were excessive for dose levels greater than 2.0 g/kg. The 2.8 g/kg dose level was administered at a volume of 2.8 mL/100 g and the 4.0 g/kg dose level was administered at a volume of 4.0 mL/100 g. The maximum acceptable volume of a water carrier is 2.0 mL/kg. The high dose volumes may have contributed to observed effects and mortality. All dose volumes below the limit dose (2.0 g/kg) are acceptable. The LD50 should then be expressed as >2000 mg/kg bw, not as reported in the study (2.2 g/kg bw; 95% confidence limits 1.9-2.7 g/kg bw).

Qualifier:

no guideline followed

Principles of method if other than guideline:

Single oral dose administered to the test animals which were then observed for 12 days.

GLP compliance:

not specified

Test type:

standard acute method

Limit test:

yes

Species:

rat

Strain:

Wistar

Sex:

male/female

Details on test animals or test system and environmental conditions:

- Initial body weight: 80-115 g
- Room temp./rel. humidity: 21-23 °C / 55-65 %
- Animals housed in: Type II macrolide cage, grated bottom, 1 animal/cage
- Feed: Altromin R, ad libitum
- Water: Tap water, ad libitum
- Acclimation: for 10  days

Route of administration:

oral: unspecified

Vehicle:

water

Details on oral exposure:

- Formulation: Emulsion
- Concentration: 10 g in 100 mL
- Denial of feed before application: 22 h
- Time of application: 10:30 am
- Period of observation after administration: 12 days

Doses:

6 doses - 0.5, 1.0, 1.4, 2.0, 2.8, and 4.0 g/kg

No. of animals per sex per dose:

5 animals per sex per dose group
total = 60 rats (30 M, 30 F)

Control animals:

no

Details on study design:

-Groups of 10 rats (Wistar SPF; 5 males/5 females) were acclimated for 10  days, then exposed to six nominal dose levels of the test material: 0.5, 1.0, 1.4, 2.0, 2.8, and 4.0 g/kg bw. 
-The test material was delivered orally as a volume/volume emulsion in  distilled water. Dose volumes ranged from 0.5 mL to 4.0 mL/100 g bw. Rats were fasted for ~22 hours prior to dosing. Following dosage, rats were provided commercial feed (e.g., Altromin R) and water ad libitum. 
-Animals were individually caged and maintained at a temperature of 21-23 °C and relative humidity of 55-65%. Animals were observed daily for signs of systemic toxicity and mortality over a 12-day observation  period, and were necropsied following death or the end of the observation period (whichever was longer).

Statistics:

LD50 values calculated using the Litchfield and Wilcoxon method (1949)

Key result

Sex:

male/female

Dose descriptor:

LD50

Effect level:

> 2 000 mg/kg bw

Based on:

test mat.

Mortality:

- There was no mortality at the following doses: 0.5, 1.0, and 2.0 g/kg bw.
- 10% mortality was observed at the 1.4 g/kg dose, 70% at 2.8 g/kg, and 100% at the highest dose of 4.0 g/kg bw. Animals died 1-10 days after dose administration.

MORTALITY (number of dead/number of animals tested):
0.5 g/kg bw: Males, 0/5; Females, 0/5
1.0 g/kg bw: Males, 0/5; Females, 0/5
1.4 g/kg bw: Males, 0/5; Females, 1/5 (@ Day 10)
2.0 g/kg bw: Males, 0/5; Females, 0/5
2.8 g/kg bw: Males, 3/5; Females, 4/5
4.0 g/kg bw: Males, 5/5; Females, 5/5
Animals in the 2.8 and 4.0 g/kg bw dose groups died 24-48 hours following dosing.

Clinical signs:

other: Apathy was reported as a typical clinical sign after administration. Signs of systemic toxicity were observed at >= the 1.4 g/kg bw dose level  and included apathy, cachexia, and mortality.  

Gross pathology:

- Animals that died: Bleeding and erosion in the gastrointestinal tract, bleeding in the pancreas, focal necrosis in the liver, kidneys, and pancreas, bloody infiltration of the mesenteric lymph nodes.
- Observations on gross necropsy included hyperemia, emphysema and lung lesions, hemorrhagic  erosion/high grade bleeding of the mucosal (stomach) glands, swelling and bloody infiltration of mesenteric lymph nodes, extensive intestinal and pancreatic bleeding, and necrosis in liver and kidneys. No abnormalities were recorded for males in the 1.0, 1.4, and 2.0 g/kg bw dose levels and only one abnormality (medium grade testicular atrophy) in  the 0.5 g/kg dose. No abnormalities were recorded for females in the 0.5, 1.0, and 2.0 g/kg bw dose levels and only one abnormality (wine-red  mucus in stomach/small intestine) in the 1.4 g/kg dose.
- Animals that were sacrificed at the end of the observation period: Unremarkable findings

Interpretation of results:

other: Not classified in accordance with EU criteria

Conclusions:

The oral LD50 for the test material in rats is reported as 2.2 g/kg bw, confidence limits (1.9-2.7 g/kg bw). However, the volumes of dosage administration were large (up to 4 mL/100 g). Hence, LD50 should be reported as >2 g/kg bw (>2000 mg/kg bw).

Executive summary:

A study was conducted in male and female Wistar rats to investigate the oral LD50 for the test material.

The animals were administered the test material orally as a 10 % emulsion in distilled water. Six doses were used: 0.5, 1.0, 1.4, 2.0, 2.8, and 4.0 g/kg body weight. After treatment the animals were observed for 12 days for clinical signs and mortality. Necropsy of all animals were performed at death or at the end of the observation period.

The method of Litchfield and Wilcoxon was used to calculate the LD50 which was reported as 2.2 g/kg body weight. The confidence limits were reported as 1.9 -2.7 g/kg body weight. Necropsy findings in animals that died were reported as bleeding and erosion in the gastrointestinal tract, bleeding in the pancreas, focal necrosis in the liver, kidney, and pancreas, and bloody infiltration of the mesenteric lymph nodes. Lethality appears to be the result of portal-of-entry corrosive effects rather than intrisic acute toxicity. The necropsy findings in the animals that survived the 12-day observation period were reported as unremarkable.

The oral LD50 for the test material in rats is reported as 2.2 g/kg bw, confidence limits (1.9-2.7 g/kg bw). However, the volumes of dosage administration were large (up to 4 mL/100 g). Hence, LD50 should be reported as >2 g/kg bw (>2000 mg/kg bw).

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

LD50

Value:

2 000 mg/kg bw

Acute toxicity: via inhalation route

Link to relevant study records

Reference

Endpoint:

acute toxicity: inhalation

Data waiving:

study scientifically not necessary / other information available

Justification for data waiving:

the study does not need to be conducted because the substance is classified as corrosive to the skin

Justification for type of information:

JUSTIFICATION FOR DATA WAIVING
In accordance with column 2 or REACH Annex VIII, information requirement 8.5 (acute toxicity), the study/ies do(es) not generally need to be conducted if the substance is classified as skin corrosion. The substance is classified as corrosive to skin and so it is considered justified to omit the acute inhalation toxicity study.

Endpoint conclusion

Endpoint conclusion:

no study available

Acute toxicity: via dermal route

Link to relevant study records

Reference

Endpoint:

acute toxicity: dermal

Data waiving:

study technically not feasible

Justification for data waiving:

the study does not need to be conducted because the substance is classified as corrosive to the skin

Justification for type of information:

In accordance with column 2 or REACH Annex VIII, information requirement 8.5 (acute toxicity), the study/ies do(es) not generally need to be conducted if the substance is classified as skin corrosion. The substance is classified as corrosive to skin and so it is considered justified to omit the acute dermal toxicity study.

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

Acute Toxicity: oral

Six studies are available on the acute oral toxicity of the substance. In addition, there is an in vivo micronucleus study that is also considered here. Vehicles used and the results from the available studies are summarised in the table below.

Report	Species	Vehicle	LD50	Klimisch score
Anon 1969	Rat	10% emulsion in water	>2000	2
Blaszcak 1986	Rat	None	250	2
Pelikan & Cerny 1970	Mouse	Oleum helianthi (sunflower oil)	1400	4
Mesch & Kugele. 1992	Rat	No information	2300	4
Walterson et al 1994	Rat	No information	2140	4
Walterson et al 1994	Mouse	No information	1400	4
Schafer & Bowles 1985	Mouse	feed	1240	4
Dance 1991 MN test*	Mouse	Corn oil	>250 <500	1

* DRF doses of 500, 1000 and 2000 mg/kg resulted in death of 3/4, 2/4 and 4/4 animals respectively. No death at 250 mg/kg

 

With the exception of Dance 1991 mouse micronucleus (MN) study, all mouse studies have been assigned Klimisch 4 on the basis of insufficient information to allow full assessment of the reliability of the data.

 

Fasted animals were dosed in all studies, except in Dance 1991 micronucleus test and thus a direct comparison between this study and the acute toxicity studies is not possible. No macroscopic/necropsy findings are reported in Dance 1991 so possible causes of death cannot be ascertained, however, all deaths/terminations occurred within 24 hours of dose administration, with one animal dosed at 2000 mg/kg found dead within 4 hours of dosing. This study provides no additional information with respect to acute toxicity, although the rapid demise of the animals would suggest portal-of-entry effects. Information from the two reliable acute toxicity studies in rats confirms that lethality is the result of portal-of-entry effects, rather than intrinsic acute toxicity.

 

According to REACh and CLP, the rat is the preferred species for acute oral and inhalation toxicity. Among all data on acute oral toxicity, Klimisch scores of 2 are assigned to two studies (i.e., Anonymous 1969 and Blaszcak DL 1986); only for these studies are complete descriptions of materials and methods, as well as detailed results available to allow accurate assessment of their reliability. Out of the two Klimisch 2 studies, Anon, 1969 is selected as the key study as more dose levels were tested in Anonymous 1969, and a larger, appropriate number of animals were used per group. It is therefore considered that Anon, 1969 is more powerful and therefore the key study for determining whether classification for acute toxicity would be required.

A summary of the available data on the acute oral toxicity of the substance is presented below.

Key Study (Anon., 1969)

A study was conducted in male and female Wistar rats to investigate the oral LD50 for the test material.

Groups of 5 male and 5 female rats were administered the test material orally as a 10 % emulsion in distilled water. Six doses were used: 0.5, 1.0, 1.4, 2.0, 2.8, and 4.0 g/kg body weight. After treatment the animals were observed for 12 days for clinical signs and mortality. Necropsy of all animals were performed at death or at the end of the observation period.

The method of Litchfield and Wilcoxon was used to calculate the LD50 which was reported as 2.2 g/kg body weight. The confidence limits were reported as 1.9 -2.7 g/kg body weight. Necropsy findings in animals that died were reported as bleeding and erosion in the gastrointestinal tract, bleeding in the pancreas, focal necrosis in the liver, kidney, and pancreas, and bloody infiltration of the mesenteric lymph nodes. The necropsy findings in the animals that survived the 12-day observation period were reported as unremarkable.

The oral LD50 for the test material in rats is reported as 2.2 g/kg bw, confidence limits (1.9-2.7 g/kg bw). However, the volumes of dosage administration were large (up to 4 mL/100 g). Hence, LD50 should be reported as >2 g/kg bw (> 2000 mg/kg bw).

The study was assigned a reliability score of 2 as it was well documented and generally meets scientific principles being very similar to OECD 401. It was conducted prior to GLP and is considered acceptable for assessment.

Supporting Study (Blaszcak, 1986)

An acute oral toxicity to rat study was carried out with the test material. Three doses were tested (single dose; 250, 500 and 1000 mg/kg) in groups of 2 male and 2 female rats, fasted for 18 hours before treatment, and observed over a 14-day observation period after administration. Animals in all dose groups exhibited clinical signs and most lost weight either before death or at 7 or 14 days. Mortalities were observed in all groups, with necropsy findings suggestive of irritant/corrosive effects in the stomach and intestine.

The LD50 was 250 mg/kg in male and female rats.

The study was assigned a reliability score of 2 as it was well documented and generally meets scientific principles being very similar to OECD 401. It is considered acceptable for assessment, however, the report does not specify if the study was conducted under GLP conditions and only 2 animals per sex per dose were dosed.

Evaluation of the results of Anon, 1969 and Blaszcak, 1986

The 10-fold difference of the LD50 values reported in rats in Anonymous 1969 and Blaszcak DL 1986 is due to the fact that no vehicle was used in the second study, and animals were fasted for longer than in in the first study. Necropsy data from both studies show that all mortalities were clearly due to massive corrosive effects, even more marked when the substance was given undiluted. Lethality is, therefore, the result of portal-of-entry effects, rather than intrinsic acute toxicity.

Disregarded Study (Pelikan & Cerny, 1970)

An acute toxicity range-finding study was conducted using 9 doses of the test material administered by gavage, ranging from 200 to 6000 mg/kg bw, and two control groups of white mice (5/sex/dose).

After 48 hours, the LD50 of the test material was reported as 1400 mg/kg bw (95% confidence limits: 780-2335 mg/kg bw). To better understand effects at acute doses, a single oral dose (4000 mg/kg) was investigated in white mice. Clinical signs were observed starting at 12 hours and by 24 hours, the animals were not responding to light or sound stimuli, were lying down, with laboured respiration, and cyanosis at the extremities. All surviving animals were terminated 24 hours after dosing. Gross findings of hyperaemia was observed in the stomach, liver, and spleen, and minor changes in the kidneys. Histological examination revealed haemorrhages in the stomach and intestine.

Under the conditions of the preliminary range-finding study, the LD50 of the test material is 1400 mg/kg bw (95% confidence limits: 780-2335 mg/kg bw).

The study was assigned a reliability score of 4 as the study documentation is insufficient for assessment and the LD50 was calculated based on mortalities recorded up to 48 h only, and no further information, or detailed results, are available. It is therefore considered the study results cannot be used for classification purposes.

Disregarded Study (Mesch & Kugele, 1992)

The test material was nontoxic by the oral route of administration. No details regarding method available. Authors state that these data were "readily available" but did not cite the source, which could be scientific publication, report or gray literature.

The oral LD50 for the test material was reported as 2300 mg/kg in rats, which indicates very low to minimal acute toxicity.

The study was assigned a reliability score of 4 as the study documentation is insufficient for assessment. No details are provided on the test methods, GLP status of the study, test animals, method of administration, doses used, clinical findings, mortality, or gross pathology. It is therefore considered the study results cannot be used for classification purposes.

Disregarded Study (Walterson et al, 1994)

Walterson et al., in Volume 1 of the KEMI Report on mono and di-substituted organotins used as plastic additives, report the oral LD50 of the test material in rats as 150 -270 mg Sn/kg bw (or 357 -642 mg/kg bw of test material). Nordenhall et al., in Volume 2 of the same report, state the oral LD50 values of the test material in mice and rats as 1400 and 2140 mg/kg bw, respectively.

The study was assigned a reliability score of 4 as the study documentation is insufficient for assessment. No details are provided on the test methods, GLP status of the study, test animals, method of administration, doses used, clinical findings, mortality, or gross pathology. It is therefore considered the study results cannot be used for classification purposes.

Disregarded Study (Schafer & Bowles, 1985)

In a repellency food reduction test, deer mice (n=5) were individually fed 25 white wheat seeds treated with 2 % test material (in water, corn oil or 1 % coropol) along with lab rodent pellets and water ad libitum for 3 days. The amount of test material during the food reduction test which killed (or did not kill) 50 % of the test mice (LDfr) was calculated to be 1240 mg/kg-day (for 3 days). In another repellency food reduction test, house mice (n=10) were individually fed 25 white wheat seeds also treated with 2 % test material for 5 days. The percentage of mice refusing to eat more than 50 % of treated seeds (REP) was 60 %.

The study was assigned a reliability score of 4 as the study documentation is insufficient for assessment. Limited information on methods and materials is reported. No details are provided on the clinical findings, mortality, or gross pathology. It is therefore considered the study results cannot be used for classification purposes.

Justification for classification or non-classification

In accordance with the criteria for classification as defined in Annex I, Regulation (EC) No 1272/2008, the substance does not require classification with respect to acute oral toxicity.

Classification for acute oral toxicity would be misleading and not protective of human health. The substance is already and properly classified as Category 1 for both skin corrosion and eye damage.