Lead dinitrate

Endpoint summary

Description of key information

Lead dinitrate does not exhibit toxicity in acute toxicity tests with experimental animals. No test results were required for acute toxicity via the inhalation and dermal route because only 0.03% of the lead dinitrate particles are within the inhalable size limits (<10 µm) and therefore an acute inhalation test is not required (see IUCLID section 4.5 for discussion of the complete dustiness test) and because Pb shows a low skin absorption, respectively. 

Key value for chemical safety assessment

Acute toxicity: via oral route

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

LD50

Value:

2 000 mg/kg bw

Quality of whole database:

Klimisch 1 and Klimisch 2 studies.

Acute toxicity: via inhalation route

Endpoint conclusion

Endpoint conclusion:

no study available

Acute toxicity: via dermal route

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

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 lead dinitrate exposures up to the limit values of acute toxicity testing (2000 mg/kg bw). Inhalation and dermal exposure of lead dinitrate were considered not relevant because of the absence of particles within the inhalable size range.

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 selection of acute toxicity – oral endpoint
No one study is selected because there are several Klimisch 2 studies.

Justification for selection of acute toxicity – dermal endpoint
No one study is selected because there are three Klimisch 2 studies conducted with read across substances.

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)

Acute toxicity is not observed in animals after oral exposures up to the limit values of acute toxicity testing for a similar lead salt, i.e. lead acetate. However lead dinitrate is classified as Acute Tox. Cat. 4 (H302) according to the official classification for lead compounds in regulation (EC) 1272/2008, which is a worst-case, precautionary approach.

Only 0.03% of the lead dinitrate particles are within the inhalable size limits (<10 µm) and therefore an acute inhalation test is not required. However, the official lead compounds classification is for the inhalation route Acute Tox. Cat. 4 (H332)

Since lead has a low skin absorption (Moore et al., 1980), testing by the dermal route is inappropriate (see waiver IUCLID section 7.2.3). Lead dinitrate is therefore not classified for Acute Tox. Cat. 4 dermal route.