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EC number: 231-100-4
CAS number: 7439-92-1
Inorganic lead compounds do not exhibit toxicity in acute toxicity tests
with experimental animals.
The acute oral toxicity of "LITHARGE lead oxide was investigated
according to ATC method in one step using 3 male and 3 female rats.
Three female animals were given a single oral administration of the test
article Litharge lead oxide at a dose of 2000 mg/kg. Clinical
observations were carried out at regular intervals during the 14-day
observation period. Body weights were determined immediately before
treatment and on 7 days and 14 p.a. Gross pathological examinations were
carried out immediately at termination on all animals.
The following results were obtained:
-No animals died during the course of the 14-day observation period
following the dose of 2000 mg/kg.
-No abnormal clinical signs were observed
-There was no influence of the treatment on the body weight development
in all male and female animals during the 14-day observation period.
-Gross pathological examinations on day 14 p.a. did not reveal test
According to the EEC Directive 2001/59, 6 August 2001 and the
Gefahrstoffverordnung (GefStoffV) of 15 November 1999 (BGB1. I, p.2233),
the test article LITHARGE lead oxide can be classified as "non-toxic",
since the oral LD50 value after 24 h and 14 days is expected to be
higher than 2000 mg/kg in male and female Wistar rats.
The aim of the present experiment was to obtain information on the acute
toxicity following single 4 -hour inhalation exposure of rats to
Litharge (Lead Oxide) in an acute toxicity study designed as a test
limit. Rats were exposed to a dust of Litharge (Lead oxide) at an actual
concentration of 5.05 +/-0.010mg Litharge/L air for 4 hours by
inhalation using a dynamic nose-only exposure chamber. In the inhalation
chamber, close to the animals' noses, the particles had a mass median
aerodynamic (MMAD) of 5.834UM as determined with a cascade impactor. The
Geometric Standard Deviation (GSD) of the MMAD was calculated as 4.814.
The geometric mean diameter of the supplied test item was 11.430 um as
determined with a Malvern Mastersizer. Under the present test
conditions, a 4-hour exposure to a dust of Litharge (lead oxide at a
concentration of 5.05 +/-0.10 mg Litharge/L air revealed no clinical
signs of toxicity. No mortality occurred. No abnormalities were detected
at necropsy. All animals gained the expected weight throughout the study
period. The LC50 can be expected above an actual concentration of 5.05
mg Litharge/L air for 4 hours at 14 days. According to the EC-Commission
directive 67/548/ECC and its subsequent amendments on the approximation
of the laws, regulations, and administrative provision relating to the
classification, packaging and labelling of dangerous substances and the
results obtained under the present test conditions. Litharge (Lead
oxide) requires no classification under CLP.
On the basis of the results obtained after a single dermal
administration of the test article "LITHARGE lead oxide" to Wistar rats,
the LD50 values after 24 h and 14 days were as follows: Male and female
> 2000 mg/kg
The acute dermal toxicity of LITHARGE lead oxide was investigated in one
group of rats comprising 5 males and 5 females. On the basis of the
range finding test, the animals were given a single dermal
administration of LITHARGE lead oxide at the dose of 2000 mg/kg. The
skin was exposed to the test articles for 24 hours. Clinical
observations were carried out at regular intervals during the 14 -day
observation period. Signs of erythema and oedema were evaluated once
daily for 14 days. Body weights were determoned immediately before
treatment and on days 7 and 14 p.a. Gross pathological examinations were
carried out at study termination on all animals. The following results
- No animal died during the 14 -day observation period.
- No abnormal clinical signs were observed.
- No signs of or skin iiritation were observed.
- The body weight development was slightly influenced in most animals
during the first week after treatment, possibly due to the
administration procedure as such. At the end of the study, 14 days after
treatment, the body weights were in the normal range
-Gross pathological examinations on day 14 p.a. did not reveal any
findings in the rats.
Since no deaths were caused in Wistar rats after dermal treatment with
the test article LITHARGE lead oxide of 2000mg/kg, the LD50 values after
24h and 14 days were as follows: Male and Female >2000 mg/kg
The above value is higher than the limit specified as harmful by the EEC
Directive 2001/59/EEC of 6 August 2001 and the Gefahstoffverordnung
(GedStoffV) of 15 November 1999 (BGB1.I, p. 2233). When administered by
the dermal route, the test article LITHARGE lead oxide may therefore be
classified as "non-toxic".
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.
The current classification of lead compounds not otherwise described in
Annex VI to CLP is:
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 this substance is low and does not
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