Cobalt oxide

Endpoint summary

Description of key information

Acute oral toxicity:
LD50 (rat)= 202 mg cobalt monoxide /kg bw (confidence interval: 136 - 300 mg/kg bw)
Acute dermal toxicity:
Conduct of an acute dermal toxicity study for cobalt oxide is unjustified since dermal uptake is considered negligible.
Acute inhalation toxicity:
LC50 (male and female rats, 4 hours): 0.06 mg/L air

Key value for chemical safety assessment

Acute toxicity: via oral route

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

LD50

Value:

202 mg/kg bw

Acute toxicity: via inhalation route

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

LC50

Value:

60 mg/m³ air

Acute toxicity: via dermal route

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Additional information

Justification for selection of acute toxicity – oral endpoint
Key study

Justification for selection of acute toxicity – inhalation endpoint
Key study

Justification for selection of acute toxicity – dermal endpoint
Weight of evidence information

Justification for classification or non-classification

Acute oral toxicity

The reference Speijers (1982) is considered as the key study for acute oral toxicity and will be used for classification. Female/male rats were dosed at 200, 300, 450, 675 and 1010 mg/kg orally via gavage. During the conduct of the study mortalities occurred, thus the following LD50 value is derived:

LD50 (combined male and female rats): 202 mg cobalt monoxide/kg bw (95 % confidence interval: 136 - 300 mg/kg bw)

The classification criteria according to regulation (EC) 1272/2008 as acutely toxic category 3 are met since the ATE is above 50 mg/kg body-weight and below 300 mg/kg body-weight.Cobalt monoxide will be classified as acutely toxic category 3 (H301).

 

Specific target organ toxicant (STOT) – single exposure: oral

The classification criteria according to regulation (EC) 1272/2008 as specific target organ toxicant (STOT) – single exposure, oral are not met since the toxic effects observed in the acute oral toxicity test already leads to an acute oral toxicity classification. No additional effects in animals or humans are known that would justify a specific target organ toxicant (STOT) – single exposure: oral classification.

 

Acute dermal toxicity

Conduct of an acute dermal toxicity study for cobalt monoxide is unjustified since dermal uptake is considered negligible.

 

Specific target organ toxicant (STOT) – single exposure: dermal

Conduct of an acute dermal toxicity study for cobalt monoxide is unjustified since dermal uptake is considered negligible.

 

Acute inhalation toxicity

The reference Haferkorn (2012) is considered as the key study for acute inhalation toxicity of cobalt oxide and will be used for classification. Male and female rats were exposed to 0.05 to 0.53 mg/L air for 4 hours. All animals died by test day 4 at a concentration of 0.11 and 0.53 mg/L air. One male died at the 0.05 mg/L air dose level. The LC50 is 0.06 mg/L air for males and females combined.

The classification criteria according to regulation (EC) 1272/2008 as acutely toxic were met (0.05 < ATE ≤0.5 mg/L). Cobalt oxide is classified as acutely toxic via inhalation Category 2.

Specific target organ toxicant (STOT) – single exposure: inhalation

The classification criteria according to regulation (EC) 1272/2008 as specific target organ toxicant (STOT) – single exposure, inhalation are not met since the toxic effects observed in the acute toxicity test via inhalation already leads to an acute inhalation toxicity classification. No additional effects in animals or humans are known that would justify a specific target organ toxicant (STOT) – single exposure: inhalation classification.