Registration Dossier

Administrative data

Description of key information

Inorganic lead compounds do not exhit toxicity in acute toxicity tests with experimental animals.

Key value for chemical safety assessment

Acute toxicity: via oral route

Endpoint conclusion
Dose descriptor:
LD50

Acute toxicity: via inhalation route

Endpoint conclusion
Dose descriptor:
LC50

Acute toxicity: via dermal route

Endpoint conclusion
Dose descriptor:
LD50

Additional information

Although lead can exert toxic effects upon multiple organ systems and body functions, this toxicity manifests under conditions of sub-chronic to chronic exposure that can range from months to years in duration. Acute toxicity is not observed in animals after oral, inhalation or dermal lead oxide exposures up to the limit values of acute toxicity testing. For oral and dermal exposures, data demonstrating lack of lead oxide toxicity are available for doses of 2000 mg/kg/bw or higher. No adverse effects of inhalation are observed up to 5 mg/L lead oxide in air. The validity of these findings is reinforced by lack of acute oral and dermal toxicity for several other inorganic lead compounds similar in chemistry and solubility. Finally, toxicity in humans after true acute exposures is limited and, when documented, is generally under conditions that yield sub-chronic or chronic exposures. This finding is not unexpected given the pharmacokinetics of lead uptake into the body. Lead uptake is generally quite low and heavily reliant upon easily saturable active transport mechanisms. Once saturation of these uptake mechanisms has occurred, uptake proceeds by inefficient passive diffusion. The uptake of lead is thus highly non-linear as a function of dose with uptake efficiency declining with the amount of lead administered to a test animal or an exposed human. Although toxic under chronic exposure situations, the acute toxicity of lead oxide is low.

Justification for classification or non-classification

The current classification of lead compounds not otherwise described in Annex I is:

Xn; R20/22 (harmful by inhalation and if swallowed)

and under CLP:

Acute Tox. 4 *                       (H332)

Acute Tox. 4 *                       (H302)

Existing classifications for acute toxicity are not supported by the existing data or read across. Acute toxicity is not observed in animals after oral, inhalation or dermal exposures, up to the limit values of acute toxicity testing, for lead oxide. Acute toxicity is not observed in animals after oral exposures up to the limit values of acute toxicity testing for six different similar inorganic lead compounds.  Two similar compounds are also lacking in dermal toxicity and in irritancy properties for the skin or eyes. Although toxic under chronic exposure situations, the acute toxicity of lead oxide is predicted to be quite low and does not require classification.