Tetraamminepalladium(2+) dihydroxide

Endpoint summary

Description of key information

No relevant acute toxicity data were identified for tetraamminepalladium dihydroxide. As a health precautionary approach, read-across from the structurally-related compound tetraamminepalladium hydrogen carbonate was considered appropriate in order to inform the potential toxicity and classification for tetraamminepalladium dihydroxide.

In an OECD guideline study, the acute oral LD50 of tetraamminepalladium hydrogen carbonate in female rats was reported to be 933 mg/kg bw (Allen, 1995).

Tetraamminepalladium hydrogen carbonate is closely related to tetraamminepalladium dihydroxide and is considered a suitable surrogate for read-across for this endpoint.

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:

No data

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: OECD guideline study. However, potential deviations could not be fully assessed as the study report appears to have some pages omitted. On closely-related surrogate.

Qualifier:

according to guideline

Guideline:

OECD Guideline 401 (Acute Oral Toxicity)

Deviations:

not specified

Qualifier:

according to guideline

Guideline:

EU Method B.1 (Acute Toxicity (Oral))

Deviations:

not specified

GLP compliance:

not specified

Test type:

standard acute method

Limit test:

no

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: no data
- Age at study initiation: no data
- Weight at study initiation: no data
- Fasting period before study: animals were fasted, but no details on duration of fasting period
- Housing: no data
- 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: no data

Route of administration:

oral: unspecified

Vehicle:

arachis oil

Details on oral exposure:

VEHICLE
- Concentration in vehicle: no data
- Amount of vehicle (if gavage): no data
- Justification for choice of vehicle: no data
- Lot/batch no. (if required): no data
- Purity: no data

MAXIMUM DOSE VOLUME APPLIED: no data

DOSAGE PREPARATION (if unusual): no data

Doses:

0.5, 1 and 2 g/kg bw

No. of animals per sex per dose:

Five females/dose, a group of 5 males also treated at 2 g/kg bw

Control animals:

no

Details on study design:

- Duration of observation period following administration: 14 days
- Frequency of observations and weighing: observed 30 minutes, 1, 2, 4 hours, and then daily and weighed at day 0, 7 and 14.
- Necropsy of survivors performed: yes
- Other examinations performed: clinical signs

Statistics:

Acute oral median lethal dose (LD50) and 95% confidence limits of the test material were calculated by the method of Thompson W.R.

Preliminary study:

In the range finding study, one male and one female received 2 g/kg bw. The male was found dead two days after dosing, the female had no signs of systemic toxicity at day 5 after dosing. Hunched posture, lethargy and pilo-erection were seen in both animals, and ptosis and occasional body tremours were also noted in the male.

Sex:

female

Dose descriptor:

LD50

Effect level:

933 mg/kg bw

Based on:

test mat.

95% CL:

664 - 1 310

Mortality:

In the main study, all 5 male and 5 female rats receiving 2 g/kg bw died by day 3, whilst 3 of 5 females died at 1 g/kg bw on days 4 to 6. No deaths were seen in the females receiving 0.5 g/kg bw.

Clinical signs:

other: Hunched posture, lethargy, decreased respiratory rate, laboured respiration and emaciation were commonly noted in all dose groups during the study. Pilo-erection and ptosis were noted in animals dosed with 1 g/kg bw and above. Ataxia was seen in females d

Gross pathology:

Haemorrhagic or abnormally red lungs, dark liver, dark or pale kidneys, gaseous distention of the stomach, dark, hardened or thickened gastric mucosa and haemorrhage of the small intestine were noted at necropsy of animals that died during the study. Sloughing of the non-glandular epithelium of the stomach with a raised limiting edge were noted in females receiving 0.5 and 1 g/kg bw killed at the end of the study period. Two female rats were found cannibalised, therefore necropsy was noted performed.

Interpretation of results:

Category 4 based on GHS criteria

Conclusions:

In an OECD guideline study, the acute oral LD50 of tetraamminepalladium hydrogen carbonate in the female rat was reported to be 933 mg/kg bw .

Executive summary:

The acute oral toxicity of tetraamminepalladium hydrogen carbonate was assessed in rats, in a study conducted according to OECD Test Guideline 401.

In the range finding study, one male and one female rat received a single dose of 2000 mg /kg bw by oral gavage. The male was found dead two days after dosing whereas the female had no signs of systemic toxicity at day 5.

Therefore, in the main study, groups of 5 females were administered 500, 1000 or 2000 mg/kg bw of the test material and a group of 5 male rats received 2000 mg/kg bw. All 10 rats receiving 2000 mg/kg bw died by day 3 of the observation period, whilst 3 of 5 females receiving 1000 mg/kg bw died on days 4 to 6. No deaths were seen in the low dose females, following the 14-day observation period. The study authors conclude that the acute oral median lethal dose (LD50) of the test material in females rats is 933 mg/kg bw. “No significant difference in toxicity was noted between male and female animals”.

Based on the results of this study, tetraamminepalladium hydrogen carbonate should be classified for acute oral toxicity (category 4) according to EU CLP criteria (EU 1272/2008).

Tetraamminepalladium hydrogen carbonate is closely related to tetraamminepalladium dihydroxide, and is considered a suitable surrogate for read-across for this endpoint. The proposed read-across is appropriate because it is expected that the target and source substances undergo biotransformation to a common product. In solution, the hydrogen carbonate and hydroxide anions are expected to dissociate from the tetraamminepalladium cation; thus, this can be regarded as the common product and toxicologically-active species of both salts. The hydroxide and hydrogen carbonate counterions would not have an impact on the overall acute toxicity of the target or source substance, respectively. Therefore, it is considered that use of in vivo acute oral toxicity data obtained in a test on tetraamminepalladium hydrogen carbonate to fill a gap in the standard information requirements for tetraamminepalladium dihydroxide is scientifically justified and suitably reliable.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

LD50

Value:

933 mg/kg bw

Acute toxicity: via inhalation route

Endpoint conclusion

Endpoint conclusion:

no study available

Acute toxicity: via dermal route

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

The acute oral toxicity of tetraamminepalladium hydrogen carbonate was assessed in rats, in a study conducted according to OECD Test Guideline 401. In the range finding study, one male and one female rat received a single dose of 2000 mg/kg bw by oral gavage. The male was found dead two days after dosing whereas the female had no signs of systemic toxicity at day 5. Therefore, in the main study, groups of 5 females were administered 500, 1000 or 2000 mg/kg bw of the test material and a group of 5 male rats received 2000 mg/kg bw. All 10 rats receiving 2000 mg/kg bw died by day 3 of the observation period, whilst 3 of 5 females receiving 1000 mg/kg bw died on days 4 to 6. No deaths were seen in the low dose females, following the 14-day observation period. The study authors conclude that the acute oral median lethal dose (LD50) of the test material in female rats is 933 mg/kg bw. “No significant difference in toxicity was noted between male and female animals” (Allen, 1995).

 

Tetraamminepalladium hydrogen carbonate is closely related to tetraamminepalladium dihydroxide, and is considered a suitable surrogate for read-across for this endpoint. The proposed read-across is appropriate because it is expected that the target and source substances undergo biotransformation to a common product. In solution, the hydrogen carbonate and hydroxide anions are expected to dissociate from the tetraamminepalladium cation; thus, this can be regarded as the common product and toxicologically-active species of both salts. The hydroxide and hydrogen carbonate counterions would not have an impact on the overall acute toxicity of the target or source substance, respectively. Therefore, it is considered that use of in vivo acute oral toxicity data obtained in a test on tetraamminepalladium hydrogen carbonate to fill a gap in the standard information requirements for tetraamminepalladium dihydroxide is scientifically justified and suitably reliable.

Justification for selection of acute toxicity – oral endpoint
OECD guideline study, with limitations, and the only acute oral toxicity study available.

Justification for classification or non-classification

Based on the results of the available and reliable acute oral rat study with tetraamminepalladium hydrogen carbonate, tetraamminepalladium dihydroxide should also be classified for acute oral toxicity (category 4) according to EU CLP criteria (EC 1272/2008).

 

No clear evidence of specific target organ toxicity was noted. As such, classification for STOT-SE is not considered appropriate.